The direct comparison of the microstructure and tensile properties of Inconel 718 fabricated by selective laser melting (SLM) or laser metal deposition (LMD) has been carried out. In the as-built state, LMD-fabricated...The direct comparison of the microstructure and tensile properties of Inconel 718 fabricated by selective laser melting (SLM) or laser metal deposition (LMD) has been carried out. In the as-built state, LMD-fabricated specimens show lower tensile yield strength and fracture elongation than SLM-fabricated specimens due to the coarser solidification microstructure, including grains, cellular dendrites and Laves phases. This is mainly because the cooling rate of the LMD process is 2 to 3 orders lower than that of the SLM process. Upon the same heat treatment, both yield strengths of SLMand LMD-fabricated specimens are enhanced significantly. Notably, LMD-fabricated specimens exhibit simultaneous improvement in the strength and ductility, which is mainly attributed to the presence of small granular Laves phases and uniformly distributed nanoscale c00 strengthening phases. The results could serve as a guidance for selecting suitable postheat treatment routes for specific additive manufacturing process to attain excellent strength-ductility synergy.展开更多
基金support by the National Natural Science Foundation of China(U1830i21 and 11988102)National Science and Technology Major Project(2017-VI-0003-0073).
文摘The direct comparison of the microstructure and tensile properties of Inconel 718 fabricated by selective laser melting (SLM) or laser metal deposition (LMD) has been carried out. In the as-built state, LMD-fabricated specimens show lower tensile yield strength and fracture elongation than SLM-fabricated specimens due to the coarser solidification microstructure, including grains, cellular dendrites and Laves phases. This is mainly because the cooling rate of the LMD process is 2 to 3 orders lower than that of the SLM process. Upon the same heat treatment, both yield strengths of SLMand LMD-fabricated specimens are enhanced significantly. Notably, LMD-fabricated specimens exhibit simultaneous improvement in the strength and ductility, which is mainly attributed to the presence of small granular Laves phases and uniformly distributed nanoscale c00 strengthening phases. The results could serve as a guidance for selecting suitable postheat treatment routes for specific additive manufacturing process to attain excellent strength-ductility synergy.
