Effects of cold rolling on microstructure and mechanical properties of Fe–30Mn–3Si–4Al–0.093C TWIP steel

The effects of cold rolling on microstructure evolution and the associated mechanical properties of Fe–30Mn–3Si–4Al–0.093C twinning-induced plasticity (TWIP) steel are examined in this work with reduction levels of 10%, 20%, 30%, 40%, 50%, 60%, and 70%. Through texture analysis and transmission electron microscopy (TEM) observations, it is suggested that slip, mechanical twinning, the interaction between dislocation/twin boundaries (TB), and shear band formation have influenced the observed mechanical behavior and development of texture. Special components of weak initial textures are preferential for mechanical twinning, resulting in an increase in strain hardening rate. By mechanical twinning, the {111}〈112〉 orientation is rotated into a position at the vicinity of the {110}〈001〉 Goss orientation, and the {552}〈115〉 (Cu-twin) texture is transformed to the {110}〈001〉 orientation. The evolution of texture is closely related to the onset of shear banding resulting from deformation twinning. The sample with 10% cold reduction exhibits a favorable combination of yield strength and ductility, indicating a considerable capacity for energy absorption. With increasing rolling reductions, the deformation of the samples becomes inhomogeneous due to the high anisotropy of the microstructure. The localized shear bands resulting from the excessive cold rolling are detrimental to the ductility of the present TWIP steel.