Dynamic restoration processes in high-Mn TWIP steels

The twinning-induced plasticity (TWIP) phenomenon is established as the most effective mechanism to enhance the formability of the advanced high-Mn (15-30 wt %) austenitic steels (known as TWIP steels). As the formability is very sensitive to the steel microstructure, the study of their hot deformation characteristics is highly desired. The aim of the present work is to investigate the effects of strain rate on the high temperature flow behavior, dynamic recrystallization (DRX) and the microstructural evolution of a grade of TWIP steels (with 29 wt % Mn) through single hit compression testing. The hot compression tests were carried out at two different temperatures (850°C and 1150°C) applying a range of strain rates (0.001-0.1 s-1). The results indicated a greater deformation resistance at higher strain rates. The detected broad stress peaks at higher strain rates were related to the occurrence of DRX. The microstructural studies revealed that, in addition to DRX, a geometrical dynamic recrystallization occurred at 850°C. This results in a microstructure with finer equiaxed grains.