Dissertations / Theses: 'Ductile cast iron'

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Boeri, Roberto Enrique. "The solidification of ductile cast iron." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30598.

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The microsegregation of Mn, Cu, Cr, Mo, Ni and Si has been measured in cast ductile iron and in ductile iron which has been quenched when partially solidified. Effective segregation coefficients have been determined for each of the elements, and used to calculate the segregation on the basis of the Scheil equation. The calculated values agree reasonably well with the values of the solute concentration as a function of the solid fraction measured in quenched samples. The microstructure of the solid phases during the solidification of ductile iron has been observed. Solidification of eutectic ductile iron begins with the independent nucleation of austenite and graphite in the melt. Later the graphite nodules are enveloped by austenite, and further solidification takes place by the thickening of the austenite layers enveloping the graphite. Isolated pockets of interdendritic melt are the last material to solidify. On the basis of the measured segregation of the different alloying elements, the mechanisms by which the segregation affects the microstructure are considered, and an explanation for the effect of segregation on the hardenability of ductile iron is proposed. A mathematical model of the solidification of eutectic ductile iron is formulated which includes heat flow, nucleation and growth of graphite nodules, and the segregation of Si. The model uses equilibrium temperatures given by the ternary Fe-C-Si equilibrium diagram. Using the mathematical model, cooling curves, nodule count and nodular size distribution are determined as a function of position in the casting sample. The results are compared to measured temperatures, nodule count and nodule size in rod castings of 12.5, 20 and 43mm radius. There is good agreement between the calculated and measured values for the 43mm radius rod, and not quite good agreement for the rods of smaller radii. The changes in solidification predicted by the model when some solidification parameters are varied are consistent with experimental observations with the same variation in the parameters.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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Andersson, Sofia. "Study of Dross in Ductile Cast Iron Main Shafts." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-37148.

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The study of dross in ductile cast iron main shafts was performed at Global Castings Guldsmedshyttan AB and presented in this master thesis. The purpose of the study was to obtain answers to why dross defects were present in some of the foundry's casted main shafts, with the main problem located at the flange of the shaft. The chemical composition of the dross formations and which steps in the casting process that increased the dross formation were of interest. The study only included dross in main shafts manufactured at Global Castings Guldsmedshyttan AB. Dross particles form when elements such as Mg, Ca, Si and Mn react with O. These elements, which are highly reactive to O, are used in ductile cast irons to achieve the spheroidal graphite nodules that regulate the cast materials ductile properties. If a higher amount of dross particles has formed, the particles will start to cluster, resulting in a growing dross formation. Dross formations works as surface crack initiation points and reduces the castings fatigue strength and ductility. During the study it was seen that the cause of dross formations is a combination of many parameters increasing the melts exposure to O resulting in dross defects. The dross formations could be connected to worn out ladles, low melt temperatures, incorrect additions of Mg treatment, lack of an extra slag removal station and finally turbulence as the melt were poured into the mould. At Global Castings Guldsmedshyttan AB a greater part of the main shafts containing dross defects were a result of worn out ladles and low melt temperatures. The types of dross found in the main shaft material were mainly Mg, Ca, Si and Al which had reacted with O. S bonded with Mg and Ca was also detected in the dross formations. It was shown that the dross particles could be derived from charge material, Mg treatment and inoculation. To avoid dross defects the first step would be to set up an extra slag station, shorten the interval of maintenance of the ladles and to better adjust the melt temperature to the condition of the specific ladle. To minimize dross due to excess Mg a better controlled process would be recommended with an increased number of monitored manufacturing parameters.
Studien av dross i axlar tillverkade av segjärn gjordes hos Global Castings Guldsmedshyttan AB och presenteras i denna examensrapport. Syftet med studien var att hitta anledningar till varför drossdefekter bildas i flänsen på vissa av gjuteriets tillverkade axlar. Drossens kemiska komposition likväl de steg i tillverkningsprocessen som inverkade på drossbildning var av intresse. Studien inkluderade endast drossdefekter i axlar tillverkade av Global Castings Guldsmedshyttan AB. Drosspartiklas bildas när till exempel Mg, Ca, Si och Mg reagerar med O. Dessa ämnen, vilka är väldigt reaktiva med syre, används vid framställning av segjärn för att de sfäriska grafitnodulerna som starkt reglerar materialets duktila egenskaper ska bildas. Ett större antal drosspartiklar i en smälta leder till kluster av dross vilka växer i takt med att nya partiklar bildas. Dross fungerar som sprickinitieringspunkter i gjutgodsytor och reducerar godsets utmattningshållfasthet och duktilitet. Under studien kunde det ses att dross bildas på grund av en kombination av parametrar som ökar smältans exponering av syre vilket resulterar i drossdefekter. Drossdefekter kunde kopplas till slitna skänkar, låga smälttemperaturer, felaktig mängd magnesiumbehandling, brist på en extra slaggstation och slutligen turbulens när smätan hälls i formen. Hos Global Castings Guldsmedshyttan AB är en stor del av axlarna med drossdefekter ett resultat av framför allt slitna skänkar och låga smälttemperaturer. Vid analys sågs det att ett antal olika typer av drosspartiklar kan bildas i det duktila gjutjärn som används till axlarna; främst Mg, Ca, Si och Al som reagerat med O. Mg och Ca som bundit med S kunde också hittas i vissa av de studerade drossformationerna. Det kunde visas att den kemiska kompositionen i drosspartiklarna var härrörande från grundmaterialet, magnesiumbehandlingen och ympmedlet. Ett första steg Global Castings Guldsmedshyttan AB skulle kunna ta för att undvika drossdefekter är att ha en extra slaggstation, införa tätare underhåll av skänkarna och bättre anpassa smälttemperaturen till skicket på den specifika skänken. För att minimera dross som bildats på grund av ett överskott av Mg skulle en mer kontrollerad process rekommenderas med ett ökat antal bevakade tillverkningsparametrar.

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Zambrano, Habib. "Fatigue Assessment of Notches and Cracks in Ductile Cast Iron." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produktutvikling og materialer, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14632.

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The steadily increasing use of ductile cast iron and the necessity for building larger cast components present new challenges to the designers. In despite of large cast components are designed adhered to standards, unexpected failure sometime occurs. One reason is the inevitable manufacturing defects containing within the cast components that behave like cracks under cyclic loading. In addition the probability of a large defect to be situated at a critical region of the component increases with the size. Another reason is the effect of geometric discontinuities such as holes, threads and fillets, which are part unavoidable of the designs. These discontinuities that are usually called notches disturb the stress field and cause high local stress concentration. Thus dealing with these severe stress risers (defects and notches) is not an easy task. Therefore most designers resort to use very high and unnecessary safety factors.

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Taivalkoski, Olivia. "Evaluation of material properties after laser welding on ductile cast iron." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254653.

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Scania wants to lower the weight of their trucks, including the goal to reduce the carbon dioxide emissions, and one way to do that is to use laser welding instead of fastenings.This bachelor thesis work is about laser welding of ductile cast iron, or spheroidal graphite cast iron or nodular cast iron, to QT-steels and case hardening steel and evaluation of the mechanical properties of the weld. Also laser welding of cast steel to the same two materials are being evaluated in this work. Tests are done to evaluate the effect on the material from laser welding. The tests are tensile tests and Vickers hardness test; both across and along the weld and in some areas of interest. EDS (Energy Dispersive X-Ray Spectroscopy) is used to analyze the composition in the weld and light optical microscope is used to look at the fusion zone (FZ) and the heat affected zone (HAZ). The results shows that the hardness is high in the heat affected zone due to the formation of martensite and that the materials mix more towards the root of the weld. The materials also mix more if the weld depth is deeper. The width of the heat affected zone seems to be longer if the heat input is higher. It is also clear that welding of cast steel is less complicated than the welding of ductile cast iron. That is because ductile cast iron gets a hard and brittle heat affected zone (HAZ) while the cast steel does not. The cast steel can also be welded without filler wire without getting to hard or to brittle. If laser welding is to be used in the future the component should be constructed in such a way that the fusion zone is not carrying the main load. Tests on fatigue strength should also first be done on a finished component as it cannot be tested on the samples in this work. This work was conducted at Scania AB and the royal institute of technology, KTH, in Sweden.
Scania vill sänka vikten på sina lastbilar, bland annat för att minska utsläppen av koldioxid, och ett sätt att göra det är att lasersvetsa istället för att använda bultar. Detta kandidatexamensarbete handlar om lasersvetsning av segjärn, eller nodulärt gjutjärn som det också kallas, till seghärdningsstål och sätthärdningsstål samt utvärdering av svetsens mekaniska egenskaper. Även lasersvetsning av gjutstål till samma stålsorter som ovan utvärderas i detta arbete.Tester görs för att utvärdera effekten på materialet från lasersvetsningen. Testerna är dragprov och Vickers hårdhetstestning; både tvärs över och längs med svetsen samt även i vissa områden av särskilt intresse. EDS (Energy Dispersive X-Ray Spectroscopy) används för att analysera sammansättningen i svetsen och ljusoptiskt mikroskop används för att se svetsgodset och den värmepåverkade zonen. Resultaten visar att hårdheten går upp i den värmepåverkade zonen på grund av martensit bildning och att materialen blandar sig mer närmare svetsroten. Materialen blandar sig också mer om svetsdjupet är djupare. Den värmepåverkade zonens bredd verkar vara större om sträckenergin är hög. Det står också klart att svetsning av gjutstål är mindre komplicerat än svetsning av segjärn eftersom segjärnet får en hög hårdhet i den värmepåverkade zonen medan det inte alls blir så för gjutstålet. Gjutstålet kunde också svetsas utan tillsatsmaterial utan att få ett för hårt eller sprött svetsgods. Om man vill använda lasersvetsning i framtiden ska komponenter konstrueras så att svetsen inte bär huvudvikten eftersom resultatet visar att svetsgodset får lägre brottgräns. Utmattningstester borde också göras på en färdig komponent eftersom det inte kan testas på proven från det här arbetet. Detta arbete utfördes på Scania AB och Kungliga Tekniska Högskolan, KTH, i Sverige.

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Ekström, Madeleine. "Development of a ferritic ductile cast iron for improved life in exhaust applications." Licentiate thesis, KTH, Mekanisk metallografi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122006.

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Due to coming emission legislations, the temperature is expected to increase in heavy-duty diesel engines, specifically in the hot-end of the exhaust system affecting components, such as exhaust- and turbo manifolds. Since the current material in the turbo manifold, a ductile cast iron named SiMo51, is operating close to its limits there is a need for material development in order to maintain a high durability of these components. When designing for increased life, many material properties need to be considered, for example, creep-, corrosion- and fatigue resistance. Among these, the present work focuses on the latter two up to 800°C improving the current material by additions of Cr, for corrosion resistance, and Ni, for mechanical properties. The results show improved high-temperature corrosion resistance in air from 0.5 and 1wt% Cr additions resulting in improved barrier layer at the oxide/metal interface. However, during oxidation in exhaust-gases, which is a much more demanding environment compared to air, such improvement could not be observed. Addition of 1wt% Ni was found to increase the fatigue life up to 250°C, resulting from solution strengthening of the ferritic matrix. However, Ni was also found to increase the oxidation rates, as no continuous SiO2-barrier layers were formed in the presence of Ni. Since none of the tested alloys showed improved material properties in exhaust gases at high temperature, it is suggested that the way of improving performance of exhaust manifolds is to move towards austenitic ductile cast irons or cast stainless steels. One alloy showing good high-temperature oxidation properties in exhaust atmospheres is an austenitic cast stainless steel named HK30. This alloy formed adherent oxide scales during oxidation at 900°C in gas mixtures of 5%O2-10%H2O-85%N2 and 5%CO2-10%H2O-85%N2 and in air. In the two latter atmospheres, compact scales of (Cr, Mn)-spinel and Cr2O3 were formed whereas in the atmosphere containing 5%O2 and 10%H2O, the scales were more porous due to increased Fe-oxide formation. Despite the formation of a protective, i.e. compact and adherent, oxide scale on HK30, exposure to exhaust-gas condensate showed a detrimental effect in form of oxide spallation and metal release. Thus, proving the importance of taking exhaust-gas condensation, which may occur during cold-start or upon cooling of the engine, into account when selecting a new material for exhaust manifolds.

QC 20130508

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Ozcan, Alper. "The Effect Of Sn Content And Isothermal Transformation Temperature On The Mechanical Properties Of Austempered Ductile Cast Iron." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1055359/index.pdf.

