摘要
搅拌摩擦焊(FSW)是一种应用广泛的固相连接技术,但仍存在部分材料焊接难度较大、接头晶粒较粗、异种材料FSW接头内金属间化合物(IMC)难以调控和接头力学性能有待进一步提高等问题,严重阻碍了FSW技术的发展。在传统FSW基础上添加辅助条件能有效克服传统FSW的不足,提高FSW接头的质量。传统FSW过程产热量有限,导致部分材料在焊接时搅拌头磨损严重且轴向力大,焊接效率低,甚至无法进行有效焊接。在焊接前添加预热措施或焊接时加入超声波辅助,可增加焊接材料的软化程度,有效降低焊接过程中搅拌头的磨损,减小焊接时的轴向力,提升焊接效率。针对传统FSW接头晶粒粗大的问题,利用超声波的机械振动作用破碎接头中已形成的再结晶晶粒,同时超声波提供的能量能够增大接头内位错密度,有效地抑制晶粒粗化;外加冷却辅助能够迅速带走焊接过程中产生的热量,使接头快速冷却,缩短晶粒生长时间,抑制晶粒长大。对于异种材料FSW,接头内生成的IMC大部分为脆硬相,是接头断裂的裂纹源和裂纹扩展路径,添加超声波辅助将已形成的IMC破碎并抑制IMC生成;外加冷却方式提高了接头的冷却速率,抑制IMC生长。为了进一步拓展FSW的应用领域,在传统FSW基础上添加了焊前预热、超声波和冷却条件等辅助手段,这对提高接头性能有一定作用,外加辅助条件能软化焊接材料,减小材料流动阻力,改善材料的流动性,避免焊缝缺陷的产生,获得良好的连接界面,有效地提升接头性能。本文从外加辅助条件的有益效果角度对外加辅助条件FSW技术进行了总结,综述了不同辅助条件下FSW在焊接过程、晶粒细化、IMC控制和性能提升方面的国内外最新研究进展,分析了不同辅助方式起到有益效果的基本原理,以期为FSW技术的研究者提供参考。
Friction stir welding(FSW)is a widely used solid phase joining technology.However,there are still a few problems for some metals such as high welding difficulty,coarse grain size,the difficulty of controlling the intermetallic compounds(IMC)in FSW joints of different materials,and the further improvement of mechanical properties of joints,which seriously hinders the development of FSW technology.Adding auxiliary conditions under the basis of the conventional FSW can effectively overcome the defects of the conventional FSW and improve the quality of the FSW joint.Limited heat production of the conventional FSW process,causing serious wear on the tool and large axial force during progress for some materials even cannot getting effective FSW joint.The researcher study on adding preheating method before welding and ultrasonic assisting during process,which effectively softened the welding material,reduced the wear of the tool during welding,reduced the axial force during welding,and improved the welding effectiveness.There are large crystal grains existed in the conventional FSW joints.The researchers used the mechanical vibration of ultrasonic to break up the dynamic recrystallized grains during the welding process,and the energy provided by the ultrasonic increases the dislocation density in the joints.The addition of the external cooling in the progress take the heat generated away,the joint can be cool rapidly,shorten grain growth time,and inhibit crystal grains growth in the joint.Most of IMCs are brittle hard phases,and they are crack sources and extension paths for joint fractures formed in the dissimilar FSW joints.The addition of ultrasonic assist can break up the formed IMC and inhi-bit formation IMC in the joint.The external cooling method can quickly take away the heat which generated in the welding process and inhibit the IMC growth.The researchers studied the effects of additional auxiliary conditions of preheating,ultrasonic and cooling conditions on the perfor-mance of joints in order to further expand the application field of FSW.These methods improve the material fluidity,obtain sound joint interface and avoiding the weld defects,which can soften the welding material with reduce the flow resistance of the material properties of the joint.This paper summarizes the additional auxiliary conditions FSW technology from the perspective of beneficial effects with additional auxiliary conditions.The latest research progress of different auxiliary methods in FSW process,grain refinement,IMC control and mechanical properties improvement are reviewed.The basic principles that various assistant modes with different beneficial effects are analyzed.This paper provide refe-rence for FSW researchers.
作者
曾金成
宋波
左敦稳
邓永芳
ZENG Jincheng;SONG Bo;ZUO Dunwen;DENG Yongfang(Engineering Research Institute,Jiangxi University of Science and Technology,Ganzhou 341000,China;School of Mechanical and Electrical Engineering,Lanzhou University of Technology,Lanzhou 730050,China;College of Mechanical and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;Ganzhou Fortune Electronic Co.Ltd.,Ganzhou 341000,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2021年第7期7162-7168,共7页
Materials Reports
基金
国家自然科学基金面上项目(51175255)
江西省自然科学基金(20171BAB216033)
江西省教育厅科学技术研究项目(GJJ170501)
赣州市科技计划项目科技创新人才计划
江西理工大学博士启动基金(jxxjbs16001)。
关键词
搅拌摩擦焊
外加辅助条件
金属间化合物
晶粒细化
friction stir welding
additional auxiliary conditions
intermetallic compound
refine grains
