Microstructures and mechanical properties of crack-free 316L stainless steel and Inconel 625 joint by using Laser Engineered Net Shaping

• SS316L/IN625 gradient joint without crack was fabricated using LENS. • The effect of gradient design on the microstructures and grain growth at interfaces of gradient zone was investigated. • The elemental ratios of SS316L/IN625 joint gradually changed with the height of the deposited layer. • The yield strength and tensile strength of the SS316L/IN625 joint were 486 MPa and 672 MPa, respectively. • The fracture mechanism of SS316L/IN625 joint was ductile fracture. The additively manufactured (AM) joint of 316L stainless steel (SS316L) and Inconel 625 (IN625) with flexible structural adjustability and good joint strength are pivotal components for aerospace and shipbuilding fields. As a promising metal additive manufacturing technology, Laser Engineered Net Shaping (LENS) technology brings possibilities for the combination of dissimilar metals. In this study, a gradient SS316L/IN625 joint with a composition ranging from 100% SS316L to 100% IN625 alloy was successfully prepared using LENS. The compositions, microstructures of each layer, and the interfaces between every two layers of the SS316L/IN625 joint were investigated. The results showed that the microstructure and elements were uniformly distributed along the deposition direction. No second phase or crack was detected in each layer or interface was observed in the SS316L/IN625 joint. The microhardness increased from 198 to 265 HV with increasing the content of IN625. The SS316L/IN625 joint showed a tensile strength of 672 MPa and a yield strength of 486 MPa.