Modelling of Static Recrystallization Behavior of High Manganese Austenitic Steels with Different Alloying Contents

Abstract

During hot rolling, austenite recrystallization determines the grain size evolution and the extent of strain accumulation, and therefore, it can be used to control the microstructure and improve the mechanical properties of the final product. However, at the moment, experimental data and models describing the recrystallization kinetics of high-Mn steels are scarce, and they do not take into account the effect of the different C and Mn alloying contents usually present in these steels. The aim of this work is to provide a quantitative model for the determination of the static recrystallization kinetics and recrystallized grain size that is valid for a wide range of high-Mn steel compositions. In order to do this, softening data determined in previous works for steels with different Mn (20 to 30%), Al (0 to 1.5%) and C (0.2 to 1%) levels were considered. In addition, new tests were carried out to determine the effect of deformation conditions on the static softening kinetics and the recrystallized grain size. The static recrystallization kinetics of the high-Mn steels follows Avrami’s law, with n Avrami exponents which are temperature dependent and lower than those determined for low C steels. A dependence of the t_0.5 (time for 50% fractional softening) on the carbon content has been observed and it was incorporated into an equation for the calculation of this parameter. An expression that is valid for predicting the recrystallized grain size as a function of deformation conditions is also proposed.