Peculiarities of DRX in a Highly-Alloyed Austenitic Stainless Steel

The features of discontinuous dynamic recrystallization (DRX) in a highly-alloyed austenitic stainless steel were studied at temperatures of 800 °C to 1100 °C. Hot deformation accompanied by DRX was characterized by an activation energy of 415 kJ/mol. The frequency of the sequential DRX cycles depended on the deformation conditions; and the largest fraction of DRX grains with small grain orientation spread below 1° was observed at a temperature of around 1000 °C and a strain rate of about 10(−3) s(−1). The following power law relationships were obtained for DRX grain size (D(DRX)) and dislocation density (ρ) vs. temperature-compensated strain rate (Z) or peak flow stress (σ(P)): D(DRX) ~ Z(−0.25), ρ ~ Z(0.1), σ(P) ~ D(DRX)(−0.9), σ(P) ~ ρ(1.4). The latter, i.e., σ(P) ~ ρ(1.4), was valid in the flow stress range below 300 MPa and changed to σ(P) ~ ρ(0.5) on increasing the stress. The obtained dependencies suggest a unique power law function between the dislocation density and the DRX grain size with an exponent of −0.5.