During resistance spot welding, the welding current is the most important process parameter, which determines the welding heat input and then has a great influence on the welding quality. In present study, the CR590T/340YDP galvanized dual phase steel widely used as automobile material was carried out using resistance spot welding. The effect of welding current on the weld formation, microstructure, and mechanical properties was studied in detail. It was found that the quality of weld appearance decreased with the increase of welding current, and there was a Zn island on the weld surface. The microstructure of the whole resistance spot welded joint was inhomogeneity. The nugget zone consisted of coarse lath martensite and a little of ferrite with the columnar crystal morphology, and the microstructure of weld nugget became coarser when the welding current was higher. There was an optimum welding current value and the tensile strength reached the maximum. This investigation will provide the process guidance for automobile body production.

Aluminum and aluminum alloys have the advantage of a high strength-to-weight ratio, but their low hardness and poor wear resistance often cause wear damage. In the present study, the cladding layer was prepared using argon-shielded arc cladding of CuZn40-WC powders which were pre-coated on a pure aluminum substrate. The effects of WC proportion on the morphology, microstructure, and properties of cladding layers were investigated in detail. The results indicated that the optimal WC proportion in CuZn40-WC powders was 60 wt.%. With the increase of WC proportion, although the morphology of the cladding layer became slightly worse, the surface quality of the cladding layer was acceptable for industrial application until the WC proportion was 80 wt.%. Meanwhile, the top width and maximum depth of the cladding layer decreased. The maximum microhardness and optimal wear resistance of the cladding layer were 4.5 and 2.5 times that of the aluminum substrate, respectively. The increased microhardness and wear resistance were mainly attributed to the formation of Al₄W in the cladding layer. The wear scar of the high wear resistance specimen was smoother and some bulk Al₄W compounds were clearly observed on the wear surface.