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Manuel Gómez - One of the best experts on this subject based on the ideXlab platform.
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Influence of the Microalloying Elements on the temporary inhibition of static recrystallization by strain-induced precipitates
steel research international, 2014Co-Authors: Manuel Gómez, Alberto Quispe, Sebastián F. MedinaAbstract:The kinetics of static recrystallization of austenite and its transitory inhibition by strain-induced precipitates have been characterized in several microalloyed steels with different compositions. This inhibition can be seen by the formation of “plateaus” in the curves of static recrystallization obtained from isothermal double-deformation tests. The influence of the type of Microalloying Element (Nb, V, Al) and the mean size of the precipitates on the duration time of the plateau of recrystallization inhibition has been studied and empirical relationships between these variables have been obtained. Al-steels present a much coarser particle size and a considerably shorter plateau compared to Nb and V-microalloyed steels.
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Influence of (Al, Nb, V) Precipitates on the Recrystallization Inhibition in Microalloyed Steels
Materials Science Forum, 2013Co-Authors: Manuel Gómez, Alberto Quispe, Sebastián F. MedinaAbstract:Under certain conditions of temperature, time and deformation, static recrystallization of austenite in microalloyed steels can be temporarily inhibited by means of the strain-induced precipitation of nanoparticles that cause a pinning effect on austenite grain boundaries in motion. This inhibition can be seen by the formation of a “plateau” in the curves of static recrystallization of austenite obtained from double-deformation tests carried out under isothermal conditions. In this work, several microalloyed steels with different compositions are studied by hot torsion tests in order to characterize the kinetics of recrystallization and its inhibition. The precipitation state in austenite is studied in several samples by means of transmission electron microscopy. The influence of the type of Microalloying Element (Al, Nb, V) and the mean size of the precipitates on the duration time of the plateau is studied and relationships between these variables can be obtained. Particularly, it is seen that Al-alloyed steels present a much coarser particle size and a considerably shorter plateau compared to Nb and V-microalloyed steels.
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Model for static recrystallisation critical temperature in microalloyed steels
Materials Science and Technology, 2001Co-Authors: Sebastián F. Medina, Alberto Quispe, Manuel GómezAbstract:AbstractBy means of hot torsion tests, the static recrystallisation critical temperature (SRCT) has been determined for 18 microalloyed steels classified into two groups. In one group the metallic Microalloying Element is vanadium, and in the other it is niobium. In both groups the Microalloying Element, carbon, and nitrogen contents vary from one steel to another. Tests have been carried out at various strains and strain rates, and recrystallisation–precipitation–time–temperature (RPTT) diagrams have been drawn for each steel in each condition. The SRCT is the asymptote of strain induced precipitation start P s and end P f curves, and its determination has permitted the construction of a model that quantifies the effects of all the external variables implicit in hot working such as strain and strain rate, and the internal variables such as austenite grain size and chemical composition of the steel. Hence, the influence of each of these variables has been quantified, and the model's prediction, comparing ...
Sebastián F. Medina - One of the best experts on this subject based on the ideXlab platform.
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Influence of the Microalloying Elements on the temporary inhibition of static recrystallization by strain-induced precipitates
steel research international, 2014Co-Authors: Manuel Gómez, Alberto Quispe, Sebastián F. MedinaAbstract:The kinetics of static recrystallization of austenite and its transitory inhibition by strain-induced precipitates have been characterized in several microalloyed steels with different compositions. This inhibition can be seen by the formation of “plateaus” in the curves of static recrystallization obtained from isothermal double-deformation tests. The influence of the type of Microalloying Element (Nb, V, Al) and the mean size of the precipitates on the duration time of the plateau of recrystallization inhibition has been studied and empirical relationships between these variables have been obtained. Al-steels present a much coarser particle size and a considerably shorter plateau compared to Nb and V-microalloyed steels.
