Microstructural features and corrosion behavior of Fe-based coatings prepared by an integrated process of extreme high-speed laser additive manufacturing

A kind of integrated process of extreme high-speed laser cladding (EHLC) and laser remelting (LR) was firstly proposed to comprehensively improve surface quality and internal interlayer bonding strength of pure EHLCed coatings. The influence mechanism of integrated process on microstructure and corrosion resistance was carefully studied. The integrated process effectively optimized the surface roughness (reduced >60%), and eliminated interlayer defects, especially for the multi-layer coating. Results indicated that both of the coatings manufactured by EHLC and EHLC-LR comprised dominant ultrafine grains. However, electrochemical measurements showed that the EHLC-LRed coating possessed better corrosion resistance and lower corrosion rate compared to EHLCed counterpart. It was proposed that this behavior was due to a high density of ultra-fine grains with numerous grain boundaries uniformly distributed on the coating surface forming a more stable oxide film.