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Correa, Zapisotski David, and Martin Wallhed. "Characterizing flowability of metal powders." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254754.
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Powder metallurgy is a growing field with much potential. The core purpose and problem in this work is attempting to describe and understand what and how metal powder properties impact powder flowability. Several powder flow experiments have been performed on eight different metal powders with varying size and of material types to examine correlations and seeing what parameters are important for a well flowing metal powder. Experiments performed consists of hall flow, tap density, angle of repose and a more complex Rheometer analysis. The results found display plenty correlations between different experiments with some deviations as expected due to the nature of occurring errors. The results are all displayed in tables comparing the different metal powders for all experiments. The powder with the best flowability (highly free flowing) scored best across all experiments and tests indicating all tests as significant. A well and free flowing powder is characterized by low values in cohesion, angle of repose, specific energy, etc.Pulvermetallurgi är en växande industri med stor potential. Syftet samt problemet med detta arbete är att försöka beskriva och förstå vilka pulveregenskaper som är betydande för flödet och hur dessa egenskaper påverkar hur pulvret flödar. Flera olika experiment har utförts på åtta olika metallpulver, av varierande sorter material och pulverstorlek, har utförts för att undersöka samband och se vilka pulveregenskaper som är viktiga för ett metallpulver ska ha eftertraktade flödesegenskaper. Utförda experiment består av Hall flöde, tappdensitet, rasvinkel (angle of repose) samt en mer komplex Rheometer analys. Resultaten visar många samband mellan olika experiment och metallpulver med en del avvikelser som väntat på grund av flertalet felkällor. Resultaten för alla pulver och experiment uppvisas i stapelgrafer för enkel överblick och jämförelse. Metallpulvret som påvisade bäst flödesegenskaper (fritt flödande pulver) rankades som bästa pulver i varje experiment vilket indikerar att alla experiment är relevanta. Ett väl flödande metallpulver indikeras av låga värden på kohesion, rasvinkel, specifik energi osv.
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Flyckt, Andreas. "Comparison of 2D and 3D investigations of non-metallic inclusions in metal samples by different analytical methods." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254379.
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The objective of this research is to make a comparison between 2D- and 3D-investigations of non-metallic inclusions (NMIs) in metal samples by different analytical methods. NMIs are undesired particles that degrade the quality of the steel through affecting the mechanical properties. It’s therefor of great importance that NMIs are carefully examined, and the correct investigation method is used depending on what the objective is. The different parameters that were used in this comparison was composition, location, morphology, number and size. The first step in this research was to complete a literature review on the different analytical methods. The examined 2D-methods were ASPEX and INCA Feature, which are automated. The examined 3D-method was electrolytic extraction followed by further examination by SEM, which is a manual examination. The second step was to make an experimental comparison between INCA Feature and electrolytic extraction. It was found that ASPEX and INCA Feature performs well in all parameters except location and morphology, and they are also time-efficient methods. Electrolytic extraction performed well in all parameters but is a time-consuming method. The 2D-methods performs well in the parameters: composition, number and size, and they are also time-efficient. The 3D-method electrolytic extraction is the best when there is a need for a more precise understanding of all the parameters but it’s time-consuming.Målet med denna undersökning är att göra en jämförelse mellan 2D- och 3D-undersökningar av icke-metalliska inneslutningar (IMIs) i metallprover genom olika analytiska metoder. IMIs är oönskade partiklar som försämrar kvalitén av stålet genom att påverkar de mekaniska egenskaperna. Detta ger oss förståelse att det är otroligt viktigt att noggrant undersöka IMIs och även använda korrekt metod beroende på vad målet är. De olika parametrarna som användes i denna jämförelsen var sammansättning, position, morfologi, antal och storlek. Första steget i denna undersökning var att genomföra en litteraturstudie av de olika analytiska metoderna. De 2D-metoder som undersöktes var ASPEX och INCA Feature, dessa är automatiska. Den 3D-metod som undersöktes var elektrolytisk extraktion där resultatet undersöktes med ett SEM. Denna metod är manuell. Det andra steget var att genomföra en jämförelse mellan INCA Feature och elektrolytisk extraktion genom experiment. Resultatet blev att ASPEX och INCA Feature fungerade väl i alla parametrar förutom position och morfologi och att de även är tidseffektiva metoder. Elektrolytisk extraktion fungerar väl i alla parametrar men är en tidsineffektiv metod. 2D-metoderna fungerar bra när det gäller parametrarna sammansättning, antal och storlek, de är även tideffektiva. 3D-metoden elektrolytisk extraktion är den som fungerar bäst när man behöver få en mer detaljerad och noggrann förståelse för de olika parametrarna men den är tidsineffektiv.
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Westerholm, Mikael. "Rheology of the mortar phase of concrete with crushed aggregate." Licentiate thesis, Luleå : Luleå University of Technology, 2006. http://epubl.ltu.se/1402-1757/2006/06/LTU-LIC-0606-SE.pdf.
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Sandberg, Erik. "Energy and scrap optimisation of electric arc furnaces by statistical analysis of process data." Licentiate thesis, Luleå, 2005. http://epubl.luth.se/1402-1757/2005/21.
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Hilding, Tobias. "Evolution of coke properties while descending through a blast furnace." Licentiate thesis, Luleå, 2005. http://epubl.luth.se/1402-1757/2005/19.
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Gahan, Chandra Sekhar. "Comparative study on different industrial oxidic by-products as neutralising agent in bioleaching." Licentiate thesis, Luleå : Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1757/2008/19/.
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Larsson, Robert. "Undersökning av defekter hos ett varmarbetsstål." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-73605.
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Tran, Sam, Niklas Lindborg, Souza Vivedes Danilo De, Johanna Sjölund, Veronica Enblom, and Mattias Sjödin. "Theoretical models of thermal conductivity and the relationship with electrical conductivity for compressed metal powder." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-387636.
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This Independent Project reviews literature about the effect of pressure and temperature on thermal conductivity in packed beds and its relationship with electrical conductivity. Exploring the relationships between thermal conductivity, porosity and pressure can give useful knowledge for further improvements in manufacturing processes in the field of powder metallurgy. The resulting theoretical models describing the effective thermal conductivity show that gas and contact conductance dominate at lower temperatures and that radiation gains dominance as the temperature increases. Modifications of the models covered in this report can be made in order to simulate the process of interest more accurately. It was also shown that Wiedemann-Franz law could be of interest when wanting to quantify the thermal conductivity in a powder compact. Furthermore, a lab manual for a future Independent Project was developed.
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Bubenko, Clara, Karl Magnil, and Melker Olofsson. "An Investigation of Stainless Steels for Long-term Use in Liquid Sodium at up to 700°C." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254324.
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The Swedish company Azelio has developed a high-efficient Stirling engine which is powered by solar energy. Since the access of solar power is limited to day-time, Azelio has also developed their own Thermal Energy Storage (TES), which collects and stores solar energy and thereby provides the engine with energy also during night-time. The engine runs a generator which produces electricity, around the clock. Liquid sodium is used as Heat Transfer Fluid (HTF) from the TES to the engine, and the temperature reaches above 600°C. At these temperatures, sodium is highly reactive and surrounding materials could strain from phenomena such as corrosion and creep. By comparing the commonly known high-temperature classified steel 253 MA to other commercially available steels, a suitable and affordable option that can withstand liquid sodium is sought. From literature studies, a list of candidates was produced. The materials were then mainly analysed upon ingoing alloying elements’ influence on material properties. The austenitic steel 153 MA has some great advantages to 253 MA at these temperatures, such as a more stable microstructure. 153 MA is therefore, from this work, recommended for further investigation.Det svenska företaget Azelio har utvecklat en stirlingmotor som drivs av solenergi. Då tillgången på solenergi är begränsad till dagtid har Azelio också utvecklat en termisk lagringsenhet (TES). Den termiska lagringsenheten absorberar och lagrar solenergi och kan därmed förse stirlingmotorn med värme även under natten. Stirlingmotorn driver i sin tur en generator vilken producerar elektricitet under hela dygnet. Natrium används som värmeledningsfluid (HTF) mellan TES och stirlingmotorn, vid temperaturer över 600°C. Vid dessa temperaturer är natrium högreaktivt och fenomen såsom kryp och korrosion kan uppstå, vilka kan påverka egenskaperna hos omgivande material. Genom att jämföra högtemperaturstålet 253 MA med andra kommersiella stål, eftersöks en kvalificerad och prisvärd legering som kan motstå flytande natrium vid dessa temperaturer. Från en omfattande litteraturstudie skapades en lista med möjliga kandidater. Materialen analyserades sedan i huvudsak utifrån ingående legeringselements påverkan på dess egenskaper. Analysen visar på att 153 MA har några betydande fördelar jämfört med 253 MA, såsom en mer stabil mikrostruktur vid de angivna temperaturerna. Detta arbete rekommenderar därför 153 MA för vidare undersökning och testning.
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Englund, Hanna, and Henrietta Isaksson. "Regulation of Nitrogen Content in High Alloyed Stainless Steels during the AOD Process." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254419.
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As a final step in the argon oxygen decarburisation (AOD) process, argon- and nitrogen gas is blown through the melt. To regulate the nitrogen content in the steel melt during this step a reliable model is needed. With data from 31 heats of the duplex stainless steel SAF2507 collected at Sandvik Materials Technology (SMT), different models are investigated. This is done by looking at the partial pressure of the nitrogen gas and the nitrogen content achieved during each heat. By calculating the nitrogen solubility in the steel melt with different models and then using Sieverts’s law, a partial pressure for the nitrogen gas is obtained for each heat and compared with the data. With adjustments done for a model obtained from J. Kijac et al., more reliable results are attained than by the model used today at SMT. It should be kept in mind that this model is based on the theory with diluted solution and is therefore not optimal for high alloyed steels, and it is suggested to develop a model from a software based on real solution such as Thermo-Calc.I slutskedet av AOD-processen blåses argon- och kvävgas genom stålsmältan. En pålitlig modell behövs för att reglera kvävehalten i stålsmältan under det här steget. Olika modeller undersöks med data från 31 charger av det duplexa rostfria stålet SAF2507 samlad från Sandvik Materials Technology (SMT). Undersökningen sker genom att titta på partialtrycket av kvävgasen och kvävehalten som uppnåddes för varje charge. Genom att beräkna kvävelösligheten i stålsmältan med olika modeller och sedan använda Sieverts lag, kan ett partialtryck för kvävgas räknas ut för varje charge och jämföras med datan. Mer exakta resultat är uppnådda med en justerad modell hämtad från J. Kijac et al. jämfört med den modell använd på SMT idag. Att ha i åtanke är att denna modell är baserad på teori med antagande om utspädd lösning, vilket inte är optimalt för höglegerade stål och ett förslag är att utveckla en modell med hjälp av ett mjukvaruprogram som baseras på äkta lösning såsom Thermo-Calc.
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Helén, Andreas, and Andreas Pettersson. "From Bloomery Furnace to Blast Furnace : Archeometallurgical Analysis of Medieval Iron Objects From Sigtuna and Lapphyttan, Sverige." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254427.
