Thermomechanical residual stress modeling of rotor shaft grade steel for power generation turbines

Abstract Steam turbines play a crucial role in power generation, requiring high efficiency, reliability, and extended service life. The rotor shaft, a critical structural component, develops residual stresses during manufacturing stages such as heat treatment, which are intended to enhance mechanical properties but can adversely affect dimensional stability and fatigue life. The specimen analyzed is a coupon extracted from a forged rotor shaft with identical alloy composition, reduction ratio, and heat-treatment history. Geometry and size effects may influence the stress distribution, but this approach preserves industrial relevance. A finite element based thermomechanical framework was developed to predict quenching-induced residual stresses and validated through x-ray diffraction measurements. The model demonstrated strong predictive capability, with a mean relative error of 9.29%, indicating its reliability for engineering design and residual stress evaluation. The model predicts the interior three-dimensional residual stress field under the following assumptions: no phase-transformation strains or transformation plasticity, temperature-independent multilinear isotropic hardening, and stage-wise constant heat-transfer coefficient and emissivity. Precise representation of stress distributions allows refinement of heat treatment protocols, enhancement of structural integrity, and reduction of reliance on costly trial-and-error experiments. Although this investigation focused on experimentally validated finite element analysis of the test coupon, the methodology provides a foundation for potential integration into future integrated computational materials engineering frameworks, where such predictive models could be combined with multiscale materials design and process optimization to support industrial component development.