摘要
焊接效率低和焊接缺陷多是回填式搅拌摩擦点焊(Refill friction stir spot welding,Refill FSSW)工业化应用的主要瓶颈问题。分别采用加工有螺纹和凹槽的套筒对6022和7075异种铝合金进行Refill FSSW试验。结果表明,与加工有螺纹的套筒(传统式Refill FSSW)相比,采用加工有凹槽的套筒(改进式Refill FSSW)进行焊接时,在套筒下方形成了材料充分混合的楔形结构。采用加工有螺纹的套筒,通过快速插入的方式(快插式Refill FSSW)可提高材料在板厚方向上的流动性,在接头界面处形成了冶金连接和机械联锁机制。此外,采用加工有凹槽的套筒,并通过快速插入的方式(凹槽套筒快插式Refill FSSW)获得的楔形结构内的材料混合程度随着焊接时间的延长而增加。改进式Refill FSSW工艺焊接过程中的最高温度为504.3℃,液化裂纹的形成与低熔点相MgZn;的熔化有关。根据热量产生原理,提出的改进式和快插式Refill FSSW工艺有助于提高接头力学性能及其稳定性,而凹槽套筒快插式Refill FSSW工艺可在1 s焊接时间内获得满足工业使用要求的无缺陷接头。
Low joining efficiency and defects are the main obstacles for the industrial application of refill friction stir spot welding(Refill FSSW). Threaded and grooved sleeve tools were applied to refill FSSW Al6022/Al7075 dissimilar welds. The results indicated that compared to that of a threaded sleeve tool(conventional refill FSSW), an arc-structured was formed around the weld, in which the top and bottom sheets materials were mixed together, when the weld was fabricated using a grooved sleeve tool(modified refill FSSW). The material flow performance in the thickness direction can be significantly improved, when the weld was fabricated using a threaded sleeve tool via a fast plunging rate(fast plunging refill FSSW). Also, metallurgical and mechanical interlocking joining mechanisms were confirmed at the interface. Furthermore, material inter-mixing increased with the increasing of welding time, when the weld was fabricated using a grooved sleeve tool via fast plunging rate(grooved sleeve and fast plunging refill FSSW). The maximum temperature was 504.3 ℃ during modified refill FSSW, and melting of MgZn;resulted in liquation cracking. Based on the fundamental of heat generation, weld stability and strength and be improved by modified and fast plunging refill FSSW, defect-free weld that meet requirement of the industry can be fabricated using grooved sleeve and fast plunging refill FSSW within 1 s.
作者
申志康
李文亚
蔡自强
葛世鹏
吴玲璐
刘小超
SHEN Zhikang;LI Wenya;CAI Ziqiang;GE Shipeng;WU Linglu;LIU Xiaochao(School of Materials Science and Engineering,Northwestern Polytechnical University,Xi'an 710072;Centre for Advance Materials Joining,University of Waterloo,Waterloo N2L3G1,Canada)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2021年第18期137-143,152,共8页
Journal of Mechanical Engineering
基金
国家自然科学基金(51975479)
中央高校基本科研业务费专项资金(3102019QD0404)资助项目。
关键词
回填式搅拌摩擦点焊
异种铝合金
材料流动
连接机理
refill friction stir spot welding
dissimilar Al alloys
material flow
joining mechanism