Hot Deformation Behavior and Microstructure Evolution of 2Cr12Ni4Mo3VNbN Steel Used for Last‐Stage Large Blades of Steam Turbine

The hot deformation behavior and microstructure evolution of a recently developed 2Cr12Ni4Mo3VNbN martensitic stainless steel are examined through hot compression tests conducted within the temperature range of 900–1200 °C and the strain rate range of 0.01–10 s−1. The constitutive equation and processing maps corresponding to hot deformation are established. The activation energy for hot deformation of 2Cr12Ni4Mo3VNbN steel is determined to be ≈457491.77 J mol−1. Simultaneously, the microstructure evolution during hot deformation is studied. Based on the processing maps and microstructure evolution analysis, it is concluded that the optimal windows for hot processing are within the temperature range of 1106–1150 °C and the strain rate range of 0.01–2.7 s−1, as well as at 1200 °C within the strain rate range of 1–2.7 s−1, exhibiting a power dissipation efficiency of 0.32. As the temperature increases and the strain rate decreases, the degree of dynamic recrystallization escalates. 2Cr12Ni4Mo3VNbN steel is a newly developed martensitic stainless steel used for last‐stage large blades of steam turbine. Herein, the hot deformation behavior and microstructure evolution of 2Cr12Ni4Mo3VNbN steel are investigated for the first time. Constitutive equations and hot‐processing maps of 2Cr12Ni4Mo3VNbN steel are established. Combined processing maps and microstructure evolution, the optimum windows of hot processing are obtained.