Enhancing AA7075 Spot Welding with Multipulsed Current and Magnetic Fields: Part 1 — Materials Characterization

Le résumé fourni par la source

High-strength, corrosion-resistant, and heat-treatable 7xxx aluminum alloys have long been important structural materials in the aerospace industry. Recently, driven by the progress in vehicle lightweighting, the application of 7xxx aluminum alloys has also emerged as a prevailing trend in high-speed rail and automotive manufacturing. However, welding 7xxx aluminum alloys with high-alloying-element content presents stubborn porosity and hot-cracking defects. The magnetically assisted resistance spot welding (MA-RSW) process has been proven to be an effective method to improve the toughness of aluminum alloy welds by introducing electromagnetic stirring. Still, it may increase the risk of expulsion. In response to these challenges, this two-part paper aims to investigate a composite process called multipulsed magnetically assisted resistance spot welding (MPMA-RSW), which combines an external magnetic field and a multipulse current schedule to improve the weldability of 7xxx sheets. This part compares material characterization using different methods, including nugget appearance, microstructure, and crack propagation. The results show that both the multipulsed resistance spot welding and the MA-RSW processes can inhibit the porosity defects but cannot avoid hot cracking. In contrast, the composite process MPMA-RSW can effectively inhibit the porosity defects, reduce the hot cracks, and refine the grains. The MPMA-RSW process can be used to address the welding challenges of 7xxx aluminum alloys, presenting a favorable outlook for industrial applications.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.