Transformation Texture Analysis of BCC and BCT Ferrous Martensite

Abstract

The theoretical prediction of transformation textures, that developed in thin sheet without external stress, was carried out based on the Bain-Strain and Twinning-Shear model, respectively. To examine the validity of the prediction, the experiments were conducted with X-ray pole figure method on Fe-30Ni and Fe-30Ni-0.8C alloy sheets. The results obtained are as follows:(1) Variant selection phenomenon depends on the crystal orientation of the parent phase and on the Bain strain in the martensitic transformation.(2) The effect of the anisotropic constraint stress on the shear deformation involved in the lattice change and on the Bain distortion appears most remarkably in the BCT martensite transformed from the cube textured parent phase.(3) It became clear that such a variant that has the largest Bain strain component to the sheet normal, that is, the variant, of which the Bain distortion is prevented least of all by the anisotropic constraint stress, forms predominantly.