Effect of V Microalloying in The Hot Working Behavior of High Mn TWIP Steels

The present work focuses on the study of static softening and strain-induced precipitation in high Mn (20%~30 %) TWIP steels microalloyed with vanadium. The effect of different V (0.1%,0.2%) and C (0.2%,0.6%,1 %) contents has been investigated. The aim is to evaluate at which conditions (composition/hot working parameters) vanadium remains available for further precipitation hardening after hot rolling. Double hit torsion tests at temperatures in the range 700~1100 ℃ and coiling simulations (from 700 to 550 ℃) were carried out. Advanced characterization techniques have been used,such as EBSD for the determination of the grain size and recrystallized fraction,and TEM for the analysis of the precipitation. The results show that precipitation of vanadium at the hot working temperature range is relatively sluggish. It only occurs for the combinations of 20Mn- 0.6C- 0.2V or 30Mn- 1C-0.1V. Reducing the carbon content to 0.2C,precipitates were only observed after coiling simulation at 650 and 700 ℃. Moreover,in those cases where strain-induced precipitation is observed there is a complex interaction between recovery,recrystallization and strain-induced precipitation. Static recrystallization is severely delayed leading to a major contribution of recovery to softening kinetics.