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Enabling Dissimilar Joining of Coated Steels to Aluminum through Impact Spot Welding
Published September 09, 2020 by SAE International in United States
Citation: Kapil, A., Mao, Y., Vivek, A., and Daehn, G., "Enabling Dissimilar Joining of Coated Steels to Aluminum through Impact Spot Welding," SAE Technical Paper 05-14-01-0004, 2020, https://doi.org/10.4271/05-14-01-0004.
Direct welding of coated steels to aluminum alloys is challenging due to high energy requirements, decreased weldability, and unstable weld quality. The present study reports the application of a new design approach in vaporizing foil actuator welding (VFAW), where an asymmetric preform shape on the target sheet generated the requisite standoff, enabling direct spot welding of a typical automotive aluminum alloy (6022 T4) and two different zinc-coated steels, galvanized high-strength low-alloy 350 and galvannealed dual-phase 590. The use of the new approach enabled for the first time the ability to spot weld through coating without any preweld surface preparation. Characterization using lap-shear and peel testing revealed strong joints for both the weld pairs (AA 6022 T4-HSLA 350 and AA 6022 T4-DP 590). The weld interface characterized by scanning electron microscopy (SEM) revealed a hierarchical structure and the presence of a typical wavy region.