利用3D EBSD-FIB(three dimensional electron backscatter diffraction-focused ion beam)技术,以高锰钢为实验材料,构建晶粒三维立体形貌,并对马氏体惯习面进行观察分析。结果表明:热致板条状马氏体表面平直,接近马氏体的{110}α,惯习面平行于奥氏体的{225}γ,其初始形核及后期生长均在{225}γ上进行;而形变诱发形成的板条状马氏体表面和惯习面分布近于{021}α和{225}γ,初始形核和前期生长沿{225}γ,后期生长沿{111}γ,由于外加应力,其表面发生弯曲变形,形核时间不同,偏离{225}γ-{111}γ程度不同。
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.
