Wetting and laser brazing of Zn-coated steel products by Cu–Si filler metal

Laser brazing is an effective process for joining of steel products widely applied in automobile industry on exposed parts, especially on two following targeted applications: roofs and hatchbacks. The obtaining of good quality joints requires an adequate understanding of interaction phenomena of the brazing filler with the steel surface. This study concerns the investigation of wetting and interfacial reactivity in Cu–Si brazing alloy/Zn-coated steel systems in order to identify how the coating influences the wettability and, consequently, the brazability of steel products. The wetting experiments are performed on hot-dip-galvanized and electro-galvanized coatings, as well as on bare steel. The morphology and chemistry of interfacial reaction products are characterized by SEM-FEG and X-microanalysis.