摘要
针对翅片管式结构的304不锈钢换热器在服役过程中出现因管壁钎焊接头处开裂导致水泄漏失效的现象,对开裂部位进行取样与深入分析,探明镍基钎料钎焊304不锈钢换热管钎焊接头的失效机理。结合渗透检测、金相分析及SEM观察,揭示了脆性磷化合物的非均匀分布降低了局部韧性。在应力作用下,焊缝沿晶断裂并产生微裂纹。这些微裂纹作为裂纹源,萌生裂纹并扩展,进而发生韧性断裂。在钎料中添加少量Cu元素可促进焊缝中韧性镍基固溶体的生成,减少脆性金属间化合物的产生,在一定程度上提高了钎焊接头的强度,有效避免了微裂纹产生,从而提高换热管的服役可靠性。该研究可为提高304不锈钢钎焊接头质量提供理论支撑。
For the tube-wall brazed joints in a 304 stainless steel heat exchanger with a finned-tube structure which experienced cracking and water leakage during service,samples taken from the cracked region were thoroughly analyzed to identify the failure mechanism of brazed joints of 304 stainless steel heat exchanger tubes using nickel-based brazing filler metals.Through penetration test,metallographic examination and scanning electron microscopy(SEM)observation,it is revealed that the non-uniform distribution of brittle phosphorous compounds reduces local toughness.Under operational stress,the joint undergoes intergranular fracture,generating microcracks that serve as whick origins for further crack propagation,ultimately leading to ductile fracture.Adding a small amount of copper to the brazing filler promotes the formation of a ductile nickel-based solid solution within the joint,thereby reduces the formation of brittle intermetallic compounds,and enhances the strength of the brazed joint in certain extent,which effectively avoids the formation of microcrack and improves the service reliability of the heat exchanger tubes.These findings provide theoretical support for improving the quality of brazed joints in 304 stainless steel.
作者
刘兵
邢亚伟
李勋
李冲
徐永航
敖三三
LIU Bing;XING Yawei;LI Xun;LI Chong;XU Yonghang;AO Sansan(Guangdong Macro Gas Appliance Company Ltd.,Foshan 528300,China;School of Materials Science and Engineering,Tianjin University,Tianjin 300350,China)
出处
《热加工工艺》
北大核心
2026年第2期170-175,共6页
Hot Working Technology
基金
国家自然科学基金面上项目(52375372)。