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During the Early Middle Ages, the iron production in Sweden depended on the bloomery furnace, which up to that point was well established as the only way to produce iron. Around the Late Middle Ages, the blast furnace was introduced in Sweden. This made it possible to melt the iron, allowing it to obtain a higher carbon composition and thereby form new iron-carbon phases. This study examines the microstructure and hardness of several tools and objects originating from archaeological excavations of Medieval Sigtuna and Lapphyttan. The aim is to examine the differences in quality and material properties of iron produced by respectively blast furnaces and bloomery furnaces. Both methods required post-processing of the produced iron, i.e. decarburization for blast furnaces and carburization for bloomeries. These processes were also studied, to better understand why and how the material properties and qualities of the items may differ. The results show that some of the studied items must have been produced from blast furnace iron, due to their material composition and structure. These items showed overall better material quality and contained less slag. This was concluded because of the increased carbon concentration that allowed harder and more durable structures such as pearlite to form. The study also involved an investigation of medieval scissors, also known as shears, made from carburized bloomery furnace iron. Here, one specific aim was to find out if the different sections of the shears had different properties, and if so, if these properties correlated with the functions of the different parts of the shears. Our microstructure analysis showed that the blade indeed was the hardest part due to intentional carburization and forming of martensite. The blade is connected to a softer ferritic handle, which in turn is connected to a ductile bow, also ferritic but with a larger grain size.Den svenska järnproduktionen var under medeltiden beroende av blästerugnen som då var väl etablerad i hela landet. Under denna period introducerades även masugnen i Sverige, vilket gjorde det möjligt att smälta järn. Den nya tekniken gjorde det möjligt att uppnå en ökad kolhalt och därmed bilda nya järn/kol-faser. Den här studien undersöker mikrostrukturer och sammansättningar i medeltida järnföremål från arkeologiska utgrävningar i Sigtuna och Lapphyttan. Syftet är att undersöka vilka egenskaper och materialkvaliteter som gick att uppnå i järn som tillverkats med masugn respektive blästerugn. Båda tillverkningsmetoderna kräver efterbearbetningar som förbättrar järnets egenskaper. Även dessa efterbearbetningsmetoder studeras, för att kunna dra slutsatser angående hur det slutligt producerade järnets egenskaper och materialkvalitet skiljer sig mellan de två produktionsmetoderna. Analyserna visade att järn som tillverkats i masugn innehöll mindre slagg och generellt var av bättre kvalitet. Detta järn innehöll även mer kol vilket tillät perlit att bildas. Därmed blev järnet betydlig hårdare. Slutsatsen är att dessa järnföremål hade övergripande bättre mekaniska egenskaper och materialkvalitet än de järnföremål som tillverkats med järn från en blästerugn. I studien undersöks även medeltida fårsaxar, tillverkade av järn från en blästerugn som sedan genomgått uppkolning. Syftet är att utifrån mikrostrukturen i materialet ta reda på om de olika sektionerna i en fårsax har olika egenskaper, och om dessa egenskaper i så fall är anpassade till den aktuella sektionens användning.Analysen visade att bladet var hårdast på grund av avsiktlig uppkolning och martensitbildning. Därefter följde ett mjukare handtag med en ferritisk struktur. Den böjda delen av saxen var den mest duktila och fjädrande, eftersom den uppvisade en rent ferritisk struktur med större kornstorlekar än i handtaget.
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Svensson, Christoffer. "Recrystallization mapping of Ni-base alloys." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-75348.
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Superalloys such as alloy 718 and 925 possesses superior properties at elevated temperatures and corrosive environments. They are commonly found in application such as oil and gas extraction, turbine engines and in the chemistry industry. These alloys were developed during the 1950s but the demand of tubes and pipes of these alloys has rapidly increased. Sandvik has recently started produce these products and faces new challenges within the production.There are several studies within the area of superalloys but the hot working behavior and flow softening mechanism are not fully understood.The goal with this master thesis is to analyze two different steel grades, alloy 718 and 925 and correlate different process parameters that will influence the recrystallization initiation and nucleation.Two ingots manufactured through electric arc furnace, argon oxygen decarburization and refined by vacuum arc remelting were analyzed followed by a homogenization heat treatment. Samples were extracted from three positions, bottom, center, top and from half the radius in the ingot. The chemical composition was analyzed and the mechanical properties was tested trough hot compression testing (Gleeble). From Gleeble testing, the true strain, stress curves were analyzed in order to determine flow softening effects. The microstructure were studied trough light optical microscopy and electron backscatter diffraction.The results reveal that discontinuous dynamic recystallization is the dominant flow softening mechanism. There was no significant difference between the three positioning within the ingot.To maximize the recrystallized area fraction higher strain and temperatures must be provided or lower strain rates.
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Larsson, Karl. "Nötning av verktygsstål vid plåtformning : Inverkan på arbetsmaterialets sträckgräns och påkletningsmotstånd för verktygsstål." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-74519.
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I dagens industri utsätts verktyg vid plåtformning för allt större krafter. Material som ska formas blir starkare behövs också större krafter för at åstadkomma en geometrisk förändring. Detta har medfört att nötningseffekter vid tillverkning har ökat, och ett av dessa problem är galling. Galling, som är ett av huvudproblemen, är en nötningseffekt på verktygen där både adhesiv och abrasiv nötning förekommer. Detta innebär att material lossnar från värdmaterialet och fastnar på verktyget. Då material har överförts till verktyget har det inte längre ursprungsformen och kan leda till ojämnheter i materialet som ska formas. Hittills har företag använt sig av smörjmedel för att minska galling. Eftersom smörjmedel regleras allt hårdare av miljöskäl, måste industrin hitta nya lösningar. En lösning är att skapa verktygsstål som är motståndskraftiga mot galling genom sin mikrostruktur. Det finns fortfarande begränsad kunskap inom området och den här studien syftar till att jämföra två verktygsstål för att avgöra vilket som är mest beständigt mot galling. Verktygsstålen Caldie och Vancron Superclean kommer glida mot materialen DP600 och DP1000. De sistnämnda är de material som formas vid plåtformningen. Där materialen har olika sträckgränser, detta för att se om den har en inverkan vid plåtformning. För att avgöra vilket verktygsstål som är mest lämpligt vid plåtformning kommer en glidsträcka tas fram med hjälp av SOFS metoden. Glidsträckan kommer att ange hur snabbt galling uppstår och således kan ett bättre material bestämmas. Nötningsspåren hos materialen analyserades med hjälp av ett elektronmikroskop för att se hur galling hade påverkat verktygsstål och ytmaterial.Resultatet visade att Vancron Superclean var mer beständigt mot galling, då verktygsstålen gled över DP600, medan ingen slutsats kunde dras när de gled över DP1000.In today's industry, tools are more exposed to larger forces in sheet metal forming. As materials become stronger, larger forces are also needed to achieve a geometric change of the materials. Because of this, abrasion effects in the processes have increased and one of the most common one is galling. Galling is a form of wear where both adhesive and abrasive wear occur. This means that material comes off of the host material and sticks to the tool. When material has been transferred to the tool, it no longer has the original shape and can lead to irregularities in the material to be formed. So far companies have used lubricants to minimize it. As lubricants are increasingly regulated for environmental reasons, the industry must find other solutions to the problem. One solution is to create materials that are resistant to galling through their microstructure. There is still limited knowledge in this area and the aim of this study is to compare two tool steels and investigate which of them is most resistant to galling. The tool steel Caldie and Vancron Superclean will be tested against the materials DP600 and DP1000 usually used in sheet metal forming. Where the materials have different yield strengths, this is to see if it has an impact on sheet metal forming. To decide which tool steel is most suitable for sheet metal forming, a sliding test will be produced using the SOFS method. The sliding distance will describe how quickly galling occurs and thus the better material is determined. The abrasive traces of the materials were analyzed using an electron microscope to see how galling affected the tool steel and surface material.The result showed that the Vancron Superclean was more resistant to galling, as the tool steel slid over the DP600, while no conclusion could be drawn when slipping over DP1000.
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Spector, Robert. "Puckelglödning : En alternativ mjukglödgningsprocess." Thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71952.
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Mjukglödgning av kullagerstål är en förutsättning för att kunna vidareförädla stålet. Processen är idag väldigt tidskrävande vilket gjort den till en flaskhals i produktionen. Detta examensarbete har gått ut på att titta närmare på en snabbare mjukglödgningscykel, kallad puckelglödgning, som idag används i Hofors och ställa det i förhållande till nuvarande cykel som används i Rullhärdugn 1. Genom labbugnstest, dilatometertester samt en skarp körning har data tagits fram för hårdhet och struktur vilket sedan analyserats och jämförts med motsvarande data från dagens process. Målet har varit att se om puckelglödgningen är en praktiskt gångbar process och om den uppfyller de krav på struktur och hårdhet som ställs på stålet efter mjukglödgning. Resultatet har visat på att puckelglödgning ger en godkänd struktur och hårdhet i labbmiljö men att processen i sig ställer höga krav på ugnens kapacitet när det kommer till att använda den i den vanliga produktionen. Resultatet från den skarpa körningen visar att cykeln har svårt att få en likvärdig struktur när större volymer mjukglödgas. Puckelglödgningscykeln som används i Hofors har fördelar jämtemot den cykel som används i Hällefors, men slutsatsen är ändå att en optimering av nuvarande cykel i Hällefors är att föredra framför ett införande av en puckelglödgningscykel.Soft annealing of ball bearing steels is a prerequisite to be able to further process the steel. The process today is very time-consuming which has made it into a bottleneck. The purpose of this thesis has been to study a faster soft annealing cycle called “hump annealing” which is used in Hofors and compare it to the current cycle used in “Rullhärdugn 1” (Roller hearth furnace 1). Through a test in a lab furnace, dilatometer tests and a live test data has been collected on hardness and structure which then has been analyzed and compared against data from the current day process. The goal has been to see if hump annealing is a practically feasible process and if it fulfills the requirements in structure and hardness that is demanded of the steel following soft annealing. The results concluded showed that hump annealing produces an acceptable structure and hardness in lab environment but that the process itself puts high demands on the furnaces capacity when it comes to using it in the regular production. The results from the live test shows that the hump annealing cycle has problems getting an equivalent structure when bigger volumes are soft annealed. The hump annealing cycle do have certain advantages compared to the cycle used in Hällefors but the conclusion is nevertheless that an optimization of the current cycle in Hällefors is preferred to adopting the hump annealing cycle.
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Karmakar, Mattias. "Additive Manufacturing Stainless Steel for Space Application." Thesis, Luleå tekniska universitet, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72901.
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Carsbring, Amanda. "Heat Treatment and Secondary Phase Formation in FeCrNi Medium Entropy Alloys." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291251.
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The topics of high entropy alloys (HEA) and medium entropy alloys (MEA) have been heavily researched in recent years. A HEA usually consists of five or more base elements, and a MEA would have three or four base elements. These types of alloys are multi-principal element alloys (MPEA) that have been thought to have interesting properties due to their high configurational entropy, which was thought to be the reason for stabilized simple solid solution phase in the HEA. The high entropy effect contributing to stable single phase in these alloys has been discussed and has not been found to be a predicament to which MPEA that will present as single phase at lowered temperatures. Still, some of the HEA and MEA investigated have interesting properties such as high ductility and good thermal properties, as is the case for the commonly researched CoCrFeMnNi HEA and the CoCrNi MEA which are both solid solution FCC phase at lower temperatures. This master thesis aims to investigate one of the less commonly researched MEA: equimolar FeCrNi. This alloy has been studied previously, and it was found there might be a possibility of precipitation hardening the alloy. To further study this alloy system, three FeCrNi alloys in the close-to equimolar range were produced and underwent a series of aging heat treatments to study the amount of precipitated secondary phase with composition changes and different aging temperatures. The objective is to evaluate and interpret the data found in the different CALPHAD databases used in Thermo-Calc and FactSage software and make comparisons to the experimental results. This to discuss the possibilities of hardening this alloy through aging treatment. The alloys selected and produced are 33Fe33Cr33Ni, 40Fe30Cr30Ni and 45Fe30Cr25Ni, all in mol%. Through experimental investigation using x-ray diffraction (XRD) analysis, it is found that Cr-rich BCC phase is formed in all alloys after most of the aging treatments performed. The volume fraction of BCC was quantified through the reference intensity ratio (RIR) method. From quantification, the largest volume fraction BCC is found in the equimolar 33Fe33Cr33Ni alloy, and the lowest fraction BCC is shown in the 40Fe30Cr30Ni alloy. The increased volume fraction of BCC coincides with an elevated hardness in all three alloys. It is also found that out of the three equilibrium phase calculations used in this project, the ThermoCalc steel database TCHEA4 seems to give results that are in closest agreement with the experimental results. For future studies in this subject, the recommendation is to further study the mechanical properties of the FeCrNi MEA and assess possibilities for application.Högentropilegeringar och mediumentropilegeringar har studerats närmre de senaste åren på grund av deras intressanta mekaniska egenskaper. En högentropilegering består vanligtvis av fem eller flera baselement, och en mediumentropilegering har tre eller fyra baselement. Detta skiljer dem från konventionella legeringar som i regel har ett, maximalt två, baselement. Dessa typer av multi-baslegeringar har ansetts ha intressanta egenskaper på grund av deras höga konfigurationsentropi, vilken tros vara orsaken till stabilisering av fast lösningsfas i legeringarna. Högentropieffekten som bidrar till stabil enfas i dessa legeringar har diskuterats och har emellertid inte visat sig vara tillförlitligt för att förutsäga vilka multi-baslegeringar som blir fast lösningsfas vid ett lägre temperaturintervall. Ändå har några av de undersökta legeringarna intressanta egenskaper som hög duktilitet och goda termiska egenskaper, vilket är fallet för högentropilegeringen CoCrFeMnNi och mediumentropilegeringen CoCrNi som båda är enkel FCC-fas vid lägre temperaturer. Detta examensarbete syftar till att undersöka en av de mindre omnämnda mediumentropilegeringarna: ekvimolär FeCrNi. Denna legering har studerats tidigare, och det visade sig att det kan finnas en möjlighet att utskiljningshärda legeringen. För att ytterligare studera detta legeringssystem producerades tre FeCrNi-legeringar i ett sammansättningsintervall nära ekvimolär sammansättning, som sedan genomgick en serie åldringsbehandlingar för att studera mängden utskild sekundär fas beroende på sammansättning och åldringstemperatur. Målet är att utvärdera och tolka data som finns i de olika CALPHAD-databaserna som används i beräkningsverktygen Thermo-Calc och FactSage, och därefter göra jämförelser med experimentresultaten. Detta för att diskutera möjligheterna att härda dessa legeringar med partikelutskiljning. De legeringar som valts och tillverkats är 33Fe33Cr33Ni, 40Fe30Cr30Ni och 45Fe30Cr25Ni, alla angivna i molprocent. Genom experimentella undersökningar med röntgendiffraktionsanalys hittades att BCC-fas med höga halter Cr bildats i alla legeringar efter majoriteten av åldringsbehandlingarna som utförts. Volymfraktionen av BCC kvantifierades genom beräkningar från referensintensitetsförhållande (RIR). Från kvantifiering fås den största volymfraktionen BCC i den ekvimolära 33Fe33Cr33Ni-legeringen, och den lägsta fraktionen BCC i 40Fe30Cr30Ni-legeringen. Högre volymfraktion BCC sammanfaller med en förhöjd hårdhet i alla tre legeringarna. Det visar sig också att utav de tre jämviktsfasberäkningarna som används i detta projekt så är det ThermoCalc-ståldatabasen TCFE10 som gett resultat som överensstämmer med experimentresultaten. För framtida undersökningar inom detta område rekommenderas att studera de mekaniska egenskaperna hos FeCrNi och bedöma möjligheterna för tillämpning av materialet.
