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 某化工厂锅炉蒸发器吊挂管在运行了5年后突然发生爆裂失效。对该吊挂管进行了化学成分分析、金相检验、扫描电镜、X射线衍射分析及力学性能测定，结果表明：吊挂管爆口附近的碳含量和力学性能均低于相关标准规定值；管外壁脱碳；内部金相组织为过热组织。这些都是由于管内壁沉积有钙盐和硅酸盐类水垢，造成管体超温运行的结果。严重沉积的水垢还导致管内壁高温氢腐蚀，壁厚由原来的6 mm减至2～3 mm，因此发生了失效爆裂。根据分析结果提出了相应的解决方案。

Failure Analysis of Bursted Evaporator Tubes of Boiler

A burst fracture occurred to a hanging tube of boiler evaporator suddenly after 5 years’ operation.Metallurgical testing,chemical analysis,SEM,X-ray diffraction and mechanical properties and other methods were used to analyze the burst hanging tubes of boiler evaporator.The results show that carbon content and mechanical properties were lower than the standard value.Calcium salts and portland scale caused the decarburization of outer surface and overheating microstructure of inner surface.Serious scale also caused high-temperature hydrogen corrosion of the inner surface.The hanging tubes were corroded from 6 mm to 2~3 mm.Therefore,the burst fracture of the hanging tubes of boiler suddenly happened,and a solution is provided.