The effect of Ti-Mo additions on microstructural evolution and superplastic deformation behavior of cold-rolled medium Mn steels

This study investigated the effect of Ti-Mo alloying on the microstructural evolution and superplastic defor-mation behavior of Fe-5.6Mn-1.1Al-0.2C steels. The steels were subjected to cold-rolling and intercritical deformation at a strain rate of 10-2 s- 1 and temperatures between 655 and 775 degrees C. The results showed that Ti-Mo added steel exhibits a significant improvement in the strength due to the high density of nano-sized (Ti, Mo)C particles and optimized superplastic elongation of approximately 1000% at 745 degrees C. The superplastic flow behavior showed a strong temperature dependence under three typical temperature regions. This can be mainly attributed to the decreased interaction between precipitation and DRX with increasing deformation temperature. The grain boundary sliding (GBS) accommodation process varied with the deformation temperature due to the difference in precipitation nature of the (Ti, Mo)C particles.