摘要
对断裂后的换热管进行失效分析,研究了换热管的显微硬度,对其元素组成及含量进行了测定。并采用金相显微镜分析显微组织,采用SEM观察断面形貌。最后对腐蚀产物的化学成分进行了分析。结果表明,换热管的显微硬度相对其固溶态较高,焊缝组织和熔合线组织均为"奥氏体+铁素体",基体组织为"孪晶奥氏体+少量形变马氏体";Ni元素含量低于标准规定值,宏观及微观形貌具有应力腐蚀特征,腐蚀产物中氯离子含量高达0.88%;换热管的失效属氯离子致应力腐蚀开裂。
The failure analysis of ruptured heat exchange tube was studied. The hardness of the tube was studied. The composition and content of elements were determined.The microstructure was analyzed by metalloscope.The fracture morphology was observed by SEM. The chemical composition of corrosion products was studied. The results indicate that the microhardness of heat exchange tube is higher than that of the tube by solution treatment. The microstructure of weld seam and fusion zone is both austenite and ferrite. The microstructure of matrix is twin austenite and less strain-induced martensite. Nickel element content is lower than standard value.The macro morphology and micro-morphology present the feature of stress corrosion. The chloride content in corrosion products is up to 0.88%. The reason for the failure of heat exchange tube is stress corrosion crack induced by chloride.
出处
《热加工工艺》
CSCD
北大核心
2017年第18期256-258,263,共4页
Hot Working Technology
关键词
换热器管
显微硬度
显微组织
应力腐蚀
heat exchange tube
microhardness
microstructure
stress corrosion
