Anisotropic tensile behavior and fracture characteristics of an additively manufactured nickel alloy without and with a heat treatment of solution aging

Additive manufacturing (AM) or 3D printing is a promising technology that can easily produce parts or components with complex configuration. IN718 or GH4169 is selected as experimental object, which is an age-hardenable Ni-based (Ni-Cr-Fe) superalloy suitable for AM and can have good plasticity in its as-printed state. Although the strength of as-printed material can be increased by solution aging treatment, the plasticity will be significantly reduced at the same time. Here, we designed, fabricated, heat-treated and machined the specimens, performed a quasi-static tension and a post-mortem analysis for the nickel alloy without and with a solution aging. As-printed and heat-treated specimens show anisotropic tensile behavior on horizontal and vertical orientations. For as-printed specimens, tensile plasticity can be slightly improved with increasing orientation, and the failure type will transit from 45° shearing of Mode-II/III to Mode-I in the core region of fracture surfaces. Due to inter/intra-granular precipitation of solution aging, heat-treated horizontal specimen will change fracture mode to coordinate tensile deformation, making a better ductility for the high-strength nickel alloy of AM.