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 SLM- and 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 γ″ strengthening phases. The results could serve as a guidance for selecting suitable post-heat treatment routes for specific additive manufacturing process to attain excellent strength–ductility synergy.

已经对通过选择性激光熔化 (SLM) 或激光金属沉积 (LMD) 制造的 Inconel 718 的微观结构和拉伸性能进行了直接比较。在竣工状态下，LMD 制造的试样显示出比 SLM 制造的试样更低的拉伸屈服强度和断裂伸长率，这是由于较粗的凝固微观结构，包括晶粒、蜂窝状枝晶和 Laves 相。这主要是因为LMD工艺的冷却速度比SLM工艺低2到3个数量级。在相同的热处理下，SLM 和 LMD 制造的试样的屈服强度都显着提高。值得注意的是，LMD 制造的试样在强度和延展性方面同时表现出改善，这主要归因于小颗粒 Laves 相和均匀分布的纳米级 γ” 强化相的存在。该结果可以作为为特定增材制造工艺选择合适的后热处理路线以获得优异的强度-延展性协同作用的指导。