Microstructural modeling and numerical simulation of multi-physical fields for martensitic stainless steel during hot forging process of turbine blade

The mechanical properties of forgings mainly depend on the microstructure evolution during closed-die forging process, during which the microstructure mainly undergoes dynamic recovery, dynamic recrystallization, static recovery, static recrystallization, and metadynamic recrystallization. The macroscopic factors such as deformation temperature, strain rate, and strain play a key role in the microstructure evolution when the material composition is given. This paper presents the mathematical models for the prediction of microstructure evolution for martensitic stainless steel based on the hot compression test. A coupled analysis system of flow stress field, temperature field, and microstructure evolution for hot forging was developed based on the commercial software. The forging process of martensitic stainless steel turbine blade was simulated by the developed system. The influence of initial temperature of billet and deformation velocity on the load and finial temperature of forging part was analyzed. The variation of strain, temperature, and recrystallization volume fraction and grain size has been analyzed through simulation of the forging process. Based on the simulation results, the optimum hot forging process for complex forging parts was obtained.