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| Study on Microstructure and Properties of Inconel 718 Fabricated by Selective Laser Melting/Hot Isostatic Pressing Hybrid Forming Process |
| TENG Qing, SUN Shanshan, XUE Pengju, SHI Yusheng, WEI Qingsong |
| (State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China) |
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Abstract Hot isostatic pressing (HIP) technology can be used to fabricate complex parts with high-performance, however, there are some problems with this technology, such as the difficulty of manufacturing capsule for complex parts and the interface diffusion between heterogeneous capsule and powder, which will harm the performance. For this reason, a study on the selective laser melting (SLM)/HIP hybrid forming process was investigated. XRD, SEM, EBSD and tensile test were used to characterize the matrix / interface microstructure and tensile properties of the hybrid forming process. The results show that there are obvious pores and micro cracks in the matrix of Inconel 718 alloy directly formed by SLM, and the density is 98.3%. After HIP process, the Inconel 718 alloy matrix does not have obvious pores and cracks, but there is obvious prior particle boundary (PPB). Under the hybrid process conditions, the pores and cracks of the Inconel 718 formed by SLM are reduced, the characteristics of the melting track on the X–Y surface disappear, and the degree of anisotropy is reduced. After HIP, there is no obvious diffusion layer between the powder particle and the SLM-formed Inconel 718, and the interface is composed of fine grains with a thickness of about 16.7μm. The 650℃ high temperature strength of the interface is 626MPa. The tensile fracture surface is flat along the SLM and HIP state bonding interface. After solid solution + aging heat treatment, the interface bonding strength is increased to 990MPa, and the fracture is distributed in the SLM forming part. By analyzing the evolution of microstructure and properties, the feasibility of using the hybrid forming process to prepare complex parts is verified.
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2020, 
