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某热采锅炉投入使用不到一年,其炉管焊接接头就发生失效,通过宏观观察、化学成分和微观组织分析、断口形貌扫描电镜观察以及焊接接头硬度分布测试,对早期失效原因进行了分析。结果表明:接头反面成型出现焊瘤,近缝区出现魏氏体过热组织,裂纹沿熔合区或过热区扩展,打底焊缝和盖面焊缝组织不均匀,打底焊位置接头的硬度分布不均匀性明显高于盖面焊缝。打底焊采用的热输入太大是炉管早期失效的根本原因。
A heat recovery boiler put into use less than a year, the furnace tube welded joints failure, macroscopic observation, chemical composition and microstructure analysis, scanning electron microscopy and weld joint hardness distribution test, the cause of the early failure analysis. The results show that there is a weld on the reverse side of the joint, and the overheated microstructure of the Westem body appears in the near-seam zone. The crack propagates along the fusion zone or overheat zone. The weld seam structure of the bottom weld seam and the overlay seam is not uniform. Unevenness is significantly higher than the cover weld. The heat input used in back-welding is the root cause of early failure of the furnace tube.