Effect of High Tensile Strain Rate on the Evolution of Microstructure in Fe-Mn-C-Al Twinning-Induced Plasticity (TWIP) Steel

Fe-17.8Mn-0.52C-0.5Al TWIP steel has been investigated under high-strain rate conditions. Twinning along with stacking faults and high dislocation densities in the austenite matrix has been evaluated by X-ray diffraction line profile analysis and transmission electron microscopy. The samples strained at 100 s(-1) show a gradient in the evolution of the dislocation density along the gage length except the fracture end where the density shows a decrease. In case of the samples strained at 1 s(-1), the evolution of density shows attainment of a near-saturation stage. Electron backscatter diffraction analysis shows that the decrease in the dislocation density as well as near-saturation stage is due to dynamic recovery as well as dynamic recrystallization at region near the fracture end. The dynamically recrystallized grains are related to the deformed matrix through twin relationship.