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1
Whateley, Philip N. "Defects in steel investment castings." Thesis, Aston University, 1991. http://publications.aston.ac.uk/11879/.
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A general investigation was performed, in an industrial environment, of the major types of defect specific to investment castings in steel. As a result of this work three types of metallurgical defect were selected for further study. In the first of these, defects in austenitic stainless steel castings were found to result from deoxidation by-products. As a result of metallographic investigation and the statistical analysis of experimental data, evidence was found to support the hypothesis that the other two classes of defects - in martensite stainless and low alloy steels -both resulted from internal or grain boundary oxidation of the chromium alloy constituent This was often found to be followed by reaction between the metal oxides and the ceramic mould material. On the basis of this study, proposals are made for a more fundamental investigation of the mechanisms involved and interim suggestions are given for methods of ameliorating the effect in an industrial situation.
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Walker, Justin Daniel. "An innovative new pouring design for steel castings." [Ames, Iowa : Iowa State University], 2008.
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Gorsky, Daniel A. "Niyama Based Taper Optimizations in Steel Alloy Castings." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1316191746.
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Galles, Daniel Joseph. "Prediction of distortions and pattern allowances in steel sand castings." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2077.
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Modeling the thermomechanical behavior of the bonded sands used for steel sand casting is of great importance for the prediction of distortions and pattern allowances. In this study, distortions created by mechanical interactions between the casting and sand mold are measured from two experimental setups and then predicted by finite element stress analyses. The casting geometries involve a hollow cylinder for the first experiment and U-shaped bracket for the second. The temporal evolutions of 1) the cylinder’s inner diameter and 2) the gap opening between the bracket legs are measured in situ utilizing LVDTs (Linear Variable Differential Transformers) connected to quartz rods. The considerable distortions measured during the cylinder and bracket experiments are mainly caused by core expansion and core restraint, respectively. For the simulations, a one-way temperature-displacement coupling is adopted, in which temperatures are predicted using commercial casting simulation software and then used as inputs for the finite element stress analyses. The steel is modeled as an elasto-visco-plastic material, whereas the Drucker Prager Cap model is employed for the bonded sand. It is found that sand dilation (i.e., the volumetric expansion of a granular media due to a shear force) must be considered for the cylinder experiments. Otherwise, the inner diameter expansion observed during solidification is far under-predicted. For the bracket, a crack plane must be included in the stress simulation model. If not, the outer mold restrains the bracket legs from being pushed outward and distortions are under-predicted. By matching the predicted displacements with the measurements, a constitutive dataset for bonded sands is developed, whose predictive capability is then demonstrated through a case study.
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Sumer, Ali. "Prototype Development and Experimental Verification of a Cast Modular Connector for Seismic-Resistant Steel Frames." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/194890.
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A cast modular connector (MC) has been developed for use in seismic-resistant steel moment frames. The MC is a field bolted beam flange connection intended to serve as the frame's special energy-dissipating detail. The connector is specifically configured for optimal seismic performance through a casting process. The MC possesses inherent ductility through variable-section arms that minimize plastic strain demand and a reliable yet economical fastening method through a base end-region that virtually eliminates prying forces on bolts.The dissertation presents three journal papers. The first paper describes the portion of the analytical research focused on establishing the optimum geometry for the energy dissipating arm elements. Key parameters were evaluated through parametric studies using nonlinear (material and geometry) finite element analysis and supported by basic theoretical models. The outcome was a set of optimum geometric ratios covering width reduction, length to thickness, aspect ratio, and fillet radius.The second paper describes the development process of the isolated connector rather than full-connection behavior. Designs were alternately evaluated for structural performance and castability through the electronic exchange of solid model files with steel foundry industry partners. The analytical results indicate the potential for excellent ductility and energy dissipation characteristics in the MC Beta prototype.The third paper focuses on the prototyping and experimental verification of the MC Beta prototype. Steel foundry industry partners cast the MC Beta prototype at approximately half-scale. The scaled MC Beta prototype was tested in isolated fashion under monotonic and cyclic loading. The experimental results confirmed the performance of the analytically-based designs. The MC Beta prototype exhibited exceptional performance in terms of stable energy dissipation, far exceeding qualifying rotational ductility capacities. In direct comparisons to a WT section of similar stiffness and strength, the MC Beta prototype possessed greatly enhanced ductility and energy dissipation characteristics.With the MC Beta prototype developed and experimentally verified under isolated conditions, an experimental verification of beam-to-column joints containing the scaled MCs were performed using accepted testing protocols. The preliminary test results indicate that the connection exceeded qualifying rotational ductility capacities and showed promise as a special energy-dissipating detail in seismic-resistant steel moment frames.
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Xie, Kelvin Yu Xuan. "The effect of niobium-rich clusters on the mechanical properties of ultra-thin strip cast steels produced by the CASTRIP® process." Thesis, The University of Sydney, 2012. http://hdl.handle.net/2123/17140.
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Federico, Giovanni. "Use of Cast Modular Components for Concentrically Braced Steel Frames." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/268572.
