Electrospark Deposited Interlayer and its Influence on Dissimilar Resistance Welding of DP600 to AA5052

Abstract

Challenges associated with the resistance spot welding of aluminum and steel must be addressed to enable wider use of low-density aluminum alloys in commercial vehicles. These challenges include the significant difference in melting point and thermal conductivity between aluminum alloys and steels – which results in a brazed joint rather than the formation of a weld nugget – and the formation of thick brittle iron aluminide intermetallic when molten aluminum is in contact with steel. This study demonstrates the use of electrospark deposited interlayers to limit the contact between molten aluminum and steel during resistance spot welding. Magnesium, aluminum, and nickel-based interlayers are studied to determine material characteristics suitable for the resistance spot welding of galvanized dual phase steel (DP600) to AA5052. Tensile lap-shear strength increases of up to 84% over the non-interlayer configuration are obtained using an optimized interlayer and resistance spot welding process, achieving 6 mm diameter joints capable of withstanding 8 kN of shear loading. This has the potential to facilitate the adoption of aluminum in the automotive industry as light weighting becomes a more critical issue.