Microstructure and Mechanical Properties of Friction Stir Spot Welded Galvanized Steel

Abstract

Joints of galvanized steel were obtained by friction stir spot welding (FSSW) with lap configuration using CPS design tool. No mechanically mixed layer was formed between the top and bottom plates at the weld nugget due to the limited tool penetration and the lower pin height of the welding tool than the steel plate thickness. A deformed region, in which ZnO particles were detected, was observed in the joint. The formation of this deformed region was attributed to the explosion of the Zn coating layer due to friction heating and tool compression. With increasing tool penetration depth, the tensile shear strength of the joint increased to a maximum value of 3.07 kN at a tool penetration depth of 0.52 mm.