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Cast modular components have been under development for earthquake resistant steel structures. These concepts take advantage of the versatility in geometry afforded with the casting process to create components specifically configured for ductile behavior. Two systems were developed as part of this dissertation research: (1) the Cast Modular Ductile Bracing system (CMDB); (2) the Floating Brace system (FB).The CMDB system makes use of cast components introduced at the ends and the center of the brace to produce a special bracing detail with reliable strength, stiffness and deformation capacity. The system takes advantage of the versatility in geometry offered by the casting process to create configurations that eliminate non-ductile failure modes in favor of stable inelastic deformation capacity. This thesis presents analytical research performed to determine the buckling strength and buckling direction of the bracing element based on the geometries of the cast components. Limiting geometries are determined for the cast components to control the buckling direction. Design formulas for buckling strength are proposed. The Floating Brace system is a new lateral bracing concept developed for steel special concentric braced frames. The concept uses a set of special plate details at the end of the brace to create a stiff, strong and ductile lateral bracing system. The plates are arranged such that some provide direct axial support for high initial stiffness and elimination of fatigue issues for daily service wind loads. The remaining plates are oriented transverse to the brace and thus provide ductile bending response for the rare earthquake event, in which the axial plates become sacrificial. The main bracing member and cast pieces remain elastic or nearly elastic. Thus, following the seismic event, the plates can be replaced. In this thesis, analytical studies using nonlinear finite element analysis are performed to determine the optimum: (a) relative strength of the end connection to the brace; and (b) ratio of strength between axial and transverse plates. Design equations are provided. Prototypes for each concept were developed. Castings were created. Large scale laboratory physical testing was performed as experimental verification (proof of concept) for the two systems.
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Grandillo, Angelo M. "A temperature control strategy for Stelco McMaster Works /." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61258.
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In this study, it was shown that improvements in the quality of continuously cast steel billets, similar to those which can be achieved by electromagnetic stirring (EMS) of the liquid pool during solidification, can be obtained if casting superheats can be consistently controlled at low levels. A lack of casting temperature control is not only detrimental to the quality of the cast product, but also to a shop's overall productivity. The important variables for temperature control in the ladle, tundish and mould were quantified and possible methods of controlling these variables were proposed.The thermal state of the ladle lining is one of the major contributors to the variability in casting temperature. It was shown that by reducing energy losses from the refractory ladle lining, by way of incorporating an insulating refractory tile between the ladle shell and the safety lining and by using a ladle lid throughout the cycle of the ladle, temperature losses from the liquid steel can be substantially decreased. (Abstract shortened by UMI.)
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Klváček, Jan. "Vliv metalurgického zpracování a podmínek odlévání na vnitřní jakost ocelových odlitků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230533.
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The aim of this thesis was to perform the classification of defects of emerging in a specific type of steel castings made by company UNEX Foundry, Ltd. and then determine the conditions of their origin. This is mainly discontinuity of casting material. The next step was to propose the corrective measures eliminating creation of these defects.
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Pernica, Vítězslav. "Optimalizace výroby těžkých ocelových odlitků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228645.
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Diploma thesis deal with definnig the casuses of stell castings defects in the DSB EURO s.r.o Foundry. The main target is to optimise technological parameters for avoiding the surface casting defects. The first stage is the identification of the defects, describing of the main reasons and mechanic. Defect quantification is make from measuring of area and volume of the mended defects. In association with surface defects, the number of the crackings was observed. Finally there are suggested correction actions based on the previous investigation.
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Čech, Jan. "Studium slévárenských vad v masivních odlitcích." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-234184.
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A massive castings defects are examined in this doctoral thesis, specialise in steels passing through peritectic transformation. There are typical types of defects at massive steel castings, as contrasted to „ordinary“ internal and surface ones. For massive steel castings are typical defects under feeders like conchoidal fractures, segregations, microporesities, reoxidation products. Combination of Al and Zr is an ordinary final deoxidation of EOP and LF steel for castings in ŽĎAS a.s. foundry. The aim of Al + Zr combination was to both deep deoxidation by Al (decrease of bubbles risk) and denitrification by Zr (decrease of conchoidal fractures). This theses refute premission mentioned above and verified persisting risk of defects under massive feeders, even though Al + Zr deoxidation is used. A final deoxidation by increased amount of Al was examinated, in combination with other deoxidation agents. Castings had 11 [cm] maximal modulus, and occurence of conchoidal fracture, reoxidation products and primary austenite grain size was evaluated. A selected optimal final deoxidations (Al, Al+Ti, Al+Zr) as a result from experiment described above, were evaluated on castings with 15 [cm] maximal modulus. The result of experiment is, that is not possible to repeatedly produce massive steel casting using EOP metallurgical equipment without defects under feeders, despite of deoxidation and pouring temperature optimalization. The defect indications look like conchoidal fracture, but there are microporesity and impurities instead. Finally, castings with maximal modulus 15 [cm] were produced using so called secondary metallurgy (LF, VD). Secondary metallurgy allowed to both significant decrease of sulfur and degassing of melted metal. Only this metallurgical procedure guarantees production of heavy steel castings without typical defects under massive feeders
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Malý, Václav. "Optimalizace výroby těžkých ocelových odlitků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229770.
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In its first part the work deals with the frequent defects of heavy steel castings. Experiments were carried out in very heavy bearing rings casting of cement kilns in order to reduce consumption of liquid metal and to increase the internal quality of castings. The progress was achieved by introducing new technologies; this thesis describes the technologies used and subsequently performs their comparison.
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Návrat, Radim. "Vliv metalurgického zpracování a slévárenské technologie na jakost ocelových odlitků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230530.
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The aim of this thesis was to determine the impact of the used chemical composure during metallurgical treatment and foundry technology on the inner and surface quality of experimental casting under operational conditions at Třinec foundry. A minor part of this thesis is focused on the determination of the effect of filtration on mechanical properties of steel.
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Kaněra, Miloš. "Výroba odlitků z austeniticko-feritických hyperduplexních korozivzdorných ocelích." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445174.
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The thesis deals with hyper duplex stainless austenitic-ferritic steels and their mechanical and castability properties. The evaluation of resistance to pitting corrosion is divided by PRE values. Steels with a PRE value higher than 48 belong to the group of hyper duplex steels. The theoretical part contains an introduction to the chemical composition, structure and properties of these steels. The practical part is focused on the conditions of tendency to crack castings during solidification and cooling. Furthermore, there is evaluated influence of intermetallic phases on mechanical properties.
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Krejčí, Martin. "Nedestruktivní zkoušení odlitků ozubených kol." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228720.
