The pitting corrosion and wear performance of additively manufactured WC/W2C reinforced stainless steel in chloride-containing solution with different pH values

One approach to enhance the surface degradation characteristics of laser powder bed fusion (LPBF) type 420 stainless steel involves the incorporation of spherical cast WC/W2C to create LPBF metal matrix composites (MMCs). However, the corrosion behaviour of stainless steel and cast WC/W2C varies inversely with different pH levels, and the phenomenon of pitting corrosion in LPBF MMCs across varying pH conditions has yet to be thoroughly investigated. In LPBF 420 + 5 wt% WC/W2C MMCs, pit occurs adjacent to cast WC/W2C in both acidic and neutral environments, attributed to the presence of chromium-rich carbides and galvanic coupling effects. The dissolution of the reinforced particles facilitates pit nucleation in alkaline conditions. Notably, in-situ reaction layers exhibit superior corrosion resistance compared to the matrix or the reinforced particles across all pH levels. The distinct corrosion mechanisms influence the pitting corrosion behaviour, with the corrosion ranking based on critical pitting potential being neutral > alkaline > acidic, which contrasts with the observed kinetics of pit growth (alkaline > acidic > neutral).