Effect of Nitrogen on the Hot Deformation Behavior of 0.4C–13Cr Martensitic Stainless Steel

Abstract

The hot deformation behaviors of 0.4C–13Cr martensitic stainless steel at the nitrogen contents of 0.13% and 0.03%, respectively, are investigated at the deformation condition featuring the temperature range of 1223–1523 K and the strain rate range of 0.01–10 s−1. The variation of flow stress curves of experimental steels with different nitrogen contents is systematically analyzed. According to the flow stress curves, the activation energies determined by regression analysis are 472.77 and 411.58 kJ mol−1 for 0.4C–13Cr steel with N contents of 0.13% and 0.03%, respectively. It demonstrates that the deformation resistance of 0.4C–13Cr steel improves with the increase in nitrogen content. The reason is related to the pinning effect of solid solution nitrogen atoms, and Cr2N particles on dislocations and grain boundaries. The dynamic recrystallization (DRX) kinetics models of experimental steels are established. Furthermore, the microstructures of experimental steels are also analyzed. The result shows that the pinning effect caused by nitrogen also plays an important role in the development of DRX and microstructure evolution. The more nitrogen addition in 0.4C–13Cr steel, the earlier achievement of DRX onset, the slower the DRX kinetics and the finer the microstructure.