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This diploma thesis resolves aplication of particular non-destructive testing methods while producing castings of steel wheels and quality control of this process. There are described fundamentals of flaw detection, determination of flaw-generation cause and suggestions for optimalization of casting process and increasing of its quality.
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Carpenter, Kristin. "The influence of microalloying elements on the hot ductility of thin slab cast steel." Department of Materials Engineering - Faculty of Engineering, 2004. http://ro.uow.edu.au/theses/161.
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Experiments were preformed on a Gleeble 3500 Thermomechanical Simulator to study the hot ductility behaviour of C-Mn-A1 steel and the influence of Nb, Ti and Nb-Ti additions. The simple hot tensile test has been shown to correlate well to the problem of transverse cracking. Therefore, the principle aim of this research is to gain a greater understanding of transverse cracking during the straightening of continuously cast slabs. In particular, attention was paid to thin slab casting conditions. Hot tensile test specimens were either solution treated in melted in-situ (direct cast) and cooled to the deformation temperature. Solution treatment tests simulated conventional casting, where slabs are cooled to room temperature than heated prior to rolling. Direct cast tests simulated hot direct rolling conditions, where slabs are rolled directly after casting without being cooled below the austenite to ferrite transformation. Specimens were cooled to the deformation temperature at two cooling rates, 100K/min and 200K/min. The cooling rate of 100K/min corresponds to the average cooling rate experienced for a conventionally cast slab, 250mm in thickness. The cooling rate of 200K/min corresponds to the average cooling rate for thin-cast slabs, 50mm in thickness. The development of the combination of thin slab casting of hot direct rolling requires hot ductility work to be performed under direct cast conditions and at higher cooling rates. Surface quality is of the utmost importance in thin slab casting so the elimination of transverse cracking is of prime economic importance. There are significant differences between as-cast (direct cast) and reheated (solution treatment) microstructures. In particular, changes in precipitate behaviour, austenite grain size, and the relationship between segregation and the position of austenite gran boundaries was investigated. An attempt has been made to determine what influences these differences in microstructure have on hot ductility. Niobium bearing steels were selected for the reason that there are still problems with Nb steels regarding transverse cracking. Furthermore, there have been contradictory reports on the effects of Ti additions on the transverse cracking behaviour of NB steels. There is evidence from commercial practice that indicates that small additions of Ti improve the transverse cracking susceptibility of Nb steels. However, laboratory results generally show Ti additions have little influence or even a detrimental effect on hot ductility. Disparities in the thermal history simulated in laboratory tests to actual conditions near the surface of a continuously cast slab is the most likely reason for this discrepancy. Therefore, the influence of more closely simulating the thermal history conditions near the surface of a continuously cast slab was evaluated for the Nb-Ti steel. Experimental work involved metallographic and scanning electron microscopy examination of the fracture surface. Transmission electron microscopy was used to determine precipitation characteristics. Tensile tests were conducted to determine mechanical properties, where reduction in area (RA) was used as a measure of ductility. The dendritic structure for direct cast and solution treatment specimens was revealed using a heat treatment procedure (normalising). Particle size was correlated to reduction of area for precipitates in the single-phase austenite temperature region. It was shown that particles below 15nm were detrimental to hot ductility. The relationship between interparticle spacing and reduction of area was also determined. Microalloying additions to C-Mn-A1 steels significantly widen the ductility trough but the depth remains similar. Low ductility was found at higher temperatures in the microalloyed steels due the intergrandular failure as a result of grain boundary sliding in the austenite. Grain boundary sliding was favoured by the slow strain rate and was enhanced by fine microalloyed nitrates and/or carbides. Fine particles can pin austenite grain boundaries, allowing sufficient time for cracks to link together, ultimately causing intergranular fracture. Increasing the cooling rate generally lowered ductility further by promoting finer precipitation. The trough depth is similar in all steels as the formation of thin ferrite films controls ductility at the minimum trough position. The formation of thin films of ferrite allowed strain to concentrate in the softer ferrite phase and intergrandular failure occurred due to microvoid coalescence. Direct cast conditions always led to lower ductility compared to solution treatment conditions. This is explained in terms of differences in the microstructure, namely, grain size, segregation and precipitation. It is recommended that direct cast conditions should be used to determine hot ductility behaviour as it more accurately simulates continuous casting conditions. It was found that simulating the thermal history near the surface of a continuously coast slab, as opposed to cooling directly to the deformation temperature, improved ductility of the Nb-Ti steel. This improvement in ductility was attributed to the thermal history providing favourable conditions for coarsening of NbTi (C,N).
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Abu, Shousha R. I. "Hot ductility of steels." Thesis, City University London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305120.
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Starkie, Bernard. "Finite element analysis of some aspects of steel casting." Thesis, University of Sunderland, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329143.
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Purkar, Pranit Pramod. "Design optimization for obtaining zero defects in steel casting." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Material och tillverkning, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-45663.
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This thesis is about the design of the gating system and selection of proper alloy for defects free (grate bar) casting. The gating system plays an important role in casting manufacturing process. The gating system has different elements like pouring cup, sprue, well, runner, riser, and ingates. The function of the gating system is to provide molten metal to the mould cavity through different gating system elements. Casting is a metal shaping process which is used to produce a cast component. The casting process depends upon the material, type of pattern, mould and various techniques like sand casting, investment casting, die casting, squeeze casting and lost foam casting. The sand mould casting process is used in this report. The casting process is used for making small to large cast parts, complicated shapes, and precision parts, etc. Making a casting without defects is an important requirement for its strength. The effective and efficient design of the gating system is necessary for making defects free castings. There are various defects like shrinkage cavity, porosity, pinholes, blowholes and incomplete filling that may occur in sand casting. The simulation software like Magma Soft and Nova Flow Solid are used to predict the possible defects in the casting. The uses of the simulation improve product quality and increase productivity. It also helps to reduce the rejection rate by identifying and controlling defects. This work is done at AB Bruzaholms Bruk as part of master thesis work at Jönköping University, Sweden. The company provides all the necessary data for simulation purposes. The design of the gating system is finalized as per company requirements and needs. The research questions that have been answered in this report based on the following points. 1) What does zero-defect mean? 2) Which is the best design among the ones that are prepared and simulated? 3) Which is the best alloy combination for casting parts that give defects free casting and better fluidity and filling?