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In this study the effects of Sn content and isothermal transformation temperature on the ultimate tensile strength (UTS), elongation and hardness of austempered ductile cast iron (ADI) was investigated. To determine the possible effect of Sn on these properties the Sn content of standard GGG30, GGG40 and GGG50 materials were taken as reference, whose chemical compositions vary from 0,016 to 0,050% in terms of Sn. However the Sn content was increased to a maximum of 0,26% for investigating the effect of Sn on mechanical properties. The test specimens were obtained from standard 1-in Y-blocks and austenitized at 925oC for 1 hour and austempered at 350oC,375oC, 400oC and 420oC for 60 minutes in a salt bath. Microstructural examination of the specimens were also done. To determine the amount of retained austenite of the specimens X-Ray analyses were used. As a result of the study The UTS increases up to 0,1% Sn and then levels off. A similar behavior is observed in the variation of hardness. Percent elongation decreases and falls to a minimum around 0,1% Sn, from this point on, a slight increase is observed. Strength and hardness increase while percent elongation decreases with decreasing temperatures.

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Sofia, Wännman. "Influence of Nitrocarburization on Thermo-Mechanical Fatigue Properties : Material Characterization of Ductile Cast Iron for Exhaust Components." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-69160.

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The large number of vehicles operating on the roads cause high emissions and consequently a negative effect on the environment. When developing and optimizing internal combustion engines, certain requirements must be considered, which are environmental regulations, reduced fuel consumption and increased specific power. In order to meet these demands, an increase of the engine combustion pressure will occur usually accompanied with a temperature increase. During start-up and shut-down of an engine, it is subjected to cyclic thermo-mechanical fatigue (TMF) loads. The turbo manifold and exhaust manifolds connected to the engine is also subjected to these thermo-mechanical fatigue loads and thereby exposed to alternating tensile and compression loads. As these TMF loads will increase in the near future due to the development and optimization of internal combustion engines, it is important to understand the limitations of the material for these loads. In collaboration with Scania CV AB in Södertälje, this thesis covers the investigation of influence of nitrocarburizing (NC) on TMF properties of three ductile irons (DCI) labelled HiSi, SiMo51 and SiMo1000 intended to be used for components in the exhaust system. Nitrocarburizing is a thermo-chemical process where nitrogen and carbon diffuses from the process medium into the surface zone of a ferrous metal. The purpose of the NC is to increase the wear properties in contact areas between different parts. The oxidation with and without nitrocarburizing are studied both after isothermal and stress free oxidation tests at 780 °C and after TMF loads with combined cyclic variation of mechanical and thermal loads. In addition, the properties such as hardness, defects, porosity, microstructure, composition of both the materials and of the oxide layer have been investigated. For SiMo1000+NC cracks formed during nitrocarburizing were positioned parallel to the surface edge in the diffusion zone and consequently an increased diffusion of nitrogen into the material, i.e. deeper diffusion depth. SiMo1000+NC showed highest hardness, highest compressive residual stresses and thickest oxide layer. SiMo1000 showed highest resistance against oxidation due to the protective aluminum oxide layer. Oxide crack initiations after thermo-mechanical tests with a protective silicon oxide layer around the cracks for HiSi and SiMo51 and a protective aluminum oxide layer around the cracks for SiMo1000. In materials with nitrocarburizing, these protective layers of either silicon oxide or aluminum oxide were more distributed into the material. In SiMo1000+NC, crack initiations were not oxidized.

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Mäkinen, Katri. "Optimisation of local material parameters : Optimising local material parameters in ductile cast iron cylinder head casting." Thesis, Jönköping University, JTH, Material och tillverkning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-54500.

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The constantly tightening emission regulations demand the engines to be moreefficient, to get more power out of smaller engines. Higher engine loads andcomponent temperatures are causing more stresses to engine components. Therefore,a company that produces engines wanted to study if it would be possible to increasethe capabilities of the components by optimising the used material. In this final project work, a cylinder head will be studied. The cylinder heads for theengines are made of ductile cast iron. The limits of that material are near safety limits,and therefore a better material is needed. In this work are some previous studiesanalysed and tried to find how to optimise the used material. The optimised materialshould have better thermal conductivity properties combined with sufficient strengthproperties. Previous studies were analysed to gather knowledge of the elements that affect thematerial parameters. Those studies showed that copper, silicon, pearlite fraction, andthe use of chills are the elements to be optimised. Silicon and pearlite fraction waschosen as optimisation parameters because of their effect on the thermal conductivityand strength properties. Copper was chosen as an optimisation variable due to its effecton the pearlite formation. Chills were used to affect the cooling rate and thereby thepearlite formation. The work was made using MAGMASOFT™ simulation software to simulate cylinderhead casting. The simulated cylinder head was divided into 4 parts for the simulations.For those sections were then set targets for pearlite fraction according to previousstudies. The silicon content was kept constant in the simulation, based on the studiespresented in this work. Copper content was simulated with variations from 0 to 0.7weight-%, and chill heights were simulated from 20 to 60 mm and without chills. After simulating the different variables, the results were analysed. Then the selectedcasting simulation result was mapped to finite element simulation mesh to include thelocal material parameters to finite element simulation. With the finite elementsimulation, the estimated lifetime of the component was simulated. By analysing the casting simulation results, an optimal combination was found. Theoptimal material parameters for a cylinder head casting would be copper 0.5weight-%, silicon 1.9 weight-% and chills thicker than 40 mm on the flame plate. Theoptimised material gives more possibilities to develop engines even further when thecomponent demands are growing.

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Eymard, Stéphanie. "Contribution à la valorisation tribologique des huiles de transformateur usagées." Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0017.

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Les prévisions alarmistes en ressources naturelles encouragent la recherche de solutions alternatives au niveau mondial. Le recyclage devient alors un défi majeur pour la société, en particulier pour les produits dérivés du pétrole comme les huiles de transformateur. Cette étude est basée sur la recherche de nouvelles voies de revalorisation de ces huiles, par l’analyse critique du contexte concurrentiel, des segments de marché potentiels, ainsi que des propriétés physico-chimiques de ces huiles. Nous nous sommes attachés à déterminer l’adéquation des performances et caractéristiques des huiles de transformateur régénérées aux exigences propres au marché de l’usinage et de la mise en forme des métaux. L’usure des matériaux dans le cadre de la lubrification limite et au-delà, est un domaine d’étude complexe combinant la mécanique, la physique du solide, la chimie ainsi que la thermodynamique des phénomènes irréversibles. Dans le cadre de cette étude les performances d’hydrocarbures neufs, usagés (pollué par les Polychlorobiphényls) et régénérés, ayant des propriétés physico-chimiques et rhéologiques proches, sont comparés dans le cadre d’essais sclérométriques et tribométriques sur une fonte à graphite sphéroïdal, matériau de frottement largement employé dans l’industrie du transport. Une séquence de techniques d’analyse de surface est développée afin de caractériser les morphologies des surfaces et quantifier les déformations de matières résultantes du frottement. La complémentarité des essais sclérométriques et tribométriques, qui permettent d’étudier les performances des hydrocarbures dans différents états de contraintes, respectivement de compression et de cisaillement, révèlent les bonnes performances des huiles de transformateurs régénérées. En quantifiant spécifiquement les performances des huiles revalorisée à travers la détermination de paramètres tribologiques classiques, comme les taux de déformations, les coefficients de frottements ou encore les temps d’initiation au grippage. La composition finale de l’huile régénérée, à savoir la longueur des chaines hydrocarbonées, les teneurs en eau et en PCB, conditionne son comportement tribologique. Suite à ce bilan positif portant sur les performances des huiles de transformateur régénérées en usure abrasive et catastrophique, la mise en forme des métaux peut être identifiée comme une nouvelle voie de valorisation matière de ces huiles
The alarming forecasts of natural resources encourage worldwide the search for alternative solutions. Hence recycling becomes a major challenge for society, especially for petroleum products such as transformer oils. This study is based on finding new ways of valorizing these oils, which is a complex problem that must meet the economic, political, regulatory, environmental and scientific constraints and challenges. A critical analysis of the competitive environment, of the potential market segments, as well as physic-chemical properties of these oils is the basis to determine new ways of revalorization. In this study, we attempted to determine the suitability and performance characteristics of transformer oil regenerated to the specific requirements of the machining and shaping of metals. The wear of materials under boundary lubrication and beyond this regime, is a complex area of study combining mechanics, solid state physics, chemistry and thermodynamics of irreversible processes. In this study the performance of new, used ( polluted by polychlorinated biphenyls ) and regenerated oils with close physic-chemical and rheological properties are compared in scratch test and tribometric with a ductile cast iron, which is friction material widely used in the transportation industry. A sequence of surface analysis techniques is developed to characterize the morphologies of the surfaces and quantify the resulting deformation of the friction material. The complementarity of scratch an tribometric tests for the study of the performance of hydrocarbons in different stress states, respectively compression and shear, reveals the good performances of regenerated transformer oils. This study has allowed discriminating the behavior of various origins oils under conditions of extreme friction, and specifically quantifying the performance of the regenerated oils through the determination of classical tribological parameters such as rate of deformation, friction coefficients or time to seizure. The final composition of the regenerated oils, ie the length and nature of the hydrocarbon chains, the water and PCBs content and the presence of polar molecules, determines its tribological behavior. Thus, the study showed that the performance of regenerated oils increases with the water and PCB content. Following this positive assessment on the regenerated oil performances in case of abrasive and catastrophic wear, machining and shaping of metals can be identified as a new way for regenerated transformers oils

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Kiattisaksri, Chatcharit. "Time-Resolved and In-Situ Study on Evolution of Spheroidal Graphite Nodules and Volume Change During Solidification in Ductile Cast Iron." Kyoto University, 2019. http://hdl.handle.net/2433/244548.

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Larsson, Karl. "Influence of nitrocarburization on the thermomechanical fatigue properties of ductile iron for exhaust components : Analysis and comparisons of TMF-properties." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-72033.

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New stricter environmental legislation requires lower emissions and fuel consumption of automotive engines. Therefore the fuel efficiency must be increased but this leads to higher loads in the engine. As for the exhaust system it is affected by higher thermomechanical loads. Until today the turbo manifold has been nitrocarburized in order to increase the wear resistance in slip joints with other exhaust components. The problem is that there is no knowledge of how the nitrocarburizing affects the thermomechanical properties of the material. The purpose of this thesis work is to examine the difference in thermomechanical properties with and without nitrocarburizing on the three different ductile irons High Silicon, SiMo51 and SiMo1000 intended for exhaust components. Thermo-mechanical fatigue (TMF) experiments were performed on test rods to evaluate difference in number of cycles to failure. In each cycle the test-rod was affected by a combination of mechanical loads and thermal loads resembling those found on exhaust components. Light optical microscopy, scanning electron microscopy and x-ray radiography were used to examine microcracks and damage mechanisms of the materials. It was found that the nitrocarburizing did not affect the number of cycles to failure in any large extent. Further, it was also found that SiMo1000 on average has the longest lifetime followed by SiMo51 and High Silicon. Although, the difference is small for many loadings and taking a 95% confidence band into account the curves overlap for many loading cases.

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Eriksson, Viktor. "Numerical Simulation of Ductile Cast Iron Fracture : A parameterization of the material model *MAT_224 in the FE-code LS-DYNA." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-37576.

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In crashes, fracture of Ductile Cast Iron (DCI) components can have a big influence on the global behaviour of the structure and the survival probability of the driver. In this thesis the material model *MAT_224 is parameterized for one ferritic-pearlitic grade, SS-0727-02, of DCI. The aim is to better describe the fracture and yielding of DCI components in crash simulations using the FE-code LS-DYNA. This is done by mechanical testing and simulations where the hardening behaviour and failure criteria are quantified. The failure criteria are defined by a failure strain surface, which depends on the stress triaxiality and the lode parameter. Tensile and torsion testing were performed to determine the model material parameters. Several different types of test specimens have been designed and tested. The goal when designing the specimen is to have a large variety of stress states at failure. To evaluate the parameterized material model three different types of validations tests, using bending and component testing, have been performed. The parameterized material model is able to predict the force at failure for several different stress states in a satisfying way. Still, the final failure is not predicted satisfactorily all the way, probably due to technological reasons. Thus, more mechanical test is recommended in order to validate the model further.
Vid krockförlopp kan brott i segjärnskomponenter ha en stor inverkan på strukturens globala beteende och även på förarens överlevnads chanser. I denna uppsats har materialmodellen *MAT_224 parametriseras för en ferritisk-perlitisk klass, SS-0727-02, av segjärn. Målet är att på ett bättre sätt kunna beskriva deformation och brott i segjärnskomponenter vid krocksimuleringar utförda med FE-koden LS-DYNA. Detta genomförs med mekanisk provning och simuleringar där hårdnandet och ett brottkriterium har kvantifierats. Brottkriteriet har definierats av en brottyta bestående av plastisk töjning, spänningstriaxialitet och lode parametern. Drag och vridprov har genomförts för att fastställa materialets parametrar. Flera olika typer av provstavar har blivit designade och testade. Målen vid konstruktionen av provstavarna är att ha en stor spridning i spänningstillstånd vid brott. För att utvärdera den parametriserade materialmodellen har tre olika typer av validerade prov, bestående av böjning och ett komponentprov genomförs. Den parametriserade materialmodellen har på ett tillfredsställande sätt kunnat förutsäga brottkraften för flera olika spänningstillstånd. Dock är den slutgiltiga brottförlängningen inte förutsagt helt tillfredsställande, detta troligen på grund av tekniska svårigheter. Komplementerande provning rekommenderas för att validera modellen ytterligare.

