Strain-induced martensites in high manganese TRIP/TWIP steels were investigated in the presence of thermal martensites and under the influence of austenitic grain orientation by X-ray diffraction （XRD）, scanning ele...Strain-induced martensites in high manganese TRIP/TWIP steels were investigated in the presence of thermal martensites and under the influence of austenitic grain orientation by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electron backscattered diffraction （EBSD）. Before deformation, the morphology of α＇- M depended mainly on the number of variants and growing period. Regardless of martensite morphologies and deformation, the Kurdjumov-Sachs （K-S） orientation relationships always maintained. The 6 α＇-M variants formed from a plate of ε-M were of 3 pairs of twins with a common axis 〈110〉α＇ parallel to the normal of {112}γ habit plane to minimize transformation strain. When α＇-M could be formed only by deformation, it nucleated at the intersection of ε-M variants and grew mainly in thick ε-M plates. Thick ε plates promoted significantly the α＇-M and weakened the influence of grain orientations. During tension, the transformation in 〈100〉-oriented grains was observed to be slower than that in 〈121〉-oriented grains. Deformation twins promoted ε-M formation slightly and had no apparent effect on α＇-M. Deformation increased the number of ε-M variants, but reduced that of α＇-M variants.展开更多
Transformation texture is normally different to deformation and recrystallization textures,thus influencing materials properties differently.As deformation and recrystallization are often inseparable to transformation...Transformation texture is normally different to deformation and recrystallization textures,thus influencing materials properties differently.As deformation and recrystallization are often inseparable to transformation in materials which shows a variety in types such as diffusional or non-diffusional transformations,different phenomena or rules of strengthening transformation textures occur.This paper summarizes the complicated phenomena and rules by comparison of a lot of authors’published and unpublished data collected from mainly electrical steels,high manganese steels and pure titanium sheets.Three kinds of influencing deformation are identified,namely the dynamic transformation with concurrent deformation and transformation,the transformation preceded by deformation and recrystallization and the surface effect induced transformation,and the textures related with them develop in different mechanisms.It is stressed that surface effect induced transformation is particularly effective to enhance transformation texture.It is also shown that the materials properties are also improved by controlled transformation textures,in particular in electrical steels.It is hoped that these phenomena and processing techniques are beneficial to the establishment of transformation texture theory and property improvement in practice.展开更多
基金funded by the National Natural Science Foundation of China (No. 50771019)Specialized Research Fund for the Doctoral Program of Higher Education (No. 20090006110013)
文摘Strain-induced martensites in high manganese TRIP/TWIP steels were investigated in the presence of thermal martensites and under the influence of austenitic grain orientation by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electron backscattered diffraction （EBSD）. Before deformation, the morphology of α＇- M depended mainly on the number of variants and growing period. Regardless of martensite morphologies and deformation, the Kurdjumov-Sachs （K-S） orientation relationships always maintained. The 6 α＇-M variants formed from a plate of ε-M were of 3 pairs of twins with a common axis 〈110〉α＇ parallel to the normal of {112}γ habit plane to minimize transformation strain. When α＇-M could be formed only by deformation, it nucleated at the intersection of ε-M variants and grew mainly in thick ε-M plates. Thick ε plates promoted significantly the α＇-M and weakened the influence of grain orientations. During tension, the transformation in 〈100〉-oriented grains was observed to be slower than that in 〈121〉-oriented grains. Deformation twins promoted ε-M formation slightly and had no apparent effect on α＇-M. Deformation increased the number of ε-M variants, but reduced that of α＇-M variants.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51771024).
文摘Transformation texture is normally different to deformation and recrystallization textures,thus influencing materials properties differently.As deformation and recrystallization are often inseparable to transformation in materials which shows a variety in types such as diffusional or non-diffusional transformations,different phenomena or rules of strengthening transformation textures occur.This paper summarizes the complicated phenomena and rules by comparison of a lot of authors’published and unpublished data collected from mainly electrical steels,high manganese steels and pure titanium sheets.Three kinds of influencing deformation are identified,namely the dynamic transformation with concurrent deformation and transformation,the transformation preceded by deformation and recrystallization and the surface effect induced transformation,and the textures related with them develop in different mechanisms.It is stressed that surface effect induced transformation is particularly effective to enhance transformation texture.It is also shown that the materials properties are also improved by controlled transformation textures,in particular in electrical steels.It is hoped that these phenomena and processing techniques are beneficial to the establishment of transformation texture theory and property improvement in practice.
