The Experts below are selected from a list of 432 Experts worldwide ranked by ideXlab platform
Daeyong Lee - One of the best experts on this subject based on the ideXlab platform.
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The effect of tooling temperature on the formability of sheet Steel
Journal of Materials Processing Technology, 1994Co-Authors: D.e. Leighton, Daeyong LeeAbstract:Abstract This paper describes the results of an investigation that was made to determine the effect of controlling the punch and die temperatures on the drawability of cylindrical sheet metal cups. Tooling temperatures may reach 100 to 200°C in commercial press forming operations due to the work of deformation and interference friction. For this reason, circular blanks of Aluminum-Killed drawing quality (AKDQ) Steel sheet were press formed into cylindrical cups using various punch and die temperature combinations in an attempt to control the strength and drawability of the sheet metal. Increasing the die temperature from 20°C to 125°C had little or no effect on sheet formability regardless of punch temperature. Cooling the punch to temperatures between 5 and 10°C, however, increased the limiting drawing ratio by about 15% and increased the forming height by approximately 50%. These observations are rationalized on the basis of the strength vs. temperature relationship for the Aluminum-Killed Steel.
D.e. Leighton - One of the best experts on this subject based on the ideXlab platform.
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The effect of tooling temperature on the formability of sheet Steel
Journal of Materials Processing Technology, 1994Co-Authors: D.e. Leighton, Daeyong LeeAbstract:Abstract This paper describes the results of an investigation that was made to determine the effect of controlling the punch and die temperatures on the drawability of cylindrical sheet metal cups. Tooling temperatures may reach 100 to 200°C in commercial press forming operations due to the work of deformation and interference friction. For this reason, circular blanks of Aluminum-Killed drawing quality (AKDQ) Steel sheet were press formed into cylindrical cups using various punch and die temperature combinations in an attempt to control the strength and drawability of the sheet metal. Increasing the die temperature from 20°C to 125°C had little or no effect on sheet formability regardless of punch temperature. Cooling the punch to temperatures between 5 and 10°C, however, increased the limiting drawing ratio by about 15% and increased the forming height by approximately 50%. These observations are rationalized on the basis of the strength vs. temperature relationship for the Aluminum-Killed Steel.
Richard J. Fruehan - One of the best experts on this subject based on the ideXlab platform.
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Liquid Inclusion Distortion by Lens Shape Effect: In Situ Observation and Quantification on LCAK Steels Using HT-CSLM
Metallurgical and Materials Transactions B, 2019Co-Authors: Mauro E. Ferreira, Petrus Christiaan Pistorius, Richard J. FruehanAbstract:Because of interfacial and surface tension, micron-sized liquid oxide droplets are expected to change from spherical (when fully immersed in liquid Steel) to lens shape on top of Steel. Inclusion sizes were measured by automated analysis of polished sections of calcium-treated Aluminum-Killed Steel. A sample of the same Steel was remelted and observed using confocal scanning laser microscopy. Droplets on the Steel surface appear to have approximately twice the diameter of fully immersed spherical inclusions.
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Effect of Silicon on the Desulfurization of Al-Killed Steels: Part I. Mathematical Model
Metallurgical and Materials Transactions B, 2013Co-Authors: Petrus Christiaan Pistorius, Richard J. FruehanAbstract:Recent observations suggest that increased silicon levels improve ladle desulfurization of Aluminum-Killed Steel. While the overall desulfurization reaction of Al-Killed Steels does not show a direct role of silicon in desulfurization, model calculations are presented which test the idea that silicon suppresses the reduction of silica which can consume Aluminum at the slag/metal interface. Consumption of Aluminum would increase the oxygen potential at the slag/metal interface and decrease the sulfur partition coefficient between slag and metal. The model considers the coupled reactions of the reduction of silica, iron oxide, and manganese oxide in the slag and desulfurization of the Steel by Aluminum. The results show that silicon can indeed suppress consumption of Aluminum at the slag/metal interface by side reactions other than desulfurization, with silicon affecting both the kinetics and the equilibrium of desulfurization.
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Effect of Silicon on the Desulfurization of Al-Killed Steels: Part II. Experimental Results and Plant Trials
Metallurgical and Materials Transactions B, 2013Co-Authors: Petrus Christiaan Pistorius, Richard J. FruehanAbstract:Recent observations suggest that increased silicon levels improve ladle desulfurization of Aluminum-Killed Steel. A kinetic model was developed and presented in part I of this paper, demonstrating that increased silicon levels in Steel suppress the consumption of Aluminum by parasitic reactions like silica reduction and FeO/MnO reduction, thus making more Aluminum available at the interface for desulfurization. The results are increases in the rate and the extent of desulfurization. Predictions were compared with laboratory induction furnace melts using 1 kg of Steel and 0.1 kg slag. The experimental results demonstrate the beneficial effect of silicon on the desulfurization reaction and that alumina can be reduced out of the slag and Aluminum picked up by the Steel, if the silicon content in the Steel is high enough. The experimental results are in close agreement with the model predictions. Plant trials also show that with increased silicon content, both the rate and extent of desulfurization increase; incorporating silicon early into the ladle desulfurization process leads to considerable savings in Aluminum consumption.
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Transient Inclusion Evolution During Modification of Alumina Inclusions by Calcium in Liquid Steel: Part II. Results and Discussion
Metallurgical and Materials Transactions B, 2011Co-Authors: N. Verma, Richard J. Fruehan, Petrus C. Pistorius, Michael Potter, Minna Lind, Scott R. StoryAbstract:The formation of intermediate reaction products after calcium addition to Aluminum-Killed Steel was studied. Steel samples were taken from laboratory and industrial heats before and at various times after calcium treatment. Inclusions were characterized by automated and manual scanning electron microscopy and X-ray microanalysis of polished cross sections and inclusions extracted by dissolution of the Steel. Industrial and laboratory melts containing more than 40 parts per million (by mass) of dissolved sulfur showed calcium sulfide as the main reaction product after calcium injection, with calcium aluminates appearing later. It is proposed that the calcium aluminates are formed by reaction between the calcium sulfide and the alumina. A laboratory heat containing 7 parts per million of sulfur showed calcium oxide as the main initial calcium reaction product. A simple mechanism is proposed for the modification of alumina inclusions by calcium, considering transient CaO and CaS formation.
