Processing map of 17-4 PH martensitic stainless steel and microstructural evolution during hot deformation

The experimental material utilised was a low-carbon 17-4PH martensitic stainless steel (MSS), and single-axis hot compression tests were executed at diverse deformation temperatures (950–1200 °C) and strain rates (0.001–10 s -1 ) employing a Gleeble 3800 thermal simulator. The thermal deformation behaviour was examined based on dynamic material model, leading to the Arrhenius constitutive equation and processing map development. Additionally, EBSD analysis was incorporated to examine the microstructural evolution and phenomenon of dynamic recrystallisation (DRX) during the hot deformation process. Furthermore, the material’s dynamic softening behaviour during hot deformation was analysed in conjunction with the θ - ε curves. The research findings demonstrated that the flow stress of the 17-4PH MSS declined with rising temperature and reducing strain rate. The activation energy for high-temperature deformation was computed as 361.725 kJ/mol employing the constitutive equation, and the processing map revealed that the ranges of 1050–1120°C, 0.001–0.06 s -1 and 1120–1190°C, 0.02–0.5 s -1 represent the optimal hot working parameters for significant deformation.