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Lishchuk, Viktor. "Geometallurgical programs – critical evaluation of applied methods and techniques." Licentiate thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26607.
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Geometallurgy is a team-based multidisciplinary approach aimed at integrating geological, mineralogical and metallurgical information and yielding a spatial quantitative predictive model for production management. Production management includes forecast, control and optimization of the product quality (concentrates and tailings) and metallurgical performance (e.g. recoveries and throughput); and minimization of the environmental impact. Favourable characteristics of an ore body calling for geometallurgical model are high variability, low mineral grades, complex mineralogy and several alternative processing routes or beneficiation methods.Industrial application of geometallurgy is called a geometallurgical program. This study undertook a critical review and evaluation of methods and techniques used in geometallurgical programs. This evaluation aimed at defining how geometallurgical program should be carried out for different kinds of ore bodies. Methods applied here were an industry survey (questionnaire) along with development and use of a synthetic ore body build-up of geometallurgical modules. Survey on geometallurgical programs included fifty two case studies from both industry professionals and comprehensive literature studies. Focus in the survey was on answering why and how geometallurgical programs are built. This resulted in a two-dimensional classification system where geometallurgical program depth of application was presented in six levels. Geometallurgical methods and techniques were summarised accordingly under three approaches: traditional, proxy and mineralogical. Through the classification it was established that due to similar geometallurgical reasoning and methodologies the deposit and process data could be organized in a common way. Thus, a uniform data structure (Papers I, II) was proposed.Traditionally the scientific development in geometallurgy takes place through case studies. This is slow and results are often confidential. Therefore, an alternative way is needed; here a synthetic testing framework for geometallurgy was established and used as such alternative. The synthetic testing framework for geometallurgy consists of synthetic ore body and a mineral processing circuit. The generated digital ore body of a kind is sampled through a synthetic sampling module, followed by chemical and mineralogical analyses, and by geometallurgical and metallurgical testing conducted in a synthetic laboratory. The synthetic testing framework aims at being so realistic that an expert could not identify it from a true one while studying data it offers. Important and unique aspect here is that the geological ore body model is based on minerals. This means that synthetic ore body has full mineralogical composition and properties information at any point of the ore body. This makes it possible to run different characterisation techniques in synthetic analysis laboratory.The first framework built was based on Malmberget iron ore mine (LKAB). Two aspects were studied: sampling density required for a geometallurgical program and difference in the prediction capabilities between different geometallurgical approaches. As a result of applying synthetic testing framework, it was confirmed that metallurgical approach presents clear advantage in product quality prediction for production planning purposes. Another conclusion was that optimising the production based solely on head grade without application of variability in the processing properties gives significantly less reliable forecast and optimisation information for the mining value chain.For the iron ore case study it was concluded that the number of samples required for a geometallurgical program must vary based on the parameters to be forecasted. Reliable recovery model could be established based on some tens of samples whereas the reliable concentrate quality prediction (e.g metal grade, penalty elements) required more than 100 samples. In the latter the mineralogical approach proved to be significantly better in the quality of prediction in comparison to the traditional approach based on elemental grades. Model based on proxy approach could forecast well the response in magnetic separation performance with the help of Davis tube test. But the lack of geometallurgical test for flotation and gravity separation caused that in total the proxy approach forecast capability was worse than in mineralogical approach. This study is a part of a larger research program, PREP (Primary resource efficiency by enhanced prediction), and the results will be applied to on-going industrial case studies.För godkännande; 2016; 20160516 (viklis); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Viktor Lishchuk Ämne: Mineralteknik/Mineral Processing Uppsats: Geometallurgical Programs – Critical Evaluation of Applied Methods and Techniques Examinator: Professor Pertti Lamberg, Institutionen för samhällsbyggnad och naturresurser, Avdelning: Mineralteknik och metallurgi, Luleå tekniska universitet. Diskutant: PhD Simon Michaux, BRGM, University of Liege, Institution of Genie Mineral, Materiaux et Environment, Brisbane Tid: Torsdag 2 juni, 2016 kl 10.00 Plats: F531, Luleå tekniska universitet
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Myrsell, Karl. "Djupkylningens inverkan på struktur och egenskaper för stålsorterna SS716 och Flap-X." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68691.
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Konkurrensen inom stålbranschen blir allt hårdare och för att stanna i toppsegmentet krävs innovation och ständiga förbättringar. Då höglegerade stål såsom rostfria stål kyls till rumstemperatur passeras inte temperaturen för fullständig martensitbildning. Genom att använda flytande kväve kan temperaturen sänkas så lågt som till -196°C. Således kan andelen martensit i provet ökas samtidigt som andelen austenit minskar. I detta examensarbete undersöks hur djupkylning med flytande kväve påverkar stålsorterna Flap-X och SS716 gentemot kylning till rumstemperatur. Målet med arbetet är att genom ett antal olika testmetoder kartlägga djupkylningens inverkan på stålens mekaniska egenskaper och ge underlag till en eventuell investering. Temperaturer och tider för värmebehandling är hämtade ur voestalpine precision strips tillverkning i Munkfors för att kunna simuleras med fullgott resultat. De olika tester som utfördes var hårdhetsmätning med Vickersmetoden, dragprov, utvärdering av mikrostruktur i laserkonfokalmikroskop samt restaustenitmätning med röntgendiffraktometer. Testerna har utförts vid voestalpine i Munkfors, Bergsskolan i Filipstad samt vid Uddeholm i Hagfors. Testresultaten visar en trend till att materialen uppnår en högre hårdhet och lägre halter av restaustenit vid djupkylning. Flap-X uppvisar även viss ökning av sträckgräns samt brottgräns vid djupkylning. SS716 visar ingen ökning av vare sig sträckgräns eller brottgräns. I den mikrostrukturanalys som utfördes av de båda stålen kunde inga större skillnader påvisas mellan djupkylda prov respektive ej djupkylda. Testresultaten ska beaktas som en trend på grund utav statistiskt osäkra värden och omständigheter vid provning såsom inverkan av textur på restaustenitmängden vid röntgenundersökning.
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Awe, Samuel Ayowole. "Hydrometallurgical upgrading of a tetrahedrite-rich copper concentrate." Licentiate thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25657.
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Removal of impurity elements in copper metallurgy is one of the major problems encountered today since pure copper ore reserves are becoming exhausted and the resources of unexploited ores often contain relatively high amounts of antimony, arsenic, mercury and bismuth, which need to be eliminated. The present work aims at pre-treating a tetrahedrite rich complex copper sulphide concentrate by selective dissolution of the impurities, therefore, upgrading it for pyrometallurgical processing. Characterisation of the complex concentrate was performed and the result shows that antimony and part of arsenic were present as tetrahedrite and bournonite. Dissolution kinetics of tetrahedrite in aqueous alkaline sodium sulphide solutions was investigated. It was found that the rate of dissolving tetrahedrite by the lixiviant increases with increase in reaction temperature, sodium sulphide concentration, sodium hydroxide concentration, and with decrease in mineral particle size. The kinetic study indicates that the rate of leaching tetrahedrite in the lixiviant under the selected conditions is chemically controlled through the particle surface reaction. The activation energies of the process were estimated as 81 kJ/mol and 75 kJ/mol, respectively, for antimony and arsenic dissolution from tetrahedrite. The estimated activation energies were within the range reported for a chemically controlled reaction process. Besides, the alkaline sulphide lixiviant proves selective and effective to dissolve these impurity elements from the concentrate with good recoveries. Further investigations on the factors influencing the leaching efficiency of the lixiviant were studied. Analysis of the leach residue indicates that copper content of the tetrahedrite has transformed into copper sulphides with the average chemical formula Cu1.64S. The grade and economic value of the concentrate were improved greatly after sulphide treatment, and therefore, suitable as a feedstock for smelting. The impurities in the concentrate were found to have reduced to a level satisfactory for smelting operation.Furthermore, modelling and optimisation of alkaline sulphide leaching of a complex copper concentrate containing 1.69% Sb and 0.14% Sn were conducted. Response surface methodology, in combination with central composite face-centred design (RSM-CCF), was used to optimise the operating parameters. The leaching temperature, sulphide ion concentration and solid concentration were chosen as the variables, and the response parameters were antimony and tin recoveries, and the time required to achieve 90% Sb dissolution. It was seen that the leaching process was strongly dependent on the reaction temperature as well as the sulphide ion concentration without any significant dependence on the solid concentration. Additionally, a mathematical model was constructed to characterise the leaching behaviour within the experimental range studied. The results from the model allow identification of the most favourable leaching conditions. The model was validated experimentally, and the results show that the model is reliable and accurate in predicting the leaching process.Godkänd; 2010; 20101029 (samawe); LICENTIATSEMINARIUM Ämnesområde: Processmetallurgi/Process Metallurgy Examinator: Professor Åke Sandström, Luleå tekniska universitet Diskutant: PhD Senior Project Manager Gouzhu Ye, Swerea MEFOS AB, Luleå Tid: Fredag den 3 december 2010 kl 10.00 Plats: F531 Bergrummet, Luleå tekniska universitet
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Larby, Line, and Annie Lundberg. "Primary Study of the Phase Relationship in the MgO-"V2O3" System at 1873 K and pO2=10-11 atm." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231901.
