Annealing treatment induced ε martensite formation and evolution in TWIP steel

Abstract Crystallographic analyses on the orientation relationships of e martensite variants were carried out by electron backscatter diffraction and transmission electron microscope in TWIP steel. Results show that the e phases are mainly distributed in single or multiple initial variants with 70.5° angle on {111}γ planes during short-time annealing. Importantly, secondary variants, which are generally considered difficult to form by thermal-induced and are also not derived directly from matrix by the well-known simple shear process for the FCC to HCP transformation, were observed at the intersection between two initial variants with 19.5° rotation angle after long-time annealing. These successfully interpret the microstructural features of e variants and their relationships.