Enhancing the corrosion-wear resistance of HVOF-sprayed Inconel 625 coatings via micro-shot peening

Abstract

This study investigates the effects of micro-shot peening (MSP) on the corrosion-wear performance of Inconel 625 coatings deposited by high-velocity oxy-fuel (HVOF) spraying process. MSP was applied under different pressures (2-4 atm) and durations (30-90 s), and the coatings were subsequently evaluated using a ball-on-disk configuration in 5 wt% NaCl solution. Results show that MSP introduced additional compressive residual stress and induced strain hardening in the near-surface region, leading to the formation of a hardened and nanocrystalline surface layer. These microstructural modifications significantly enhanced resistance to shear stress and reduced the coefficient of friction during corrosion-wear, while only slightly increasing surface roughness (Sa < 3 mu m). With increasing MSP intensity, residual stress, surface hardness, and thickness of the nanocrystalline layer increased, resulting in further improvement of corrosion-wear resistance. Under chloride-containing conditions, the beneficial effect of MSP was dominated by the enhancement of wear resistance rather than a marked change in corrosion behavior. Overall, MSP is demonstrated to be a controllable and practical post-treatment method for extending the service life of HVOF-sprayed Inconel 625 coatings in aggressive environments.