Role of layer thickness and grain size contrast in rolling contact fatigue of coarse/fine-grained layered materials: A crystal plasticity study

Heterogeneous layered materials combine high strength and ductility, offering improved damage tolerance under tribological loading. Among the key microstructural factors, layer thickness and grain size contrast have a critical influence on the mechanical behavior during rolling contact fatigue (RCF). A crystal plasticity finite element (CPFE) model was developed to simulate rolling contact responses in coarse-grained (CG)/fine-grained (FG) layered structures. The simulations reveal that layer thickness modulates strain localization, dislocation activity, and damage evolution in a sliding-orientation-dependent manner. FG layers serve as barriers to strain transmission and suppress damage propagation from adjacent CG layers. Furthermore, dislocation partitioning at CG/FG interfaces promotes strain delocalization and enhances RCF resistance. These findings provide mechanistic insights for optimizing layered microstructure design for advanced tribological applications. • A dislocation-based crystal plasticity model simulates rolling contact fatigue in layered structures. • Stored energy density (SED) serves as a damage indicator for fatigue damage initiation and growth. • Layer thickness and sliding orientation jointly control surface roughening and damage accumulation. • Grain size contrast hinders damage propagation across coarse-grained (CG) and fine-grained (FG) layers. • Dislocation partitioning between CG and FG layers enhances strain delocalization and fatigue resistance.