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Vanadium can be found in some iron ores as an impurity. Since vanadium is a valuable alloy element there lies an interest in development of a stable and economic way for extraction of it. For this, knowledge about the thermodynamics behind the V-O system combined with other elements, like Mg, is indispensable. A transitional metal like vanadium exists in multiple valences which makes it difficult to study. When vanadium oxide is mixed with other metal oxides the vanadium tends to concentrate in spinels. To investigate the types of phases formed in the Mg-O-V system at 1873 K and an oxygen partial pressure of 10-11 atm, multiple samples containing MgO and V2O3 in different proportions were equilibrated under these conditions. The samples were examined using SEM/EDS and XRD. A three, one and two phase region were found during analysis. In the three phase region MgV2O4, Mg2VO4 and an unidentified solid solution were found when the fraction of V2O3 was 0,234 and 0,448. In the one phase region only MgV2O4 was found at a V2O3 fraction interval of 0,500-0,530. Lastly in the two phase region MgV2O4 and V2O3 was found within the V2O3 fraction interval of 0,549-0,799. In conclusion when there was a higher amount of V2O3 more vanadium rich spinels were formed until a certain point where the spinel was saturated.Vanadin finns i vissa typer av järnmalm som ett spårämne. Eftersom vanadin är ett värdefullt legeringsämne finns det ett stort intresse av att hitta ett hållbart och ekonomiskt sätt att utvinna detta. För att göra det krävs kännedom om termodynamiken bakom V-O-systemet kombinerat med andra ämnen som Mg. Övergångsmetaller som vanadin existerar i ett flertal valenser vilket kan göra det svårt att undersöka dem. När vanadinoxid blandas med andra metalloxider tenderar vanadin att samlas i spineller. För att undersöka vilka faser som bildas i Mg-O-V-systemet vid 1873 K och ett syrepartialtryck på 10-11 atm läts en serie prover bestående av olika andelar MgO och V2O3 nå jämvikt under dessa förhållanden. Analys av dessa prover gjordes med SEM/EDS och XRD. Analysen visade att det existerade ett tre-, en- och tvåfasområde i serien. I trefasområdet hittades MgV2O4, Mg2VO4 och en oidentifierad fast lösning vid V2O3- fraktionen 0,234 och 0,448. I enfasområdet hittades MgV2O4 vid V2O3-fraktionen 0,500-0,530. Till sist hittades MgV2O4 och V2O3 i tvåfasområdet vid V2O3-fraktionen 0,549-0,799. Utifrån detta drogs slutsatsen att mer vanadinrika spineller bildades då fraktionen V2O3 ökar till en viss gräns efter vilken spinellfasen blev mättad.
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Svensson, Josefin. "The effect of carbonaceous iron on slag foaming." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233008.
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The practise of slag foaming has become increasingly important within the scrap-based steelmaking, conducted in the electric arc furnace, due to its many advantages. In addition to increasing the efficiency in the furnace, the foaming protects the furnace equipment from wear and reduces noise pollution. The purpose of this project was to investigate the slag foaming generated through chemical reactions that occur at the addition of carbonaceous iron to the slag, as well as to evaluate the experimental method used. A slag composition of 25 wt% FeO, 40 wt% CaO and 35 wt% SiO2 was chosen. The experiments were conducted using an induction furnace, in a magnesium oxide crucible, placed in a graphite crucible. Iron particles with varying carbon content were added to the magnesium oxide crucible and the subsequent foaming was filmed and observed from above. The method enabled a division of foaming into four stages, which were studied and evaluated separately. The results indicate that the incubation time, referring to the time that passes from the addition of carbonaceous iron particles to the slag until the reactions occur, is dependent of size. A correlation can also be seen between carbon content and foaming time, where increased carbon content results in lengthier foaming.Utövandet av slaggskumning har blivit allt viktigare inom den skrotbaserade ståltillverkningen som utförs i ljusbågsugen, på grund av dess många fördelar. Förutom att öka effektiviteten i ugnen så skyddar den skummande slaggen även ugnsutrustningen mot slitage och reducerar buller. Syftet med detta projekt var att undersöka slaggskumning genererad genom de kemiska reaktioner som inträffar vid tillsats av kolhaltigt järn till slaggen, samt att utvärdera den experimentella metoden som användes. En slaggsammansättning av 25 vikt% FeO, 40 vikt% CaO och 35 vikt% SiO2 valdes. Experiment genomfördes med hjälp av en induktionsugn, i en magnesiumoxiddegel, placerad i en grafitdegel. Järnpartiklar med varierande kolhalt tillsattes i magnesiumoxiddegeln och den efterföljande skumningen filmades och observerades från ovan. Metoden möjliggjorde en uppdelning av skumning i fyra stadier, vilka studerades och utvärderades separat. Resultaten visar på att inkubationstiden, alltså tiden som passerar från att järnpartiklar tillsätts till slaggen, till dess att reaktioner sker, har ett storleksberoende. Ett samband kan även ses mellan kolhalt och skumningstid, där en ökad skumningstid ges av en högre kolhalt.
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Lotfian, Samira. "Alternative reducing agents in metallurgical processes : Experimental study of thermal characterization of shredder residue material." Licentiate thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26641.
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Coal used in metallurgical processes can participate in reduction reactions to produce metals and alloys from oxides. Base metals production leads to generation of slag, which contains valuable metals that can be recovered and recycled. There are several options to treat the slag, depending on the metal content in the slag. One is slag fuming, which is a well-established process that is traditionally used to vaporize zinc from zinc containing slags, mainly lead blast furnace slag, but is applied in a few plants for copper smelting slags. In this process reduction is achieved using pulverized coal, lump coal or natural gas. Conventionally pulverized coal injected to the furnace is utilized both to participate in reduction reactions and also to supply heat. On the other hand, the amount of possible alternative reducing agents such as residue plastic material is increasing steadily and the issue of sustainable disposal management of these materials has arisen. As carbon and hydrogen are major constituents of the residue plastic-containing materials, they have the potential to be an auxiliary source of reducing agents, to partially replace conventional sources such as coal. Shredder Residue Material (SRM) is a plastic-containing residue material after separation of main metals. Utilization of SRM as an alternative reducing agent, would lead to not only decreased dependency on primary sources such as coal but also to an increase in the efficiency of utilization of secondary sources. This calls for systematic scientific investigations, wherein these secondary sources are compared with primary sources with respect to e.g., devolatilization characteristics, gasification characteristics and reactivity. As a first step, devolatilization characteristics of SRM are compared with those of coal using thermogravimetric analysis. To study the reduction potential of the evolved materials, composition of evolved off-gas was continuously monitored using quadrupole mass spectroscopy. To gain a better understanding of possible interaction of plastics in a mixture, the devolatilization mechanisms and the volatile composition of three common plastics; polyethylene, polyurethane and polyvinylchloride and their mixture have been studied. Furthermore, gasification characteristics and reactivity of char produced from SRM is compared with coal char. The effect of devolatilization heating rate on gasification rate of char was investigated. Proximate analysis has shown that SRM mainly decomposes by release of volatiles, while coal shows high fixed carbon content, which is reported to contribute to reduction reactions. The composition of volatiles shows H2, CO and hydrocarbons which are known to have reduction potential. Therefore, it is essential that SRM be used in a process that could utilize the evolved volatiles for reduction. The results confirm the interaction between the plastics within the binary and ternary mixtures, which suggests that similar phenomenon may occur during devolatilization of SRM. Although the char produced from SRM contains lower amounts of fixed carbon compared to coal char, it has a porous structure and high surface area, which makes it highly reactive during gasification experiments. In addition to physiochemical properties, the catalytic effect of ash content of SRM char contributes to its higher reactivity and lower activation energy value compared to coal char. Moreover, the gasification reactivity of char produced at fast devolatilization heating rate was highest, due to less crystalline structure of produced char.Godkänd; 2016; 20160517 (samlot); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Samira Lotfian Ämne: Processmetallurgi /Process Metallurgy Uppsats: Alternative Reducing Agents in Metallurgical Processes Experimental Study of Thermal Characterization of Shredder Residue Material Examinator: Professor Caisa Samuelsson, Institutionen för samhällsbyggnad och naturresurser, Avdelning: Mineralteknik och metallurgi, Luleå tekniska universitet. Diskutant: PhD Noureddine Menad, BRGM, Geoscience for Sustainable Earth, France. Tid: Fredag 17 juni, 2016 kl 10.00 Plats: F343, Luleå tekniska universitet
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Kilpinen, Markus. "Tillsats av bränd dolomit som slaggbildare för ett minskat infodringsslitage." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70539.
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Fredriksson, Daniel. "Kartläggning av partikelstorleksfördelningar med varierande parametrar vid spraytorkning." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71772.
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Welander, Henrik. "Preliminary experimental study on the affect of water of the hydrogen reduced hematite pellet." Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293914.
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Global warming is one of the most important challenges that we are facing today. Since carbon dioxide (CO2) is by far our most common green house gas pollutant, most large corporations need to reconsider how their production is performed to keep the global warming below 2 ◦C. Today the steel production in Sweden accounts for 10% of its total annual emission of CO2. HYBRIT (Hydrogen Breakthrough Ironmaking Technology) is a joint venture between LKAB, SSAB and Vattenfall which aims to develop a new iron making route by reducing iron ore pellets with hydrogen gas, producing water as off-gas instead of CO2. Due to the endothermic nature of the reduction between iron oxide and H2 the reaction requires energy to proceed. During the reduction of a spherical pellet the reduction proceeds through dif- ferent stages, where all of them contains the reaction product of water vapor. This thesis will present and discuss the effect of water vapor during the reduction of a single hematite pellet at 700 ◦C and 900 ◦C, this report also includes a description of the making of an ex- perimental setup to control the H2O partial pressure in the reaction gas. Both temperatures includes three experiments each consisting of different amount of water vapor in the reduction gas, namely, 0% (pure H2), 5.5% and 10% H2O, all reductions were carried out for 60 minutes. The first experiment with pure H2 is used as a reference experiment as comparison to the latter, to be able to discuss the effect of the water vapor. The mass loss during reduction is measured using a thermogravimetric method to calculate the degree of reduction. The results showed that higher temperature led to higher rate of reduction. Further, increasing amount of water vapor decreased the reduction rate. The effect of water was found substantial. The 900 ◦C experiments reached 100% reduction during the 60 minutes. The 900 ◦C experiments reached a reduction of 95% after: 19.6 minutes (pure H2), 23.7 minutes (5.5% H2O) and 38.6 minutes (10% H2O). The 700 ◦C experiments only reached a reduction of around 90%. They reached 85% reduction after 40.6 minutes (pure H2), 45.1 minutes (5.5% H2O) and 53.2 minutes (10% H2O). At 900 ◦C, the reduction with 10% H2O needs double the time compared to 0% H2O to reach the same degree of reduction. The results show that water vapor affect the mass transfer of hydrogen in the gas phase and to the reaction sites as well as the driving force of the reaction.Global uppvärmning ar en av de viktigaste utmaningarna vi står inför idag. Eftersom koldioxid (CO2) är vår överlägset mest förorenande växthusgas måste de flesta stora företag överväga hur deras produktion utförs for att hålla den globala uppvärmningen under 2 C. Idag står stålproduktionen i Sverige för 10% av de årliga koldioxidutsläppen. HYBRIT (Hydrogen Breakthrough Ironmaking Technology) är ett gemensamt forskningsprojekt mellan LKAB, SSAB och Vattenfall som utvecklar en ny järnframställningsväg genom att reducera järnmalmspellets med vätgas och producera vatten som avgas istället för CO2. På grund av den endotermiska naturen vid reducering av järnoxid med H2, kräver reaktionen energi för att fortgå. Under reduceringen av en sfärisk pellet fortskrider reduktionen genom olika steg, där alla innehåller reaktionsprodukten vattenånga. Denna avhandling kommer att presentera och diskutera effekten av vattenånga under reduktionen av en hematitpellet vid 700 C och 900 C, samt en experimentell inställning för att kontrollera H2O partialtrycket i reaktionsgasen. Båda temperaturerna inkluderar tre experiment som var och en består av olika mängder vattenånga i reduktionsgasen, nämligen 0% (ren H2), 5,5% och 10% H2O, alla reduktioner var på 60 minuter. Det första experimentet med ren H2 används som referensexperiment som jämförelse med senare for att kunna diskutera effekten av vattenångan. Massminskningen under reduktion mäts med hjälp av en termogravimetrisk metod för att beräkna reduktionsgraden. Resultaten visade att högre temperatur ledde till högre reduktionshastighet. Vidare minskade den ökande mängden vattenånga reduktionshastigheten. Effekten av vatten befanns vara betydande. 900 C experimentet uppnådde en reduktion på 100% efter 60 minuter. 900 C nådde en reduktion pa 95% efter 19,6 minuter (ren H2), 23,7 minuter (5,5% H2O) och 38,6 minuter (10% H2O). 700 C experimenten nådde endast en reduktion på cirka 90% med 85% reduktion efter 40,6 minuter (ren H2), 45,1 minuter (5,5% H2O) och 53,2 minuter (10% H2O). Vid 900 C behöver reduktionen med 10% H2O dubbla tiden jämfört med 0% H2O för att uppnå samma grad av reduktion. Resultaten visar att vattenånga påverkar masstransporten av väte i gasfasen och till reaktionspunkterna, liksom reaktionens drivkraft.
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Danielsson, Patrik. "En studie av reelriktens inställningar i Färdigställning 13 vid Sandvik Materials Technology Primary Products : Utförd med FEM-simulering och mikrohårdhetsmätning." Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-295586.
