Effect of Laser Power and Travel Speed on the Welding Process and Tensile Strength of Rolled Zinc Alloy Laser Welds

For thin zinc sheets for construction purposes different welding techniques like tungsten inert gas (TIG), plasma arc (PAW) or micro-friction stir (μFSW) welding can be used. However, low ultimate tensile strength (UTS) often leads to cracking in the weld even at low loads. The characteristics of laser welding make it particularly suitable for joining thin sheets and low-melting materials. Nevertheless, little is known about the weldability of thin zinc sheets by laser welding and the effects of the basic process parameters of laser power and travel speed on the welding process and the UTS of the weld. In this study, thin zinc sheets were welded at different laser powers and travel speeds. Tensile testing of the welded joint showed, that the UTS and elongation at break increase with the energy input per unit length, but the welding process became gradually unstable and the susceptibility for welding defects increased. This leaves only a few laser powers and travel speeds that produce good welds with respect to UTS and elongation at break. Under these conditions laser welding is an alternative processing technique to TIG, PAW and μFSW, but needs further investigation to improve its stability. To implement laser welding in highly automated production processes further research is required on laser welding of rolled zinc alloys