Experimental and numerical modelling and analysis of microstructural residual stresses in hot-formed components with targeted cooling

Hot forming offers particular potential for the targeted adjustment of residual stresses in the finished component by using the interaction of mechanical, as well as thermal and metallurgical process parameters.

The long-term goal of this project is the controlled use of residual stresses in hot massive forming, for example, to avoid spring-back effects or to increase the fatigue strength of the component. In the first funding phase, it will be investigated whether stable residual stresses can be introduced into components in a targeted and reproducible manner. Due to the polymorphic material behaviour, the steels undergo various structural transformations during the cooling phase after hot forming. Accordingly, the material parameters must be recorded in experiments depending on the different material phases. Based on this data, a phenomenological simulation model can be built and validated using compression tests. This model will also allow observation of the microstructure morphology during the cooling process. However, no statements can be made about residual stresses at the micro-level. For this purpose, the development of a phase-field model from the experimental and numerical obtained data is planned. Thus, the influences of the residual stresses of the micro-level on the residual stresses of the macro level are to be analysed.