On the influence of zinc coating and outdoor exposure on the strength of adhesive, clinched, and hybrid joints of batch hot-dip galvanized steel

For decades, it has been common practice to manufacture steel products by welding and then batch hot-dip galvanizing these finished or at least semi-finished components. The joining of such galvanized parts to structures has so far been achieved by means of screws or bolts. With advances in joining and galvanizing technologies, new joining concepts are now conceivable. As part of an extensive testing campaign, joints of small-scale, batch hot-dip galvanized steel specimens were prepared using three joining techniques: adhesive bonding, clinching, and adhesive-clinch hybrid joining. The zinc coating was varied using conventional hot-dip galvanizing as well as thin-film galvanizing with a zinc-5% aluminium alloy. The strength of the joints was investigated by shear tensile testing. Different weathering conditions, achieved by outdoor exposure of samples for over 2 years, were used to investigate such effects on the joint strength.