不锈钢换热器不等间隙钎焊接头失效分析

发布时间：2018-03-04 19:56

本文选题：不锈钢换热器　切入点：钎焊　出处：《材料热处理学报》2017年01期 　论文类型：期刊论文

【摘要】：从整车试验中发生内漏的304不锈钢换热器失效问题入手,采用宏观检查、金相检验、能谱分析和有限元仿真模拟方法,从组织形貌、合金元素扩散、应力集中等角度分析了不锈钢换热器钎焊接头的失效原因,讨论了不等间隙接头的形成原因及对接头应力集中情况的影响。结果表明:换热器失效原因为产品凸台处钎焊接头发生疲劳断裂,裂纹在钎缝圆角处萌生,并在剪应力作用下扩展至钎缝下侧界面,随后沿强度相对较低的钎焊界面进一步扩展。钎焊过程中接头成形较好,无明显焊接缺陷。但由于焊前装配误差造成凸台位置接头钎焊间隙不等,工况下局部位置的应力集中使得接头服役寿命有所降低。
[Abstract]:Starting with the failure problem of 304 stainless steel heat exchanger with internal leakage in the whole vehicle test, macroscopical inspection, metallographic examination, energy spectrum analysis and finite element simulation were used to analyze the microstructure and diffusion of alloy elements. The failure reasons of brazed joints in stainless steel heat exchangers are analyzed from the angle of stress concentration. The forming reason of unequal gap joint and its influence on the stress concentration of joint are discussed. The results show that the failure reason of heat exchanger is fatigue fracture of brazed joint at the crown of the product and crack initiation at the corner of brazing seam. The joint is expanded to the lower side of the brazing seam under shear stress and further along the brazed interface with relatively low strength. The joint is well formed during the brazing process. There is no obvious welding defect, but the gap of brazing joint is different due to the assembly error before welding, and the service life of the joint is reduced by the stress concentration of the local position under the working condition.
【作者单位】：南昌航空大学航空制造工程学院;哈尔滨工业大学先进焊接与连接国家重点实验室;浙江银轮机械股份有限公司;
【基金】：国家自然科学基金(51365044) 江西省研究生创新基金(YC2015-S318) 郑州机械研究所新型钎焊材料与技术国家重点实验室开放基金(SKLABFMT201404)
【分类号】：TK172;TG454

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