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Elfsberg, Jessica. "Oscillation Mark Formation in Continuous Casting Processes." Licentiate thesis, KTH, Casting of Metals, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1653.
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Leckenby, B. M. "Finite element analysis of bulging during the continuous casting of steel slabs and blooms." Thesis, University of Sunderland, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382766.
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Tuncer, Munir Cihangir. "Precision forging hollow parts." Thesis, University of Birmingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558075.
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Lebeau, Timothy Charles. "Brake drum production by centrifugal casting." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/lebeau.pdf.
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Mimura, Yoshihito. "Sticking-type breakouts during the continuous casting of steel slabs." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27941.
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Sticking of the shell in the mold, which often occurs in a high-speed continuous slab casting machine, can be detected with thermocouples in the mold copper plates and prevented from developing into a breakout by reduction of the casting speed. However, a rapid reduction of the casting speed causes some quality problems and a low slab temperature. Thus, sticking-type breakouts remain a concern to the steel industry, and it is still not clear how and why the sticking initiates at the meniscus. The objectives of this study were to identify the causes of sticking at the meniscus, to elucidate the mechanism of sticking and finally to propose methods to reduce the occurrence of sticking.
In order to identify the causes of sticking, it was necessary to examine a sticking-type breakout shell metallurgically, especially the dendrite structure at the shell surface. To link the metallurgical information to the casting conditions, the validity of a correlation in the literature between secondary arm spacing and local cooling rate has been examined. The secondary dendrite arm spacing in the subsurface of a slab has been measured and linked to a local cooling rate calculated from the measured mold heat-flux with this correlation. From this analysis, it was confirmed that Suzuki's correlation between secondary dendrite arm spacing and local cooling rate can be applied for a high cooling rate such as in continuous casting. A sticking-type breakout slab exhibiting five sticking events of 0.08% carbon steel, has been studied and it has been found that small holes exist at the surface in the sticking shells (most likely the site of entrapment, of solid mold flux). The shell which initially sticks exhibits a coarse dendrite structure and, in a longitudinal section, the shape of the initial sticking shell is parabolic. Moreover, with one exception, segregation lines typically 1-3 mm below the surface and almost parallel to the surface have been found in most of the sticking shell. From secondary ion mass spectroscope studies, the solutes concentrating in these segregation lines were determined to be Mn and S.
Apparently, the sticking occurs at the meniscus where heat extraction is greatest and molten mold flux flows between the shell and solid mold flux rim oscillating with the mold. Therefore, to explain these meniscus phenomena, mathematical models of heat transfer at the meniscus and fluid flow in the mold flux channel have been formulated. To analyze the initial sticking event, the meniscus level has been changed in the computer simulations and the following mechanism has been proposed to explain the initiation of a sticking-type breakout. If the meniscus level rises, a deep notch forms in the shell due to the interaction between the mold flux rim and the shell. When a thick mold flux rim moves downward, it contacts the shell above the notch and the shell sticks to the mold flux rim. During the upstroke motion of the mold, tensile forces on the shell cause a rupture at the deep notch which is the hottest and weakest. The predicted solid flux rim profile agrees well with the parabolic shell shape measured in a longitudinal section of the sticking shell.
Since the hot spot is the most likely point to be ruptured, conditions which minimize the hot spot were sought with the models. It was found that most of the conditions required to reduce hot-spot formation are exactly opposite to those required to minimize oscillation mark depth. Notwithstanding this, there are a few techniques to reduce the occurrence of sticking and to improve the surface quality: use a low melting point mold flux and, probably, maintain a deep mold flux pool. An interesting finding with respect to oscillation mark formation is that, if the mold flux rim is thick, the oscillation mark is caused by the interaction of the flux rim with the solidifying shell, while the fluid pressure development in the molten flux film dominates the mark formation in the case of a thin flux rim.
For the analysis of the segregation line, a mass transfer model has been formulated based on a consideration of δ — γ transformation. From this analysis, it was found that the segregation observed in the sticking shell is a band of interdendric segregation enhanced by enlarged primary dendrite arm spacing which, probably, is caused by the appearance of an air gap due to the shell shrinkage.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Khurana, Shuchi P. "Improvement of Mold Conditions for Thin Slab Casting of Steel." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392800635.
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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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Archer, Lucas Andrew. "Development of high-performance cast steel crankshafts." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/2179.
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To produce cast steel crankshafts, risering and gating systems are developed. Filling and solidification simulations of the steel crankshaft rigging are carried out to confirm that the rigging developed will produce a low porosity casting. A sand mold is created with Computer-aided design software, based on the developed crankshaft and rigging. Two prototype crankshafts are cast from the sand molds, and analyzed for porosity. The porosity analysis results are compared directly to the simulated porosity, and found to be in good agreement. From the analysis of the prototype crankshaft, rigging systems for a two-on and single-throw crankshaft are developed.
A new casting method for steel is developed. The counter-gravity with pressurization during solidification casting method utilizes vacuum pressure of 7.3 psia to draw liquid steel into a mold, where it is held until the inlet has solidified. Once the inlet has solidified, the vacuum pressure is released, and the pressure of the entire system is raised to 45 psia. Exothermic hot topping keeps the top of the riser liquid while the rest of the casting forms a solid shell. Therefore, the pressure only acts on the liquid metal at the top of the riser, forcing the liquid metal to feed farther into the casting. The new method is tested with simple bar castings. Analysis of cast bars shows that centerline porosity is fed by the riser when pressurized, while the gravity-filled control casting is not.
