High‐Temperature Mechanical Behavior Assessment based on a Developed Constitutive Model of Inconel 718 Fabricated by Selective Laser Melting

Abstract

Inconel 718, a typical nickel‐based superalloy, is widely used to fabricate high‐temperature components in aerospace and power industries. Conventional “subtractive” processes confront numerous problems due to the complicated structures. The application of selective laser melting (SLM), as one of the additive manufacturing (AM) techniques, is promising in part fabrication and repairment in the aerospace industry. Tensile tests with different strain rates and strain‐controlled cycling tests with different strain amplitudes are conducted in this study at a high temperature of 600 °C to assess the mechanical behavior of SLM‐built Inconel 718 and reinforce its application. Experimental data reveal that a relatively concise constitutive model incorporating damage is proposed on the basis of Chaboche's framework. Modifications to isotropic hardening and damage evolution rules are performed to embed lifetime prediction capacity. Simulated results achieve a good agreement with the experimental results. Microstructures of fatigue fracture surface are analyzed to further understand the fracture mechanism. The results show that both intergranular and intragranular fracture modes and the dimples signify ductility. Overall, this study presents significant techno‐economic implications in assessing the competence of SLM‐built Inconel 718 components used in real serving conditions and also provides a reference to improve the SLM preparation process.