Effect of Molybdenum on the Full Annealing Temperature in TWIP Steels

TWinning Induced Plasticity (TWIP) steels, with high manganese percentage (17-35%), are used in automotive bodies. Their microstructure at room temperature is austenitic and due to low stacking fault energy, major deformation mechanism in them is twinning inside austenite grains which on the other hand, leads to enhanced mechanical strength in steel. Due to important effect of heat treatment process on mechanical properties, full annealing heat treatment and effect of Molybdenum were investigated in this study. To this aim, the steel was casted and hot rolled and then heat treated at different temperatures and the obtained microstructures were analyzed using optical, SEM and TEM microscopes. The results showed that the full annealing temperature for steel without Mo was determined to be 1100 C. and addition Mo to the steel annealing Temperature by 50 C reduced.