Comparative study of Ni-, Co- and Fe-based laser cladding coatings for wear and corrosion resistance

Comparative study of Ni-, Co- and Fe-based laser cladding coatings for wear and corrosion resistance Among hardfacing processes using welding, laser cladding is nowadays one the most efficient surface coating techniques used to increase wear and corrosion resistance of machine parts as a result of the process unique characteristics such as low heat input (smaller HAZ), distortion free clad layers, lower dilution rate, finer coating microstructure as well as good metallurgical bonding at the coating/substrate interface. A wide range of new hardfacing materials and corrosion-resistant alloys are available on the market and in this study, different coatings of Ni-, Co- and Fe-based alloys as well as carbide-based metal matrix composites have been deposited by laser cladding for benchmarking purposes. Coatings were deposited onto mild steel substrates using a 2.2 kW high-power diode laser. Coating microstructure and hardness were investigated as well as their tribological properties such as 2-body abrasion (JIS H 8306), 3-body abrasion (ASTM G65), slurry abrasion (ASTM G75) and cavitation erosion (ASTM G32) resistance. Corrosion performance of coatings was also investigated with the salt spray test (ASTM B117). Coatings are ranked according to their performance in the different tests and relationships between microstructure and coating properties are discussed.