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对长时高温服役状态下发生开裂的T91/Inconel601异种钢焊接接头进行了组织结构表征和失效原因分析。结果表明,焊接接头的开裂性质为蠕变损伤造成的脆性开裂。焊接接头较高应力水平是构成开裂的力学因素,而熔合线靠近T91钢一侧碳化物富集带的产生是开裂的冶金因素。碳活度差异驱动的碳元素迁移和镍基焊缝中较低的碳原子扩散速度的综合作用造成熔合线附近T91钢侧碳化物富集析出。
T91 / Inconel601 dissimilar steel welded joints cracking under long-term high temperature service were characterized by microstructure and failure analysis. The results show that the cracking property of welded joint is brittle cracking caused by creep damage. The higher stress level of welded joint is the mechanical factor of cracking, and the generation of carbide-rich zone near the weld line near T91 is the metallurgical factor of cracking. The combined action of carbon migration driven by carbon activity difference and diffusion of lower carbon atoms in the Ni-based weld resulted in the enrichment and precipitation of carbides in the T91 steel near the weld line.