Development of a technology for the flux-free brazing of galvanized steel

At the moment, fluxes are still being used for the brazing/soldering of galvanized sheets in order to remove the surface oxides. However, because of the corrosive effect, it is necessary to carry out a subsequent cleaning process on the joining point. Furthermore, brazing solders with high application temperatures can easily lead to zinc evaporation. Therefore, the objective was to develop a process for the flux-free brazing of galvanized sheets. The processes chosen were induction brazing and gas-shielded resistance brazing. The brazing solders used first of all were two commercial copper-zinc brazing solders. When the brazing parameters had been optimized, the aim was to develop additional brazing-solder alloys in order to achieve better direct wetting of the parent metal and a reduction in the process temperature. The test brazed joints were analyzed using optical and electron microscopes and their strength and corrosion behaviour was investigated. It was primarily copper-manganese brazing-solder alloys which proved to be promising in this respect.