A Calorimetric Study of Recovery and Recrystallization in Fe–14.4 Cr–15.4 Ni–2.4 Mo–2.36 Mn–0.25 Ti–0.04 C–0.05 P (mass %) Austenitic Stainless Steel

Abstract

AbstractThe stored energy release and the kinetics of recovery and recrystallization processes in 70 and 85% coldworked nuclear grade austenitic stainless steel have been investigated by dynamic calorimetry, the results of which are supplemented by optical microscopy and microhardness measurements. Distinct thermal arrests arising from recovery and recrystallization events that occur upon slow heating are around 815 and 1070 K, respectively. The peak recovery and recrystallization temperatures are found to be sensitive to prior coldwork and heating rate. Faster rates of heating pushed the recovery stage to higher temperatures overlapping with the domain of recrystallization, which resulted in a decreased dissipation of stored energy due to recovery. As a result, faster heating rates, served to accelerate the kinetics of recrystallization owing to higher driving force. It is also found that the dissolution of fine TiC particles lead to secondary recrystallization at higher temperatures. Modeling of lattice softening kinetics yielded values of effective activation energies for recovery and recrystallization processes in the range, 198 and 336 kJ mol−1, respectively.