The Experts below are selected from a list of 3138 Experts worldwide ranked by ideXlab platform
Joëlle Demurger - One of the best experts on this subject based on the ideXlab platform.
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Three Dimensional Methodology to Characterize Large Dendritic Equiaxed Grains in Industrial Steel Ingots
Materials, 2018Co-Authors: Marvin Gennesson, Julien Zollinger, Dominique Daloz, Bernard Rouat, Joëlle DemurgerAbstract:The primary phase grain size is a key parameter to understand the formation of the macrosegregation pattern in large Steel ingots. Most of the characterization techniques use two-dimensional measurements. In this paper, a characterization method has been developed for equiaxed dendritic grains in industrial Steel Castings. A total of 383 contours were drawn two-dimensionally on twelve 6.6 cm 2 slices. A three-dimensional reconstruction method is performed to obtain 171 three-dimensional grains. Data regarding the size, shape and orientation of equiaxed grains is presented and thereby shows that equiaxed grains are centimeter-scale complex objects. They appear to be a poly-dispersed collection of non-isotropic objects possessing preferential orientations. In addition, the volumetric grain number density is 2.2 × 10 7 grains/m 3 , which compares to the 0.5 × 10 7 grains/m 3 that can be obtained with estimation from 2D measurements. The 2.2 × 10 7 grains/m 3 value is ten-times smaller than that previously used in the literature to simulate the macrosegregation profile in the same 6.2 ton ingot.
Zinhyoung Lee - One of the best experts on this subject based on the ideXlab platform.
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the effect of nitrogen and heat treatment on the microstructure and tensile properties of 25cr 7ni 1 5mo 3w xn duplex stainless Steel Castings
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2001Co-Authors: Young Hwan Park, Zinhyoung LeeAbstract:Abstract The effects of nitrogen content and solution treatment temperature on the microstructure and tensile properties of 25Cr–7Ni–1.5Mo–3W–xN Duplex stainless Steel (DSS) Castings were investigated. An increase of nitrogen decreases the ferrite volume fraction and also can cause gas defects and change the solidification mode from ferrite single phase to ferrite–austenite mode. An increase of heat treating temperature increases the ferrite volume fraction, which decreases the tensile strength and the elongation but increases the yield strength almost linearly.
Z Y - One of the best experts on this subject based on the ideXlab platform.
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enhanced mechanical properties of medium carbon Steel casting via friction stir processing and subsequent annealing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Wenxue Li, D Wang, W G Wang, B L Xiao, Z YAbstract:Abstract This study provides an effective surface processing technology to increase the local mechanical properties of medium carbon Steel Castings. Ultrafine dual-phase structure of the ferrite and the martensite was obtained in the processed zone with a depth of 1 mm via submerged friction stir processing (FSP). Significantly enhanced yield strength (YS) of 2070 MPa was achieved in the FSP Steel compared to that of the base material (BM) with a relatively low YS of 590 MPa, but a low uniform elongation (UE) of 3.0% was achieved compared to that of the BM (9.4%). After annealing, obvious carbide precipitation was observed in the original quenched martensite phases. Therefore, good strength-ductility synergies with high YS of 1020 MPa and 925 MPa, and acceptable UE of 5.9% and 9.3% were achieved in the FSP Steel after annealed for 2 h at 500 °C and 600 °C, respectively.
C. Beckermann - One of the best experts on this subject based on the ideXlab platform.
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Rayleigh Number Criterion for Formation of A-Segregates in Steel Castings and Ingots
Metallurgical and Materials Transactions A, 2013Co-Authors: M. Torabi Rad, P. Kotas, C. BeckermannAbstract:A Rayleigh number-based criterion is developed for predicting the formation of A-segregates in Steel Castings and ingots. The criterion is calibrated using available experimental data for ingots involving 27 different Steel compositions. The critical Rayleigh number above which A-segregates can be expected to form is found to be 17 ± 8. The primary source of uncertainty in this critical value is the dendrite arm spacing. The Rayleigh number criterion of the current study is implemented in a casting simulation code and used to predict A-segregates in three case studies involving Steel sand Castings. By comparing the predictions with observations made in the actual Castings, the Rayleigh number criterion is shown to correctly predict the regions where no A-segregates form. However, the regions where A-segregates do form are somewhat over-predicted. Based on the results of the three case studies, the primary reason for this over-prediction is persumed to be the presence of a central zone of equiaxed grains in the casting sections. A-segregates do not form when the grain structure is equiaxed.
