Residual stress engineering for highly loaded rolling-sliding contacts: Finding the sweet spot for maximum durability by hard turning and deep rolling

The durability of highly loaded rolling-sliding contacts, such as those in rolling bearings, is critically determined by subsurface microstructure and residual stresses engineered during manufacturing. This study systematically investigates the interplay between thermal and mechanical process parameters during deep rolling, using bearing inner rings as a representative example, to identify optimal conditions for maximizing fatigue life. By isolating the effects of process temperature (20–400 °C) and deep rolling pressure (200–400 bar), we demonstrate that moderate mechanical loading at room temperature can more than double bearing life through beneficial compressive residual stresses, while excessive pressure or thermal input above 200 °C sharply reduces durability. Notably, we reveal a previously unrecognized mechanism of hidden thermal degradation that limits lifetime, even when conventional hardness or microstructural metrics remain unchanged. These results define a process window for residual stress engineering in bearing steels and provide generic guidelines for hybrid manufacturing of rolling-sliding components subjected to severe tribological loading. The findings advance fundamental understanding of process-induced fatigue mechanisms and offer a framework for the rational design of subsurface-optimized, durable, and sustainable machine elements.