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Influence of (Al, Nb, V) Precipitates on the Recrystallization Inhibition in Microalloyed Steels
Materials Science Forum, 2013Co-Authors: Manuel Gómez, Alberto Quispe, Sebastián F. MedinaAbstract:Under certain conditions of temperature, time and deformation, static recrystallization of austenite in microalloyed steels can be temporarily inhibited by means of the strain-induced precipitation of nanoparticles that cause a pinning effect on austenite grain boundaries in motion. This inhibition can be seen by the formation of a “plateau” in the curves of static recrystallization of austenite obtained from double-deformation tests carried out under isothermal conditions. In this work, several microalloyed steels with different compositions are studied by hot torsion tests in order to characterize the kinetics of recrystallization and its inhibition. The precipitation state in austenite is studied in several samples by means of transmission electron microscopy. The influence of the type of Microalloying Element (Al, Nb, V) and the mean size of the precipitates on the duration time of the plateau is studied and relationships between these variables can be obtained. Particularly, it is seen that Al-alloyed steels present a much coarser particle size and a considerably shorter plateau compared to Nb and V-microalloyed steels.
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Model for static recrystallisation critical temperature in microalloyed steels
Materials Science and Technology, 2001Co-Authors: Sebastián F. Medina, Alberto Quispe, Manuel GómezAbstract:AbstractBy means of hot torsion tests, the static recrystallisation critical temperature (SRCT) has been determined for 18 microalloyed steels classified into two groups. In one group the metallic Microalloying Element is vanadium, and in the other it is niobium. In both groups the Microalloying Element, carbon, and nitrogen contents vary from one steel to another. Tests have been carried out at various strains and strain rates, and recrystallisation–precipitation–time–temperature (RPTT) diagrams have been drawn for each steel in each condition. The SRCT is the asymptote of strain induced precipitation start P s and end P f curves, and its determination has permitted the construction of a model that quantifies the effects of all the external variables implicit in hot working such as strain and strain rate, and the internal variables such as austenite grain size and chemical composition of the steel. Hence, the influence of each of these variables has been quantified, and the model's prediction, comparing ...
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Influence of Alloying Elements in Solution on Static Recrystallization Kinetics of Hot Deformed Steels
ISIJ International, 1996Co-Authors: Sebastián F. Medina, Juana E. MancillaAbstract:Using torsion tests and applying the back extrapolation method, a study has been made of the influence on static recrystallization kinetics of the most common Elements (C, Si, Mn, Mo) in low alloy steels and the most common Elements (Ti, V, Nb) in microalloyed steels. In the latter case, this influence is studied only at the temperatures at which these Elements are in solution, except for Titanium which was partially precipitated in the form of nitrides. Activation energy is the parameter most sensitive to variations in the chemical composition and an expression has been determined to predict its value as a function of the content of each alloying Element. Of the different non precipitate-forming alloys sillicon is shown to be the Element which most delays recrystallization. Carbon and vanadium in solution have no influence on recrystallization kinetics. It is demonstrated that Nb is the Microalloying Element which most delays recrystallization.
Shigeharu Kamado - One of the best experts on this subject based on the ideXlab platform.
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Effect of Zr addition on the mechanical properties of as-extruded Mg–Zn–Ca–Zr alloys
Materials Science and Engineering: A, 2010Co-Authors: Tomoyuki Homma, Chamini Lakshi Mendis, Kazuhiro Hono, Shigeharu KamadoAbstract:Abstract Extrudable Mg–6Zn–0.2Ca(–0.8Zr) alloy (mass%) has been developed. The Mg–Zn–Ca–Zr alloy shows excellent mechanical properties in the as-extruded state with the ultimate tensile strength of 357 MPa and elongation to failure of 18%. These properties are related to dynamic recrystallization, texture and precipitation. Dynamically recrystallized grains are pinned by fine precipitates, resulting in very fine grain size. The extruded sample also exhibits a higher average {0 0 0 2} 〈 1 1 2 ¯ 0 〉 Schmid factor due to the presence of unrecrystallized regions, leading to texture strengthening. Zr may work as a Microalloying Element, resulting in fine and dense distribution of a MgZn2 based phase involving Ca and Zr.
Alberto Quispe - One of the best experts on this subject based on the ideXlab platform.
