Towards a Multi Phase Field Model to Analyze Residual Stresses

Nowadays, research regarding residual stress focuses on the targeted induction of residual stresses during the manufacturing of a component instead of the minimization of these stresses. Thereby, cost and time consuming process steps such as subsequent heat treatment or shot peening can be omitted. Moreover, the idea is to induce residual stress states that improve the component's properties depending on the component's usage. In this context, hot bulk forming processing enables the controlled modification of residual stresses and, thus, helps to avoid costly and time‐consuming subsequent process steps. Numerical modeling with the finite element method of such manufacturing is a valuable tool for process design. Such simulations have been studied in previous works to show that it is possible to adapt the (macroscopic) residual stresses in a predefined manner during the manufacturing of a component by applying a customized cooling scheme. Now, focus is on the associated phase transformation giving rise to residual stresses at the microscale of the component. Therefore, an elastic multi phase field model is set up to study the microscale with respect to the phase evolution and resulting stress distribution by analyzing a boundary value problem that is one‐way coupled to a macroscopic finite element analysis of the cooling step of the hot bulk forming. In order to improve the results, we extended our analysis using an elasto‐plastic multi phase field model in a second step. We observe stress values exceeding the macroscopic residual stresses in the final state, which shows the importance of microscopic analyses.