Investigation of welding parameters on microstructure and mechanical properties of laser beam-welded joint of 2060 Al–Cu–Li alloy

Abstract

2060 Al–Cu–Li alloy plates with 2- and 1-mm thickness were welded by a fiber laser beam. The weld microstructure features and the mechanical properties such as microhardness and tensile strength of 2060 Al–Cu–Li alloy laser beam-welded joint were investigated to study the influence of welding parameters on the weld bead. By microstructure and mechanical property analysis, it is found that weld width as well as penetration depth increases with the increase of laser power when the welding speed is constant. The microstructures of the fusion line and fusion zone show similar dendrite morphologies with traditional cast structure under the thermal cycling. Fine grain zone can be observed near the fusion line. Welding porosities exist in the microstructure of 2060 Al–Cu–Li laser beam-welded joint. Porosity ratio increases at first, and then declines, and then increases again with the increase of laser power. The larger heat input causes the lower microhardness distribution of the corresponding joint. The optimized welding parameters of fiber laser beam welding of 2- and 1-mm-thick 2060 Al–Cu–Li alloys are 2500 W and 3 m/min and 2300 W and 4 m/min, respectively.