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Hedman, Daniel. "Casting and Characterization of Advanced High Strength Steels." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81098.
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The Latin American steel making company Ternium S.A. aims to develop and produce a new type of advanced high strength steel (AHSS) in which the main alloying elements are carbon, aluminium, manganese, and silicon. The present work is the first phase of the development project and it involves casting and characterization of four steel compositions with varying amounts of the aforementioned elements. The results revealed that the Mn-content had a large impact on the development of hard phases during solidification. A steel with a Mn-content of 2 %wt. had almost completely transformed to pearlite during cooling, while a steel with a 4 %wt. Mn-content consisted of primarily martensite and retained austenite. Only the impact of the Mn-content is evaluated. The columnar grain size for two of the four steel compositions were in the range of 20-30 mm, which is similar to those observed from continuous casting. This indicate that the heat transfer rate was slow enough to allow these grains to grow. Measurements during casting showed an initial cooling rate of 10-20°C/min at a distance of 10 mm inside the ingot, which is much slower than the surface cooling rate during continuous casting (100-150°C/min). It was assumed that the cooling rate was similar for all castings since the methodology was identical. However, the steel used for cooling rate measurements was not characterized, why a correlation between cooling rate and composition could not be obtained. A heat transfer model was developed to gain further knowledge of the solidification process. As a reference to the heat transfer model, a eutectic Bi-42Sn alloy was cast with temperaturemonitoring using a casting setup identical to that of the steel castings. A similar cooling rate tothe Bi-42Sn reference casting was obtained where the cooling was faster from above of the ingot than below. Thus, the last part of the metal to solidify during the simulation was situated in the lower half of the ingot. This provides a model for testing future steel compositions.
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Miklin, Anton. "Entwicklung einer Fertigungstechnologie für dünnwandigen Stahlguss." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2010. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-38945.
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Im Rahmen der Dissertation wurde eine Fertigungstechnologie entwickelt, die die Überleitung des Stahlniederdruckgießverfahrens (3CAST) in die Produktion und somit die Erzeugung des dünnwandigen Stahlgusses ermöglicht.
Die konventionellen Stahlgusswerkstoffe sowie ihre Gießbarkeit und Wärmebehandlung wurden untersucht und an die Besonderheiten des neuen Verfahrens und dünnwandigen Stahlgusses angepasst. Auf der Basis von schon existierenden Gießtechnologien wurde eine Formträgertechnologie (FTTech) entwickelt, die unter Berücksichtigung ökologischer Aspekte eine hohe Gussteilqualität und Wirtschaftlichkeit des Gießverfahrens sichert.
Die gewonnen Ergebnisse wurden anhand eines Formträgerprototyps unter produktionsnahen Bedingungen erfolgreich erprobt. Somit ist eine Grundlage für den bei der Fa. Evosteel GmbH geplanten Aufbau der Fertigungstechnologie zur Serienproduktion von komplexen dünnwandigen Stahlgussteilen geschaffen.
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Galles, Daniel Joseph. "Measurement and prediction of distortions during casting of a steel bar." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/4986.
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An elasto-visco-plastic deformation model predicts stresses and distortions in a low-carbon steel casting. Features of the model include rate and hardening effects, temperature-dependent properties, and pressure-dependent deformation in the mushy zone. A volume-averaging technique considers the multiple phases during solidification and is used to formulate the conservation equations, which (due to a weak link between temperatures and deformations) are decoupled and solved sequentially using commercial software. Temperature fields are calculated first using MAGMAsoft (MAGMAsoft, MAGMA GmbH, Kackerstrasse 11, 52072 Aachen, Germany) and then exported to a finite element software package, ABAQUS (Abaqus/Standard, Abaqus, Inc., Providence, RI, 2006), which predicts stresses and distortions. In order to simulate the conditions encountered in an industrial casting process, predicted temperatures and distortions are matched with experimental data from in situ casting trials. Preliminary simulations do not agree with the experimental distortions, which suggest that stress-strain data from mechanical tests (from which the mechanical properties were estimated) does not accurately characterize the material behavior of a casting during solidification and cooling. The adjustments needed to match measured and predicted distortions provide valuable insight to the effect a solidified microstructure has on its mechanical properties.
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Du, Pengfei. "Numerical modeling of porosity and macrosegregation in continuous casting of steel." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/2482.
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The continuous casting process is a widely used technique in modern steel plants. However, it is a complicated process that is not well understood. The objective of this research is to model the porosity and macrosegregation due to shrinkage related effects and solid deformation in the continuous casting of steel.
Solid phase movements due to bulging and variable roll gap are modeled with a simple algebraic equation based on assumed slab surface deflection. A simplified single domain fluid flow model is derived to predict the pressure field. When liquid pressure drops to zero, porosity starts to form. The distribution of porosity is calculated using the porosity equation which is based on the mass conservation. A macrosegregation model based on the species conservation is derived. With the relative velocity calculated from the pressure results and the solid velocity, macrosegregation is obtained. Since the solid phase velocity is not zero and mixture density is not assumed to be constant, porosity and macrosegregation due to both solid deformation and shrinkage effects are incorporated.
In order to validate the model, the pressure field of a three-dimensional pure metal solidification system is simulated. The results show the feasibility of the proposed model to predict the fluid flow. The porosity and macrosegregation prediction for different casting conditions are performed. The results confirm the necessity of including solid phase deformation in the prediction of porosity and centerline macrosegregation. The results also reveal the relations between different operating conditions (such as degree of bulging, soft reduction, and casting speed) and the porosity/macrosegregation defects in the final product.
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Venus, Anthony Derek. "The application of computer based modelling to steel foundry design for manufacture." Thesis, University of Sunderland, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319769.
