Deformation mechanisms during large strain deformation of high Mn TWIP steel

摘要

The evolution of texture and microstructure has been studied up to very large strains (ε_t ≈ 3.9) on a twinning induced plasticity (TWIP) steel. Different micromechanisms have been envisaged during different deformation regimes. At early stage of deformation, the mechanism is normal slip dominated, while deformation twining starts at ~20% rolling and increases up to ~40% deformation level. Further deformation takes place by macroscopic shear banding (SBs). A Brass (Bs) type texture forms and strengthens throughout the deformation, which has been simulated by visco-plastic self consistent (VPSC) modelling. The results of VPSC simulations correlate the relative contributions of normal slip, Shockley partials and twin activities at different strain levels, which were observed by microstructural investigation. The Lankford parameter is estimated from texture, indicate that above 70% deformation level, the material develops very high in-plane anisotropy.