The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled... more The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled plate was investigated in this work. Uniaxial compression tests were carried out on samples cut along the rolling direction (RD) and normal direction (ND) of rolled AZ31 Mg plate at various temperatures (RT, 150, 200, 250, 300, 350, 400, 450°C) with the fixed strain rate (0.01s-1). The results showed that the primary twinning system of AZ31 Mg alloy (c-axis extension twin) occurred actively in the RD compression specimens, which promoted homogeneous deformation as compared to the ND compression specimens. The effect of temperature on the formation of deformation twins was also investigated, and slip/twin transition temperature was found to be 250°C.
High Mn steels demonstrate an exceptional combination of high strength and ductility owing to the... more High Mn steels demonstrate an exceptional combination of high strength and ductility owing to their sustained high work hardening rate during deformation. In the present work, the microstructural evolution and work hardening of Fe–30Mn and Fe–24Mn alloys during uniaxial tensile testing at 293K and 77K were investigated. The Fe–30Mn alloy did not undergo significant strain-induced phase transformations or twinning during
The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled... more The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled plate was investigated in this work. Uniaxial compression tests were carried out on samples cut along the rolling direction (RD) and normal direction (ND) of rolled AZ31 Mg plate at various temperatures (RT, 150, 200, 250, 300, 350, 400, 450°C) with the fixed strain rate (0.01s-1). The results showed that the primary twinning system of AZ31 Mg alloy (c-axis extension twin) occurred actively in the RD compression specimens, which promoted homogeneous deformation as compared to the ND compression specimens. The effect of temperature on the formation of deformation twins was also investigated, and slip/twin transition temperature was found to be 250°C.
Nb carbides have attracted significant attention to enhance the resistance of tempered martensiti... more Nb carbides have attracted significant attention to enhance the resistance of tempered martensitic (TM) steel to hydrogen embrittlement (HE). However, previous studies have elucidated the role of Nb carbides in HE resistance without categorizing their types (i.e., undissolved and newly precipitated). This study focuses on the effect of “undissolved” Nb carbides on the tensile and fatigue properties of hydrogen-precharged TM steels. It validated the following two factors for the HE resistance of the TM steels containing undissolved Nb carbides: hydrogen-trapping by the carbides and refinement of prior austenite grain. The former factor rarely affected the HE resistance owing to the interfacial incoherency between the undissolved carbides and ferritic matrix. Such results are distinguished from previous studies focusing on the newly precipitated carbides. In contrast, the latter factor contributed significantly to the HE resistance via the decrease in hydrogen contents per unit surfac...
Product miniaturization is a trend for facilitating product usage, enabling product functions to ... more Product miniaturization is a trend for facilitating product usage, enabling product functions to be implemented in microscale geometries, and aimed at reducing product weight, volume, cost and pollution. Driven by ongoing miniaturization in diverse areas including medical devices, precision equipment, communication devices, micro-electromechanical systems (MEMS) and microsystems technology (MST), the demands for micro metallic products have increased tremendously. Such a trend requires development of advanced micromanufacturing technology of metallic materials for producing high-quality micro metallic products that possess excellent dimensional tolerances, required mechanical properties and improved surface quality. Micromanufacturing differs from conventional manufacturing technology in terms of materials, processes, tools, and machines and equipment, due to the miniaturization nature of the whole micromanufacturing system, which challenges the rapid development of micromanufacturi...
Austenitic high Mn twin-induced plasticity (TWIP) steels have been widely investigated due to its... more Austenitic high Mn twin-induced plasticity (TWIP) steels have been widely investigated due to its excellent combination of strength and ductility [1]. However, its high susceptibility of hydrogen embrittlement (HE) limits the wide spread of TWIP steels in producing structural components such as oil pipeline, LNG tank, and offshore structure. Therefore, many investigations have been made to elucidate the mechanisms responsible for the HE, and to alleviate HE either by alloy addition [2] or microstructure modification [3]. Nevertheless, there have been many issues to be clarified, such as (1) precise analysis on the amount of hydrogen, which is responsible for the HE, (2) interaction of hydrogen and various defects (dislocations and grain boundaries) and so on. Visualization of local presence of hydrogen is a difficult task due to its low mass, very low detection sensitivity, very low concentration and high mobility [4]. Various approaches have been made for direct observation of hydr...
