K4169高温合金铸件铸造缺陷修复及疲劳性能研究

TIG welding method was used to repair the defects of the cast structure in the K4169 superalloy plates, and the fatigue performance test and microstructure analysis of the alloy plates before and after repair were performed. The results show that casting defects have a great in-fluence on the fatigue performance of alloy plates. The fatigue life of alloy plate with casting defects is less than 30 000 cycles, while the fatigue life of alloy plate without free casting defects reaches 71 000 cycles. After TIG welding repair of the defective specimens, the fatigue life of the specimen reaches 60 000 to 90 000 cycles, which is close to or even exceeding the fatigue life of the samples without defects. This shows that suitable welding repair method will not reduce the fatigue performance of K4169 superalloy. The reason for the high fatigue life of castings after welding repair is that the number of coarser phases precipitated in the weld is large and evenly distributed, and more secondary cracks are gene-rated during the fatigue crack propagation process, which leads to crack offset and growth path growth.