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Kryštůfek, Tomáš. "Odlévání tenkostěnných litinových odlitků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445175.

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This diploma thesis is focused on production and problems in production of thin-walled ductile iron castings, especially in the inoculation process. The focus is on the influence of elements on the structure and mechanical properties of ductile iron and as well as the influence of some elements, that are commonly used in inoculation alloys. Furthermore, the factors that affect the production technology are written, i.e., solidification rate, wall thickness, cooling rate, and factors used for affecting the thin-walled castings production, i.e., the use of insulating moulding compounds and increasing the graphite nodule count. At the end of the theoretical part, important production processes are analysed, namely inoculation and spheroidization. The experimental part is focused on influencing the structure and mechanical properties using several types of inoculants of different chemical compositions, whereas the tested thicknesses of the test plates are 3-, 5- and 8-mm. Hardness, tensile strength and ductility are evaluated on these plates. Finally, the volume of ferrite in the structure, shape and size of the graphite nodules were examined.

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Nyékyová, Dominika. "Vliv očkování litiny očkovadly s obsahem vizmutu na strukturu a mechanické vlastnosti." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417173.

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The diploma thesis deals with the modification and inoculation of cast iron with spheroidal graphite, the influence of the chemical composition on the shape and size of the graphite nodules and ferrite/perlite ratio in the structure. The aim of the practical part was to determine the effect of inoculant containing bismuth (SMW 605) on microstructure and mechanical properties of ferritic ductile cast iron GJS 400-15. The dissolving time of mold inoculant was further investigated. The samples were subjected to a tensile test, Charpy impact test, hardness test and graphite morphology and ferrite/perlite examination using standard ČSN EN ISO 945-1.

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Persson, Daniel, and Eric Vinjegaard. "Undersökning av materialegenskaper för nytt segjärn i jämförelse med traditionellt." Thesis, Högskolan Väst, Avd för maskinteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5348.

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I denna rapport beskrivs en undersökning och jämförelse av två olika sorters segjärn. Detvå materialen som har studerats har varit det segjärnet som används i Parker Hannifinsnuvarande hydraulikmotorer och ett nytt segjärn, vars mekaniska egenskaper har påståttsvara mer fördelaktiga. Målet med arbetet var att få fram en tillförlitlig jämförelse av de olikamaterialen och avgöra om det fanns ett tydligt underlag för att inleda processen av ett byteav material i vissa komponenter i Parker Hannifins produkter.Det utfördes jämförelser mellan de olika materialens mekaniska egenskaper baserade delspå information som redan fanns om materialen och dels på data insamlad vid tester medskärande bearbetning. Förslitning på verktygen vid fräsning studerades tillsammans medskärkraften med olika sorters skärdata. Restspänningar efter ingreppen i de båda materialenmättes med en röntgendiffraktometer.Resultaten gav inga signifikanta indikationer på att ett materialbyte skulle innebära en lägreproduktionskostnad, dock visade analyser att det nya materialet tål att bearbetas fortare ändet traditionella segjärnet och att fler undersökningar bör göras. Efter att ha analyseratmekaniska egenskaper så som hållfasthet, hårdhet, hårdhetsspridning och styvhet kundeslutsatser dras. Det visade sig att det nya segjärnet hade högre hållfasthet och jämnarehårdhet, men det hade även lägre styvhet. Styvheten i materialet är en viktig faktor dåläckage kan uppstå i hydraulikmotorer om materialen inte har tillräckligt hög styvhet.Mätningarna av skärkraften hos de båda materialen tydde på att det kunde uppstå högrestandardavvikelse, eller variationer av skärkraften vid fräsning av det traditionella segjärnet.Eftersom dessa variationer endast visade sig ett fåtal gånger går det inte att entydigtkonstatera att det nya materialet har mer fördelaktiga bearbetningsegenskaper. För att draen sådan slutsats hade det krävts ytterligare analyser på fler detaljer.
This report describes a study and comparison of two different types of ductile iron. Thetwo materials that have been studied have been the ductile iron used in Parker Hannifin'scurrent hydraulic motors and a new ductile iron, whose mechanical properties are said tobe more advantageous. The goal of this study was to obtain a reliable comparison of thedifferent materials and determine if there were clear grounds for initiating the process of achange of material in certain components of Parker Hannifin’s products.Comparisons between the mechanical properties of the materials were based partly oninformation that was already available and partly on data collected through machining trails.The wear on the tools after milling was studied along with the cutting force from variouskinds of cutting data. Residual stresses after the operation in both materials were measuredby an X-ray diffractometer.The results yielded no significant indication that a change of material would result in lowerproduction cost, however, analyses showed that the new material can withstand beingprocessed faster than the traditional ductile iron and that more studies should beconducted. After analyzing the mechanical properties, such as strength, hardness, hardnessvariation and stiffness, conclusions could be drawn. It turned out that the new ductile ironhad higher strength and more uniform hardness, but it also had lower stiffness. Thestiffness of the material is an important factor because if the materials do not havesufficient rigidity, leakage can occur in hydraulic motors. Measurements of the cutting forceof the two materials indicated that there could be a higher standard deviation, orfluctuation of the cutting force during milling of the traditional ductile iron. Since thesevariations only appeared a few times, it is difficult to conclude that the new ductile ironwould be more advantageous when it comes to machining. To be able to draw that kind ofconclusion would require more collected data.

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Buljac, Ante. "Compréhension, observation et quantification des mécanismes de rupture ductile par imagerie 3D." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN036/document.

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Au cours des dernières décennies, des efforts importants ont été menés dans la modélisation des processus de rupture ductile entraînant des progrès substantiels. Cependant, la compréhension complète des mécanismes de rupture ductile dans des états de contraintes spécifiques demeure une question ouverte. Ceci est dû au manque de bases des données expérimentales et à la non validation des modèles pour ces conditions de chargement. Dans ce travail, les acquisitions de données sont principalement obtenues en utilisant la laminographie, ce qui rend possible l'imagerie de régions d'intérêt d'échantillons plats. L'utilisation d'éprouvettes larges (et minces) permet de générer différents états de contraintes et des conditions aux limites pertinentes pour l'ingénierie, qui ne pouvaient pas être évaluées jusqu'à présent en trois dimensions et en essais in-situ à des échelles micrométriques. La corrélation d'images volumiques (DVC) est utilisée pour mesurer les champs de déplacement à l'intérieur des échantillons en acquérant des images de laminographie 3D. Deux classes de matériaux représentatives de deux modes génériques de rupture ductile ont été examinées, à savoir les alliages d'aluminium (rupture par instabilité) et la fonte à graphite sphéroïdal (rupture par croissance de vide et coalescence).L'observation de la microstructure et les interactions déformations-endommagement pour différentes géométries d'échantillons et pour différents niveaux de triaxialité des contraintes associés ont été étudiées pour des alliages d'aluminium à une résolution micrométrique. De plus, un cadre combiné numérique-expérimental (DVC-FE) est introduit pour valider les simulations numériques à l'échelle microscopique pour la fonte à graphite sphéroïdal. Les simulations par éléments finis (FE), qui représentent la microstructure des matériaux étudiés, sont conduites avec des conditions aux limites de Dirichlet extraites des mesures DVC. Enfin, le cadre DVC-FE a été amélioré et utilisé comme une procédure d'identification intégrée pour l'étude du comportement élasto-plastique de la matrice ferritique de la fonte, non seulement en termes de champs cinématiques induits par la microstructure aléatoire, mais aussi avec les niveaux de charge globaux
In the last few decades significant efforts have been made in modeling ductile failure processes resulting in substantial progress. However, the full understanding of ductile failure mechanisms under specific stress states still remains an open question. This is partly due to missing experimental data and validation of models for such loading conditions.In this work, data acquisitions are mainly obtained by using laminography, which makes the imaging of regions of interest in flat samples possible. The use of large (and thin) specimens allows various stress states and engineering-relevant boundary conditions to be generated, which could not be assessed in three dimensions and in-situ at micrometer scales before. Digital Volume Correlation (DVC) is used for measuring displacement fields in the bulk of samples by registering 3D laminography images. Two material classes that are representative of two generic modes of ductile failure have been examined, namely, Al-alloys (failure by instability) and cast iron (failure by void growth and coalescence). The observation of microstructure and strain-damage interactions at micrometer resolution for various specimen geometries and associated levels of stress triaxiality are studied for Al-alloys. Additionally, a combined computational-experimental (DVC-FE) framework is introduced to validate numerical simulations at the microscopic scale for nodular graphite cast iron. Finite Element (FE) simulations, which account for the studied material microstructure, are driven by Dirichlet boundary conditions extracted from DVC measurements.Last, the DVC-FE framework is upgraded to an integrated identification procedure to probe elasto-plastic constitutive law of the cast iron ferritic matrix not only in terms of kinematic fields induced by the random microstructure but also by overall load levels

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Maluf, Omar. ""Influência do roleteamento no comportamento em fadiga de um ferro fundido nodular perlítico"." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-17032004-163144/.

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O processo de roleteamento é um tratamento superficial, comumente utilizado em peças fabricadas em aços e ferros fundidos nodulares, em regiões onde há concentradores de tensões, com o intuito de melhorar as propriedades de resistência à fadiga. Este processo endurece e introduz tensões residuais compressivas na camada superficial do material, através de deformação controlada, provocando uma redução das tensões de tração que atuam na superfície da peça submetida a carregamentos cíclicos. Este trabalho teve como principal objetivo o estudo do efeito do roleteamento superficial sobre o comportamento em fadiga de um ferro fundido nodular de matriz perlítica, utilizado na fabricação de virabrequins pela indústria automobilística. Foram realizados ensaios de fadiga por flexão rotativa em corpos de prova lisos e com entalhe. Os corpos de prova com entalhe foram divididos em dois grupos, com e sem roleteamento superficial. Foi utilizado entalhe com geometria semicircular com raio de 1,20mm e profundidade de 0,70mm. Para o processo de roleteamento foi utilizado um rolete com diâmetro de 15,00mm e com raio de curvatura de 1,30mm e aplicada uma força de compressão de 2390N. A introdução de tensões residuais compressivas pelo trabalho a frio, dificultou a nucleação e a propagação de trincas na camada superficial dos entalhes roleteados. Isto ficou evidenciado pelo aumento do valor do limite de fadiga para 483MPa obtido para o material entalhado e roleteado, enquanto que para o material nas condições de sem entalhe e somente entalhado estes valores foram de 300MPa e 168Mpa, respectivamente.
Surface rolling is a mechanical treatment commonly used in parts fabricated with steel and ductile cast iron, specifically in stress concentration regions, to improve fatigue properties. This process hardens and introduces compressive residual stresses to the surface of the material through the application of controlled strains, thus provoking a reduction of resulting tensile stress at its surface under cyclic loading. This work deals with the effect of surface rolling on high cycle fatigue behavior of a pearlitic ductile cast iron used in crankshaft by automotive industries. Rotating bending fatigue tests were performed in both smooth and notched specimens. The notched specimens were divided into two groups: with and without surface rolling treatment. The specimens notch geometry was semicircular with radius of 1.20mm and depth of 0.70mm. The rolling treatment was carried out using a roller with diameter of 15,00mm, curvature radius of 1.30mm and a compression force of 2390N. The introduction of compressive residual stresses under cold work made difficult the nucleation and propagation of the crack on the rolled surface of the notch. It was confirmed by the increase of the endurance limit of the surface rolled specimens to 483MPa in comparison with the smooth and notched specimens, respectively, 300MPa and 168 MPa.

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Rosário, John Ferney Alvarez. "Avaliação da integridade da superfície no torneamento de um ferro fundido nodular com carboneto." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3132/tde-05092006-131535/.