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Med allt strängare yt- och rakhetstoleranser på stångprodukter för försäljning samt vidare bearbetning inom Sandvik Materials Technology närmar sig vissa produkter gränsen för vad den existerande riktningsutrustningen har kraftkapacitet för. Detta påskyndas i kombination med introduktion av hårdare material i större dimensioner än tidigare. Riktning utförs primärt genom böjriktning med korslagda valsar. De stångprodukter som har studerats är det duplexa stålet 2RD99 i Ø 169 mm samt borrstålen 4HS64 i Ø 149 mm, 5HS23 i Ø 135 mm och 19HS20 i Ø 124,4 mm. För att utvärdera om produkterna kunde riktas på ett pålitligt sätt beräknades och FEM- simulerades processen för att bestämma de för varje produkt specifika parametrar som krävdes för att uppfylla ett uppskattat riktningsvillkor. FEM-modellen verifierades genom att använda föreslagna parametrar i bearbetningen och ta provbitar på vilka Vickers hårdhetsprovning utfördes. Hårdhetsprofiler skapades för att utvärdera om produktens deformationshårdnande följde den av FEM-simuleringen förutsedda plastiska deformationen. Hårdhetsprofilerna i kombination med rakhetsmätningar efter bearbetning tyder på att produktionsutrustningen har kapacitet att bearbeta samtliga produkter. En FEM-simulering av riktningsprocessen modellerad med slitna valsar visade att den erforderliga valskraften ökade kraftigt på grund av den förändrade geometrin hos de slitna komponenterna och att specifika produkter inte längre kunde bearbetasmed inställningar som faller inom riktningsmaskinens begränsningar.With increasing demands on the surface quality and straightness of bar products for both sale and additional processing at Sandvik Materials Technology certain products are approaching the limits of the existing straightening equipment. This is accelerated when combined with the introduction of harder materials in larger dimensions. Straightening is primarily performed with cross-roll bend straightening. The studied bar products are the duplex steel 2RD99 in Ø 169 mm as well as the rock drill steel 4HS64 in Ø 149 mm, 5HS23 in Ø 135 mm and 19HS20 in Ø 124,4 mm. In order to evaluate if the products could be reliably straightened the process was modelled with analytical calculations and FEM simulations to acquire the specific parameters for each product that fulfilled an estimated straightening condition. The FEM model was verified by using the suggested parameters in the straightening of bars and taking samples from a series of products on which Vickers hardness tests were performed. Hardness profiles were created to evaluate if the deformation hardening followed the plastic deformation anticipated by the FEM simulations. The hardness profiles combined with post processing straightness measurements indicated that the straightening equipment has the capacity to process them. A FEM simulation of the straightening process modelled with worn rollers showed that the required roller force greatly increased because of a change in geometry of the worn component and that specific products could no longer bestraightened within the limits of the straightening machine.
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Rosqvist, Emil, and Theodore Vassi. "Characterization of phases in Argon Oxygen Decarburization slag." Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298409.
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Slag is an important part of steelmaking with the AOD (Argon Oxygen Decarburization) process. In this work the focus was on developing a methodology for characterizing phases in slagsamples obtained after decarburization, reduction and desulphurization. Six samples from two heats, or batches, (heat A and B) were prepared by baking in Bakelite and polishing. These were analysed in SEM (Scanning Electron Microscope), with BSE (Backscattered Electrons) and EDS (Energy Dispersive XraySpectroscopy). Images from BSE were then processed inImageJ with a denoise method for advanced fraction analysis. Average composition for each noticed phase analysed with EDS is presented in element tables. A systematic portraying of the cross section was performed on samples from heat B. This gave a more in-depth composition and fraction analysis. Due to the nature of slag, scratches were often induced during polishing.The negative effect of these scratches could be reduced with the denoise method in the fraction analysis. There are three main phases in each stage of the AOD process with similar composition and structure between the two heats. Results showed the importance of measuring different zones of the slag due to its heterogeneity. More specifically, at least four random images from the cross section were required for accurate fraction analysis of samples after decarburization. Overall, the methodology for characterization was sufficient for samples after decarburization and desulphurization.Slagg är en viktig del av ståltillverkning med AOD-processen (Argon Oxygen Decarburization). Fokus i detta arbete var att utveckla en metod för att karakterisera faser i slaggprover erhållna efter avkolning, reduktion och avsvavling. Sex prover från två batcher (batch A och B) förbereddes genom bakning i bakelit och polering. Dessa prover analyserades i SEM (Svepelektronmikroskop), med BSE (Backscattered Electrons) och EDS (Energy Dispersive Xray Spectroscopy). Bilder från BSE bearbetades sedan i ImageJ med en denoise-metod för avancerad fraktionsanalys. Genomsnittlig sammansättning för varje fas analyserad med EDS presenteras i elementtabeller. En systematisk undersökning av heterogenitet hos slagg utfördes på prover från batch B. Detta gav en mer noggrann komposition och fraktionsanalys. På grund av slaggens karaktär uppkom ofta repor under poleringen. Den negativa effekten av dessa repor kunde minskas med denoise-metoden i fraktionsanalysen. Det finns tre huvudfaser i varje steg i AOD-processen med liknande sammansättning och struktur för de två batcherna. Resultaten visade betydelsen av att mäta slaggprovet i olika zoner på grund av dess heterogenitet. Mer specifikt krävdes minst fyra slumpmässiga bilder från tvärsnittet för noggrann fraktionsanalys av prover efter avkolning. Sammantaget var metoden för karaterisering av slagger tillräcklig för prover efter avkolning och avsvavling.
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Fischbein, Ellinor, and Felicia Larsson. "Metallurgical analysis of some osmund iron from Sweden and Estonia : A short historical review of medieval iron production and export." Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298414.
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During the Middle Ages, Sweden was a coveted exporter of high-quality iron in Europe. Bloomery furnaces could have produced osmund iron. However, most osmund iron was produced in blast furnaces. The iron was then treated in the finery process and cut into pieces. Previous studies establish osmund iron’s definition regarding properties, microstructure and trace elements. They were often slag-rich and varied greatly in carbon content, proportion of inclusions, corrosion and microstructure. The report examined osmund iron as related to medieval iron production, exports and quality. This was done by comparing the microstructures and slag inclusions in Swedish and Estonian pieces of medieval iron, through analyses by SEM-EDS and under an optical microscope. The Estonian samples had more slag inclusions. The samples with corroded inclusions/slag were rejected. The varying microstructure can be linked to the cooling rate and the actual production in the blast furnace, bloomery furnace and finery process. It gave materials with poor properties. A large proportion of the samples had one side with a higher carbon content while the other had lower carbon content. The iron with lower carbon content could be connected to come from the bloomery furnace and the higher to the blast furnace. The samples containing higher levels of silica, magnesium and calcium could be connected to the blast furnace. In summary, the Swedish samples were of better quality than the Estonian ones and all pieces were considered to come from the blast furnace.Under medeltiden var Sverige en eftertraktad exportör av högkvalitativt järn i Europa. Osmundjärn kunde produceras i en blästerugn, men det mesta osmundjärnet framställdes i masugnen. Därefter färskades järnet och höggs upp i delar. Tidigare analyser definierar osmundjärns utseende, egenskaper, mikrostruktur och spårämnen. De var ofta slaggrika och varierade mycket i kolhalt, andel inneslutningar, mikrostruktur och mängd korrosion. I den här studien analyserades osmundjärn relaterat till medeltida järnframställning, export och kvalité. Det gjordes genom att jämföra mikrostrukturer och slagginneslutningar i svenska och estniska prover av medeltida järn, genom analyser i SEM-EDS och i ljusmikroskop. De estniska proverna hade mer slagginneslutningar. Proverna med korroderade inneslutningar/slagg uteslöts ur analysen. Den varierande mikrostrukturen kan kopplas till kylningshastigheten och själva produktionen i masugnen, blästerugnen och färskningsprocessen. Det gav material med dåliga egenskaper. En stor andel prover hade en sida med högre kolhalt och den andra delen hade lägre kolhalt. Järnet med lägre kolhalt kan kopplas till att komma från blästerugnen och det med högre kolhalt till masugnen. De proverna som innehöll högre halter kiseldioxid, magnesium och kalcium kan kopplas till masugnen. De svenska proverna hade sammanfattningsvis bättre kvalité än de estniska och alla bitar ansågs komma från masugnen.
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Jespersson, Niklas, and Torbjörn Sandberg. "Evaluation of different non-metallic inclusions in steel chips by using electrolytic extraction : Evaluation of a methodology for electrolytic extraction and scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS) analysis." Thesis, KTH, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298419.
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Analysing non-metallic inclusions (NMI) by conventional microscopy is prone to errors. Better imaging can be achieved by using electrolytic extraction (EE) to effectively dissolve the metal matrix, freeing the inclusions so that they can be collected on a filter. This method of studying NMI was tested on a 157C steel chip, with EE taking place three times on the same surface with increasing levels of charge applied. The relationship between charge and extracted layer depth was examined, so as to facilitate the targeting of NMI from specific depths. A selection of the extracted inclusions were micrographed with scanning electron microscopy (SEM) and had their compositions measured with energy dispersive spectroscopy (EDS). Based on this data, two methods of classifying NMI were briefly examined: manual classification, mostly based on images, and a semi-automated process based on a sorting algorithm applied to the compositions. The study implies that it is possible to dissolve a 157C steel to a desired depth by applying a charge proportional to it, but the current method introduces an error which might limit the resolution of depth by a significant amount. Also in the current method, there was no systematic way to select NMI for micrography, and no solution to this problem was found. The semi-automated classification algorithm was compromised by inaccurate readings of compositions from the EDS, and could not be thoroughly tested.Konventionell mikroskopi kan lätt ge felaktig information vid analys av icke- metalliska inneslutningar (NMI), men bättre resultat kan uppnås om metall- matrisen löses upp med elektrolytisk extraktion (EE), så att inneslutningarna frigörs och kan samlas upp på ett filter. Denna metod att studera NMI testades på ett spån av 157C-stål, med trefaldig EE på samma yta och successivt ökande maximal laddning. Sambandet mellan laddning och upplöst lagerdjup undersöktes för att möjliggöra extraktion av NMI från givna djup. Ett urval av de frigjorda inneslutningarna fotograferades i ett SEM och sammansättningarna fastslogs av EDS. Dessa data låg till grund för en undersökning av två klassifikationsmetoder för NMI: manuell klassificering, till största del bildbaserad, och en halvautomatisk klassificering där en algoritm sorterar efter sammansättningar. Denna studie antyder att ett 157C-stål kan lösas upp till önskat djup genom att åläggas en laddning proportionell mot djupet, men den nuvarande metoden introducerar ett fel som kan ha betydande påverkan på noggrannheten. Den aktuella metoden saknar ett systematiskt sätt att välja NMI för mikroskopfotografi, och ingen lösning har kunnat framföras på detta problem. Den halvautomatiska klassifikationsalgoritmen rubbades av störningar i EDS-resultaten och kunde inte undersökas till fullo.
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Glans, Magnus. "Klena dimensioner vid etappglödgning." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-75589.
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Ávila, Braz Thaís. "Shrinkage Calculation in the Continuous Casting of Duplex Stainless Steel." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76516.
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Kylström, Sanna. "The Effect of Twinning on the Mechanical Properties of Alloy 825." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254760.
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Twinning is a known phenomenon in material science, but how is it connected with grain size and yield strength? Investigations are made on alloy 825 with light optical microscopy for 19 samples to calculate the twin fraction and grain size. Afterwards, the results are compared to yield strength throughout tensile tests. The samples have different reduction of dimension by hot rolling and have been annealed for different time intervals. It turns out that twinning makes alloy 825 slightly softer and more ductile on a smaller scale, since the twin fraction increases when the yield strength decreases. However, the grain size also slightly increases when the yield strength decreases, which is important to have in mind for the connection with the three of them.Tvillingbildning är ett känt fenomen inom materialvetenskap, men hur hör tvillingar, kornstorlek och sträckgräns ihop? Finns det ett samband? Undersökningar utförs med ett ljusoptiskt mikroskop för legering 825 på 19 prover, för att räkna ut tvillingfraktionen och kornstorleken. Detta jämförs sedan med sträckgränsen som man tillhandahåller från dragprov. Proverna har olika reduktion av sin dimension genom valsning och har glödgats olika tider. Det visar sig att tvillingbildning gör legering 825 något mjukare och mer duktil på en mindre skala, eftersom tvillingfraktionen ökar då sträckgränsen sjunker. Dock ökar även kornstorleken när sträckgränsen minskar, vilket är viktigt att tänka på när det kommer till sambandet mellan kornstorlek, tvillingar och sträckgräns.
