长时高温服役T91/Inconel601异种钢焊接接头失效分析

Failure analysis of T91/Inconel601 dissimilar metal welded joint under long-time and high-temperature service

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 metal weld joint which cracked during long-time and high-temperature service was characterized in terms of mierostructure and the reason of failure was also analyzed. The results show that weld joint fails in the mode of brittle cracking caused by creep damage. Relatively high stress level of weld joint is the mechanical factor of cracking, and the presence of carbide-rich zone formed along the fusing line near T91 steel is the metallurgical factor. Due to synergetic effect of carbon diffusion driven by difference of carbon activity and relatively lower carbon atom diffusion speed in the nickel-based weld metal, carbide enriched and precipitated in the zone of T91 steel near the fusing line.