Microstructure and flow behavior of cast 2304 duplex stainless steel at elevated temperatures

Hot deformation characteristics of 2304 duplex stainless steel were analyzed by hot compression tests at temperature range of 850-1150 degrees C and strain rates of 0.001-1 s(-1). The flow curves at low temperatures and high strain rates were suggesting sluggish dynamic recovery (DRV) in ferrite and partial dynamic recrystallization (DRX) in austenite. However, at high temperatures and low strain rates, the flow curves showed implied the domination of DRV in ferrite. The hyperbolic sine equation with activation energy of 508 kJ/mol could relate the processing parameters. Microstructural observations showed that DRV in ferrite is the controlling mechanism at all deformation conditions. However, at high temperatures and strain rates partial DRX could also occur in austenite. Based on the law of mixture and Baragar's equations a modified model was proposed to consider work hardening and dynamic softening in the constituents. The model could satisfactorily predict the flow curves at different deformation regimes.