Multiscale modeling of tempering of AISI H13 hot-work tool steel - Part 2: Coupling predicted mechanical properties with FEM simulations

Simulation of austenitization and quenching of steel using the Finite Element Method (FEM) is nowadays a common tool to predict residual stresses and deformations during these processes. However the simulation of tempering, which determines the final residual stresses and distortions has been often neglected or performed in a purely phenomenological and highly simplified way. The objective of this study is to precisely predict the relaxation of internal stresses during tempering, taking explicitly into account the evolution of the microstructure. Mechanical properties which determine the relaxation of stress; namely the drop of the yield stress and the creep mechanism are the key factors for the success of the simulation. These mechanical parameters can be determined experimentally for a specific tempering temperature. However tempering temperature for most steels varies for each industrial application in order to adjust the desired hardness-toughness relation. Consequently, experimentally measurement of decisive mechanical properties which determine the amount of stress relaxation for each tempering temperature is very costly. Therefore, these material parameters were simulated from physically based material models with coupled microstructural simulations in the first part of this two-part investigation. In this part of the study, the simulated mechanical properties will be coupled with the FEM simulations using "Abaqus (R)", in order to simulate the stress relaxation during the tempering process of a thick-walled workpiece made of hot-work tool steel AISI H13 (DIN 1.2344, X40CrMoV5-1). Utilizing this methodology, different tempering conditions (soaking time, tempering temperature) can be considered in the model to predict the stress relaxation in macroscopic scale. (C) 2015 Elsevier B.V. All rights reserved.