Development of a Prediction Model and Process–Microstructure–Property Database on Forging and Heat Treatment of Superalloy 720Li

Abstract

A process–microstructure–property database on forging and heat treatment of superalloy 720Li was established by high precision large-scale 1500 ton forging simulator and laboratory-scale forging simulator. The database was utilized to determine the parameters of flow stress, microstructure, and strength prediction models. The models were integrated to CAE software to predict process–microstructure–property relationships. In the integrated model, the stress, strain, and temperature distributions and their temporal development are calculated by using flow stress model and thermophysical properties. The calculated stress, strain, and temperature data are inputted into the microstructure model. The microstructure model considers grain growth, recrystallization, and precipitation of γ′ and calculates the temporal evolution of microstructural features. The strength model considers solution, grain boundary, and precipitation strengthening and calculates high-temperature 0.2% tensile proof stress, which is related to creep and low-cycle fatigue properties, from the calculated microstructural features. The integrated model successfully predicted the load, microstructure, and strength distribution of a prototype forging experiment conducted by the Hitachi Metals 6000 ton forging machine. The integrated model is a promising tool to design the forging and heat treatment process of the alloy.