Very high cycle fretting fatigue of Nimonic 80A modified by laser cladding with Stellite X-40 and In625/20 % WC

Nimonic 80A alloy is widely used in rotor blades, guide vane supports and other aeroengine components. It is exposed to harsh fretting wear and high temperature loads, which reduces the fatigue resistance of the components. Laser cladding (LC) technology is utilized to improve structural integrity and fatigue resistance. The aim of the research is to assess the resistance of Nimonic 80A in the very high cycle fretting fatigue (VHCFF) after cladding with Stellite X-40 and In625 + 20 wt% WC. The wear morphology and fracture mechanism of the specimens were studied using scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). The results show that the crack initiation sites are mainly classified into three types, namely surface initiation, interior initiation, and LC interface initiation. The fretting wear introduces compressive residual stress along the wear depth, as well as the bulk stress, residual stress, and cladding defects all play dominant roles in crack initiation. Especially up to 108 cycles, the glaze oxide layer (GOL) helps to reduce friction coefficient and make the compaction of wear debris easier, inhibiting the crack nucleation. The different distribution of residual stress in on the LC layer and the stronger wear resistance of WC particles lead to the higher fatigue strength and life of the specimen with In625 + 20 wt% WC cladding material compared with the Stellite X-40 ones.