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Neste trabalho, estudou-se a integridade superficial durante o torneamento de um ferro fundido nodular com carbonetos, considerando a heterogeneidade microestrutural (fração volumétrica, tamanho e morfologia de grafita e dos carbonetos) e os efeitos dos parâmetros de corte (avanço, velocidade de corte e profundidade de corte), baseados num planejamento fatorial fracionário 24-1. Este texto apresenta, numa primeira parte, uma revisão baseada em referências bibliográficas clássicas da engenharia de superfícies, na tentativa de definir os conceitos que compõem a integridade da superfície. Posteriormente, descrevem-se os resultados de ensaios preliminares, realizados com a finalidade avaliar os níveis do processo e os efeitos desses parâmetros na integridade da superfície. Finalmente, realizaram-se os ensaios de usinagem em corpos-de-prova de ferro fundido nodular com carboneto, nos diâmetros de 80 mm e 140mm. Durante os ensaios de torneamento empregaram-se duas velocidades de corte (60 m/min e 180 m/min), dois avanços (0,1 mm/rev e 0,3 mm/rev) e duas profundidades de corte (0,2 mm e 0,3 mm). Após os ensaios de usinagem, foram realizadas: a avaliação das propriedades do material usinado (dureza e microestrutura), a análise de topografia da superfície usinada mediante avaliação da rugosidade, e a avaliação da influência dos parâmetros de usinagem na rugosidade. Encontrou-se uma dependência estatisticamente significativa da variação nas propriedades mecânicas dos corpos-de-prova em função da microestrutura, e mostraram-se os efeitos dessas variações em termos da integridade da superfície usinada.
In this work, the surface integrity of a ductile cast iron with carbides was studied during turning operations, considering the microstructural heterogeneity (volume fraction, size and morphology of the graphite and carbides) and the effect of the machining parameters (feed, cutting speed and depth of cut), based on a fractional factorial design 24-1. This work presents, initially, a literature review based on classic works on surface engineering, as an attempt to define the main concepts of surface integrity. Later, the results of preliminary test are described, which were conducted in order to define the process levels and the effects of these levels on the surface integrity. Finally, turning tests were conducted on specimens of ductile iron with carbides, at diameters of 80 and 140 mm. Two cutting speeds (60 m/min and 180 m/min), two feeds (0,1 mm/rev and 0,3 mm/rev) and two depths of cut (0,2 mm and 0,3 mm) were selected during the tests. Machined specimens were analyzed in terms of the properties of the machined material (hardness and microstructure) and of the roughness of the machined surface. The effect of the machining parameters on the roughness was also studied. A statistically significant dependence was observed for the properties of the machined specimens as a function of the microstructure and the effect of these properties on the surface integrity is presented.

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Dong, Ming-Jing. "Effet de l'endommagement sur la ténacité de la fonte à graphite sphéroïdal." Châtenay-Malabry, Ecole centrale de Paris, 1995. http://www.theses.fr/1995ECAP0392.

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Cette étude porte sur l'influence de l'endommagement sur la loi de comportement et sur la ténacité de la fonte a graphite sphéroïdal. La microstructure des fontes GGG 40, GS 52 5%, GS 52 25%, a été caractérisée par analyse à la microsonde, observation au MEB, et analyse d'images. L’endommagement est décrit d'une part à l'échelle macroscopique par les paramètres D, le coefficient de dilatance et l'évolution du coefficient de poisson plastique, et d'autre part a l'échelle microscopique par observation au MEB des différents stades de la décohésion de l'interface graphite/matrice. Nous trouvons que la décohésion apparait des les premiers stades de la déformation plastique macroscopique. D augmente de 30% quand la déformation plastique varie de 0 à 2%, puis l'endommagement se stabilise jusqu'a la rupture finale. Les différents types de graphite donnent les mécanismes d’endommagement différent. La fonte ne peut donc pas être considérée comme un matériau dense. La contrainte critique à l'interface pour la décohésion est de 82 MPA. La modélisation numérique de la loi de comportement montre que en tenant compte des effets du palier de plasticité, de l'empilement des nodules, des contraintes résiduelles, les nodules de graphite peuvent être remplacés par des cavités en accord avec les observations des mécanismes d'endommagement. La taille de la zone endommagée en tête de fissure a été déterminée par observation sur une éprouvette CT 25 de fonte GGG 40 et par des calculs analytique et numérique rendant compte de l'effet de la contrainte hydrostatique. Les résultats expérimentaux et ceux des modèles montrent bien que l'endommagement joue un rôle important dans le cas des éprouvettes CT 25. L’endommagement en tête de fissure modifie la valeur conventionnelle de kC, et entraine une augmentation de la ténacité par comparaison avec celle de la matrice massive. En présence de cavités nous montrons que, l'état de contrainte ne joue pas le même rôle sur la taille de la zone plastique que dans les matériaux denses.

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Nishikawa, Arthur Seiji. "Têmpera e partição de ferros fundidos nodulares: microestrutura e cinética." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-05022019-092855/.

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Este trabalho está inserido em um projeto que procura estudar a viabilidade técnica da aplicação de um relativamente novo conceito de tratamento térmico, chamado de Têmpera e Partição (T&P), como alternativa para o processamento de ferros fundidos nodulares com alta resistência mecânica. O processo T&P tem por objetivo a obtenção de microestruturas multifásicas constituídas de martensita e austenita retida, estabilizada em carbono. A martensita confere elevada resistência mecânica, enquanto a austenita confere ductilidade. No processo T&P, após a austenitização total ou parcial da liga, o material é temperado até uma temperatura de têmpera TT entre as temperaturas Ms e Mf para produzir uma mistura controlada de martensita e austenita. Em seguida, na etapa de partição, o material é mantido isotermicamente em uma temperatura igual ou mais elevada (denominada temperatura de partição TP) para permitir a partição de carbono da martensita para a austenita. O carbono em solução sólida diminui a temperatura Ms da austenita, estabilizando-a à temperatura ambiente. O presente trabalho procurou estudar aspectos de transformações de fases -- com ênfase na evolução microestrutural e cinética das reações -- do tratamento térmico de Têmpera e Partição (T&P) aplicado a uma liga de ferro fundido nodular (Fe-3,47%C-2,47%Si-0,2%Mn). Tratamentos térmicos consistiram de austenitização a 880 oC por 30 min, seguido de têmpera a 140, 170 e 200 oC e partição a 300, 375 e 450 oC por até 2 h. A caracterização microestrutural foi feita por microscopia óptica (MO), eletrônica de varredura (MEV), difração de elétrons retroespalhados (EBSD) e análise de microssonda eletrônica (EPMA). A análise cinética foi feita por meio de ensaios de dilatometria de alta resolução e difração de raios X in situ usando radiação síncrotron. Resultados mostram que a ocorrência de reações competitivas -- reação bainítica e precipitação de carbonetos na martensita -- é inevitável durante a aplicação do tratamento T&P à presente liga de ferro fundido nodular. A cinética da reação bainítica é acelerada pela presença da martensita formada na etapa de têmpera. A reação bainítica acontece, a baixas temperaturas, desacompanhada da precipitação de carbonetos e contribui para o enriquecimento em carbono, e consequente estabilização, da austenita. Devido à precipitação de carbonetos na martensita, a formação de ferrita bainítica é o principal mecanismo de enriquecimento em carbono da austenita. A microssegregação proveniente da etapa de solidificação permanece no material tratado termicamente e afeta a distribuição da martensita formada na etapa de têmpera e a cinética da reação bainítica. Em regiões correspondentes a contornos de célula eutética são observadas menores quantidades de martensita e a reação bainítica é mais lenta. A microestrutura final produzida pelo tratamento T&P aplicado ao ferro fundido consiste de martensita revenida com carbonetos, ferrita banítica e austenita enriquecida estabilizada pelo carbono. Adicionalmente, foi desenvolvido um modelo computacional que calcula a redistribuição local de carbono durante a etapa de partição do tratamento T&P, assumindo os efeitos da precipitação de do crescimento de placas de ferrita bainítica a partir da austenita. O modelo mostrou que a cinética de partição de carbono da martensita para a austenita é mais lenta quando os carbonetos precipitados são mais estáveis e que, quando a energia livre dos carbonetos é suficientemente baixa, o fluxo de carbono acontece da austenita para a martensita. A aplicação do modelo não se limita às condições estudadas neste trabalho e pode ser aplicada para o planejamento de tratamentos T&P para aços.
The present work belongs to a bigger project whose main goal is to study the technical feasibility of the application of a relatively new heat treating concept, called Quenching and Partitioning (Q&P), as an alternative to the processing of high strength ductile cast irons. The aim of the Q&P process is to obtain multiphase microstructures consisting of martensite and carbon enriched retained austenite. Martensite confers high strength, whereas austenite confers ductility. In the Q&P process, after total or partial austenitization of the alloy, the material is quenched in a quenching temperature TQ between the Ms and Mf temperatures to produce a controlled mixture of martensite and austenite. Next, at the partitioning step, the material is isothermally held at a either equal or higher temperature (so called partitioning temperature TP) in order to promote the carbon diffusion (partitioning) from martensite to austenite. The present work focus on the study of phase transformations aspects -- with emphasis on the microstructural evolution and kinetics of the reactions -- of the Q&P process applied to a ductile cast iron alloy (Fe-3,47%C-2,47%Si-0,2%Mn). Heat treatments consisted of austenitization at 880 oC for 30 min, followed by quenching at 140, 170, and 200 oC and partitioning at 300, 375 e 450 oC up to 2 h. The microstructural characterization was carried out by optical microscopy (OM), scanning electron microscopy (SEM), backscattered diffraction (EBSD), and electron probe microanalysis (EPMA). The kinetic analysis was studied by high resolution dilatometry tests and in situ X-ray diffraction using a synchrotron light source. Results showed that competitive reactions -- bainite reaction and carbides precipitation in martensite -- is unavoidable during the Q&P process. The bainite reaction kinetics is accelerated by the presence of martensite formed in the quenching step. The bainite reaction occurs at low temperatures without carbides precipitation and contributes to the carbon enrichment of austenite and its stabilization. Due to carbides precipitation in martensite, growth of bainitic ferrite is the main mechanism of carbon enrichment of austenite. Microsegregation inherited from the casting process is present in the heat treated material and affects the martensite distribution and the kinetics of the bainite reaction. In regions corresponding to eutectic cell boundaries less martensite is observed and the kinetics of bainite reaction is slower. The final microestructure produced by the Q&P process applied to the ductile cast iron consists of tempered martensite with carbides, bainitic ferrite, and carbon enriched austenite. Additionally, a computational model was developed to calculate the local kinetics of carbon redistribution during the partitioning step, considering the effects of carbides precipitation and bainite reaction. The model showed that the kinetics of carbon partitioning from martensite to austenite is slower when the tempering carbides are more stable and that, when the carbides free energy is sufficiently low, the carbon diffuses from austenite to martensite. The model is not limited to the studied conditions and can be applied to the development of Q&P heat treatments to steels.

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Zander, Patrik, and Johan Hammarström. "Värmebehandling av segjärn med hög kiselhalt." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Maskinteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-16377.

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Bakgrunden till detta examensarbete var att Qumex Materialteknik vid ett flertal tillfällen konstaterat att material av typen SS 0725 har uppvisat bristfälliga härdresultat. Materialet, som är relativt nytt på marknaden, är ett gjutjärn av typen segjärn och utmärker sig gentemot andra segjärn på grund av sitt höga innehåll av kisel. Då segjärn enligt den nu gällande EN-standarden klassificeras efter sina mekaniska egenskaper uppstår ett problem gällande SS 0725. Materialet uppfyller de krav som är ställda för EN-GJS-500-7 och hamnar därmed under samma materialbeteckning som ett segjärn med betydligt lägre kiselhalt. Att två material med olika kemisk sammansättning hamnar under samma beteckning kan innebära problem. Syftet med denna rapport är att fastslå vilken påverkan den höga kiselhalten har på materialet vid värmebehandling av typen släckhärdning med efterföljande anlöpning. I försöken ingick fyra material. Det som skiljde materialen åt var halterna av koppar och kisel. De härdades vid tre olika temperaturer och under tre olika tider för att sedan släckas i olja. Målet med släckhärdningen var att materialen skulle få en helt martensitisk struktur vilket då klassades som ett bra härdresultat. Resultatet utvärderades sedan genom optisk mikroskopi och hårdhetsmätningar. En undersökning av materialens fasomvandlingstemperaturer genomfördes med hjälp av Differential Scanning Calorimetry. Resultatet visar att kiselhalten har stor påverkan på den temperatur som krävs för att erhålla ett bra härdresultat. För material med låg kiselhalt uppnåddes fullständig martensitbildning efter släckhärdning från 840°C. För material med hög kiselhalt uppnåddes liknande strukturella och hårdhetsmässiga resultat först vid en så hög temperatur som 900°C och behandlingstider längre än 1 h. Den relativa skillnad som uppmättes i fasomvandlingstemperatur med hjälp av Differential Scanning Calorimetry mellan högkiselmaterial och lågkiselmaterial var 45°C. Detta resultat kombinerat med analyserna av härdprocesserna visar att det krävs kraftigt ökad temperatur vid värmebehandling av högkiselmaterialet SS 0725.
The background to this thesis was that Qumex Materialteknik at several occasions had received material of type SS 0725 that had shown deficient heat treatment results. The material, which is relatively new, is a cast iron of type ductile iron and differ against other ductile irons because of its high silicon content. According to EN standard ductile irons are classified by their mechanical properties. A problem then occurs with the new material SS 0725 because of this. The material fulfils the requirements for EN-GJS-500-7 and is therefore in the same classification as a ductile iron with much lower silicon content. Two materials having major differences in chemical composition ending up in the same classification can be problematic. The purpose of this report is to determine impact of high silicon content in ductile iron when heat treated and quench hardened. The experiment included four materials, and the major difference between the materials were their content of copper and silicon. The heat treatment process was performed at three different temperatures and three different treatment times. Afterwards the samples were quenched in oil. The ambition of the quench hardening was to obtain a material structure of 100% martensite. By optical microscopy and hardness measurements the results then were evaluated. An investigation of the phase transformation temperature in the materials was made by using Differential Scanning Calorimetry. The results show that the amount of silicon content has great influence on the temperature for receiving good hardening results. To achieve 100% martensite after quench hardening in materials with low silicon content the temperature needs to be over 840°C. For material with high level of silicon content the temperature for achieving 100% martensite needs to be 900°C and the treatment time should be over 1 h. The relative difference in phase transformation temperature was measured using Differential Scanning Calorimetry. The results of the measurements between the materials with high silicon content and materials with low silicon content was 45°C. This result combined with the analysis of the heat treatment process shows that a major increase of the temperature is needed to heat treat SS 0725.

