Prediction of Microstructure Evolution during High Temperature Blade Forging of a Ni-Fe Based Superalloy, Alloy 718

Abstract

The mechanical properties of the Ni-Fe-based Alloy 718 depend very much on grain size, as well as the strengthening phases, gamma' and gamma". The grain structure of the superalloy components is mainly controlled during thermo-mechanical processes by the dynamic, meta-dynamic recrystallization and grain growth. In this investigation, the evolution of the grain structure in the process of two-step blade forging was experimentally and numerically dealt with. The evolution of the grain structure in Alloy 718 during blade forging was predicted using a 2-D FE simulator with implemented constitutive models on dynamic recrystallization and grain growth. The comparison of the simulated microstructure with the actual grain structure of the forged parts validated the prediction of the grain structure evolution. The effect of dynamic recrystallization on the evolution of grain structure is highlighted in this article.