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De, Wet Gideon Jacobus. "CFD modelling and mathematical optimisation of a continuous caster submerge entry nozzle." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-01312006-141026.
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Elahipanah, Zhaleh. "Thermo-Physical Properties of Mould Flux Slags for Continuous Casting of Steel." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-101270.
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Due to the high efficiency and productivity of continuous casting process, this method has been the most employed process to produce steel in past decades. The need to improve and optimize the finished product made it essential to gain more knowledge about the process, types of defects that may occur and the reasons for them. Moreover, the solutions for reducing the shortcomings in continuous casting process have been an intriguing subject to study. Many attempts have been done in order to reach this goal. Understanding, determining and optimizing the mould flux slag properties is especially important, since it plays an important and significant role in this process. For this, it is of outmost importance to acquire more knowledge about different properties of mould flux powders. Hence, there has been a world wide effort to measure and model the properties of mould flux properties, such as liquidus and solidus temperatures, heat capacity, enthalpy, thermal expansion, density, viscosity, electrical conductivity, surface tension and thermal conductivity. This thesis presents a brief review on continuous casting process, mould flux powder and its properties and characteristics. Furthermore, it focuses on the thermo-physical properties of mould fluxes. In present work, different industrial mould flux powders have been analyzed to measure their viscosity, break temperature, physical properties such as density, flowablity of powder, slag structure and chemical composition. The experimental data have been compared to some of the most commonly used models such as Riboud model, Urbain model, Iida model and KTH model.
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Yu, Peter Tong-Kan. "Simulation of transport phenomena during phase change in continuous casting of steel." Thesis, University of Ottawa (Canada), 1985. http://hdl.handle.net/10393/4675.
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Yamauchi, Akira. "Heat transfer phenomena and mold flux lubrication in continuous casting of steel /." Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3121.
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Hill, N. J. "Visco-plastic and thermal stress analysis in the continuous casting of steel." Thesis, Teesside University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376088.
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Kundu, Amrita. "Grain structure development during casting, reheating and deformation of Nb-microalloyed steel." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2917/.
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This thesis looks at the effect of micro segregation of Nb, generated from the continuous casting on grain structure development during reheating and deformation. The amount of segregated material present in the microstructure has been quantified in the as-cast condition and that has been used to model grain size distribution after reheating and deformation which is required for subsequent toughness prediction in 0.045 wt % Nb steel. The limits of validity of the original Dutta-Sellars model for predicting the amount of recrystallisation; investigating the influence of the variables such as starting grain size distribution, strain and Nb content has been examined. A modified Dutta-Sellars model considering the starting grain size distribution has been found to be more accurate in quantifying the amount of recrystallisation. This approach has been used to model grain size distribution after deformation both in the homogenised and in presence of Nb segregation. The effect of AlN, to replace Nb(C,N), on pinning the austenite grain boundaries during reheating has been investigated, as the segregation tendency of Al is much less compared with Nb.
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Fager, Fredrick, and Serg Chanouian. "Nuclear Waste Canister : Evaluating the mechanical properties of cassette steel after casting." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209803.
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Företaget Svensk Kärnbränslehantering AB (SKB) håller på att utveckla en slutförvaringskapsel som kommer innehålla avfall från den svenska kärnkraften. Det är dock fortfarande en process under utveckling och därför undersöks olika typer av metoder och kapselmaterial för att kunna tillverka en hållbar och säker kapsel. Kapseln består av ett hölje av kopparrör med svetsad botten och lock och en insats med stållock. Insatsen är en cylindrisk konstruktion av segjärn och innehåller en svetsad stålkassett för att skapa utrymmen till det använda kärnbränslet. Insatsen innehåller bland annat stålrör som under tillverkning får utstå en gjutprocess med segjärn och erhåller efter det icke homogena egenskaper. Målet med undersökningen är hur stor påverkan gjutningen har på stålets kemiska sammansättning samt mikrostrukturer. Det som orsakar de inhomogena egenskaperna är främst värmebehandlingen som driver diffusionen av kol från gjutjärnet till stålet, som då ger ett hårdare men sprödare material. Med hjälp av experiment och simuleringar upptäcks hur mycket kol som diffunderar in i stålet samt ändringar i den kemiska sammansättningen i de påverkade zonerna. Identifiering av fasomvandlingar, diffusion och ändringar i mikrostrukturer är stora faktorer som i sin tur ändrar de mekaniska egenskaperna i stålet.The Swedish Nuclear Fuel and Waste Management Company (SKB) have developed a final storage canister that will contain waste from the Swedish nuclear power plants. However, it is still in a development phase and therefore different types of methods and canister materials are investigated to produce the most durable and safe canister. The canister is made of a copper tube with a welded bottom and lid with an insert. The insert is a cylindrical construction of nodular cast iron that contains a welded steel cassette, to make space for the spent fuel, and a steel lid. The steel tubes showed inhomogeneous properties after being exposed to a casting around them. The aim of this investigation is to clarify the impact of casting on the chemical composition of the steel as well as the microstructure. The cause to the inhomogeneous properties were the diffusion of carbon from the cast iron to the steel, which then produced a harder and more brittle material. Experiments and simulations were used to see the carbon diffusion into the steel as well as what happens with the chemical composition in the affected zones. Identification of phase changes, diffusion and microstructures contributed to changes of mechanical properties in the steel.
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Sung, Pil Kyung 1961. "Segregation and structure in continuously cast high carbon steel." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277066.
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After hot rolling, the presense of segregation in the center of wire-rod can lead to a nonuniform transformation, resulting in bands of martensite in the microstructure. This is considered to be a defect, called center-martensite, because it can cause cracks and breaks during wire drawing. To identify the mechanism for the formation of center-martensite in wire-rod, the structure, macrosegregation and microsegregation in unworked billets were characterized. Based on measurements of secondary dendrite arm spacings, cooling rates during solidification were estimated. It appears that the macrosegregation of carbon and manganese in the billets manifests itself as the microsegregation in wire-rod, which is an agent in forming the center-martensite. Thus, electromagnetic stirring is proposed as a means to reduce the macrosegregation in the billet and, thereby, reduce the occurrence of center-martensite in wire-rod.
