The anisotropic of stress rupture properties of additive manufacturing superalloys at high temperatures affect their further applications in the aerospace field. In this study, selective laser melting (SLM) was used to prepare Inconel 718 blocks with axial direction normal or parallel to the building direction. The microstructure of different specimens was designed by process parameter control and post-processing. Tensile properties of horizontal and vertical specimens were tested at room temperature, and the stress rupture tests were performed at 650 °C under 690 MPa. The relationship between different microstructure and the anisotropy of stress rupture properties was studied. It is found that the grain morphology, grain boundary state and the morphology and location of precipitated phase have strong influence on the anisotropy. After the newly designed post-treatment including HIP + solution + aging, the normal temperature tensile property of vertical and horizontal specimens are maintained at a high level, besides the stress rupture life of vertical and horizontal specimens has the average time reach 173 and 131 hours at high temperature, respectively. This provides a basis for how to reduce the anisotropic stress rupture properties of SLM Inconel 718, which will have a positive impact on its wider application in engineering.

增材制造高温合金的应力断裂性能各向异性影响了它们在航空航天领域的进一步应用。本研究采用选择性激光熔化 (SLM) 方法制备轴向垂直或平行于建筑方向的 Inconel 718 块体。通过工艺参数控制和后处理设计不同试样的显微组织。水平和垂直试样的拉伸性能在室温下进行测试，应力断裂试验在 650 ℃和 690 MPa 下进行。研究了不同显微组织与应力断裂特性各向异性的关系。发现晶粒形貌、晶界状态以及析出相的形貌和位置对各向异性有很大的影响。经过全新设计的HIP+固溶+时效后处理，垂直和水平试样的常温拉伸性能保持在较高水平，垂直和水平试样的应力断裂寿命平均达到173和131小时在高温下，分别。这为如何降低SLM Inconel 718的各向异性应力断裂特性提供了依据，这将对其在工程中更广泛的应用产生积极影响。