Significant influence of rolling modes on martensitic transformation, microstructural evolution and texture development in a 304 stainless steel

Abstract

A 304 stainless steel was deformed by two different rolling modes (unidirectional cold rolling and cross rolling) at room temperature. The effects of rolling modes on martensitic transformation, microstructural evolution, and texture development were investigated. The results showed that martensitic transformation was enhanced significantly by cross rolling. The underlying reason was the increase in the amounts of nucleation sites for α′-martensite, i.e., intersections of shear bands. The transformation of austenite to martensite was found to be followed the sequence of γ → ε → α′ regardless of rolling modes. Rolling modes had great influences on deformation textures in both the remaining austenite and α′-martensite. For unidirectional cold-rolled samples, the main texture components of deformed austenite were Brass ({110}〈112〉) and S ({123}〈634〉) texture, while the α′-martensite phase exhibited {112}〈110〉, {223}〈121〉, and {554}〈225〉 orientations. However, ζ-fiber (〈110〉//ND) component, which was characterized by oscillation between Brass and G/B ({110}〈111〉) texture, was formed in remaining austenite during cross rolling, accompanied by a weakening of S component. Meanwhile, the α′-martensite phase in cross-rolled samples exhibited η-fiber (〈001〉//ND), and the dominant texture components were Rotated Cube ({001}〈110〉) and {001}〈160〉. The stability of the orientations during cross rolling can be responsible for texture development in both austenite and α′-martensite.