INCONEL 718 Recrystallization in the Delta Supersolvus Domain

An experimental study of compression tests at high temperature and different engineering strains was carried out on INCONEL 718 above the delta phase solvus. The objective is to investigate the mechanical behaviour in relation with the microstructure evolution. After deformation the samples were quenched with helium gas to avoid metadynamic recrystallization (MDRX). The quench efficiency is discussed by microstructural and hardness comparison. During forging process and without MDRX, there is generally a competition between deformation and dynamic recrystallization state (DRX) i.e. a dependence on dislocation density increase and dislocation annihilation, respectively. To investigate this competition, samples are characterized at different scales by EBSD method to determine local texture and grain size and by TEM to understand the dislocation evolution and determine the nucleation mechanism. In parallel, a numerical model using a three-dimensional finite element model of crystalline plasticity (CristalECP) has been developed in ABAQUS™ finite element code and coupled with a Recrystallization Cellular Automaton (CA_ReX). Results of forging process simulations are compared to those of experimental studies presented before and then discussed in terms of evolution.