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Saraswat, Rajil. "Modelling the influence of mould flux on steel shell formation during continuous casting." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434907.
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Fernandez, Marcos Zambrano. "Mathematical modeling of ripple- and oscillation-mark formation in the casting of steel." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-12112018-162119/.
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Ripple marks and oscillation marks are undesirable defects which occur on the surface of solidified steel produced industrially in the ingot and the continuous casting processes, respectively; these defects are characterized by more or less evenly spaced indentations on the metal surface. Although the mechanisms for their formation are thought to be qualitatively understood, there is still considerable scope for improvement as regards quantitative mathematical modeling. In this thesis, models for the two processes are developed. For the case of ripple marks, transient twodimensional (2D) momentum and heat transfer in ingot casting is considered, and a criterion is derived, in terms of the process parameters, that can help to inform how to avoid such marks. For the case of oscillation marks in continuous casting, a novel numerical formulation for a transient 2D model is developed with the aim of tracking the spatial location of the first point of molten steel to solidify, since this determines the profile of the final oscillation mark. In both cases, the models are nondimensionalized, and the sizes of the dimensionless parameters that appear are used to derive asymptotically reduced models, with a view to not only clarifying the qualitative behavior, but also as a means to reducing the computational expense; both finite-difference and finite-element methods are used to solve the resulting model equations. One of the conclusions is that, although experimentalists and metallurgists have, in the past, treated the two cases as being linked, the present modeling approach shows quite clearly, and perhaps for the first time, how they quantitatively differ.Marcas de ondulação e marcas de oscilação são defeitos indesejáveis que ocorrem na superfície do lingote de aço solidificado produzido industrialmente; esses defeitos são caracterizados por recortes mais ou menos uniformemente espaçados na superfície do metal. Embora se acredite que os mecanismos para sua formação sejam entendidos qualitativamente, ainda há considerável espaço para melhorias no que diz respeito à modelagem matemática quantitativa. Nesta tese, os modelos para os dois processos são desenvolvidos. Para o caso de marcas de ondulação, considera-se a transferência bidimensional e transitória (2D) de calor e de momento no lingotamento, e um critério é derivado, em termos dos parâmetros do processo, que pode ajudar a informar como evitar tais marcas. Para o caso de marcas de oscilação em lingotamento contínuo, uma nova formulação numérica para um modelo 2D transiente é desenvolvida com o objetivo de rastrear a localização espacial do primeiro ponto de aço fundido para solidificar, pois isso determina o perfil da marca final de oscilação. Em ambos os casos, os modelos são adimensionalizados, e os tamanhos dos parâmetros adimensionais que aparecem são usados para derivar modelos assintoticamente reduzidos, visando não apenas esclarecer o comportamento qualitativo, mas também como meio de reduzir o gasto computacional; ambos os métodos de diferenças finitas e elementos finitos são usados para resolver as equações do modelos resultantes. Uma das conclusões é que, embora os experimentalistas e metalúrgicos tenham, no passado, tratado os dois casos como estando ligados, a presente abordagem de modelagem mostra claramente, e talvez pela primeira vez, como eles diferem quantitativamente.
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Damle, Chandrashekharr. "Melt flow, mixing and grade change studies in the continuous casting of steel /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859313344697.
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Sakalli, Erhan. "Nozzle Blockage In Continuous Casting Of Al-killed Sae 1006 And Sae 1008 Steel Grades In Iskenderun Iron And Steel Works." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604856/index.pdf.
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In this work, nozzle clogging in the submerged entry nozzle in continuous casting of Al killed steels has been studied. The study has been based on low silicon Al killed SAE 1006 (1.2006) and SAE 1008 (1.2008) grades. In this study, castabilities of 75 heats for 1.2006 steel grades and 75 heats for 1.2008 steel grades have been investigated. Castabilities of the experimental heats have been found to be affected by Al content in oxide form (Aloxy) and Ca content of the liquid steel. Castabilities have been found to decrease with increase in Aloxy and to increase with increase in Ca content and Ca/Aloxy ratio. Reoxidation has been found not to affect the castability appreciably.
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Svensson, Jennie. "An Experimental Study to Improve the Casting Performance of Steel Grades Sensitive for Clogging." Doctoral thesis, KTH, Tillämpad processmetallurgi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202539.
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In this study, the goal is to optimize the process and to reduce the clogging tendency during the continuous casting process. The focus is on clogging when the refractory base material (RBM) in the SEN is in contact with the liquid steel. It is difficult or impossible to avoid non-metallic inclusions in the liquid steel, but by a selection of a good RBM in the SEN clogging can be reduced. Different process steps were evaluated during the casting process in order to reduce the clogging tendency. First, the preheating of the SEN was studied. The results showed that the SEN can be decarburized during the preheating process. In addition, decarburization of SEN causes a larger risk for clogging. Two types of plasma coatings were implemented to protect the RBM, to prevent reactions with the RBM, and to reduce the clogging tendency. Calcium titanate (CaTiO3) mixed with yttria stabilized zirconia (YSZ) plasma coatings were tested in laboratory and pilot plant trials, for casting of aluminium-killed low-carbon steels. For casting of cerium alloyed stainless steels, YSZ plasma coatings were tested in laboratory, pilot plant and industrial trials. The results showed that the clogging tendency was reduced when implementing both coating materials. It is also of importance to produce clean steel in order to reduce clogging. Therefore, the steel cleanliness in the tundish was studied experimentally. The result showed that inclusions originated from the slag, deoxidation products and tundish refractory and that they were present in the tundish as well as in the final steel product.QC 20170227
VINNOVA
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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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Siyasiya, Charles Witness. "The transformation behaviour and hot strength of 3CR12 during the continuous casting process." Diss., Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-06202005-134528.
