Effect of Cryogenic Treatment on Inconel 718 Produced by DMLS Technique 2019-28-0140
The main purpose of this study is to investigate additive manufactured Inconel super alloy subjected to cryogenic treatment (CT). Cryogenic treatment is mainly used in aerospace, defense and automobile application. Direct metal laser sintering is an additive manufacturing technique used for manufacturing of complex and complicated functional components. Inconel is an austenitic chromium nickel based super alloy often used in the applications which require high strength & temperature resistant. In this work, a study is carried out on microstructure and mechanical properties of additive manufactured Inconel 718 when subjected to cryogenic treatment at three different time intervals. The micro-structural evolution of IN718 super-alloy before and after CT was investigated by both optic microscope and scanning electron microscope. Surface roughness and hardness at different CT time intervals has also analyzed. Additionally, XRD technique was used to analyze the surface residual stress. The result shows after three cycles of cryogenic treatment, the hardness of Inconel 718 has been substantially improved at room temperature. Microstructure shows grains in one of the test condition, a larger number of refined and uniformly distributed strengthening precipitates which dispersed along the dislocation lines and grain boundaries and 26.9 % increase in macro hardness on surface. Micro hardness has been analyzed and found 30 % increase on surface of material due to effect of hardened matrix formed by precipitation hardening and grain size refinement.