Microstructural analysis and characterization of nickel deposition on 316H stainless steel via gas tungsten arc welding and powder laser cladding

Molten salt reactors operate under high-temperature molten salt environments, rendering the use of materials used in traditional pressurized water reactors unsuitable. Therefore, nickel cladding, characterized by excellent corrosion resistance, has been applied to molten salt reactor systems. In this study, the microstructural characteristics and mechanical properties of nickel cladding fabricated using gas tungsten arc welding (GTAW) and powder laser cladding (PLC) were examined. The GTAW process yielded a cladding with excellent mechanical performance and no internal defects. However, extensive intergranular corrosion was observed after a 100-h immersion test, attributable to the presence of high-energy grain boundaries. Conversely, the PLC specimen exhibited cracks and porosity. However, the presence of low-energy grain boundaries contributed to uniform corrosion behavior and enhanced corrosion resistance. These findings underscore the complementary advantages and limitations of both techniques, highlighting the necessity for further optimization to ensure reliable performance in high-temperature reactor environments.