Kishor B Joshi - One of the best experts on this subject based on the ideXlab platform.
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heating rate effects during non isothermal annealing of aik Steel
Journal of Materials Engineering and Performance, 2003Co-Authors: Satyam S Sahay, Kishor B JoshiAbstract:The effects of heating rate on microstructural size and shape parameters during annealing of cold rolled Aluminum Killed Steel strips have been examined under non-isothermal condition. It is shown that decrease in the heating rate results in accelerated grain growth behavior compared with the prediction by quasi-isothermal based kinetics. The {111} and {112} crystallographic orientations, which enhance the normal anisotropy and deep drawability of cold rolled annealed sheets, are found to exhibit a strong correlation with the grain shape anisotropy. This grain shape anisotropy itself is strongly dependent on heating rates. Lower heating rates result in higher aspect ratios and thus better drawability of the cold rolled sheets. A Hall-Petch type relationship is observed between grain size and hardness of the annealed samples.
Petrus Christiaan Pistorius - One of the best experts on this subject based on the ideXlab platform.
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Liquid Inclusion Distortion by Lens Shape Effect: In Situ Observation and Quantification on LCAK Steels Using HT-CSLM
Metallurgical and Materials Transactions B, 2019Co-Authors: Mauro E. Ferreira, Petrus Christiaan Pistorius, Richard J. FruehanAbstract:Because of interfacial and surface tension, micron-sized liquid oxide droplets are expected to change from spherical (when fully immersed in liquid Steel) to lens shape on top of Steel. Inclusion sizes were measured by automated analysis of polished sections of calcium-treated Aluminum-Killed Steel. A sample of the same Steel was remelted and observed using confocal scanning laser microscopy. Droplets on the Steel surface appear to have approximately twice the diameter of fully immersed spherical inclusions.
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Rate of MgO Pickup in Alumina Inclusions in Aluminum-Killed Steel
Metallurgical and Materials Transactions B, 2018Co-Authors: Deepoo Kumar, Petrus Christiaan PistoriusAbstract:This work aims to clarify the rate and mechanism of MgO pickup by alumina inclusions and the effect of oxide impurities in MgO crucibles on this transformation. Two MgO crucibles from different batches from the same supplier were used in laboratory experiments with Al-Killed Steel. A kinetic model was developed, based on mass-transfer control in the liquid Steel. Rate constants were fitted using inclusion analysis. The rate of magnesium transfer from the two types of crucibles was found to differ by a factor of 20; faster magnesium transfer was associated with formation of a slag layer on the inner surface of the crucible wall (rather than a solid spinel product layer). The kinetic model was also used to simulate industrial scale ladle refining (1) to illustrate the effects of total oxygen concentration and (2) to evaluate the contribution of Steel-refractory reaction (in addition to Steel-slag reaction) on the rate of MgO pickup in alumina inclusion. The rate of MgO pickup was higher with a lower inclusion concentration. For ladle desulfurization, the extent of MgO pickup in inclusions is directly linked to the extent of desulfurization; both reactions are controlled by the oxygen potential at the Steel-slag interface.
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Effect of Silicon on the Desulfurization of Al-Killed Steels: Part I. Mathematical Model
Metallurgical and Materials Transactions B, 2013Co-Authors: Petrus Christiaan Pistorius, Richard J. FruehanAbstract:Recent observations suggest that increased silicon levels improve ladle desulfurization of Aluminum-Killed Steel. While the overall desulfurization reaction of Al-Killed Steels does not show a direct role of silicon in desulfurization, model calculations are presented which test the idea that silicon suppresses the reduction of silica which can consume Aluminum at the slag/metal interface. Consumption of Aluminum would increase the oxygen potential at the slag/metal interface and decrease the sulfur partition coefficient between slag and metal. The model considers the coupled reactions of the reduction of silica, iron oxide, and manganese oxide in the slag and desulfurization of the Steel by Aluminum. The results show that silicon can indeed suppress consumption of Aluminum at the slag/metal interface by side reactions other than desulfurization, with silicon affecting both the kinetics and the equilibrium of desulfurization.
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Effect of Silicon on the Desulfurization of Al-Killed Steels: Part II. Experimental Results and Plant Trials
Metallurgical and Materials Transactions B, 2013Co-Authors: Petrus Christiaan Pistorius, Richard J. FruehanAbstract:Recent observations suggest that increased silicon levels improve ladle desulfurization of Aluminum-Killed Steel. A kinetic model was developed and presented in part I of this paper, demonstrating that increased silicon levels in Steel suppress the consumption of Aluminum by parasitic reactions like silica reduction and FeO/MnO reduction, thus making more Aluminum available at the interface for desulfurization. The results are increases in the rate and the extent of desulfurization. Predictions were compared with laboratory induction furnace melts using 1 kg of Steel and 0.1 kg slag. The experimental results demonstrate the beneficial effect of silicon on the desulfurization reaction and that alumina can be reduced out of the slag and Aluminum picked up by the Steel, if the silicon content in the Steel is high enough. The experimental results are in close agreement with the model predictions. Plant trials also show that with increased silicon content, both the rate and extent of desulfurization increase; incorporating silicon early into the ladle desulfurization process leads to considerable savings in Aluminum consumption.