Retained Austenite Stabilization Through Solute Partitioning During Intercritical Annealing in C-, Mn-, Al-, Si-, and Cr-Alloyed Steels

Retained austenite fractions, predicted to be stable at room temperature assuming ortho-equilibrium solute distribution during intercritical annealing, were calculated for medium-Mn steels with varying Mn, C, Al, Si, and Cr additions using SSOL 2 and TCFE 7 Thermo-Calc (R) databases. While Mn additions increase retained austenite levels, increased C levels are not predicted to greatly impact austenite fractions. Additions of Si reduce the levels, whereas opposing trends are predicted for Al additions by the employed ThermoCalc (R) databases. Chromium significantly reduces the dependence of retained austenite fraction on annealing temperature. Alloying effects are explained through four critical phase transformation temperatures. (C) The Minerals, Metals & Materials Society and ASM International 2014