Effect of Heat Treatment on Microstructure and Mechanical Properties of Inconel 718 Alloy Fabricated by Selective Laser Melting

作者：Zhang Rong; Liu Zhongqiang; Huang Jiahao; Zhu Quanli; Xiao Zhiyu^*

来源：RARE METAL MATERIALS AND ENGINEERING, 2021, 50(1): 255-262.

• Inconel 718 alloy
• selective laser melting
• heat treatment
• microstructure
• mechanical properties

The effect of three different heat treatments, solution-aging (SA), homogenization+solution-aging (H+SA), and hot isostatic pressing+solution-aging (HIP + SA), on the microstructure and mechanical properties of selective laser melting (SLM) formed Inconel 718 alloy. The as-built Inconel 718 has a large number of dendritic structures, and there are many brittle laves phases precipitating among the interdendritic region. The 6 phase is prone to precipitate when the alloy is treated by proper homogenization, but the material can not be strengthened without gamma '' and gamma' phases. Hot isostatic pressing (1080 degrees C, 148 MPa, 2 h) can considerably remove laves phases and micro pores of the as-fabricated samples, and combine with the solution aging treatment subsequently. It's conductive to refine the grain size of the as-built samples, flat the grain boundaries, and promote the precipitation of gamma '' and gamma' phases, so HIP+SA treatment significantly increases the strength of Inconel 718 alloy. The mechanical properties of Inconel 718 alloy reach the optimum combination at UTS=1361 MPa, 0.2% YS=1191 MPa, and HV0.2=4900 MPa, and the elongation after breaking is 13.30%.