The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled... more The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled plate was investigated in this work. Uniaxial compression tests were carried out on samples cut along the rolling direction (RD) and normal direction (ND) of rolled AZ31 Mg plate at various temperatures (RT, 150, 200, 250, 300, 350, 400, 450°C) with the fixed strain rate (0.01s-1). The results showed that the primary twinning system of AZ31 Mg alloy (c-axis extension twin) occurred actively in the RD compression specimens, which promoted homogeneous deformation as compared to the ND compression specimens. The effect of temperature on the formation of deformation twins was also investigated, and slip/twin transition temperature was found to be 250°C.
High Mn steels demonstrate an exceptional combination of high strength and ductility owing to the... more High Mn steels demonstrate an exceptional combination of high strength and ductility owing to their sustained high work hardening rate during deformation. In the present work, the microstructural evolution and work hardening of Fe–30Mn and Fe–24Mn alloys during uniaxial tensile testing at 293K and 77K were investigated. The Fe–30Mn alloy did not undergo significant strain-induced phase transformations or twinning during
The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled... more The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled plate was investigated in this work. Uniaxial compression tests were carried out on samples cut along the rolling direction (RD) and normal direction (ND) of rolled AZ31 Mg plate at various temperatures (RT, 150, 200, 250, 300, 350, 400, 450°C) with the fixed strain rate (0.01s-1). The results showed that the primary twinning system of AZ31 Mg alloy (c-axis extension twin) occurred actively in the RD compression specimens, which promoted homogeneous deformation as compared to the ND compression specimens. The effect of temperature on the formation of deformation twins was also investigated, and slip/twin transition temperature was found to be 250°C.
Nb carbides have attracted significant attention to enhance the resistance of tempered martensiti... more Nb carbides have attracted significant attention to enhance the resistance of tempered martensitic (TM) steel to hydrogen embrittlement (HE). However, previous studies have elucidated the role of Nb carbides in HE resistance without categorizing their types (i.e., undissolved and newly precipitated). This study focuses on the effect of “undissolved” Nb carbides on the tensile and fatigue properties of hydrogen-precharged TM steels. It validated the following two factors for the HE resistance of the TM steels containing undissolved Nb carbides: hydrogen-trapping by the carbides and refinement of prior austenite grain. The former factor rarely affected the HE resistance owing to the interfacial incoherency between the undissolved carbides and ferritic matrix. Such results are distinguished from previous studies focusing on the newly precipitated carbides. In contrast, the latter factor contributed significantly to the HE resistance via the decrease in hydrogen contents per unit surfac...
Product miniaturization is a trend for facilitating product usage, enabling product functions to ... more Product miniaturization is a trend for facilitating product usage, enabling product functions to be implemented in microscale geometries, and aimed at reducing product weight, volume, cost and pollution. Driven by ongoing miniaturization in diverse areas including medical devices, precision equipment, communication devices, micro-electromechanical systems (MEMS) and microsystems technology (MST), the demands for micro metallic products have increased tremendously. Such a trend requires development of advanced micromanufacturing technology of metallic materials for producing high-quality micro metallic products that possess excellent dimensional tolerances, required mechanical properties and improved surface quality. Micromanufacturing differs from conventional manufacturing technology in terms of materials, processes, tools, and machines and equipment, due to the miniaturization nature of the whole micromanufacturing system, which challenges the rapid development of micromanufacturi...
Austenitic high Mn twin-induced plasticity (TWIP) steels have been widely investigated due to its... more Austenitic high Mn twin-induced plasticity (TWIP) steels have been widely investigated due to its excellent combination of strength and ductility [1]. However, its high susceptibility of hydrogen embrittlement (HE) limits the wide spread of TWIP steels in producing structural components such as oil pipeline, LNG tank, and offshore structure. Therefore, many investigations have been made to elucidate the mechanisms responsible for the HE, and to alleviate HE either by alloy addition [2] or microstructure modification [3]. Nevertheless, there have been many issues to be clarified, such as (1) precise analysis on the amount of hydrogen, which is responsible for the HE, (2) interaction of hydrogen and various defects (dislocations and grain boundaries) and so on. Visualization of local presence of hydrogen is a difficult task due to its low mass, very low detection sensitivity, very low concentration and high mobility [4]. Various approaches have been made for direct observation of hydr...
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