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Carlsson, Sofia. "Grain refinement of aluminium by titanium diboride particles : The importance of nucleation, growth restriction, and cooling rate." Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-266096.
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The grain refinement of aluminium by titanium diboride particles, TiB2, using Ti/B grain refiners is common practice in the aluminium industry, but exactly how this grain refinement is achieved is uncertain. Current addition of grain refiner is therefore rarely optimal and excessive addition rates of grain refiner is common. This study investigates grain refinement of aluminium by titanium diboride to create a method and/or model which can be used to aid in addition rate optimisation. The effect of different parameters on grain refinement is the focus and includes cooling rate, properties of the nucleant particles, and growth restriction. A number of experiments using different test methods was applied to investigate this. The study reveals how the parameters investigated affect grain refinement, and how these can be used to optimises grain refiner addition rate. A model aiding in dealing with the varying abilities of nominally identical grain refiners to produce grains is introduced.The conclusion emphasizes the importance of optimising addition rates of grain refiners, for mechanical as well as environmental reasons, and how this can be achieved by changing the investigated parameters.Kornförfining av aluminium med titandiboridpartiklar, TiB2, genom användning av Ti/B kornförfinare är standard inom aluminiumindustrin. Det är dock inte helt utrett hur denna kornförfining går till. Rådande tillsatsmängder av kornförfinare är därför sällan optimala och alltför stora tillsatsmängder av kornförfinare är vanligt förkommande. Denna studie undersöker kornförfining av aluminium med titandiborid med målet att skapa en metod och/eller modell som kan användas för att underlätta optimering av tillsatsmängder. Fokus ligger på hur olika parametrar influerar kornförfiningen och inkluderar kylningshastighet, egenskaperna hos de kärnbildande partiklarna, och tillväxthämning. Experiment med olika testmetoder utfördes för att undersöka detta. Studien visar hur de undersökta parametrarna påverkar kornförfiningen och hur dessa kan användas till att optimera tillsatsmängden av kornförfinare. En modell användbar för att hantera de skillnader nominellt identiska kornförfinare uppvisar i sin förmåga att producera korn presenteras. Slutsatsen betonar vikten av att optimera tillsatsmängden av kornförfinare, både av materialmässiga och miljömässiga skäl, och hur detta kan uppnås genom ändringar i undersökta parametrar.
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Sadeghi, Mohammad. "Optimization product parts in high pressure die casting process." Licentiate thesis, Mälardalens högskola, Framtidens energi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-27733.
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This thesis describes optimization of die temperature in high pressure die-casting (HPDC) of A380 alloy by experimental observation and numerical simulation with the use of statistical tools. The goal of this research is to determine the optimum die temperature to minimize incidence of these defects and thus maximize production of parts without defects. In HPDC, molten metal is injected into the die at high speed (40-60 m/s for aluminum alloys). Die temperature plays an important role on the rate of rejected parts. Therefore, flow patterns of molten metal in HPDC of an automotive component with very complex geometry (the ladder frame from the EF7 motor) were examined to determine the optimal die temperature. Defects in the production process fall into three categories, including surface, internal and dimensional defects. Samples produced in the experiments were classified according to any present defects. Another important parameter that influences casting defects is the cooling rate. Die temperatures were measured at the initial step and final filling positions. Experiments were performed with die temperatures ranging from 150 °C to 250 °C. The results show that the melt temperature difference in the die between the initial step and the final filling position was between 20 and 25 °C. Statistical tools such as regressions, relationships, max, min, correlations, ANOVA, T-test, Principal Component Analysis (PCA) and descriptive statistics were used to facilitate interpretation of data from the die-cast experiments. Perform some case studies in order to study the process behavior, take a better knowledge of effective parameters, and measure the required parameters. The collected data are utilized to: Set the model Validate/ verify the model ProCast software was used to simulate the fluid flow and solidification step, and the results were verified by experimental measurements. The optimal die temperature for this alloy was found to be above 200 oC. Statistical analysis of the experimental results found that defects were minimized and confirmed parts were maximized in HPDC of the ladder frame within a die temperature range of 210° C to 215° C.
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Dellamary, Edward. "Cu2O/TiO2 Nanorod Heterojunctions: Synthesis, Characterization and Applications as Solar Cells on the Nanoscale." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-77369.
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Novel solar cells are being synthesized from sustainable, non-toxic, and economic materials. All metal oxide semiconductors are one such class of these materials. Synthesis of different combinations of p and n type MO semiconductors heterojunctions as well as high throughput characterization is crucial to improve their applications in fields such as solar cells. A Cu2O/TiO2 Nanorods heterojunction is synthesized on a fluorine doped tin oxide substrate. The TiO2 Nanorods are synthesized via a two-step, solvothermal method. The Cu2O is deposited conformally on the TiO2 NRs via a physical vapor deposition method known as RF magnetron sputtering, with thicknesses of 100, 50 and 25 nm. Characterization methods are used to first determine that the correct materials were synthesized and deposited. Scanning electron microscopy demonstrated that nanorods were made of length, 750 nm, and width, 45 nm. Optical measurements were taken, including: absorbance, transmittance, and reflectance; trends followed the optical data as the thickness of the p-type material increased. From the absorbance data, the bandgap of the materials could be calculated from the generated Tauc plot. The bandgap of TiO2 was calculated to be 3.0 eV which agreed with literature values. The bandgap of Cu2O was calculated to be 2.76 eV which is not in agreement with literature values. X-ray diffraction demonstrated that TiO2 rutile phase was grown, with diffraction angles at: 36.45, 62.747 and 69.766 with their lattice planes being (011), (002) and (112) respectively. Raman spectroscopy demonstrated TiO2 in the rutile phase with Raman shifts at both 447 cm-1 (Eg) and 609 cm-1(A1g). There is a minor peak at 522 cm-1 (T2g) which correlates to Cu2O. Macro-electrical measurements were taken to plot a current vs voltage curve (IV curve), under dark and light conditions. From the macro-electrical measurements Isc, Voc and η (photoconversion efficiency) were calculated: 2.38 E-09 A, -0.18 V, 7.25E-07 respectively (under light, 1 sun equivalent). Atomic force microscopy (AFM) was used to attain topographical images, force/deflection curves, IV curves/maps, and surface potential maps. Conductive-AFM (c-AFM) and Kelvin Probe Force Microscopy (KPFM) were the specific AFM techniques used. From the KPFM measurements it was possible to measure the work functions of TiO2 NRs and Cu2O/TiO2 NRs by using highly oriented pyrolyzed graphite as a reference. The work function for TiO2 NRs was: 4.24 eV and 4.14 eV under dark and light conditions respectively. The work function of the 100 nm Cu2O/TiO2 NRs heterojunction was 4.44 eV and 4.35 eV under dark and light conditions respectively. The apparent work functions that were calculated via this KPFM method were not in agreement with literature values of the respective materials. This thesis has proved that Cu2O/TiO2 Nanorod Heterojunctions can be synthesized using previously known solvothermal synthetic methods. Furthermore these Cu2O/TiO2 Nanorod Heterojunctions have an increase in current under illumination. This current response under illumination has been studied on the nanoscale, using KPFM and C-AFM, as well as on the macroscale. Further investigations on the nanoscale are to be done, which can shed light on how and why these all metal oxide nanorod heterojunctions are functioning as solar cells.
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Jonzon, Andreas. "Characterization of High-silicon alloy ductile iron in very thick sections." Thesis, Luleå tekniska universitet, Mineralteknik och metallurgi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79194.
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Valmet AB has ha foundry located I Karlstad, Sweden. The foundry has specialized in large components in ductile and gray iron. This report is a part of an evaluation of a new alloy that Valmet has produced. The alloy is called S550 where 550 is the expected tensile strength in a cast on sample. S550 is a ferritic ductile alloy with 4,15-4,25% silicone. In this experiment the alloy is casted in very large sections to better match the intended final product. The purpose of the report is to promote a better understanding of how silicon works in large castings. Ultimate tensile strength, yield strength and elongation will be measured. The microstructure will be mapped and described. This as a step to ensure that the material is ready to use to produce castings in large dimensions. In the experiment, the microstructure is examined from 3 charges. Mechanical properties are collected from the 3 charges by widened specimens from 3 details of 2785 kg/piece and 4 drilled samples from 4 details about 600 kg/piece. The samples are processed to test bars according to standard SS-EN1563: 2012. Thereafter the rods are dragged in a tensile testing machine to collect data. The microstructure is mapped through light optic microscopy. The samples where machined according to SS-EN1563:2012. Tensile testing machine was used to record the mechanical values. Microstructure was mapped using a light-optic microscope. The material achieved a tensile strength of 544 MPa on average which is below the expected value. The yield strength was 436 MPa in average. The material shows low dispersion, mainly in fracture limit and yield limit. The elongation in average 12.8% varied in the different geometries but with lower variations within the same geometry. The alloy got better mechanical values on Detail B that had a shorter cooling time. In Detail A, micro porosity and slag were found which adversely affected their mechanical properties. The ground mass is considered as ferritic. The graphite nodes had a size of 82μm and a nodule density of 75 nodules / mm2. Most nodules had graphite form VI, small amount of graphite V and III have been found. No degenerated graphite forms as chunky or exploded graphite has been found.
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Nordenskiöld, Simon, and Reiland Elias Nybacka. "The disclosure of Otto Meyer's secret : An evaluation of composition and casting properties of the Fritzi alloy." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277876.
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The increased copper price during the first world war forced the Swedish master founder OttoMeyer to invent a new alloy in order to continue casting artworks at a reasonable cost. The recipe of the alloy was a secret that Meyer kept to himself even unto death. The name of the alloy became Fritzi, but the number of objects cast in this alloy was never published.However, among the art pieces is G. Lindberg’s statuette “Vågen”. In this project, the composition of Fritzi was determined using SEM and EDS analysis on a sample from “Vågen”, and some thermodynamic, physical, and casting properties were evaluated usingsimulations and calculations. In addition to this, a 3D-replica of “Vågen” was created.Det ökade kopparpriset under första världskriget tvingade gjutmästaren Otto Meyer attuppfinna en ny legering för att kunna fortsätta driva sitt konstgjuteri. Legeringen fick namnet Fritzi och blev tillverkad i ett okänt antal föremål. Receptet skrevs aldrig ned och fick följa med sin skapare ned i graven. Bland konstverken som göts i Fritzi finns G. Lindbergs statyett “Vågen”, från vilken prover har tagits i analyssyfte. Som en del av projektet har sammansättningen av Fritzi bestämts med SEM- och EDS-analys och några termodynamiska, fysikaliska och gjuttekniska egenskaper har bestämts genom simuleringar och beräkningar.Utöver detta har en 3D-replik av “Vågen” tillverkats.
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Rosén, Rebecca. "A literature study on measurement methods for calculating the FeO activity in slag." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277890.
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During the time we live in, climate change is more important than ever. HYBRIT, formed bySSAB, LKAB, and Vattenfall, is an initiative set out to make the steel production fossil free, by developing a novel process that produce direct reduced iron (DRI) using hydrogen as reagent. Electric arc furnaces (EAF) will then be employed to melt the DRI. For SSAB, it is important to obtain a satisfied dephosphorisation in the EAFs for the production of high strength steel. The composition of the DRI, has a big impact on the dephosphorisation and it is important that the slag has an optimal basicity and FeO content. To better understand the impact that FeO has on dephosphorisation, experimental data has to be collected and the FeO activity calculated in different slag systems. Activity measurements of FeO is rather complex. In this thesis, three methods were looked at: experimental determination, electrochemical methods and equilibrating the slag. Equilibrating the slag turned out to be the best suitable method forcalculating the FeO activity and is recommended to be evaluated further.I den tid vi lever i nu är frågan om klimatförändringarna viktigare än någonsin. HYBRIT, bildatav SSAB, LKAB och Vattenfall, är ett initiativ som syftar till att göra stålproduktionen fossilfri genom att utveckla en ny process som producerar direkt reducerat järn (DRI) med väte som reagens. Elektriska bågugnar (EAF) kommer sedan att användas för att smälta DRI. För SSAB är det viktigt att få en bra fosforrening i EAF:erna för produktion av höghållfast stål. DRI:s sammansättning har stor inverkan på fosforreningen och det är viktigt att slaggen har en optimal basicitet och FeO-innehåll. För att bättre förstå vilken inverkan FeO har på fosforreningen måste experimentella data samlas in och FeO-aktiviteten beräknas i olika slaggsystem. Aktivitetsmätningar av FeO är ganska komplicerade. I denna avhandling undersöktes tre metoder: experimentell bestämning, elektrokemiska metoder och jämvikt av slaggen. Jämvikt av slaggen visade sig vara den mest lämpliga metoden för beräkning av FeO-aktiviteten och rekommenderas att utvärderas ytterligare.
