The Effect of Variant Selection on Texture of TWIP/TRIP Steels During Uniaxial Tensile Loading

Abstract

The aim of the present manuscript is to reveal the role of variant selection associated with the γ → ε and γ → ε → α′ transformations in the resulting texture of γ, ε and α′ phases of FeMnCr steels during uniaxial loading. Tensile tests were carried out at temperatures well above and close to the martensite start temperature of the ε phase (Msε). Pole figures were obtained from the cross-section of the fractured specimens by X-ray diffraction (XRD). The γ 〈111〉 texture developed regardless of test temperature. It was found that the ratio of diffracted intensity in the 0 and ~ 70 deg directions with respect to tensile axis notably changed with test temperature. The difference was caused by variant selection accompanying the γ → α′ transformation. At high temperatures, α′ martensite formed only in the ~ 70 deg directions, where the mechanical driving force is large. At lower temperatures, however, α′ martensite formed in the ~ 70 and 0 deg directions as well. It is also shown that stress/strain-induced ε martensite can only form in the ~ 70 deg directions. The results apply for all three examined steels.