为评价选区激光熔化成形GH3536航空发动机零件的高温服役性能,采用既定工艺制备了拉伸试棒,并对其进行了去应力退火和热等静压(HT+HIP)处理,然后测试了其在20~815 ℃的拉伸性能,并分析了合金的显微组织、断口形貌和断裂机制。结果表明:HT+HIP处理后,晶界析出(Cr,Mo)23C6,晶粒发生部分等轴化转变,但仍保留了定向凝固特性,垂直于成形方向的截面组织中的晶粒更细、晶界更多,沿晶界析出的链状碳化物使得晶界弱化,断裂机制以沿晶断裂为主;晶粒尺寸的各向异性是不同成形方向试棒力学性能和断口形貌存在差异的主要原因;随着测试温度升高,抗拉强度下降,延伸率先升后降;断裂机制随温度升高发生转变,高温下的沿晶断裂机制比室温下的更明显,塑性变形程度更小,裂纹更长。

To evaluate the elevated-temperature service performance of aero-engine components of GH3536 alloy formed via selective laser melting (SLM), tensile specimens were manufactured via SLM with optimized parameters and were treated using stress relieving and hot isostatic pressuring (HT+HIP). The tensile properties of the specimens were tested at 20--815 ℃ and the microstructures, fracture morphology, and fracture mechanism were analyzed. The results show that after HT+HIP treatment, (Cr,Mo)23C6 precipitates at the grain boundaries, a columnar-to-equiaxed transition partially occurs, however, the directional solidification characteristic is still present. There are finer grains and more grain boundaries on the transverse section. Fracture analysis shows chains of precipitated carbides along the grain boundaries weaken the grain boundaries; in addition, intergranular fracture was observed. Owing to the anisotropy of the grain size, the mechanical properties and fracture morphologies vary with the specimen building direction. As the temperature increases, the tensile strength decreases and the elongation first increases and then decreases. The tensile failure mechanism changes as the temperature increases; this is characterized by stronger trend of intergranular fracture, smaller plastic deformation, and longer cracks at elevated temperature.