Study on Porosity Defects and Corrosion Resistance of Laser Cladding Hastelloy C276 on Nodular Cast Iron

In order to replace the expensive and difficult-to-process overall nickel-based alloy materials used in corrosive working environments, Hastelloy C276 alloy coating on ball-milled cast iron QT500-7 substrate was prepared by using laser cladding technology.The effects of laser power and scanning speed on the porosity and dilution rate of the coating were studied.The structure, hardness and corrosion resistance of the coating were studied by OM, SEM and microhardness tester and electrochemical workstation.The results show that under the selected process parameters, both the coating and the substrate can form a good metallurgical bond without cracks.As the laser power increases or the laser scanning speed increases, the coating dilution rate and porosity both tend to increase.The coating structure is dominated by dendrites, and the phase is mainly composed of γ-Ni solid solution and carbides M₂₃C₆, M₃C₇, and Ni₆Mo₆C.The average hardness of the coating is 379.38HV, which is 1.98 times than that of the substrate.In 3.5wt%NaCl solution, Hastelloy C276 alloy coating has a higher self-corrosion potential than ductile iron and a lower self-corrosion current density than ductile iron.The lower the heat input process parameters, the better the corrosion resistance of the coating.