Metallic bump assisted resistance spot welding (MBaRSW) of AA6061-T6 and bare DP590: Part I-printing of metallic bump

Abstract A novel joining method, i.e., metallic bump assisted resistance spot welding (MBaRSW) was proposed, in which, a third-party aluminum metallic bump was printed on either aluminum alloy or steel sheet through modifying the Fronius cold metal transfer (CMT) pin process, and then a resistance spot weld was made via the bump to solve the problems of low joint strength and severe weld thinning in conventional Al/steel resistance spot welds. This two-part paper aims at investigating the mechanism of the novel RSW process. In this part, Fronius CMT pin process was first investigated to examine its control mechanism on pin-like or bump-like morphology of products, and then an exclusive bump printing process was developed. Results showed that due to better wettability the bumps printed on Al substrate were bigger, shorter and much stronger than that on steel substrate in which intermetallic compound (IMC) layer formed along bump/steel interface. The study laid a foundation for development of the novel Al-steel MBaRSW process.