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Martins, Marcelo Sampaio [UNESP]. "Fadiga do aço para molas de válvulas SAE 9258 produzido industrialmente por lingotamento convencional e contínuo." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/94447.
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O presente trabalho tem por objetivo apresentar uma nova proposta de produção do aço para molas de válvulas para motores de combustão interna SAE 9258. Atualmente, este aço é produzido pela rota de lingotamento convencional, e pretende-se adotar o processo de lingotamento contínuo, mantendo-se todas as características mecânicas e metalúrgicas do aço produzido convencionalmente. Cuidados especiais durante o processo de refino secundário (fase líquida) foram levados em consideração para que sejam obtidas inclusões de silicatos deformáveis, essenciais para se conseguir uma vida em fadiga segura para as molas durante a vida útil do motor. Para avaliar essas características do aço foram feitas análises metalográficas da microestrutura em amostras na fase de processamento do aço (fio-máquina) e na fase final do processo (arames), realizados ensaios de tração, ensaios de fadiga axial em corpos-de-prova padronizados (ASTM E 466), ensaios de fadiga por flexão rotativa no arame (Nakamura test), ensaio de fadiga nas molas e análise das superfícies de fratura por fadiga com auxílio de microscopia eletrônica de varredura (MEV), para as duas rotas de produção (lingotamento convencional e contínuo). Os resultados obtidos mostram que não há diferenças com relação a microestrutura, propriedades mecânicas e comportamento em fadiga do aço na fase final de produção (arame) e na forma de produto (molas). Por outro lado, os resultados obtidos para o aço na fase intermediária do processamento (fiomáquina) mostram diferenças com relação à microestrutura, (presença de maior quantidade de carbonetos nas amostras do lingotamento contínuo), e menor redução de área com a consequente redução da resistência à fadiga.
This paper aims to present a new proposal for production of steel for valve springs for internal combustion engines SAE 9258. Currently this steel is produced by ingot casting route, and intended to adopt the continuous casting process, maintaining all the mechanical and metallurgical characteristics of the steel produced conventionally. Special attention during the process of refinement (liquid phase) were taken into account are obtained for silicate inclusions deformable essential to achieving a safe fatigue life for the springs during the life of the engine. To evaluate these features were made of steel metallographic analysis of microstructure in specimens during processing of steel (wire rod) and the final stage (wires) performed tensile tests, axial fatigue tests on specimens standard (ASTM E 466), fatigue tests in rotating bending on the wire (Nakamura test), the fatigue test the springs and examination of the areas of fatigue fracture with the aid of scanning electron microscopy (SEM) for the two production routes (ingot and continuous casting). The results show no differences with respect to microstructure, mechanical properties and fatigue behavior of steel in the final stages of production (wire) and the product form (spring). Moreover, the results obtained for steel in the intermediate stage of processing (wire rod) show differences from the microstructure (the larger amount of carbides in the samples of the continuous casting), lower area reduction with the consequent reduction resistance to fatigue.
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Doostmohammadi, Hamid. "A Study of Slag/Metal Equilibrium and Inclusion Characteristics during Ladle Treatment and after Ingot Casting." Doctoral thesis, KTH, Materialvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11596.
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Today, there is a high demand on clean steel for high performance materialproperties. Thus, steel producers try to deliver a steel product with the highestquality and cleanliness to the market. The number of parameters that affect thesteel cleanliness may vary depending on the required material properties of thefinal product. However, the non-metallic inclusion characteristics represent one ofthe most important parameters. More specifically, the composition, size, numberand morphology affect steel cleanliness. In this work, selected parameters affectingthe inclusion characteristics were studied using the following methods: i)thermodynamic calculations (including computational thermodynamiccalculations), ii) inclusion determinations using a cross sectional (CS) method (2Dinvestigations) and iii) inclusion determinations using an electrolytic extraction(EE) method (3D investigations). The computational thermodynamic calculations of the slag-steel and inclusion-steelequilibriums were carried out using the Thermo-Calc software. With the help ofthese calculations, the influence of the slag carryover on the top slag, aluminumcontent in steel and sulfur distribution ratio as well as predictions of stable phasesof inclusions were studied. In addition, inclusion determinations of tool steel gradesamples collected during various stages of the ladle treatment in a scrap-based steelplant were carried out using both 2D and 3D methods. Furthermore, inclusiondeterminations of bearing steel grade samples from a runner system after ingotcasting were performed using a 2D metallographic method (CS-method). Also, theINCAFeature software was used, when using cross sectional method, in order tocollect more statistics of the inclusion characteristics. It was found that slag carryover has a large influence on the composition of theactual top slag as well as the aluminum content in the steel as well as the sulfurdistribution ratio. In addition, steel and slag were found to be in “near”-equilibriumconditions, after the completion of the vacuum degassing operation. Furthermore,the composition of small-size inclusions in samples taken from tool steel was foundto be very scattered. Moreover, the composition of the large-size inclusions wasfound to be less scattered. Furthermore, closer to the top slag composition insamples collected after vacuum degassing. Finally, the accuracy of the inclusioncomposition determinations of tool steel samples using the electrolytic extractionmethod was found to be better than for the cross sectional method. The worseaccuracy of the CS-method is due to a considerable effect of matrix elements oninclusion composition.QC 20100709
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ASUMADU, TABIRI KWAYIE. "MACRO INCLUSION RESEARCH : DETECTION AND EVALUATION OF MACRO INCLUSIONS IN SPECIAL STEELS." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-101452.
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If these macro inclusions are not detected before the material is put in used, its mechanical properties are greatly affected and this can lead to outrageous consequences in the engineering application.