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22

Jacumasso, Tiago. "INFLUÊNCIA DOS PARÂMETROS DE AUSTÊMPERA EM FERRO FUNDIDO NODULAR: MICROESTRUTURA, PROPRIEDADES MECÂNICAS E ASPECTOS DA GEOMETRIA FRACTAL NA FRATURA." Universidade Estadual de Ponta Grossa, 2018. http://tede2.uepg.br/jspui/handle/prefix/2684.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A mecânica da fratura foi desenvolvida, utilizando-se uma descrição geométrica euclidiana que pressupõem uma trinca lisa sem irregularidades. Por esta razão, a modelagem matemática de uma trinca rugosa, usando a geometria fractal, tem sido a preocupação de vários autores nas últimas décadas. O intuito destes pesquisadores é descrever o fenômeno da fratura de forma mais autentica e precisa. Uma das formas de se avaliar as propriedades mecânicas de um material fraturado é usando o conceito de integral-J. Este conceito aplicado ao fenômeno da fratura define uma curva de resistência ao crescimento de trinca chamado de curva J-R. Sendo assim, vários modelos fractais de curva J-R têm sido propostos. Um dos modelos que vem ganhando destaque na literatura científica foi proposto por ALVES (2010, 2011). Por esta razão investigou-se, neste trabalho, a aplicação desse modelo no estudo da fratura do ferro fundido nodular e ferro fundido nodular austemperado (ADI). O objetivo foi avaliar os efeitos dos tratamentos térmicos de austêmpera na microestrutura e nas propriedades mecânicas de uma liga de ferro fundido nodular. Para tanto foi empregado duas rotas de tratamentos térmicos: austêmpera convencional, consistindo de austenitização a 900ºC por 60min, seguida de austêmpera até 250ºC e à 300ºC, com permanência por 60min e 120min para cada temperatura, totalizando quatro condições, com resfriamento ao ar. As amostras tratadas termicamente foram caracterizadas com auxílio de microscopia óptica, microscopia eletrônica de varredura (FEG) e difração de raios X (DRX), com objetivo de determinar suas fases e microconstituintes. O efeito das condições de tratamento nas propriedades mecânicas foi verificado por ensaios de dureza Vickers e de impacto instrumentado Charpy. Por meio de ensaios de impacto instrumentado e solicitação mecânica de tração e com o auxílio de microscopia eletrônica por emissão de campo (FEG) foi possível estudar o crescimento de trincas rugosas na fratura do ferro fundido nodular austemperado, comparando os resultados entre as quatro condições de tratamento térmico de austêmpera. Deste modo, foi possível fornecer dados experimentais para comprovar a validade da equação da curva J-R na presença de uma trinca rugosa proposta por ALVES (2010, 2011) com base na geometria fractal e na mecânica da fratura. Os resultados obtidos permitiram comparar e discutir o efeito das rotas de tratamento térmico, no sentido de desenvolver as propriedades mecânicas do ferro fundido nodular para aplicações diversas. As curvas D J ajustadas pelo modelo fractal mostraram-se em boa concordância com aquelas obtidas pelo método descrito na ASTM E1820-17a (2017). O ADI tratado a 300ºC por 60 minutos foi o material que apresentou as melhores condições de resistência mecânica a tração e ao impacto, superando o material bruto de fundição na tenacidade a fratura, calculada pelos parâmetros fractais da curva. Este ferro fundido nodular austemperado é comparado ao da classe de alta resistência de ADI.
The mechanics of the fracture were developed using a geometric Euclidean description that assumes a smooth crack without irregularities. For this reason, the mathematical modeling of a rough crack, using fractal geometry, has been the concern of several authors in the last decades. The aim of these researchers is to describe the fracture phenomenon more authentically and accurately. One of the ways to evaluate the mechanical properties of a fractured material is by using the concept of integral-J. This concept applied to the fracture phenomenon defines a crack growth resistance curve called the J-R curve. Thus, several fractal J-R curve models have been proposed. One of the models that have gained prominence in the scientific literature was proposed by ALVES (2010, 2011). For this reason we investigated the application of this model in the study of nodular cast iron and austempered nodular cast iron (ADI). The objective was to evaluate the effects of thermal treatments of austempering in the microstructure and mechanical properties of a ductile cast iron alloy. Two routes of thermal treatments were used: conventional austenitic, consisting of austenitization at 900ºC for 60min, followed by tempering up to 250ºC and at 300ºC, with permanence for 60min and 120min for each temperature, totaling four conditions, with air cooling. The thermally treated samples were characterized by optical microscopy, scanning electron microscopy (FEG) and X - ray diffraction (XRD), in order to determine their phases and microconstituents. The effect of the treatment conditions on the mechanical properties was verified by tests of Vickers hardness and instrumented impact Charpy. By means of instrumented impact and mechanical tensile stress tests and with the aid of field emission electron microscopy (FEG), it was possible to study the growth of rough cracks in austempered nodular cast iron fracture, comparing the results between the four conditions of heat treatment. Thus, it was possible to provide experimental data to prove the validity of the J-R curve equation in the presence of a rough crack proposed by ALVES (2010, 2011) based on fractal geometry and fracture mechanics. The results obtained allowed to compare and discuss the effect of heat treatment routes in order to develop the mechanical properties of nodular cast iron for different applications. The D J curves fitting by the fractal model show in agreement with the curves obtained by the method described in the ASTM E1820-17a (2017). The ADI treated at 300ºC for 60 minutes was the material that presented the best conditions of tensile and impact mechanical strength, surpassing the crude casting material in the fracture toughness, calculated by the fractal parameters of the curve. This austempered nodular cast iron is compared to that of the ADI high strength class.

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23

Tesařová, Hana. "Strukturní a mechanické charakteristiky niklových litin s kuličkovým grafitem." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233891.

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The aim of this dissertation work is the evaluation of the influence of nickel alloying on the structure and mechanical properties, both monotonic and dynamic, of nodular cast iron with ferritic and bainitic matrix. Two chock melts with 0.5 and 2.7 % Ni were used to study the nickel influence. The quantitative evaluation of structure of these melts using image analysis was done and basic tensile mechanical properties were determined. Subsequently, the time optimization of two-stage ferritic annealing and isothermal austempered heat treatment at 375 °C was performed with the aim to obtain optimal ferritic and bainitic structures with best static and dynamic mechanical properties. After ferritic annealing the nickel alloying contributes to substitution hardening of ferritic matrix which positively affects its strength and other mechanical properties. The higher nickel content in the bainitic structure causes the shift of phase transformation times to longer times which results in restricted production of small carbides and in bigger volume of retained austenite. These features were confirmed by observation in transmission electron microscope. Precise tensile and low cycle fatigue tests at temperatures 23 and – 45 °C were performed on the optimized structures of both nodular cast irons. As a result of the notch effect of graphite nodules, microplastic deformation of both nodular cast irons was observed at stresses which were lower than the yield stress. The Hollomon's equation very well describes the individual parts of tensile curves for both nodular cast irons including their mutual comparison. From the low cycle fatigue tests, the cyclic hardening/softening curves, the evolution of elastic modulus and hysteresis loop shape parameters, cyclic stress-strain curves and fatigue life curves were obtained for both temperatures and materials. Moreover, the decrease of retained austenite volume was measured by neutron diffraction and the evolution of surface relief was characterized during cyclic straining for both austempered nodular cast irons at both temperatures. On the basis of these results both cyclic plasticity and fatigue degradation mechanisms in relation to the cyclic strain localization were described for both nodular cast irons.

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Melado, André Caetano. "Ferros fundidos nodulares de alta resistência obtidos por tratamento térmico de têmpera e partição: microestrutura e comportamento mecânico." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-16072018-134449/.

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A aplicação do novo conceito de tratamento térmico, chamado de têmpera e partição (Q&P), desenvolvido para a obtenção de aços da terceira geração da classe AHSS (Advanced high strengh steel ou aços avançados de alta resistência), mostra-se uma alternativa para o processamento de ferros fundidos nodulares com alta resistência mecânica. No processo Q&P, o carbono presente na martensita supersaturada, formada na etapa de têmpera, é utilizado para estabilizar a austenita não transformada durante a etapa de partição, mantendo-a estável na temperatura ambiente. Essa rota de tratamento térmico consiste em realizar uma têmpera no material (após uma etapa prévia de austenitização) numa faixa de temperatura entre o Ms e Mf (temperatura de início e fim da transformação martensítica, respectivamente), seguido de um reaquecimento e manutenção a uma temperatura acima do Ms (etapa isotérmica de partição) com o objetivo de que o carbono migre da martensita supersaturada para a austenita remanescente promovendo sua estabilização. Essa partição do carbono só é possível caso a precipitação da cementita seja suprimida, e isso é conseguido com a presença de elementos de liga, como o Si e/ou Al. Neste trabalho foi feito um estudo sobre as características microestruturais e mecânicas de um ferro fundido nodular (3,47%C; 2,47%Si; 0,2%Mn) submetido ao tratamento térmico de têmpera e partição, o qual foi denominado neste trabalho como, Q&PDI (Quenched and Partitioned Ductile Iron ou Ferro Fundido Nodular Temperado e Particionado). Para isso foi realizada uma austenitização plena nas amostras, a 880°C, por duas horas, seguida de uma têmpera em óleo pré-aquecido nas temperaturas de 140 e 170°C. A etapa de partição foi feita nas temperaturas de 300, 375 e 450°C, com intervalos de tempo variando de 5 a 120 minutos. A caracterização microestrutural foi realizada através de microscopia ótica, microscopia eletrônica de varredura e EBSD. A técnica de difração de raios-X foi empregada para quantificar a fração volumétrica e o teor de carbono na austenita retida. Ensaios de dilatometria, difração de raios-X \"in situ\" e nanoindentação foram empregados para auxiliar na análise das transformações de fases que ocorreram na etapa de partição, como a transformação bainítica e a precipitação de carbonetos de transição nas placas de martensita. A caracterização mecânica foi feita através de ensaios de tração, impacto, dureza, nanoindentação, tenacidade à fratura e resistência à fadiga. Ensaios de compressão auxiliaram na análise da transformação martensítica induzida por deformação. Os resultados obtidos mostraram que é possível obter ferros fundidos nodulares com alta resistência mecânica (limite de resistência >1450 MPa), com consideráveis ductilidade (de até 9%) e energia absorvida sob impacto (de até 81 J), bem como tenacidades à fratura de 55 MPa.m1/2 e limites de fadiga de 550 MPa. Este comportamento é proporcionado por uma microestrutura singular, constituída por uma dispersão homogênea de placas de martensita numa matriz de ausferrita bastante refinada, com consideráveis frações volumétricas de austenita retida (max. 23%).
Quenching and partitioning (Q & P), a new heat treatment concept developed to obtain third generation AHSS (Advanced High Strength Steel), is an alternative for processing of nodular cast irons in order to obtain high mechanical strength. In the Q & P process, the carbon present in the supersaturated martensite formed in the quenching step diffuses towards the untransformed austenite during the partition step, keeping it stable at room temperature. This heat treatment route consists of quenching the material (after a previous step of austenitization) in a temperature range between Ms and Mf (beginning and end temperature of the martensitic transformation, respectively), followed by reheating and maintenance at a temperature above the Ms (isothermal stage of partition) allowing the carbon to migrate from the supersaturated martensite to the remaining austenite, promoting its stabilization. This partition of carbon is only possible if precipitation of cementite is suppressed; this is achieved adding alloying elements such as Si and/or Al. In this work a study was made on the microstructural and mechanical characteristics of a ductile iron (3.47%C; 2.47%Si; 0.2%Mn), submitted to a Q&P heat treatment, in this work named Q & PDI (Quenched and Partitioned Ductile Iron). A full sample austenitization was carried out at 880 ° C for two hours, followed by a pre-heated oil quanching at temperatures of 140 and 170 ° C. The partitioning step was at temperatures of 300, 375 and 450Â ° C, with time intervals ranging from 5 to 120 minutes. Microstructural characterization was performed through optical microscopy, scanning electron microscopy and EBSD. The X-ray diffraction technique was used to quantify the volumetric fraction and the carbon content in the retained austenite. Dilatometry, X-ray diffraction \"in situ\" and nanoindentation were also used to aid in the analysis of the phase transformations that occurred in the partitioning stage, such as the bainitic transformation and the precipitation of transition carbides in the martensite plates. Mechanical characterization was performed through tensile, impact, hardness, nanoindentation, fracture toughness and fatigue strength tests. Compression tests aided in the analysis of the deformation induced martensitic transformation. The results showed that it is possible to obtain nodular cast irons with high mechanical strength (resistance limit> 1450 MPa), with considerable ductility (up to 9%) and energy absorbed under impact (up to 81 J), as well as fracture toughness of 55 MPa.m -1 / 2 and fatigue limits of 550 Mpa. This behavior is provided by a unique microstructure, consisting of a homogeneous dispersion of martensite plates in a very refined ausferrite matrix, with considerable volumetric fractions of retained austenite (max. 23%).

