A Holistic Concept for the Numerical Determination of Residual Stresses during Heat Treatment and Hard Turning of Case-Hardened Steel

Surface integrity plays a key role in the functional performance of highly loaded components, with residual stresses being a major factor governing fatigue behavior. In case-hardened steels, the residual stress state after hard turning results from a complex interaction of mechanical, thermal, and microstructural effects. This interaction is significantly affected by the preceding heat treatment condition. Variations in tool condition and machining parameters alter residual stress distributions and subsurface microstructures, including strain-induced transformation of retained austenite, highlighting the sensitivity of the final component state to the overall process chain. However, existing modeling approaches treat machining as an isolated process step and therefore do not adequately capture the initial material state. In this context, this work presents a holistic numerical framework for process chain-based modeling of residual stress formation in case-hardened steels. The paper focuses on the conceptual and methodological foundations of the framework and represents the first contribution in a planned publication series. Subsequent studies will address quantitative aspects in detail. The novelty of the proposed concept lies in the consistent consideration of strain-induced transformation of retained austenite during both case hardening and subsequent hard turning, enabling virtual process chain evaluation and fatigue-oriented process design.