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prediction of reoxidation inclusion composition in casting of Steel
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2006Co-Authors: Liang Wang, C. BeckermannAbstract:A model is developed to calculate the composition of reoxidation inclusions that form during pouring of Steel Castings. The software package Thermo-Calc is used to obtain the inclusion phase fractions and compositions as a function of the temperature and oxygen content of the Steel. Oxygen is assumed to be continually absorbed by the Steel until the liquidus temperature is reached. Both lever rule and Scheil-type analyses are performed. The model is applied to reoxidation of two carbon Steels, one low-alloy Steel and one high-alloy Steel. The effects of variations in the Steel composition and the oxygen absorption rate on the inclusion composition are investigated in a parametric study. The mass fraction of absorbed oxygen is determined by matching predicted with previously measured reoxidation inclusion compositions for the various Steels. Good agreement is obtained for most phases present in the inclusions. Interestingly, the agreement in the inclusion compositions occurs for all Steel grades when the percentage of absorbed oxygen is equal to 0.9 wt pct. This value is explained using a separate model for the rate of oxygen absorption at the Steel-atmosphere interface. Various scenarios are outlined that allow for the 0.9 wt pct of absorbed oxygen to be achieved. The model is then used to calculate the amount of alloy elements consumed and inclusions formed as a function of the oxygen boundary layer thickness in the atmosphere and the integrated free surface area of the liquid Steel during pouring. It is found that for unprotected liquid Steel transfer operations, such as tapping and ladle filling, the integrated free surface area and exposure time product can reach values of the order of 100 m2s per ton of Steel, and that the air-to-Steel volume ratio during pouring can be as large as 40. It is concluded that, in order to create a comprehensive tool for simulating reoxidation formation, more detailed models are needed for the external oxygen transfer in the atmosphere, the flow of the liquid Steel during pouring, and the internal transport and reactions of chemical species in the Steel.
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development of a hot tear indicator for Steel Castings
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Charles Monroe, C. BeckermannAbstract:Abstract A hot tear indicator based on the physics of solidification and deformation is presented. This indicator is derived using available data from computer simulation of solidification and solid deformation. Hot tears form when the mushy zone is starved of liquid feeding and deformed in tension. The unfed tensile deformation causes a small additional porosity. A physical model based on a mass balance is developed to find the additional porosity formed. This additional porosity or porosity due to solid deformation (PSD) is a locator for initiation sites for hot tears in the casting, not a full tear predictor. Simulation results for various “T”-shaped Steel Castings show good agreement with previous experimental findings. Reducing the strain in the casting and increasing the feeding of the section are found to decrease the hot tear tendency.
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development of new feeding distance rules using casting simulation part i methodology
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: Kent D Carlson, Richard A. Hardin, C. BeckermannAbstract:A methodology is developed to relate measured shrinkage porosity levels in Steel Castings to predictions from casting simulations, in order to determine feeding distances. Low-alloy Steel casting trials were conducted to acquire a statistically meaningful set of experimental data for top-risered cast Steel sections having various ASTM shrinkage X-ray levels. Simulations of the casting trials were then performed, using casting data recorded at the foundries during the trials. The actual casting soundness resulting from these trials, measured in terms of the ASTM shrinkage X-ray level, is quantitatively compared to the soundness predicted by simulations, measured in terms of a local thermal parameter known as the Niyama criterion. A relationship is shown to exist between the X-ray level and both the minimum Niyama criterion value as well as the area (in the plane of the X-ray) with Niyama values below a threshold value. Once the correlations developed in Part I of this article were established, an extensive set of additional casting simulations was performed to determine the feeding distances for Castings with a wide variety of casting parameters. These data were then used to develop a new set of feeding-distance rules, which are given in Part II of this article.
Marvin Gennesson - One of the best experts on this subject based on the ideXlab platform.
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Three Dimensional Methodology to Characterize Large Dendritic Equiaxed Grains in Industrial Steel Ingots
Materials, 2018Co-Authors: Marvin Gennesson, Julien Zollinger, Dominique Daloz, Bernard Rouat, Joëlle DemurgerAbstract:The primary phase grain size is a key parameter to understand the formation of the macrosegregation pattern in large Steel ingots. Most of the characterization techniques use two-dimensional measurements. In this paper, a characterization method has been developed for equiaxed dendritic grains in industrial Steel Castings. A total of 383 contours were drawn two-dimensionally on twelve 6.6 cm 2 slices. A three-dimensional reconstruction method is performed to obtain 171 three-dimensional grains. Data regarding the size, shape and orientation of equiaxed grains is presented and thereby shows that equiaxed grains are centimeter-scale complex objects. They appear to be a poly-dispersed collection of non-isotropic objects possessing preferential orientations. In addition, the volumetric grain number density is 2.2 × 10 7 grains/m 3 , which compares to the 0.5 × 10 7 grains/m 3 that can be obtained with estimation from 2D measurements. The 2.2 × 10 7 grains/m 3 value is ten-times smaller than that previously used in the literature to simulate the macrosegregation profile in the same 6.2 ton ingot.