3D processing maps and a modified constitutive model of 16Cr-5Ni-Mo supermartensitic stainless steel

Abstract

The hot deformation behavior of 16Cr-5Ni-Mo supermartensitic stainless steel was investigated using a Gleeble-1500D thermo-mechanical simulator in the temperature range of 850 to 1150 °C and strain rate range of 0.01 to 10 s⁻¹. The hot deformation apparent activation energy of the steel was obtained as 424.173 kJ/mol. Arrhenius type constitutive equation was established according to flow stress data to describe the flow behavior. Meanwhile, the 3D maps of power dissipation and processing based on dynamic materials mode (DMM) were developed for the typical strains of 0.2, 0.4, 0.6 and 0.8, respectively. The results show that with the high deformation temperature (1000-1150°C) and low strain rate (0.01—0.1 s⁻¹), it is dominated by the dynamic recrystallization (DRX) for the softening mechanism. And the critical strains for the onset of DRX at different conditions are obtained. The optimized processing parameters for hot working of 16Cr-5Ni-Mo supermartensitic stainless steel are in the temperature range of 980—1150°C and strain rate range of 0.02—0.36 s⁻¹ at strains of 0.6 and 0.8.