Prediction and Control of Microstructure Evolution of a Novel P/M Nickel-Based Superalloy During Near-Isothermal Forging

Near-isothermal forging (NIF) is an effective method for forming P/M nickel-based superalloys. Prediction and control of microstructure evolution during NIF has long been a great challenge. This paper established a mathematical model coupled with dynamic recrystallization kinetics and grain size evolution for a novel P/M nickel-based superalloy. Then the microstructure evolution of the superalloy during the NIF process was simulated by embedding the model into the DEFORM finite element platform. The effect of initial billet temperature, die temperature, the height-to-diameter ratio of the billet, and the forging strain rate on grain size distribution was further discussed. To tailor the ideal deformed microstructure, the average grain size and its standard deviation were chosen as the optimization target. Artificial neural network was adopted to build the relationship between processing parameters and microstructure. The optimized NIF processing window was further determined by the genetic algorithm. Our work provides helpful guidance for controlling the microstructure in the industrial production of high-performance P/M superalloy parts.