Mechanical characterization of CO2 laser beam butt welds of AA5083

Laser beam welding experiments have been carried out on 3-mm thick aluminium-magnesium alloy 5083 specimens in butt-joint configuration. The mechanical properties of the joints have been evaluated by performing tensile tests, hardness profiles across the weld sections, porosity measurements and EDX analyses. A design of experiment technique has been used to study the effects of the welding speed (v) and the incident laser power (P) on the aforementioned response variables that are considered to be representative for the weld quality. By comparing the welds obtained by operating at constant linear energy input released onto the material (P/v ratio), the best results have been found for higher laser powers and welding speeds. A clear correlation was found between the incidence of porosity, the tensile strength and the hardness of the fused zone. Welding reliability was enhanced for selected sets of process parameters capable of producing butt-joints showing mechanical properties very competitive if compared with the performances obtained, on similar aluminium alloys, using alternative joining technologies like friction stir welding or gas tungsten arc welding.