Effect of beam diameter on microstructure evolution and corrosion resistance of laser-cladded high-chromium nickel based alloy coatings

Laser cladding has been widely employed for surface modification and repair of structural components exposed to corrosive environments. In this study, high-chromium nickel-based alloy coatings were fabricated using three coupled, beam-diameter-dependent parameter sets. Laser power and powder feed rate were increased proportionally with beam diameter, while the scanning speed was kept constant, to maintain comparable laser specific energy and powder deposition density. Mechanical testing revealed that decreasing beam diameter led to increased hardness and wear resistance, which were attributed to finer microstructures and improved metallurgical bonding. Electrochemical measurements in 3.5% NaCl solution demonstrated that the corrosion resistance of the coatings was significantly enhanced as the beam diameter decreased. Moreover, molecular dynamics simulations were performed to elucidate the mechanisms at the atomic scale, revealing the correlation between microstructural evolution and corrosion resistance. Coatings prepared with larger beam diameters exhibited higher efficiency, while those fabricated with smaller beams offered superior corrosion protection. These findings provide both experimental and theoretical insights for optimizing laser beam design in the fabrication of high-performance corrosion-resistant coatings.