While material qualification tests are frequently based on similar welding configurations, real car body applications are quite systematically dissimilar configurations. For spot welds failing in plug mode, the strength of the assembly only depends on the weakest material strength. In the case of AHSS+AHSS welded combinations, however, things turn out differently. Similar-grade but dissimilar-thickness high-strength-steel configurations have been spot welded and tested in cross-tension. The following main conclusions can be highlighted: (1) For dissimilar-thickness configurations, the cross-tensile strength is above the standard "minimum rule" assumptions, this phenomenon being called a "positive deviation". (2) Limited thermal and notch location effects can explain part of this positive deviation, but the main reason is mechanical. (3) As evidenced through several analytical and numerical studies, this mechanical effect is due to the less severe local stresses at the notch in case of uneven thickness, and improves the positive deviation when the thickness ratio increases. Although widely used for material qualification and scientific purposes, similar configurations appear as the worst case in terms of cross-tension performance for high-strength steels. Actual vehicle design should consider positive deviation in dissimilar configurations to maximize the potential strength of spot welds in high-strength steels.
Spot welding different sheet metal grades and gauges
Welding Journal, New York ; 93 , 1 ; 38-43
2014
6 Seiten, 10 Bilder, 4 Tabellen, 16 Quellen
Article (Journal)
English
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