Performance Steel Castings. The dramatic reduction in weight and increase in capability will require high performance SFSA developed innovative casting design and manufacturing processes for high performance parts. SFSA is. Multiphysics modeling of the steel continuous casting process.
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Performance Steel Castings. The dramatic reduction in weight and increase in capability will require high performance SFSA developed innovative casting design and manufacturing processes for high performance parts. SFSA is. Multiphysics modeling of the steel continuous casting process. This work develops a macroscale, multiphysics model of the continuous casting of steel. The complete model accounts for the turbulent flow and nonuniform distribution of superheat in the molten steel , the elastic-viscoplastic thermal shrinkage of the solidifying shell, the heat transfer through the shell-mold interface with variable gap size, and the thermal distortion of the mold.
These models are coupled together with carefully constructed boundary conditions with the aid of reduced-order models into a single tool to investigate behavior in the mold region, for practical applications such as predicting ideal tapers for a beam-blank mold.
The thermal and mechanical behaviors of the mold are explored as part of the overall modeling effort, for funnel molds and for beam-blank molds. These models include high geometric detail and reveal temperature variations on the mold-shell interface that may be responsible for cracks in the shell.
Specifically, the funnel mold has a column of mold bolts in the middle of the inside-curve region of the funnel that disturbs the uniformity of the hot face temperatures, which combined with the bending effect of the mold on the shell, can lead to longitudinal facial cracks. The shoulder region of the beam-blank mold shows a local hot spot that can be reduced with additional cooling in this region.
The distorted shape of the funnel mold narrow face is validated with recent inclinometer measurements from an operating caster.
The calculated hot face temperatures and distorted shapes of the mold are transferred into the multiphysics model of the solidifying shell. The boundary conditions for the first iteration of the multiphysics model come from reduced-order models of the process ; one such model is derived in this work for mold heat transfer.
The reduced-order model relies on the physics of the solution to the one-dimensional heat-conduction equation to maintain the relationships between inputs and outputs of the model. The geometric. Thermomechanical processing of microalloyed powder forged steels and a cast vanadium steel. Rolling was carried out in the austenitic range below the recrystallization temperature. Equiaxed grain structures were produced in specimens subjected to different reductions and different cooling rates.
The ferrite grain size decreased with increasing deformation and cooling rate. Ferrite nucleated on second phase particles, deformation bands, and on elongated prior austenite grain boundaries; consequently a high fractional ferrite refinement was achieved. Deformation raised the ferrite transformation start temperature while the time to transformation from the roll finish temperature decreased.
Intragranular ferrite nucleation, which played a vital role in grain refinement, increased with cooling rate. Fully bainitic microstructures were formed at higher cooling rates in the cast steel. Fracture Analysis of Cast Steel Sling. The fracture reasons of ZG cast steel sling are analyzed through such means as macroscopic morphology analysis, chemical composition analysis, and microscopic metallography analysis.
Results: coarse Widmanstatten structure and casting defects occurring in casting and subsequent heat treatment process reduce the strength, plasticity and toughness of the steel , which is the main reason of brittle fracture of the sling during work, and corresponding improvement suggestions are proposed herein. Quantitative examination of carbide and sulphide precipitates in chemically complex steels processed by direct strip casting. A high strength low alloy steel composition has been melted and processed by two different routes: simulated direct strip casting and slow cooled ingot casting.
The microstructures were examined with scanning and transmission electron microscopy, atom probe tomography and small angle neutron scattering SANS. Slow cooling resulted in the development of classical Nb C,N precipitation, with an average diameter of 7. However, after rapid cooling both the SANS and atom probe tomography data indicated that the Nb was retained in the matrix as a random solid solution. There was also some evidence that O, N and S are also retained in solid solution in levels not found during conventional processing.
Castings , Steel , Homogenization of Steel Castings. YD- 1 t Harich, Riffin, -ri Bolotsk Defects in carbon- steel or alloy- steel castings may be repaired by welding. The repairs Evolution of microstructure, texture and inhibitor along the processing route for grain-oriented electrical steels using strip casting. Liu, Hai-Tao, E-mail: liuht ral. In the present work, a regular grade GO sheet was produced successively by strip casting , hot rolling, normalizing annealing, two-stage cold rolling with intermediate annealing, primary recrystallization annealing, secondary recrystallization annealing and purification.
The aim of this paper was to characterize the evolution of microstructure, texture and inhibitor along the new processing route by comprehensive utilization of optical microscopy, X-ray diffraction and transmission electron microscopy. As a result, the origin of Goss nuclei capable of secondary recrystallization lied in the grains already presented in Goss orientation in the intermediate annealed strip after first cold rolling. Another finding was that fine and dispersive inhibitors mainly AlN were easy to be produced in the primary recrystallization microstructure due to the initial rapid solidification during strip casting and the subsequent rapid cooling, and the very high temperature reheating usually used before hot rolling in the conventional production route could be avoided.
Improving Metal Casting Process. Don Sirois, an Auburn University research associate, and Bruce Strom, a mechanical engineering Co-Op Student, are evaluating the dimensional characteristics of an aluminum automobile engine casting. More accurate metal casting processes may reduce the weight of some cast metal products used in automobiles, such as engines.