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Influence of the Microalloying Elements on the temporary inhibition of static recrystallization by strain-induced precipitates
steel research international, 2014Co-Authors: Manuel Gómez, Alberto Quispe, Sebastián F. MedinaAbstract:The kinetics of static recrystallization of austenite and its transitory inhibition by strain-induced precipitates have been characterized in several microalloyed steels with different compositions. This inhibition can be seen by the formation of “plateaus” in the curves of static recrystallization obtained from isothermal double-deformation tests. The influence of the type of Microalloying Element (Nb, V, Al) and the mean size of the precipitates on the duration time of the plateau of recrystallization inhibition has been studied and empirical relationships between these variables have been obtained. Al-steels present a much coarser particle size and a considerably shorter plateau compared to Nb and V-microalloyed steels.
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Influence of (Al, Nb, V) Precipitates on the Recrystallization Inhibition in Microalloyed Steels
Materials Science Forum, 2013Co-Authors: Manuel Gómez, Alberto Quispe, Sebastián F. MedinaAbstract:Under certain conditions of temperature, time and deformation, static recrystallization of austenite in microalloyed steels can be temporarily inhibited by means of the strain-induced precipitation of nanoparticles that cause a pinning effect on austenite grain boundaries in motion. This inhibition can be seen by the formation of a “plateau” in the curves of static recrystallization of austenite obtained from double-deformation tests carried out under isothermal conditions. In this work, several microalloyed steels with different compositions are studied by hot torsion tests in order to characterize the kinetics of recrystallization and its inhibition. The precipitation state in austenite is studied in several samples by means of transmission electron microscopy. The influence of the type of Microalloying Element (Al, Nb, V) and the mean size of the precipitates on the duration time of the plateau is studied and relationships between these variables can be obtained. Particularly, it is seen that Al-alloyed steels present a much coarser particle size and a considerably shorter plateau compared to Nb and V-microalloyed steels.
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Model for static recrystallisation critical temperature in microalloyed steels
Materials Science and Technology, 2001Co-Authors: Sebastián F. Medina, Alberto Quispe, Manuel GómezAbstract:AbstractBy means of hot torsion tests, the static recrystallisation critical temperature (SRCT) has been determined for 18 microalloyed steels classified into two groups. In one group the metallic Microalloying Element is vanadium, and in the other it is niobium. In both groups the Microalloying Element, carbon, and nitrogen contents vary from one steel to another. Tests have been carried out at various strains and strain rates, and recrystallisation–precipitation–time–temperature (RPTT) diagrams have been drawn for each steel in each condition. The SRCT is the asymptote of strain induced precipitation start P s and end P f curves, and its determination has permitted the construction of a model that quantifies the effects of all the external variables implicit in hot working such as strain and strain rate, and the internal variables such as austenite grain size and chemical composition of the steel. Hence, the influence of each of these variables has been quantified, and the model's prediction, comparing ...
Shahrzad Esmaeili - One of the best experts on this subject based on the ideXlab platform.
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Improving microstructure and ductility in the Mg–Zn alloy system by combinational Ce–Ca Microalloying
Materials Science and Engineering: A, 2015Co-Authors: Brian Langelier, Ali Nasiri, Soo Yeol Lee, Michael A. Gharghouri, Shahrzad EsmaeiliAbstract:Abstract A strategy is proposed to enhance the microstructure and mechanical properties of Mg–Zn alloys by combining Microalloying additions of the rare earth Element Ce and the non-rare earth Element Ca. The double additions of Ce–Ca are found to significantly increase tensile elongation compared to binary Mg–Zn, or single additions of either Ce or Ca. Microstructure analysis reveals that the Ce–Ca additions increase ductility by modifying texture and refining grain size. Texture modification is attributed to solute effects from the Microalloying Elements, particularly Ca, while grain refinement is additionally influenced by a fine dispersion of Mg 6 Ca 2 Zn 3 precipitates that form during rolling and pin grain boundaries. The Microalloying Element additions also lead to large secondary phase particles in the alloys, which can limit ductility enhancement by promoting early fracture. By scaling Zn content in the Mg–Zn–Ce–Ca alloys, the Mg 6 Ca 2 Zn 3 phase fraction and Zn solute content can be controlled for optimum ductility or strengthening potential.