Individual and synergistic effects of thermal and mechanical surface post-treatments on wear and corrosion behavior of laser powder bed fusion AlSi10Mg

Materials fabricated by laser powder bed fusion (LPBF) are generally characterized with internal defects, inhomogeneous microstructure and rough surface with multiple forms of irregularities in their as-built state. Post-treatments are needed to resolve the issues associated with these imperfections. In this study, the individual and synergistic effects of different post-treatments including heat treatment, shot peening and ultrasonic nanocrystalline surface modification on microstructure, surface morphology, roughness, mechanical, corrosion and tribological properties of LPBF AlSi10Mg specimens have been investigated. Two different sets of parameters were considered for the surface treatments, both with mechanical energy source. Apart from surface characteristics, various properties including microhardness and residual stresses as well as wear and corrosion behavior of post-processed specimens were analyzed and compared with those of the as-built condition. The results indicated that hybrid post-treatments have the highest positive effects on wear and corrosion resistance as their kinetic energy affected multiple physical aspects; these include the microstructure leading to surface grain refinement paired with deep compressive residual stress field and improved surface morphology offering a more regular surface.