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研究了钨极氩弧焊GH625高温合金焊接接头的室温疲劳裂纹扩展行为。采用金相显微镜及扫描电镜对其焊接接头的显微组织和疲劳裂纹扩展断口形貌进行观察。结果表明,GH625高温合金的钨极氩弧焊焊接接头主要是由枝晶状焊缝组织和γ奥氏体等轴晶母材组成,焊缝区析出大量的白色针状δ-Ni3Nb相和块状颗粒状Laves相;其焊接接头的显微硬度高于母材;室温下,在低ΔK区间,GH625高温合金钨极氩弧焊焊接接头的疲劳裂纹扩展速率比母材低,这是由于焊缝处硬质的析出相、二次裂纹以及扩展路径的曲折多样使得其裂纹扩展时需要消耗更多的能量;在高ΔK区间内,焊接接头疲劳裂纹扩展速率高于母材。
The fatigue crack propagation behavior at room temperature of the GTAW GH625 superalloy welded joints was studied. The microstructure and fatigue crack propagation morphology of welded joints were observed by optical microscopy and scanning electron microscopy. The results show that the GTAW joints of GH625 superalloy mainly consist of dendritic weld and γ austenite equiaxed base metal. A large amount of white acicular δ-Ni3Nb phase and massive Granular Laves phase; the microhardness of the welded joint is higher than that of the base metal; the fatigue crack growth rate of GHG25TGT welded joint at room temperature is lower than that of the base metal in the low ΔK interval, At the high ΔK interval, the fatigue crack growth rate of welded joints is higher than that of the base metal.