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25

Ceccon, Lorenzo. "Effetto dell'esposizione ad alta temperatura su microstruttura e proprietà meccaniche di ghise sferoidali." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

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Lo scopo della presente ricerca è stato valutare l’effetto dell’esposizione ad alta temperatura su microstruttura e proprietà meccaniche di quattro ghise sferoidali prodotte dalle Fonderie Zanardi: ADI 1050 (ghisa duttile austemperata), IDI 800 (ghisa perlitica isotermica), GJS/800-2 (ghisa sferoidale perlitica) e GJS/400-18 (ghisa sferoidale ferritica). Lo studio ha previsto il degrado in temperatura dei quattro materiali, l’analisi delle proprietà meccaniche statiche dopo degrado termico mediante prove di durezza Brinell, analisi microstrutturali, XRD, prove di trazione sia a freddo che alla temperatura di degrado. Per quanto concerne le prove di durezza, è emerso che superata la temperatura di 500 °C la durezza dei materiali ADI 1050 e IDI 800 cala significativamente, la durezza della GJS/800-2 risulta stabile fino a 550 °C, mentre per la GJS/400-18 la durezza rimane pressoché costante fino a 600 °C. Le analisi microstrutturali hanno mostrato che nell’ADI 1050, IDI 800 e GJS/800-2 la matrice si trasforma sino a diventare quasi completamente ferritica a temperatura di degrado di 600 °C mantenuta per 120 ore. Nella ghisa sferoidale ferritica invece non vi sono mutamenti significativi nella microstruttura dopo degrado. Le prove di trazione svolte sulla lega ADI 1050 hanno evidenziato una diminuzione di circa 50-60 % della tensione di rottura e quella di snervamento nei provini degradati e trazionati a 500°C rispetto ai provini degradati trazionati a temperatura ambiente, ed una diminuzione di circa 20 % della tensione di rottura e quella di snervamento nei provini degradati rispetto ai provini non degradati trazionati a temperatura ambiente. Le prove di trazione a temperatura ambiente su ghisa sferoidale perlitica degradata hanno mostrato un calo delle proprietà resistenziali di circa il 6% nei provini degradati a 240 ore mentre nella ghisa IDI 800 degradata si è notato un calo di circa il 10% delle proprietà resistenziali già nei provini degradati a 72 ore

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26

Viskupič, Adam. "Vysokoteplotní koroze litin s kuličkovým grafitem typu SiMo." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319266.

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While using iron castings behind temperature of 500 C namely at cyclic heat straining degradation of structure and breaching iron castings. For this purpose introduce cast iron with content of Si and Mo. Focusing on improvement of SiMo51 for increased high-temmperature corrosion-and fatigue life in exhaust-gas temperatures up to 800 C. Thesis set up chemical microheterogeneity, properties, high temperature corosion and microhardness

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Magalhães, Elton Franco de. "Caracterização e proposição de métodos estimativos das propriedades monotônicas e cíclicas dos ferros fundidos nodulares." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-03052012-165941/.

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Para o correto dimensionamento da maioria dos componentes estruturais é necessário informações sobre a resposta do material quando submetido à fadiga de alto e baixo ciclo, bem como conhecer as propriedades monotônicas (não-cíclicas) e cíclicas dos materiais. Na literatura são encontradas amplas divulgações de dados sobre diversos materiais de engenharia (Ex. SAE J1099 Technical Report on Fatigue Properties). Porém, quando se trata de ferro fundido nodular estas informações são limitadas, sendo assim, visa-se neste trabalho caracterizar as propriedades monotônicas e cíclicas destes materiais em complemento aos trabalhos já publicados na literatura e propor métodos para a estimativa destas propriedades a partir da dureza. Faz-se necessário a proposição de métodos estimativos das propriedades mecânicas destes materiais baseados na dureza devido às suas grandes variações que são inerentes ao processo de fundição. Em um mesmo componente podem existir diferentes classes de ferro fundido, que apesar de possuir a mesma composição química, podem apresentar variações nas propriedades mecânicas devido à formação de diferentes estruturas metalúrgicas que são sensíveis às taxas de resfriamento do material que variam de acordo com as características geométricas da peça que está sendo fundida, principalmente a variação da espessura. Neste estudo a determinação das relações entre as propriedades monotônicas e cíclicas dos ferros fundidos nodulares foram obtidas a partir do tratamento dos dados publicados na literatura levando-se em consideração o índice de qualidade. Foi proposto um modelo contínuo com relação à dureza para a estimativa das propriedades monotônicas, do coeficiente de resistência cíclico e do expoente de encruamento cíclico e para a estimativa das propriedades cíclicas que experimentalmente demonstraram não ter correlação com a dureza foi proposto uma forma discreta, que consistiu na recomendação de valores típicos definidas por faixas de dureza.
For the correct design of the most part of structural components is necessary to have information about the material response under both high cycle and low cycle fatigue, as well as the knowledge of monotonic and cyclic materials properties. In literature a major publication of several engineering material data can be found (e.g, SAE J1099 - Technical Report on Fatigue Properties), but regarding to ductile iron this information is quite limited. Therefore, this work aims to characterize the monotonic and cyclic properties of this material in complementing to the available data in the literature and also make a proposition of methods to estimate this properties from hardness. The mechanical properties estimation model from hardness is relevant to take into account the inherent variations of casting process, which for the same chemical composition can be found different grades in a same part. This fact occurs due to the formation of different metallurgical structures that is influenced by cooling ratio which changes accordingly to geometrical characteristic of the part, especially the thickness variation. In this study the determination of the relation between monotonic and cyclic properties from hardness has been determined from literature data processing taking into account the Quality Index. For monotonic properties, the cyclic strength coefficient and the cyclic strain hardening exponent estimation has been proposed a continuous method based on hardness and for the cyclic properties that experimentally showed to remain independent of hardness has been recommended one set of properties for specific hardness ranges.

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Zapletal, Josef. "Nízkocyklové a vysokocyklové únavové vlastnosti ADI." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233981.

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The thesis is focused on assessment of fatigue behaviour of austempered ductile iron with nodular graphite. Optimal period of transformation was determined based on the best combination of stress and strain characteristics established by tensile test. Cyclic response and low-cycle fatigue life were studied under both stress-control and longitudinal strain-control mode at room temperature. For both modes, shapes of cyclic hardening curves are dependent on stress amplitude. Cyclic deformation curves (CDC) were fitted by power regression function. Results were compared with CDC established by multiple step test in both modes with verification of the influence of cyclic creep (high stress levels, stress-control mode). Experimental data of S-N curves are in agreement with the Manson-Coffin and the Basquin law. Fatigue and cyclic parameters were compared. Fatigue life time in high-cycle fatigue region was determined. Experimental data were fitted by suitable regression functions. Regression parameters and fatigue limit were established by means of each regression function. Experimental data in low- and high-cycle fatigue regions were used to construct S-N curve and to determine relevant parameters. Discontinuity of experimental data was not observed. Low-cycle fatigue behaviour was predicted. Approximation of tolerance bands was realized in high-cycle and both high and low cycle fatigue regions.

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Ekström, Madeleine. "Oxidation and corrosion fatigue aspects of cast exhaust manifolds." Doctoral thesis, KTH, Mekanisk metallografi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166274.

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Emission regulations for heavy-duty diesel engines are becoming increasingly restrictive to limit the environmental impacts of exhaust gases and particles. Increasing the specific power output of diesel engines would improve fuel efficiency and greatly reduce emissions, but these changes could lead to increased exhaust gas temperature, increasing demands on the exhaust manifold material. This is currently the ferritic ductile cast iron alloy SiMo51, containing about 4 wt% Si and ~1 wt% Mo, which operates close to its fatigue and oxidation resistance limits at peak temperature (750C). To ensure high durability at higher temperatures, three different approaches to improving the life of exhaust manifolds were developed in this thesis. The first approach was to modify SiMo51 by adding different combinations of Cr and Ni to improve its high-temperature strength and oxidation resistance, or by applying a thermal barrier coating (TBC) to reduce the material temperature and thereby improve fatigue life. In the second approach, new materials for engine components, e.g. austenitic ductile iron and cast stainless steel, were investigated for their high-temperature fatigue and oxidation properties. In order to identify the most suitable alloys for this application, in the third the environmental effects of the corrosive diesel exhaust gas on the fatigue life of SiMo51 were investigated. The high-temperature oxidation resistance of SiMo51 at 700 and 800C in air was found to be improved by adding Cr, whereas Ni showed adverse effects. The effects of solid-solution hardening from Ni and precipitation hardening from Cr were low at 700C, with improvements only at lower temperatures. Applying a TBC system, providing thermal protection from a ceramic topcoat and oxidation protection from a metallic bond coat, resulted in only small reductions in material temperature, but according to finite element calculations still effectively improved the fatigue life of a turbo manifold. Possible alternative materials to SiMo51 identified were austenitic cast ductile iron Ni-resistant D5S and austenitic cast stainless steel HK30, which provided high durability of exhaust manifolds up to 800 and 900C, respectively. Corrosion fatigue testing of SiMo51 at 700C in diesel exhaust gas demonstrated that the corrosive gas reduced fatigue life by 30-50% compared with air and by 60-75% compared with an inert environment. The reduced fatigue life was associated with a mechanism whereby the crack tip oxidized, followed by crack growth. Thus another potential benefit of TBC systems is that the bond coat may reduce oxidation interactions and further improve fatigue life. These results can be used for selecting materials for exhaust applications. They also reveal many new research questions for future studies. Combining the different approaches of alloy modification, new material testing and improving the performance using coatings widened the scope of how component life in exhaust manifolds can be improved. Moreover, the findings on environmental interactions on SiMo51 fatigue provide a completely new understanding of these processes in ductile irons, important knowledge when designing components exposed to corrosive environments. The novel facility developed for high-temperature corrosion fatigue testing can be useful to other researchers working in this field.

QC 20150507

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30

Mariani, Fábio Edson. "Tratamentos térmicos e termoquímicos de boroaustêmpera em ferros fundidos nodulares e caracterização dos produtos resultantes." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-05092014-082721/.

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Amostras de ferros fundidos nodulares ligados com Cu, Cu-Ni ou Cu-Ni-Mo foram austemperadas, boretadas e boroaustemperadas e caracterizadas quanto à dureza e o comportamento ao desgaste microadesivo, tendo sido também estudada a cinética de formação da camada. O método de boretação utilizado foi via líquida em banho de bórax fundido, com tempos de permanência de 2 e 4 horas nas temperaturas de 850, 900 e 950ºC. Procedeu-se o tratamento direto de austêmpera, a partir dessa temperatura, em banhos de sal fundidos nas temperaturas de 240, 300 e 360ºC com tempos de permanência de 4 horas (boroaustêmpera). Realizou-se também, para fins de comparação, tratamento convencional de austêmpera. Microscopias óptica e eletrônica de varredura, EDS por raios-X, testes de dureza Brinell (substrato) e Vickers (revestimento) foram realizados, bem como ensaios de desgaste microadesivo do tipo esfera presa. A boretação resultou na formação de camadas de elevadas durezas, na faixa de 1300 a 1700 HV, e elevadas resistências ao desgaste. As resistências ao desgaste das amostras boretadas ou boroaustemperadas foram aumentadas em até 40x em relação às amostras brutas de fundição ou apenas austemperadas, indicando a grande eficácia do tratamento neste tipo de propriedade.
Samples of ductile cast iron alloyed with Cu, Cu-Ni or Cu-Ni-Mo were austempered, borided and boroaustempered and afterwards characterized for hardness and micro-adhesive wear behavior. The kinetics of layer formation were also studied. The boriding method used was liquid molten borax bath, in periods of 2 and 4 hours at temperatures of 850, 900 and 950°C. The direct austempering treatment was performed from the borax bath temperature using molten salt baths at temperatures of 240, 300 and 360°C for 4 hours (boroaustempered). For comparative purposes, the conventional austempering treatment was also conducted. Optical microscopy, scanning electron microscopy, EDX, Brinell hardness measurements (substrate) and Vickers (coating) were performed, as were the tests for micro-adhesive wear. The boriding treatment resulted in the formation of layers with high hardness, in the range of 1300 to 1700 HV and high wear resistance. The wear resistance of borided or boroaustempered samples were increased by 40 times when compared to cast irons or austempered samples, indicating the high efficiency of this type of treatment in increasing the wear resistance of this material.

