Hot ductility behavior of high-Mn austenitic Fe-22Mn-1.5Al-1.5Si-0.45C TWIP steels microalloyed with Ti and V

This research work studies the influence of microalloying elements (Ti and V) and the solidification route on the hot ductility behavior of high-manganese TWIP steels. Uniaxial hot tensile tests in the temperature range of 700-1100 °C under a constant strain rate of 10−3 s−1 were carried out. Hot ductility as a function of reduction of area (RA) showed a significant improvement in the V-microalloyed TWIP steel, when compared to a non-microalloyed TWIP steel with a similar composition, in the intermediate temperature range of 800-900 °C. The highest value of 86% RA is attributed to the onset of dynamic recrystallization (DRX) near to the fracture tip. On the other hand, Ti addition to TWIP steel did not exhibit any improvement on the hot ductility, resulting in the worst hot ductility behavior, with a maximum value of 34% RA. The TWIP steels solidified in metallic ingot molds (MM) showed higher peak stress (σp) and ductility values than the sand mold (SM) cast ingots at low and intermediate temperatures, respectively, which is associated with the finer microstructure generated during solidification. Grain boundary sliding was recognized as the failure mechanism associated with second-phase particles precipitated at the grain boundaries, which play the role of nucleation and propagation sites of void-cracks.