Study on Microstructure and Properties of Welded Joint of Galvanized Steel Sheet for Building

The welding process of galvanized steel plate was carried out using the method of resistance spot welding, the microstructure and mechanical properties of nugget zones of welded joints from different welding currents studied, and the effects of current intensity on the performance and microstructure of galvanized steel plate analyzed. The results show that the galvanized steel substrate is composed of bright white martensite and grey ferrite, and that martensite islands are uniformly distributed in the ferrite matrix; When the welding current increases from 8.5 kA to 12.0 kA, the nugget zone has no welding defects, but the increasing of the welding current makes columnar grains in the nugget becoming thicker, and grains in nugget center has been coarsened; With the increasing of welding current, tensile shear and nugget diameter of galvanized steel increase to the maxium when the carrent is 10.5 kA and then decrease.