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31

"Ductile white cast iron." 2008. http://library.cuhk.edu.hk/record=b5896770.

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Ho, Ching Man = 可柔韌的白鑄鐵 / 何靜雯.
Thesis submitted in: November 2007.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2008.
Includes bibliographical references (leaves ).
Text in English; abstracts in English and Chinese.
Ho, Ching Man = Ke rou ren de bai zhu tie / He Jingwen.
Chapter Chapter 1: --- Introduction --- p.1
Chapter 1.1 --- Introduction of Composites --- p.1
Chapter 1.1.1 --- Dispersion-Strengthened composites --- p.2
Chapter 1.1.2 --- True Particulate Composites --- p.2
Chapter 1.1.3 --- Fiber-Reinforced Composites --- p.2
Chapter 1.1.4 --- Laminar Composites --- p.3
Chapter 1.2 --- Mechanical Properties of Metal Matrix Composites --- p.4
Chapter 1.2.1 --- Stress-Strain Test --- p.4
Chapter 1.2.2 --- "Stiffness, Strength and Ductility" --- p.4
Chapter 1.2.3 --- Hardness --- p.5
Chapter 1.3 --- Fabrication of Metal Matrix Composites --- p.5
Chapter 1.3.1 --- Liquid ´ؤ´ؤ State Processing --- p.6
Chapter 1.3.1.1 --- Infiltration Processes --- p.6
Chapter 1.3.1.2 --- Dispersion Processes --- p.7
Chapter 1.3.1.3 --- Spray Processes --- p.7
Chapter 1.3.1.4 --- In - Situ Processes --- p.8
Chapter 1.3.2 --- Solid - State Processing --- p.8
Chapter 1.3.2.1 --- Diffusion Bonding --- p.8
Chapter 1.3.2.2 --- Deformation Processing --- p.9
Chapter 1.3.2.3 --- Deposition Techniques --- p.9
Chapter 1.4 --- Fabrication of Metal Matrix Composites by Spinodal Decomposition --- p.10
Chapter 1.4.1 --- Phase Transformation --- p.10
Chapter 1.4.2 --- Nucleation and Growth --- p.12
Chapter 1.4.2.1 --- Kinetics of Nucleation and Growth --- p.12
Chapter 1.4.2.2 --- Phase Separation by Nucleation and Growth --- p.14
Chapter 1.4.3 --- Spinodal Decomposition --- p.14
Chapter 1.4.3.1 --- Phase Separation by Spinodal Decomposition --- p.14
Chapter 1.4.3.2 --- The Diffusion Equation for Spinodal Decomposition --- p.15
Chapter 1.4.4 --- Methods to obtain large undercooling --- p.17
Chapter 1.5 --- Aim of This Project --- p.18
Chapter Chapter 2: --- Experimental --- p.26
Chapter 2.1 --- Preparation of fused silica tube --- p.26
Chapter 2.2 --- Preparation of Sample --- p.26
Chapter 2.2.1 --- Weighing and Alloying --- p.26
Chapter 2.2.2 --- Fluxing --- p.27
Chapter 2.3 --- Slow Cooling --- p.28
Chapter 2.4 --- Microstructure Analysis --- p.28
Chapter 2.4.1 --- Optical Microscope (OM) Analysis --- p.28
Chapter 2.4.2 --- Sample Preparation for Scanning Electron Microscope (SEM) Analysis --- p.29
Chapter 2.4.3 --- Sample Preparation for Transmission Electron Microscope (TEM) Analysis --- p.29
Chapter 2.4.3.1 --- Specimen Requirement --- p.29
Chapter 2.4.3.2 --- "Cutting, Grinding and Polishing" --- p.30
Chapter 2.4.3.3 --- Ion Milling --- p.31
Chapter 2.5 --- Microstructure Characterization by TEM --- p.31
Chapter 2.5.1 --- Indexing Diffraction Pattern --- p.31
Chapter 2.5.2 --- Energy Dispersive X-Rav (EDX) Analysis --- p.32
Chapter 2.6 --- Mechanical Properties --- p.33
Chapter 2.6.1 --- Hardness Testing --- p.33
Chapter 2.6.2 --- Compression Testing --- p.33
Chapter 2.7 --- Characterizations of Non-spinodal Samples --- p.34
Chapter Chapter 3: --- Study of the Relationship between Microstructures and Undercooling of Fe81C14Si5 --- p.41
Chapter 3.1 --- Abstract --- p.41
Chapter 3.2 --- Introduction --- p.42
Chapter 3.3 --- Experiment --- p.42
Chapter 3.4 --- Results --- p.44
Chapter 3.5 --- Discussion --- p.46
Chapter 3.6 --- Conclusion --- p.46
Chapter Chapter 4: --- Ductile white cast iron --- p.56
Chapter 4.1 --- Abstract --- p.56
Chapter 4.2 --- Introduction --- p.57
Chapter 4.3 --- Experimental --- p.58
Chapter 4.4 --- Results --- p.60
Chapter 4.5 --- Discussions --- p.66

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32

Shama, Shaik. "Comparison of Mechanical Properties of Austenitic Ductile Cast Iron with Ferritic/Pearlitic Ductile Cast Iron." Thesis, 2017. http://ethesis.nitrkl.ac.in/8480/1/2016_PhD._SShama_613MM3016.pdf.

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Austenitic ductile iron belongs to the family of ductile iron which performs better properties than conventional ductile iron due to its soft matrix. Ductile iron (DI) has got enormous applications in different fields such as wind turbines, automotive components, spun pipe and fittings etc. As mechanical properties are primarily dependent on the matrix structure, different heat treatments are performed to the ductile iron to achieve required matrix. Alloying additions are made to stabilize the matrix structure at all the temperatures. In the present work, investigation has been conducted on mechanical properties of Ferritic/PearliticDuctile Iron and Austenitic Ductile Iron and comparison has been made by varying different heat treatments. Here, Austenitic phase is stabilized by adding Nickel as alloying element. Stress relieving and austempering heat treatments are performed to Ferritic/Pearlitic Ductile Iron. Stress relieving treatment is carried out by heating the specimen to 600˚C, furnace cooling to 290˚C followed by air cooling to room temperature. Austempering treatment is carried out by heating the sample to 925˚C, quenching in salt solution maintained at 475˚C followed by air cooling to produce ausferritic matrix. Annealing treatment is done to Austenitic Ductile iron by heating the specimen to 1000˚C and then furnace cooled to room temperature to produce coarse grain structure. The microstructures of all the heat treated and as cast specimens are viewed under optical microscope and planes obtained for different phases are determined using X-Ray diffractometer. Morphological quantification like nodularity, nodule count are determined by following ASTM E2567-13a standard. Mechanical properties like tensile tests and hardness are conducted on (UTM) INSTRON-1995 and Vickers hardness tester respectively. Impact energies at room temperature and -20˚C are determined from Charpy impact tester. Fractures surfaces are viewed under scanning electron microscope in order to find out the type of fracture the specimen has undergone. The results showed that the microstructures of as cast and stress relieved Ferritic/Pearlitic Ductile iron have 98% modularity with approximately83% ferrite as its matrix and 17% graphite, leading to higher amount of ductility and impact toughness. Whereas ADI consists of 93 % upper bainite and7% graphite nodules, resulting in higher hardness with considerable amount of ductility due to 95% nodularity. The redistribution of Carbon in austenite was shown 1.104%. Austenitic Ductile iron consists of uniform 88 % austenitic matrix and 12% graphite nodules embedded in it with around 96 % nodularity. Austenitic Ductile Iron showed lower hardness and tensile strengths with higher elongations when compared to all the as cast and heat treated Ferritic/PearliticDuctile iron. As cast and stress relieved Ferritic/PearliticDuctile iron showed lower impact energies with quasi cleavage mode of fracture at room temperature but at -20˚C the values were decreased leading to slight brittleness in the material. Austempered Ductile iron showed brittle fracture at -20˚C from quasi cleavage fracture at room temperatures. Whereas austenitic ductile to brittle transition has occurred.

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Patra, Sanjeev Kumar. "Characterization of Dual Matrix Structured Ductile Iron." Thesis, 2016. http://ethesis.nitrkl.ac.in/8384/1/2016_MT_711MM1087_SKPatra.pdf.

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The dual matrix structured ductile iron consists of a soft phase(ferrite)and a hard phase(martensite).The combination of soft and hard phase increases the toughness and strength significantly and meets the requirement of automotive industries for their application in suspension parts.This investigation relates the variation of mechanical properties of dual matrix structured ductile iron with different ferrite and martensite volume fraction as the microstructure and amount of distribution of these phases control the mechanical properties.The DMS ductile iron was obtained by heating the as cast ductile iron to intercritical austenizing temperature of 800°C then holding for 2 mins and followed by quenching in mineral oil.The ferrite and martensite volume fraction was calculated by image analysing software.The effect of ferrite and martensite volume fraction on tensile strength,yield strength and percentage elongation was studied.In this investigation it was found that the Ultimate tensile strength increases and ductility decreases with the increase in martensite volume fraction and decrease in ferrite volume fraction.The dual matrix structured ductile iron with higher volume fraction of martensite results in higher tensile strength and hardness and reduction in ductility.And subsequently the DMS ductile iron with higher ferrite volume fraction results increase of ductility and decrease of hardness and tensile strength.The ultimate tensile stress of DMS ductile iron is much higher than ferritic grades and ductility is somewhat lower than ferritic grade of ductile iron.

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34

Chou, Jaw-Min, and 周兆民. "Austenitic Transformation in Ferritic Ductile Cast Iron." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/54515720878251638679.

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35

Panda, Ranjit Kumar. "Effect of copper on austempering behavior of ductile iron." Thesis, 2011. http://ethesis.nitrkl.ac.in/2868/1/thesiss.pdf.

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Even since its discovery in 1948, the use of ductile iron is increasing continuously, this is due to the combination of its various excellent mechanical properties. Excessive amount of research is being carried out to develop even better properties. Austempererd ductile iron is the most recent development in the area of ductile iron or S.G. ron. This is formed by an isothermal heat treatment of the ductile iron. The newly developed austempered ductile iron is now replacing steel in many fields so it has becoming very important to various aspects of this material. In the present work the effect of copper along with the process variables (austempering temperature and austempering time) on the properties (Hardness, Tensile strength and Elongation) and microstructure of ductile iron is studied. With increasing austempering time hardness, tensile strength and elongation are increasing but with increasing austempering temperature hardness and tensile strength are decreasing and elongation increasing. Austempered ductile iron with copper is showing some higher strength, hardness and lower elongation than the austempered ductile iron without copper. In microstructure ferrite is increasing with increasing austempering time and austenite is increasing with increasing austempering temperature in both the grades.

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36

Behera, Litu. "Mechanical property investigation of hardened and tempered ductile iron." Thesis, 2014. http://ethesis.nitrkl.ac.in/6374/1/E-31.pdf.

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In their attempt to develop a particular type of cast iron having better mechanical properties than the malleable iron, the scientists ultimately discovered the spheroidal graphite (S.G) Iron. In this type of cast iron, graphite is present in the form of nodules so it doesn’t break the continuity of structure. Moreover due to the regular shape of graphite, it provides ample amount of plasticity unlike gray cast iron where the flake of graphite acts of sharp notches and thus destroy plasticity. Due to its excellent combination of strength, ductility and toughness the S.G Iron is now being widely used in different structural applications and now-a-days it is replacing steel in various fields. The properties of S.G Iron can be improved further by means of proper heat-treatment procedure. In the present work, efforts have been made to study the effect of tempering on S.G Iron and correlate the properties with the micro-structure.

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37

Oliveira, Carlos Manuel Gomes. "Effect of lanthanum addition in ductile cast iron." Master's thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/89138.

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38

Misorski, Christopher John. "Solidification developments in heavy section ductile cast iron." 1988. http://catalog.hathitrust.org/api/volumes/oclc/19034680.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1988.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 140-148).

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39

Oliveira, Carlos Manuel Gomes. "Effect of lanthanum addition in ductile cast iron." Dissertação, 2013. https://repositorio-aberto.up.pt/handle/10216/89138.

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40

Behera, Gourahari, and Soumya Ranjan Sohala. "Effect of copper on the properties of austempered ductile iron castings." Thesis, 2012. http://ethesis.nitrkl.ac.in/3835/1/2012BTECHTHESIS.pdf.

