Metal flow behaviour and processing maps of high heat resistant steel during hot compression

This article reports the flow stress behaviour of ASTM A335 P92 steel. Uniaxial isothermal compression experiments were conducted to examine the hot deformation behaviour of P92 steel in a Gleeble® 3500 thermal-mechanical simulator. The test conditions were: 0.01–10 s − 1 strain rate and 850–1000°C deformation temperature. Constitutive equations and processing maps developed were used to describe the hot deformation process. The results showed that the flow stress-strain curves exhibited a dynamic recovery (DRV) behaviour as the dominant softening mechanism. The flow stress decreased with an increase in the deformation temperature or a decrease in strain rate. Using the Arrhenius equation, the stress exponent and the activation energy values were: 8.0 and 487.56 kJmol − 1 , respectively. The correlation between the constructed processing maps and microstructure showed that the optimal process parameters occurred at a lower strain rate in the region of 0.1 s − 1 and deformation temperatures of 900–950°C and 1000°C for the steel investigated.