Selective laser melted 316L stainless steels duplex-treated by shot peening and TiAlCuN coating: Elucidating the enhanced cavitation erosion resistance

To improve the cavitation erosion resistance of additive-manufactured stainless steels, the effects of TiAlCuN hard coating on selective laser melted (SLM) 316L are investigated in this work. The comparative study on as-wrought 316L and SLM 316L also indicates that the surface depressions on additive-manufactured samples can benefit the cavitation erosion resistance due to the inhibited secondary cavitation and accelerated energy dissipation. However, compared to the coated as-wrought 316L, the TiAlCuN coating plays a much less favorable effect on SLM 316L as the surface defects greatly lower the coating quality. Comparing a series of shot peening, TiAlCuN coating and duplex treatment, the duplex-treated SLM 316L shows the best cavitation erosion resistance, characterized by only partial interface delamination and mitigated coating fracture. Such noteworthy promotion profits from the improved coating quality, enhanced load-bearing capacity from the shot-peened subsurface layer, surface hardening and anti-corrosion from the upper TiAlCuN coating. This work provides an effective surface engineering solution for enhancing the cavitation erosion resistance of additive-manufactured metallic parts.