Mechanical performance of resistance spot welds in dissimilar AHSS combinations

Increased use of advanced high strength steels (AHSS) has lead to a wider range of possible material combinations in resistance spot welding (RSW) of body-in-white assemblies. Lately, improved crash performance has been achieved by replacing mild and HSLA steels with DP and TRIP alloys. While these steels are often welded in similar configurations, it is more common to find dissimilar combinations as material properties are tailored for the local requirements. Most studies, however, focus on evaluation of weld performance in similar joints and there is a lack of available data on weld properties in dissimilar material combinations. The objective of this work is to evaluate mechanical properties of RSW joints in dissimilar combinations of AHSS grades, including DP, and TRIP, besides, HSLA steel is also included with single pulse welding. Standard recommended test practices have been used to observe the typical strength and failure mode for various combinations of AHSS, which are then compared to weld performance in similar joints. Full button pullout was found for all material combinations with failure occurring in the heat-affected-zone or in the base metal, depending on the combination. Copyright © 2007 MS&T'07®.