Simulation of microstructures for Alloy 718 blade forging using 3D FEM simulator

Mechanical properties of Ni–Cr–Fe-based Alloy 718 depend very much on the grain size, as well as the presence of strengthening phases, γ′ and γ″. The grain size of superalloy parts can be controlled by the thermo-mechanical processes, including heating, forging and cooling sequences. In order to predict the evolution of grain size in Alloy 718 blade forging, a series of constitutive equations for dynamic recrystallization, meta-dynamic recrystallization and grain growth were developed and implemented into a 3D FE simulator. The evolution of grain structure in the process of two-step blade forging of Alloy 718 was simulated using the 3D FE simulator combined with a microstructure module. The microstructure prediction tool was validated by comparing the simulated grain structure with that of the experimental blade-type forging.