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Brisenmark, Emil, and Valencik Jane Jönsson. "Evaluation of the Effect of Non-Metallic Inclusions on the Corrosion Resistance of Stainless Steels and Nickel-based Alloys." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277900.
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Non-metallic inclusions (NMI) are small impurities that can always be found in steel and other materials. NMIs are of great importance because they may negatively impact various properties of the steel, depending on their composition, morphology and numbers. In the oil and gas industry, one of the most concerning property that can be affected by the NMIs is corrosion resistance. In this report, certain aspects of NMIs were investigated, such as size or composition and effect which they have on the corrosion resistance. To accomplish this, two different steel alloy samples from pipelines were analyzed using electrolytic extraction,a scanning electron microscope (SEM) and a software called ImageJ. The results showed that only Niobium-Titanium carbides (NbTi-C) which were found on one of the samples had the potential to be dangerous, due to them causing pits ranging from 1 to 12.5 times their inclusion size. It was also found out that the size of the inclusions did not affect the size of the pitting that they caused.Icke metalliska inneslutningar (NMI) är små föroreningar som alltid finns i stål och andramaterial. NMI:er är mycket viktiga eftersom de kan negativt påverka olika egenskaper hos stål, beroende på deras komposition, morfologi och antal. I olje -och gasindustrin är en särskilt oroande egenskap som kan påverkas av NMI:er deras korrosionsmotstånd. I denna rapport undersöktes hur olika aspekter hos NMI:er, som storlek eller komposition, påverkade korrosionsmotståndet i rostfritt stål. För att utföra detta analyserades två olika stållegeringsprovbitar från pipelines med elektrolytisk extraktion, ett svepelektronmikroskop (SEM) och ett program som kallas ImageJ. Från resultatet framkom det att baraNiob-Titankarbider (NbTi-C) som fanns på en av provbitarna hade potentialen att vara farlig, då den orsakar gropar som är 1 till 12.5 gånger större än sin egen storlek. Det framkom också att storleken på inneslutningarna inte påverkade storleken på deras gropar.
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Augustson, Julia, and Madeleine Bogg. "Impact Damage Assessment : In collaboration with Saab aerostructures." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277881.
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This project that has been executed in collaboration with Saab aerostructures deals with how three materials, aluminum, titanium and corrosion resistant steel react when they are affected by different energy levels. These energy levels serve the purpose of representing damages that can happen in storage and handling to components used in production. A literature study was made to gather information regarding the treated materials as well as some methods that can be used to test a materials property. The goal of the project is to create a tool for Saab to use in their production in order to first estimate the energy levels that created a mark on a material and secondly evaluate if a crack can be suspected, by consequence evaluate if a NDT (non-destructive test) is required. The experiment was executed as such that all of the materials were put through drop-tests simulating different energy levels, with two different strikers, blunt and sharp, and then the materials were examined. Non-destructive testing was made on all of the marks made on the different materials using penetrant- or eddy current-method to see if there were any cracks formed in the material after impact. The experiment did not show signs of any cracks from the tested energy levels. However, it showed that crack propagation is highly dependent on the shape of the striker. To make the experiment more reliable and give a better result more energy levels would have needed to be tested. Also, a large number of different strikers and more non-destructive testing methods would have to be used.Detta projekt som har utförts i samarbete med Saab aerostructures behandlar hur tre material, aluminium, titan och rostfritt stål reagerar när de blir utsatta för olika energinivåer. Dessa energinivåer ska simulera skador som kan uppkomma under hantering och förvaring av komponenter i Saabs produktion. En litteraturstudie har utförts för att samla information om materialen samt om några testmetoder som kan användas för att utvärdera ett materials egenskaper. Målet med projektet är att få fram ett tillvägagångssätt för Saab att i första hand uppskatta energinivåerna bakom ett slagmärke i ett material, därefter bedöma ifall en sprickinitiering kan misstänkas och därmed avgöra huruvida komponenter som utsatts för energinivåer behöver undergå oförstörande provning eller om de kan fortsätta användas i produktionen utan någon form av testning. Ett experiment utfördes genom att utsätta samtliga av materialen för dropp-tester med olika energinivåer med två olika slagdon, trubbigt och spetsigt, för att sedan kunna undersöka om sprickor hade propagerats. Oförstörande provning gjordes på alla simulerade skador antingen via penetrantmetoden eller virvelströmsprovning, för att se om det bildats sprickor i de olika materialen efter slaget. Experimentet visade inte på några sprickor vid de testade energinivåerna. Däremot såg man att sprickinitiering beror bland annat på slagdonets utformning, där en skarpare form ökade risken för sprickor. För att experimentet ska bli mer pålitligt och ge ett bättre resultat hade fler energinivåer behövt testas, en större variation av slagdon hade behövt användas samt att man hade behövt använda fler typer av oförstörande provning.
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Morata, Royes Joan. "Wear resistance of heat-treated Advanced High Strength Steels and casting." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80526.
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The necessity to improve the durability of the machinery used in the milling industry has lead to several types of research. One study is focused on the plates that are located in the stationary and moving jaws of crushers to diminish particles sizes of Gneiss and Diabase rocks. Thus, one type of approach to increase its durability is by reducing the material loss of the plates. Amongst all the parameters to reduce the wear ratio that includes inputs from geometry to load, just the hardness input of the material can be in constant development. Consequently, there are two well-known types of heat treatment that can produce this change in hardness and are named Carbide Free Bainite (CFB) and Quenching and Partitioning (QP). In this master thesis the topic is to perform the QP heat treatments for two compositions A and B to obtain the microstructure of the steels that consist in a mix of austenite, bainite and martensite which considerably increase the hardness while the toughness is not drastically reduced due to the austenite soft phase. Five samples have been studied at four different partitioning temperatures: QP250 A, QP180 B, QP210 B, QP240 B and Mn Steel as it is the composition most used nowadays in the industry. In order to characterise both mechanical properties and microstructural features, different analysis had been performed with Micro-indentations, Charpy-V, Gouging Abrasion Tests, Optical Microscopy, Scanning Electron Microscopy and X-Ray Diffraction. These analysis had been done in the samples before and after wear as a result in change of the microstructure. As the abrasive-impact of the rocks collide with the sample, austenite transforms to martensite by induced plasticity called TRIP effect. Thus, the surface of the alloy is harder than the bulk material as no austenite is found and the wear ratio is seen to be improved. The results have shown several behaviours. Austenite transforms in its majority to fresh martensite which is an unstable martensitic phase but harder than tempered martensite that is the stable martensitic phase. Moreover, the difference in hardness between the bulk and the surface produce an affected depth layer as a consequence of the abrasive-impact penetration of rocks in which the microstructure has fully transformed to martensite on the surface and the austenite phase increases as it goes further inside the steel. The thinner this layer is, the better wear ratio presents the alloy. From all the samples, the best combination of hardness and toughness is for QP210 B.
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Philipson, Harald. "The effect of thickness and compaction on the recovery of aluminium in recycling of foils in salt flux." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280048.
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In Norway, more than 40.000 tonnes of aluminum (Al) in food packaging goes to incineration annually. Recycling this waste would save more than 1.5 TWh of energy and several hundred thousand tonnes of CO2 emissions. However, recycling thin aluminum foil in small packaging is more difficult than recycling of larger and cleaner scrap. In this thesis, properties of compacted coating-free Al foil with five different thicknesses (15, 30, 100, 200, 300 𝜇𝜇m) were investigated and related to percentage Al recovery during remelting in salt flux. This thesis consists of five main parts. Two initial studies involved shredding of the foil into a controlled chip size and compaction of these chips to briquettes of a wide range of bulk densities using three types of compaction techniques. In the following two studies, relevant briquette properties and oxidation behavior were determined. Finally, chips and briquettes were melted in salt flux and the percentage Al recovery was calculated. The bulk density, porosity and surface areas of the briquettes were significantly influenced by the type of compaction technique. Applied torque and heat in addition to uniaxial pressing were found to be effective measures to increase bulk density. Oxidation was higher for thin Al foil due to higher specific surface area and micro roughness. However, the oxidation of briquettes significantly decreased as the bulk density exceeded 2.4 g/cm3. Briquetting led to significantly increased recovery of the two thinnest foils. For the three thickest foils the effect of briquetting was smaller. For the thinnest foil, recovery increased with compaction. For this foil, even significantly oxidized chips compacted to bulk density 2.6 g/cm3 resulted in 99-100 % recovery. The specific surface area of the aluminum was the most important material property influencing recovery. It is expected that an optimum amount of salt flux and fluoride contentrelated to specific surface area of the scrap can be developed.I Norge förbränns mer än 40 000 ton aluminiumförpackningar årligen. Återvinning av denna mängd aluminiumförpackningar skulle spara 1,5 TWh energi och hundratusentals ton av koldioxidutsläpp. Det mycket svårare att återvinna tunn aluminiumfolie i förpackningar än större och renare aluminiumskrot. I denna uppsats har egenskaper hos komprimerad beläggningsfri aluminiumfolie med fem olika tjocklekar (15, 30, 100, 200, 300 𝜇𝜇m) bestämts. Dessa egenskaper är sedan till kopplade till återvinningsgraden efter smältning i saltfluss. Uppsatsen består av fem huvuddelar. I de två inledande delarna strimlas foliet till en bestämd spånstorlekt varpå dessa komprimeras med tre olika presstekniker till briketter av olika bulkdensiteter. I de nästa två delarna bestäms relevanta brikettegenskaper och oxidationsbeteendet. I den sista delen bestäms återvinningsgraden av spån och briketter som smälts i saltfluss. Briketternas bulkdensitet, porositet och ytarea varierade beroende på pressningsteknik. Högtryckvridning under tillförd värme var ett effektivt sätt att öka bulkdensiteten. Tunnare folie oxiderade mera på grund av stor specifik ytarea och hög mikrosträvhet. Oxidationsgraden för briketter med bulkdensitet över 2.4 g/cm3 var betydligt lägre än briketter med lägre bulkdensitet. Briketter av de två tunnaste folierna ledde till högre återvinningsgrad jämfört med motsvarande spån. Effekten av kompression på återvinningsgraden var mindre för de tre tjockaste folierna. Återvinningsgraden ökade med ökad kompression för det tunnaste foliet. Trots att denna folie oxiderades relativt mycket var återvinningsgraden 99-100 % efter kompression till 2.6 g/cm3. Resultatet indikerar på att främst specifika ytarean påverkar återvinningsgraden av aluminiumet. Baserat på den föreslagna teorin borde ett optimum avsaltmängd, fluorinnehåll och ytarea skrot kunna utvecklas för att maximera återvinningsgraden.
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Kamalasekaran, Arun. "Numerical and experimental investigations of gas jet used in atomisation of metal powders." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281858.
