Inconel 718 alloy was fabricated by selective laser melting (SLM) and treated with different solutions and two-stage aging heat treatments (H1-H4). The microstructure evolution of the alloy under four different heat treatments was analyzed, and the influence of the size and quantity of precipitates on the mechanical properties of the alloy under different aging mechanisms was explored. The results showed that after solution treatment at 1020 °C, the structural segregation at the boundaries of columnar and equiaxed crystals disappeared, the Nb-rich Laves phase and carbides were dissolved into the matrix. After aging treatment, γ′ and γ″ strengthening phases were precipitated in the matrix, and the fine needle-like γ″ phase was uniformly distributed, which played the role of dispersion strengthening and significantly improved the strength of the alloy. Under the double aging system of 720 °C + 620 °C (H4), the average size of precipitates was 26.47 nm, and the properties of the alloy tend to be isotropic. After H4 heat-treated, the σ_UTS and σ_0.2 of the sample reached 1520 MPa and 1272 MPa, respectively. There was no obvious fracture and spalling on the worn surface of the alloy, thus it showed good friction and wear resistance. At the same time, it was proved that the temperature change at the first stage of double aging had a greater influence on the precipitation of the strengthening phase than that at the second stage.

Inconel 718 合金采用选择性激光熔化 (SLM) 制造，并经过不同溶液和两阶段时效热处理 (H1-H4) 处理。分析了合金在四种不同热处理条件下的显微组织演变，探讨了不同时效机制下析出物的大小和数量对合金力学性能的影响。结果表明，1020℃固溶处理后，柱状晶和等轴晶边界处的结构偏析消失，富Nb的Laves相和碳化物溶解到基体中。时效处理后，γ '和γ “强化相在基体中析出，微细针状γ″相分布均匀，起到弥散强化作用，显着提高合金的强度。在720℃+620℃（H4）双时效体系下，析出物平均尺寸为26.47 nm，合金性能趋于各向同性。H4热处理后，试样的σ _UTS和σ _0.2分别达到1520 MPa和1272 MPa。合金磨损表面无明显断裂和剥落现象，表现出良好的摩擦磨损性能。同时证明双时效第一阶段温度变化对强化相析出的影响大于第二阶段。