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
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.