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The environmental impact caused by the traditional production techniques has led to increased research in the field of alternative production techniques such as additive manufacturing. However, the environmental sustainability of the manufacturing techniques that produce and supply powders to the additive manufacturing process can be improved significantly. This project deals with improving the fraction of powder produced by gas atomisation that is suitable for any specific manufacturing process, by optimising the convergent-divergent nozzle used in the process. In order to identify the influential in- put parameters affecting the characteristics of the gas jet exiting a convergent- divergent nozzle, the relative effects of the input parameters were studied. A computational fluid dynamics model of the convergent-divergent nozzle was created and validated using images obtained through the shadow-graph technique. The results of the model and the experiment followed similar trends, but the absolute scale of gas jets did not match. This discrepancy was attributed to assumptions made about the conditions used as inputs to the computational fluid dynamics model, such as gas density and viscosity. Furthermore, a qualitative parametric study performed on the same computational fluid dynamics model revealed that the angle of the nozzle's diverging section to be the most significant parameter that controls the gas jet length.The findings of this study can be used to predict the gas flow through the convergent-divergent nozzle. This will enable more effective design of the gas atomisation process and gas flows in other processes such as in a rocket motor,the lance used in the basic oxygen furnace and the blast furnace tuyere.Miljöpåverkan av traditionella tillverkningstekniker har lett till ökad forskning inom alternativa tillverkningstekniker, som till exempel additiv tillverkning. Dock kan hållbarheten hos tillverkningstekniker som producerar och levererar pulver till de additiva tillverkningsprocesserna förbättras avsevärt. Detta projekt handlar om att öka andelen pulver som produceras genom gasatomisering som är lämplig för en specifik tillverkningsteknik. Detta kommer att uppnås genom optimering av de Laval-munstycket som används i gasatomiseringsprocessen. För att identifiera de variabler som påverkar egenskaperna hos gasstrålen som kommer ut från munstycket studerades den relativa betydelsen och effekterna av variablerna. En CFD-modell av de Laval-munstyckena skapades och validerades genom användning av bilder som skapades genom skuggrafteknik. Resultaten av modelleringen och de experimentella resultaten visade samma trend, men längden på gasstrålen matchade inte. Avvikelsen tillskrevs antaganden om gasegenskaperna som används som parametrar till CFD-modellen, till exempel densitet och viskositet. Dessutom avslöjade en kvalitativ studie av parametrarna utförd på samma CFD-modell att vinkeln på de Laval-munstyckens divergerande del är den avgörande parametern som kontrollerar längden på gasstrålen. Resultaten av denna studie kan användas för att förutsäga gasflödet genom de Laval-munstycket. Detta kan möjliggöra effektivare design av gasatomiseringprocesser och gasflöden i andra processer, till exempel i en raketmotor, i lansen som används i den basiska syreugnen och dysor i masugnen.
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Selldén, Adam. "Evaluation of Heat Treatments for the Nickel-Based Superalloy Haynes® 282® Manufactured by Selective Laser Melting : A Study Based on Microstructural Examinations and Mechanical Testing." Thesis, Linköpings universitet, Konstruktionsmaterial, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-170844.
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Nickel-based superalloys have a wide range of applications, mainly in gas turbines for power generation and aircraft propulsion. They are superior to competing alloys in maintaining excellent mechanical properties for extended durations at extreme temperatures and loads, all while resisting corrosion and oxidation. Haynes 282 is a new age-hardenable nickel-based superalloy that is reported to have a remarkable combination of creep strength, thermal stability, weldability and formability that gives it potential for new applications. Additive manufacturing (AM) is often referred to as 3D printing and the term comprises a number of techniques with the commonality of producing components layer-by-layer with a 3D CAD model as basis. The AM methods allow for unprecedented design freedom and the possibility of replacing complex multi-part components with single part components. The AM methods also enable shorter lead times in many cases and repairs where only part of a component can be replaced instead of replacing the whole component. Selective laser melting (SLM) is a metal AM method that involves a metal powder bed and a laser beam that fuses the powder by melting it according to the predefined geometry. The aim of this project was to evaluate the effect of different heat treatments for Haynes 282 components produced by SLM and it was done by microstructural studies and mechanical testing. Comparisons were made between literature reports on the conventionally produced material, the as-manufactured SLM material and three different heat treatments of 1120-2h-WQ+1010-2h-AC+788-8h-AC, 1170-8hWQ+1010-2h-AC+788-8h-AC and 1170-8h-WQ+1010-4h-AC+788-8h-AC. The first one is recommended by Haynes for conventionally produced material. The microstructural studies focused on identifying occurring phases and their distribution. The grain boundary carbide precipitation after heat treatment was shown to be rather different from the conventionally produced material both in terms of carbide types and their distributions. Grain boundary carbide networks were formed after all the heat treatments. A fine intragranular distribution of a titanium-rich phase that could not be identified was found in all examined SLM specimens. The mechanical testing consisted of tensile testing at room temperature and 600°C, impact testing and hardness testing. The heat treated specimens exhibited remarkable strength but significant embrittlement that was believed to be caused by the grain boundary carbide networks.
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Johansson, Carl, Amanda Engström, Emil Lundgren, Emma Klåvus, Felix Ekholm, Johan Magnusson, and Tinde Höjer. "Heat transfer in pressed steel powder - Part 1: Temperaturemeasurements in capsules." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388887.
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El, Mouhib Sabrina. "Effect of Stainless Steel Additive Manufacturing On Heat Conductivity and Urea Deposition." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287314.
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Hydroforming is the manufacturing process that Scania uses to produce exhaust pipes with complex shape and high durability. Selective Laser Melting is the process used by designers to print prototype pipes and perform emissions tests before mass production. Results from previous tests at Scania showed superior performance of 3D printed pipes compared to hydroformed components during emissions test as the 3D printed pipes were able to transfer heat faster than hydroformed pipes. To understand the reason behind this mismatch, the effect of selective laser melting parameters on energy density, relative density, grain size and thermal conductivity are investigated. These properties have direct impact on heat transfer. Ten samples were fabricated using the same laser power and layer thickness but different combinations of scanning speed and hatch distance. Samples were then subject to microstructural analysis using an optical microscope and average grain size measurement using image analysis software called Imagej. The density of each sample was measured using the Archimedes method. Moderate correlation is found between energy density and relative density. No ranking of the selective laser melting parameters with respect to forming the highest density was achieved because of the high uncertainties involved with the density measurement technique. Thermal conductivity was measured us- ing the one dimensional heat flow equation with an appropriate experimental set up. Thermal conductivity seems to be more influenced by relative density and direction of printing layers than the energy density and grain size. This conclusion is not statistically significant due to high uncertainty involved in the measurement of thermal conductivity. More advanced and accurate tech- nologies need to be used in the future to measure both density and thermal conductivity in order to find the most suitable selective laser melting parameters for Scania’s prototype pipes. The findings of this research can be used as a foundation for future research related to urea deposition on 3D printed pipes.Hydroforming är den tillverkningsprocess Scania använder för att producera avgasrör som har en komplex form och hög hållbarhet. Selektiv lasersmältning är den process som används av konstruktörer för att skriva ut prototyprör och utföra utsläppstester före massproduktion. Resultat från tidigare utsläppstes- ter på Scania visade en överlägsen prestanda för 3D-tryckta rör jämfört med hydroformade komponenter, eftersom 3D-tryckta rör kunde överföra värme snabbare än hydroformade rör. För att förstå orsaken bakom denna skillnad undersöks effekten av selektiva lasersmältningsparametrar som energitäthet, relativ densitet, kornstorlek och värmeledningsförmåga. Dessa egenskaper har direkt inverkan på värmeöverföringen. 10 prover tillverkades med samma laserkraft och skikttjocklek, men med olika kombinationer av skanningshastighet och kläckavstånd. Proverna utsattes sedan för en mikrostrukturell analys med hjälp av ett optiskt mikroskop, samt genomsnittlig kornstorleksmätning med hjälp av bildanalysprogramvaran Imagej. Densiteten för varje prov mättes med Archimedesmetoden. Måttlig korrelation kunde identifieras mellan energitätheten och relativ densitet. Ingen rangordning av de selektiva lasersmältningsparametrarna med avseende på bildning av den högsta densiteten uppnåddes på grund av de höga osäkerhetsfaktorer som är involverade i densitetsmättekniken. Värmeledningsförmågan mättes med hjälp av den endimensionella värmeflödesekvationen, med en lämplig experimentell uppställning. Värmeledningsförmågan tycks påverkas mer av tryckskiktens relativa densitet och riktning än energidensiteten och kornstorleken. Denna slutsats är inte statistiskt signifikant på grund av hög osäkerhet i mätningen av värmeledningsförmåga. Mer avancerade och noggranna teknologier måste användas i framtiden för att mäta både densitet och värmeledningsförmåga, för att hitta de mest lämpliga selektiva lasersmältningsparametrarna för Scanias prototyprör.
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Singh, Sandeep. "Varmduktilitet vid stränggjutning av duplexa rostfria stål." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219751.
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Abstract Hot ductility during continuous casting of duplex stainless steels In the continuous casting of the duplex stainless steel, longitudinal corner cracks in the first casted bloom of SAF 2507 have been discovered by Sandvik. SAF 2205 contains the same alloying substances as SAF 2507, but with some difference in the concentration of the elements. Despite this similarity, the occurrence of corner cracks in SAF 2205 is minimal and thus is not considered to be a significant problem. The reason for the appearance of hot cracks in SAF 2507 may be due to reduced ductility and due to stress variations in the material that occurs during casting. An earlier research for mapping longitudinal corner cracks in SAF 2507 and SAF 2205 proved to occur due to thermal stresses created by shrinkage of the shell in the mold. A reduced ductility can be obtained by embrittlement of grain boundaries that may arise with a brittle phase. The high amount of alloy elements in duplex stainless steels can result in precipitation of intermetallic phase, which is a brittle phase. Through a mapping of microstructure of continuous casted SAF 2507 and SAF 2205, intermetallic phase was observed in samples from SAF 2507.In order to gain an understanding of the appearance of hot cracks in SAF 2507, in situ hot tensile tests were performed. The hot tensile tests were performed in order to compare and analyze the ductile behavior of SAF 2507 with SAF 2205. The purpose of the tensile tests was to simulate continuous casting process at Sandvik.The results from the tensile tests show that SAF 2507 and SAF 2205 are not sensitive to hot cracking at temperatures near solidus. However, intermetallic phases were found in SAF 2507 during hot tensile testing at 800 ° C. But no intermetallic phase could be found in SAF 2205. Temperature measurements and calculations by CFD during continuously casting of SAF 2507 showed that intermetallic phases could possibly precipitate in the mold. In a previous research done by Sandvik Materials Technology, shows how thermal stresses can occur on the corners of a cast inside the mold, during continuous casting of SAF 2205 and SAF 2507.The conclusion of this work is that longitudinal corner crackers in SAF 2507 can be initiated in the mold, because of a combination of thermal stresses and intermetallic phases. Keywords ∙ Duplex rostfritt stål ∙ Varmsprickkänslighet ∙ SAF 2507 ∙ SAF 2205 ∙ Stränggjutning ∙ Duktilitet ∙ Sigma ∙ Kromnitrider ∙
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Ma, Ping. "Experimental studies on treatment and recycling of pickling sludge generated in stainless steel production." Licentiate thesis, Luleå tekniska universitet, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18242.
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Pickling sludge generated in the stainless steel industries contains large amounts of calcium fluoride and water and relatively small amounts of metals. Therefore, such sludge is difficult to be directly recycled back to the EAF process and would be harmful to the environment if deposited as landfill for a long term. The main objective of the present thesis work is to find out proper ways to treat the pickling sludge and to recover useful metals from it. For this, characterisations, solid-state reduction and smelting reduction tests on the pickling sludge were carried out in the laboratory. Likewise, comparison studies on solid-state reduction of pure metal oxides with graphite and on pickling sludge with p-coke were conducted using TGA. In addition, the off-gas generated by smelting reduction of pickling sludge was monitored by measurements with a mass spectrometer. Through the present thesis study it can be concluded that it is possible to treat and recycle pickling sludge by using both solid-state reduction and smelting reduction methods. In order to completely separate the reduced metals from the sludge, the smelting reduction method would be preferred.Godkänd; 2001; 20070313 (ysko)
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Ökvist, Lena Sundqvist. "Optimisation of the slag formation in a blast furnace charged with 100% pellets." Licentiate thesis, Luleå tekniska universitet, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18685.
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This work is based on experiences from industrial blast furnaces. Process irregularities when testing self-fluxed pellets Process disturbances when charging increased proportions of coarse pellets Laboratory tests to evaluate the effect of basic fluxes on the slag formation in the bosh and in the raceway have been carried out. Pilot scale tests have been performed to verify the effect of coarse pellets. The effect of reduction degree and the reduction behaviour on the slag formation and blast furnace performance have been evaluated It was found that decreased degree of reduction of pellets or lowly reduced core of coarse pellets decrease the melting temperature and increase the softening and melting temperature interval. Basic fluxes have a negative effect on the melting properties of the self-fluxed pellets and a positive effect on the melting properties of the olivine pellets. Basic fluxes have a positive effect on the melting properties of tuyere slags.Godkänd; 2001; 20070313 (ysko)
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Ryk, Lennart. "Kolvariationer och leveransuppföljning." Licentiate thesis, Luleå tekniska universitet, 1985. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16823.
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