Impact Damage FE Simulation of HVAF-Sprayed Monolayer and Al2O3 Reinforced Stainless Steel Coatings and Experimental Validation

Understanding the microscopic damage process of Al₂O₃ particle-reinforced stainless steel composite coatings under impact loading is vital for the design of impact-resistant coatings, but also complex and challenging due to their inferior toughness. In this work, the stress/strain fields and coating cracks of HVAF-sprayed monolayer and Al₂O₃ particle (two different sizes)-reinforced stainless steel composite coatings under falling ball impact were analyzed by means of finite element simulation and experimental verification. The results showed that three types of cracks, including circular cracks, cone cracks and radial cracks, were generated in the coating during impact, which were mainly induced by the tensile stress at the edge of the impact crater, the shear stress inside the coating, and the equivalent plastic strain on the interface of the coating/substrate, respectively. Compared to the monolayer coating, the stress concentration of the composite coating under impact was dispersed by the Al₂O₃ particles (mainly around the particles). The crack propagation was hampered and deflected by the interface between the particles and the matrix, and the particle fracture would dissipate the impact energy. It was also found that the stress amplitude around the larger Al₂O₃ particles was smaller and the probability of crack initiation was lower, resulting in better impact resistance of this coating. The comparison of the simulation results with the impact experimental results verified that the impact damage of the coating could be effectively predicted by finite element simulation.