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Two types of ductile iron has been taken for the present investigation. Both austempering time and temperature are considered as the main variables for structure property correlation of Austempered Ductile Iron. The two types of spheroidal graphite iron (differ by copper percentage) were austempered at four differing austempering temperatures viz. 250oC, 300oC, 350oC and 400oC for 60min, 90 min and 120 min respectively. The effect of austempering variables on the mechanical properties of spheroidal graphite iron was investigated as a function of austempering time and temperature. The cooling rate and the quenching techniques followed in the present study plays an important role for the property development of spheroidal graphite iron. The tensile properties have been correlated with the graphite morphology for both grades of ADI. SEM micrographs have been taken from fracture surfaces of the tensile specimen under different austempering conditions. It has been found from the result that ADI having the alloying element (copper) achieved significant mechanical properties as compared to ADI without having copper throughout the different austempering processes adopted in this study.

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41

Das, Amar Kumar. "Effect of Processing Parameters on Properties of Alloyed Austempered Ductile Iron." Thesis, 2012. http://ethesis.nitrkl.ac.in/5461/1/AKD_M._Tech_(R)_Thesis.pdf.

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Ever since its discovery in 1948, the use of ductile iron is increasing continuously, this is due to the combination of its various excellent mechanical properties of the material. Extensive research is being carried out to develop even better properties. Austempered ductile iron is the most recent development in the area of ductile iron or S.G. iron. This is formed by an isothermal heat treatment of the ductile iron. The newly developed austempered ductile iron is now replacing steel in many fields so it is becoming very important to study various aspects of this material. In the present work the effect of Copper and Nickel as alloying element along with the process variables (austempering temperature and austempering time) on the properties (Hardness, Tensile strength and Elongation) and microstructure of ductile iron has been studied. With increasing austempering time hardness, tensile strength and elongation are increasing but with increasing austempering temperature hardness and tensile strength are decreasing and elongation increasing. Austempered ductile iron with alloying element (Cu or Ni) is showing some higher strength, hardness and lower elongation than the unalloyed austempered ductile iron. In microstructure ferrite is increasing with increasing austempering time and austenite is increasing with increasing austempering temperature in all the Cu alloyed, Ni alloyed and unalloyed grades.

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42

Tangi, Lakshmana Rao. "Effect of processing parameters on austempering behavior of alloyed/unalloyed ductile iron." Thesis, 2012. http://ethesis.nitrkl.ac.in/3880/1/Laxman_Thesis.pdf.

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Ever since its discovery in 1948, the use of ductile iron is increasing continuously due to the combination of its various excellent mechanical properties. Excessive amount of research is being carried out to develop even better properties. Austempererd ductile iron is the most recent development in the area of ductile iron or SG iron. Two types of spheroidal graphite (SG) cast iron samples with different weight percentage of copper were austempered at four different temperatures. The austempering temperatures were 200°C, 300°C, 350°C, 400°C.The influence of austempering process (i.e time and temperature) on the mechanical properties of spheroidal graphite iron was investigated as a function of austempering time and temperature. The cooling rate and the quenching technique adopted play an important role for the property development of spheroidal graphite iron. XRD analysis has also been carried out to study the formation different phases during isothermal transformation at different austempering conditions. Graphite morphology has been studied by SEM. The samples were taken for XRD analysis from the centre of the castings for this investigation. It was found that both the austenite (111) and ferrite (110) lines are identified nearly in all cases. The maximum intensity of the austenite (111) line is increasing with increasing temperature but ferrite (110) line is increasing with increasing austempering time and decreasing with austempering temperature. Hence austempering calls for very precise control of process variables (austempering time and temperature). It has been found from the result that ADI having the alloying element copper (grade N2) achieved significant mechanical properties as compared to other grade (N1) throughout the different austempering process adopted in this study.

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43

Ranjan, Atul, and Manindra Ranjan. "Effect of Isothermal Annealing Temperature and Cooling Rate on Mechanical Properties of Ductile Iron." Thesis, 2013. http://ethesis.nitrkl.ac.in/4893/1/109MM0125.pdf.

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A block of ductile Iron of known composition was procured and samples for various testing were cut out from that block. Tensile test specimens were machined from the block according to the ASTM E8 (Flat sub-size specimen) standard. From a set of nine specimens, three were kept untreated whereas the other six specimens were annealed isothermally following different cooling rates. All the six specimens were heated isothermally to 1000°C and held there for 90 minutes. Out of the six, three specimens were first cooled to 700°C immediately after 90 minutes and held there for 330 minutes and followed by cooling to room temperature. The rest three were immediately cooled after 90 minutes to room temperature. All the six specimens were cooled inside the furnace. Tensile test was performed at room temperature using INSTRON 1195 UTM at a crosshead speed of 1mm/min. After completion of tensile test the broken specimens were cut down to small pieces to study the fracture surface. Hardness values were recorded from Vickers hardness tester by application of 20Kg load at room temperature. X-ray diffraction technique was employed for phase analysis with Philips PANalytica x-ray diffractometer. Graphs were plotted comparing yield strength, elongation and hardness values for the “as-cast” and both the annealed samples.

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44

Kumar, Ravindra. "Effect of Tempering Temperature and Time on Strength and Hardness of Ductile Cast Iron." Thesis, 2015. http://ethesis.nitrkl.ac.in/7285/1/2015_Effect_Kumar.pdf.

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The use of ductile cast iron is as an engineering materials has been increase day by day. it is widely used in manufacturing industry. It have excellent combination of mechanical properties due to same heat treatment process at different time and temperature. It have an excellent combination of tensile strength, wear resistance, good corrosion resistance, good ductility, toughness, impact strength, by using different types of heat treatment process. The effects of tempering temperature and time on the mechanical properties of ductile cast iron is investigated in the current work. The all sample were austenitized at 900°C for 120 minutes and then quenched in mineral oil at room temperature. After quenching the specimens were tempered at 400°C and 200°C for 60min, 90min, and 120min, respectively. In the tempering temperature range of 200°C - 400°C, there is sudden increase in impact strength, ductility and toughness of the materials, as the temperature and time increase. The Ultimate tensile strength drops initially, and hardness of materials will also depends on amount of matrix phase of martensitic and retain- austenitic /ferrite and graphite nodules. In this work alloying elements also effected the microstructure of the specimen. And due to increase tempering time the amount of martensitic phase will decrease and austenitic phase will increase, austenitic phase is softer then martensitic so hardness will decrease. And sample treated to ball on plate wear tester under 20N load at constant speed 10rpm with different times 10min, 20min, 30min for sliding distance 4mm track diameter respectively of same sample. Weight loss was observed in all sample after wear test, the wear resistance was calculated according to the ASTM G 65 standard, and the result showed that in all cases, when the nodules count and nodularity increase the wear resistance decrease and when tempering time and temperature increase the wear resistance will also effected. And by XRD investigate the different matrix and volume fraction, peak analysis.

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45

Javaid, Amjad. "Morphological features of spheroidal graphite in ductile cast iron." 1989. http://catalog.hathitrust.org/api/volumes/oclc/20078809.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1989.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 108-113).

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46

Nikolai, Michael F. "Effects of tinned steel scrap in ductile cast iron." 1994. http://catalog.hathitrust.org/api/volumes/oclc/32845522.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1994.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves vi-vii).

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47

Simonite, Kenneth G. "An investigation of possible superplastic conditions in ductile cast iron." 1992. http://hdl.handle.net/1993/18686.

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48

Lu, Guan-Long, and 呂冠龍. "Study on the Silicon Solution Strengthened Ferritic Ductile Cast Iron." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8fq8e4.

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碩士
國立臺灣大學
機械工程學研究所
105
The objective of this research is to evaluate the property characteristics of solution strengthened ferritic ductile iron (SSF), the so-call second generation of ductile irons, with different Si contents, ranging from 4.0 to 4.5 wt%. In addition, the properties of SSF ductile irons (grade EN-GJS-600-10) were compared with the conventional ductile iron grade of EN-GJS-600-3 and the Austempered Ductile Iron (ADI) grade of . The tensile test results of SSF ductile irons show that both the tensile and yield strengths increases, while the elongation decreases, as the Si content increases. This is due to the solution strengthening effect of Si on the ferrite phase in the matrix. However, the impact property of SSF ductile irons decreases with increasing Si content due to its embrittling effect. Furthermore, the variation in hardness or the section size sensitivity is the least for SSF, which is followed by ADI, and then the conventional ductile irons. At an approximately same level of tensile strength, SSF ductile irons exhibit higher yield strength and much better elongation (some 2 to 3 times higher) than the conventional ductile irons. On the other hand, both the tensile and yield strengths and impact property of ADI are substantially higher than those of SSF ductile irons, however, the elongation values of ADI are much lower than those of SSF ductile irons.

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49

Mohanty, Sabyasachi. "Effect of Micro Constituents on Wear Properties of Alloyed Ductile Iron." Thesis, 2016. http://ethesis.nitrkl.ac.in/8105/2/2016-MT-214MM1436-Micro_constituents.pdf.

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The current study was focused to study the behavior of DI under dry sliding wear condition and observe the effect of micro constituents, achieved by alloy addition and heat treatment processes. To carry out the study two ductile irons with different compositions were chosen, so that effect of chemical composition can be studied. The DI specimens of both alloys were then subjected to annealing, normalizing, quenching & tempering and austempering heat treatment processes to achieve different microstructure and micro constituents for the alloys. The as-cast and heat-treated specimens were then subjected to Ball-on-plate wear tester under 20N load for 5, 10, 15 and 20 minutes run. The surface morphology and wear mechanism was studied by observing under FESEM. Both the alloys achieved fully ferritic, pearlitic/ferritic, tempered martensitic and coarse upper bainitic matrix with graphite nodules lodged into the respective matrices after subjected to annealing, normalizing, quench & tempering and austempering heat treatments respectively. Whereas the as-cast microstructure for alloy SG-1 was found to be ferritic and that of alloy SG-2 was Bull’s eye ferritic/pearlitic. The Bull’s eye ferritic/pearlitic matrix resulted in higher hardness of SG-2 as-cast specimen than that of SG-1 as-cast specimen with ferritic matrix. Quench and tempering treatment resulted in transformation of as-cast matrix into hard brittle tempered martensitic matrix whereas austempering treatment was resulted in bainitic matrix transformation. The specimens when subjected to Ball-on-plate wear system it was observed that soft annealed and austempered specimens had maximum wear compared to as-cast, normalized and quench & tempered specimens. This behaviour was attributed to the hardness of respective material. Alloy SG-1 was observed to lower wear rate than that of SG-2 due to its higher hardness. The wear behaviour when studied for individual alloys it was observed that specimens subjected to higher cooling rate had better wear resistance due to their hardness but simultaneously considerable wear was also observed due to the increased nodule count that encourages more sites for material removal. The wear was observed to increase linearly with time for all of the heat treated specimens. An adhesive wear phenomenon was observed for as-cast and annealed specimens characterized by the presence of delaminated layer over the worn surface. Whereas for normalized, quench & tempered and austempered specimens plastic deformation was observed characterized by the cracks over the worn surface.

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Swain, S. K. "Effect of Chemistry and Processing Variables on the Mechanical Properties of Thin-wall Ductile Iron Castings." Thesis, 2008. http://ethesis.nitrkl.ac.in/1562/1/SUSANTA_THESIS_PDF.pdf.

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Cast iron is an alloy of iron containing more than 2% carbon as an alloying element. It has almost no ductility and must be formed by casting. Ductile iron structure is developed from the melt of cast iron. The presence of silicon in higher amount promotes the graphitization, inhibiting carbon to form carbides with carbide forming elements present. The carbon forms into spheres when Ce, Mg are added to the melt of iron with very low sulphur content. Due to this special microstructure containing graphite in nodular form ductile iron possesses ductility & toughness superior to that of any cast iron & steel structure resulting in numerous successes in industrial application. Ductile iron castings with 3 and 12 mm thickness with varying chemical composition were cast in furan resin sand molds to identify the effect of sample thickness on microstructural changes and selected mechanical properties. The effect of melt chemistry and molten metal processing variables (i.e., pre-conditioning of the base iron, inoculation type and practice, and pouring temperature, etc.) on the tensile and impact properties of thin-wall ductile iron castings has been investigated. Comparison of 3 and 12 mm sections within the same casting showed that section size was the main factor influencing tensile properties of ductile irons. While many samples from 3 mm sections showed low elongation values, likely caused by a high pearlite content or presence of carbides, many others showed higher elongations and superior strengths well above those required in ASTM A536 grades. At moderate to high elongations, the thin-wall samples were significantly stronger than samples from identical irons of 12 mm section. A direct comparison between impact values could not be made due to different test specimen sizes, but it is clear that toughness in the two section sizes was roughly equivalent when account was made for the total cross sectional area. The main difference between the Impact properties in the two section sizes lay in the relative insensitivity of the thin-section specimens to either melt chemistry or molten metal processing variables. Of the elements contained in the iron, silicon had the greatest effect on the tensile properties of the thin-wall sections. The same increase in silicon content of the thin-wall sections had little effect on impact toughness. As expected, any processing variable that led to an increase in nodule count (with a corresponding increase in ferrite content) led to greater ductility, lower strength, and improved toughness. Of the v variables studied the greatest effect was found to be from late inoculation, base iron preconditioning, and the use of an inoculant containing bismuth and rare earths.

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