en.Wedoany.com Reported - A research team at the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI) in Hyderabad, India, has fabricated a crack-free bimetallic structure by joining stainless steel with a nickel-based superalloy using laser powder bed fusion (PBF-LB/M) additive manufacturing technology.
The team directly deposited SS316L stainless steel onto a ground Inconel 718 (IN718) substrate, with no visible cracks or porosity at the interface. Microhardness testing revealed a peak hardness of approximately 310 HV at the interface, while tensile testing yielded an ultimate tensile strength of 550 ± 30 MPa. Fracture occurred on the stainless steel side, which has weaker mechanical properties, rather than at the bonding interface, indicating a strong interfacial bond.
According to the Department of Science and Technology (DST), India, this research integrates the toughness and corrosion resistance of stainless steel with the high-temperature strength and creep resistance of nickel-based superalloys into a single component, addressing a long-standing manufacturing challenge in the field. For example, different regions within a single gas turbine component may be exposed to temperatures approaching 2000 degrees Celsius, alongside much cooler sections. When using conventional welding processes to join SS316L and IN718, solidification cracks, porosity, and brittle phases tend to form at the joint due to mismatches in chemical composition, melting point, and thermal expansion coefficient between the materials.
The DST reports that this additive manufacturing process allows expensive superalloys to be precisely applied to areas subjected to the highest thermal loads, thereby reducing the total amount of superalloy used in components and decreasing reliance on imported materials. This achievement can be applied to fields such as boiler tubes, heat exchangers (suitable for nuclear power plants and ultra-supercritical coal-fired power plants), other energy systems, nuclear reactors, and oil and gas processing equipment, all of which demand high corrosion resistance and high-temperature strength. In the aerospace sector, bimetallic components can combine steel load-bearing structures with heat-resistant Inconel alloy sides, with additive manufacturing enabling the superalloy to function only in areas of the component subjected to extreme thermal exposure. The related research findings have been published in the journal Progress in Additive Manufacturing.
