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采用钨极氩弧焊接工艺对镍基变形高温合金GH625进行焊接。系统研究焊接接头的显微组织、元素分布、晶界特征和力学性能。结果表明:焊缝组织为奥氏体树枝晶结构,未见明显的热影响区,焊接熔合区的枝晶间区域均匀分布着大量的δ相。与母材相比,焊接熔合区同时具备较高的硬度和较大的晶粒,这可能与焊接熔合区的δ析出相有关。母材较高的强度主要归因于较多的细小晶粒和孪晶界,而焊接接头较低的伸长率可能是由于δ相。
The TIG welding process was used to weld the GH625 Ni-based superalloy. The microstructure, elemental distribution, grain boundary characteristics and mechanical properties of welded joints were studied systematically. The results show that the microstructure of the weld is austenite dendrite structure, and no obvious heat affected zone is observed. A large number of δ phases are uniformly distributed in the interdendritic region of the weld zone. Compared with the base metal, the weld zone has both higher hardness and larger grains, which may be related to the δ-precipitation phase in the weld zone. The higher strength of the base metal is mainly due to more fine grains and twin boundaries, while the lower elongation of the welded joints may be due to the δ phase.