Research in low gravity has taken an important first step toward making metal products used in homes, automobiles, and aircraft less expensive, safer, and more durable. Auburn University and industry are partnering with NASA to develop one of the first accurate computer model predictions of molten metals and molding materials used in a manufacturing process called casting. Ford Motor Company's casting plant in Cleveland, Ohio is using NASA-sponsored computer modeling information to improve the casting process of automobile and light-truck engine blocks.
Rapid Cycle Casting of Steel. The average casting composition was 0. The segregation at Results The casting composition carbon content as a function of casting location is given in Table D-IV. Phase transformations in cast duplex stainless steels.
Duplex stainless steels DSS constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as sigma sigma and chi chi can also form during casting or high-temperature processing and can degrade the properties of the DSS. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy SEM, TEM and wavelength dispersive spectroscopy WDS.
To examine in more detail the effects of these elements of the phase stabilities, a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc.
In general, a was stabilized with increasing Cr addition and chi by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in. To determine the potential for strip casting in the steel industry and to develop the fundamental knowledge necessary to allow the role of strip casting in the modern steel industry to be understood.
Based upon a study of carbon steel strip castings that were either produced for the program at British Steel or were received from a pre-commercial production machine, the following conclusions were made. The potential of strip casting as a casting process to be developed for steel castings is very high as the cast strip has some very novel characteristics.
Direct cast carbon strip has better surface quality, shape and profile than any other casting process currently available. The more rapidly solidified structure of direct cast strip tends to be strong with low ductility; however, with adequate thermal treatment, it is possible to develop a variety of properties from the same grade. The process is more amenable at this time to production tonnages per year of the order of , tons and as such will first find niche type applications.
This technology is an additional technology for steel production and will be in addition to, rather than a replacement for, current casting machines.
Fuzzy control strategy for secondary cooling of continuous steel casting. The purpose of this paper is to create an original fuzzy solution on the existing structure of the control system of continuous casting that eliminates fissures in the poured material from the secondary cooling of steel.
For this purpose a system was conceived with three fuzzy database decision rules, which by analyzing a series of measurements taken from the process produces adjustments in the rate of flow of the cooling water and the speed of casting and determine the degree of risk of the wire. In the specialized literature on the national plan and the world, there is no intelligent correction in the rate of flow of the cooling water and the speed of casting in the secondary cooling of steel.
The database of rules was made using information collected directly from the installation process of continuous casting of the Arcelor Mittal Hunedoara.
In this study, the alloy shrinkage factors were obtained for the investment casting of PH stainless steel parts. For the investment casting process , unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively.
Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine in order to obtain the actual tooling allowances. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. The numerical simulation results for the shrinkage factors were compared with experimental results.
Recently a low cost casting method known as lattice block casting has been developed by JAM Corporation, Wilmington, Massachusetts for engineering materials such as aluminum and stainless steels that has shown to provide very high stiffness and strength with only a fraction of density of the alloy. NASA Glenn Research Center has initiated research to investigate lattice block castings of high temperature Ni-base superalloys such as the model system Inconel IN for lightweight nozzle applications.
Although difficulties were encountered throughout the manufacturing process , a successful investment casting procedure was eventually developed. Wax formulation and pattern assembly, shell mold processing , and counter gravity casting techniques were developed.
Ten IN lattice block castings each measuring cm wide by cm long by 1. Details of the processing and resulting microstructures are discussed in this paper. Post casting processing and evaluation of system specific mechanical properties of these specimens are in progress. TiC reinforced cast Cr steels. A new class of materials, namely TiC-reinforced cast chromium Cr steels , was developed for applications requiring high abrasion resistance and good fracture toughness. The research approach was to modify the carbide structure of commercial AISI C steel for better fracture resistance while maintaining the already high abrasion resistance.
The new alloys contained 12Cr, 2. Their microstructure was composed primarily of a martensitic matrix with a dispersion of TiC precipitates. Modification of TiC morphology was accomplished through changing the cooling rate during solidification. Laser surface texturing of cast iron steel : dramatic edge burr reduction and high speed process optimisation for industrial production using DPSS picosecond lasers.
In this work we present picosecond DPSS laser surface texturing optimisation of automotive grade cast iron steel. This application attracts great interest, particularly in the automotive industry, to reduce friction between moving piston parts in car engines, in order to decrease fuel consumption.
This is accomplished by partially covering with swallow microgrooves the inner surface of a piston liner and is currently a production process adopting much longer pulse microsecond DPSS lasers.
Viking Phase III. The Viking Primary Mission phase was concluded in November, , when the reins were passed on to the second phase - the Viking Extended Mission. The Extended Mission successfully carried spacecraft operations through the desired period of time needed to provided a profile of a full Martian year, but would have fallen a little short of connecting and overlapping a full Martian year of Viking operations which scientists desired as a means of determining the degree of duplicity in the red planet's seasons - at least for the summer period. Without this continuation of spacecraft data acquisitions to and beyond the seasonal points when the spacecraft actually began their Mars observations, there would be no way of knowing whether the changing environmental values - such as temperatures and winds atmospheric dynamics and water vapor, surface thermal dynamics, etc.
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