Modeling residual stress evolution during ESR (Electro Slag Remelt) process.

Among the key melt practices used to produce high performance aerospace alloys, ESR process when executed with sub optimal melt conditions is known to leave behind internal cracks that retard productivity of subsequent melt stages. Current work evaluates the complete history of evolving residual stresses during ESR process by coupling solidification induced thermal history to predict deformation response leading to residual stresses. Model space is used to represent the ESR process accounting for complex thermal interactions of various structural elements and cooling circuits with ESR furnace for a given melt rate and power recipe. The thermal history of the process for complete ingot thus captured is fed to deformation models to predict residual stress evolution during the ESR process. Model procedures developed help us to evaluate residual stresses and their relation to factors controlling the ESR process. Measured data for hot ductility along with residual stress predictions from model space were used to track material damage criteria to identify process conditions with higher risk of internal cracks. This work also covers how this model-based insight led us to near optimal melt conditions along with the right balance of thermal processes that follow ESR melt stage.