激光快速成形GH4169合金显微组织与力学性能

Microstructure and Mechanical Properties of Laser Melting Deposited GH4169 Superalloy

利用GH4169合金粉末进行激光快速成形实验,制备出GH4169合金块状试样,并进行固溶时效热处理。利用扫描电镜(SEM)及能谱分析(EDS)等方法分别对激光成形沉积态及固溶时效态试样进行显微组织及元素偏析分析,并测试显微硬度、室温及高温拉伸性能。结果表明:沉积态微观组织为生长方向不一的细长柱状树枝晶,组织细小致密;经过固溶时效热处理后晶粒得到细化,晶粒内部仍保留枝晶亚结构;固溶时效态试样较沉积态显微硬度及抗拉强度大幅提高,塑性有所下降,但整体优于锻件技术标准。断口形貌表现为韧性穿晶断裂方式。

The block samples of a Ni-based superalloy named GH4169 were prepared by laser melting deposited method using the corresponding GH4169 alloy powders, and then were heat treated with so-lution treatment followed by double aging. The microstructure and element segregation analysis of both as-deposited and heat treated samples were studied by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. The microhardness as well as tensile properties at room and el-evated temperatures were tested. The results indicate that the microstructure of as-deposited sample mainly consists of columnar dendritic crystals that grow along with different directions. Grains are re-fined after solution and aging heat treatment, but remain dendritic crystals substructure inside. Com-pared with the as-deposited sample, the microhardness and tensile strength of the heat treated sample increase substantially, but the plasticity somewhat decreases. Nonetheless the tensile properties are superior to the standard values of forgings. The fracture surface exhibits ductile transcrystalline frac-ture mode.