Surface modification of 304 stainless steel by ultrasonic strengthening grind process with Al2O3-MoS2-WC hybrid ceramic particles for wear resistance enhancement

Abstract

In this study, Al₂O₃ and self-lubricating MoS₂ powders were incorporated into WC balls to impact the 304 stainless steels through ultrasonic strengthening grind process (USGP). By subjecting the steel to controlled USGP treatment, remarkable enhancements in surface properties were achieved, as evidenced by comprehensive microstructural and mechanical analyses. Key findings revealed that the 12-min USGP-treated sample exhibits exceptional wear resistance, with a dramatic 83.1 % reduction in wear volume (1.24 × 10⁶ μm³ under 10 N load) compared to untreated specimens. This outstanding performance is partially attributed to the formation of a micro-textured MoS₂ + Al₂O₃ coating, where MoS₂ provides superior self-lubrication while Al₂O₃ enhances surface hardness. Moreover, significant Grain refinement, high-density dislocations, and stacking faults were induced by severe plastic deformation. Furthermore, the emergence of dispersion-strengthened granular martensite and a stress-driven FCC-to-BCC phase transformation, further reinforcing the material's wear resistance. The multi-scale structural evolution (nano-to-micro) and self-lubricating/hardening synergy establish USGP as a promising approach for extreme-wear applications.