Investigation of rolling/sliding contact fatigue failure mechanism and lifetime of Fe-based plasma sprayed coating remelted by GTA process

In this study, Fe-based plasma sprayed coating was prepared on the AISI 1045 substrate, and then gas tungsten arc welding (GTA) process was employed to remelt the coating. The contact fatigue performance of the coatings before and after remelting was tested by the contact fatigue/wear multifunctional machine, and the failure probability Weibull diagram was established. The results show that the failure mode of the as-sprayed coating is delamination, while, the main failure modes of the remelted coating are abrasion and spalling. Delamination is mainly due to poor adhesive strength between the as-sprayed coating and the substrate; The abrasion failure is mainly related to the microsliding between the contact pair and the remelted coating; The spalling failure is related to the maximum shear stress. The characteristic lifetime of the remelted coating is 19.6 times higher than that of the as-sprayed coating. The shape parameter of the remelted coating is larger than that of the as-sprayed coating, so the lifetime distribution of remelted coating is relatively concentrated and the lifetime prediction is more accurate. Therefore, the GTA process has remarkably improved the rolling/sliding contact fatigue property of the as-sprayed coating.