Effect of Zr on static recrystallization of deformed austenite and strain-induced precipitation in Ti microalloyed steel

Abstract

The static recrystallization and strain-induced precipitation behavior of Ti and Ti-Zr low carbon microalloyed steels were studied through isothermal stress relaxation experiments at different deformation temperatures (875–1025 °C). The precipitation kinetic curves of microalloyed carbides were obtained, and the effect of Zr on the precipitation kinetics of microalloyed carbides was analyzed. Two static recrystallization kinetic models were established, and the activation energies for static recrystallization of Ti steel and Ti-Zr steel were calculated to be 312.44 and 246.59 kJ/mol, respectively. The results indicate that the addition of Zr lowers the nose point temperature of the precipitation–time–temperature curve, shortens the incubation period for the nucleation of precipitates, promotes the nucleation of strain-induced precipitates in Ti microalloyed steel, and reduces the coarsening rate of precipitates particles by an order of magnitude. In addition, the addition of Zr also advances the end time of static recrystallization of deformed austenite, inhibits the growth of static recrystallization austenite grains in Ti steel during the isothermal process, and makes the austenite grains finer and more uniform.