Microstructure and mechanical characterization of laser welded 6013 aluminum alloys overlap joint

In this paper, 6013 aluminum alloy with the thickness of 2.5mm was overlap welded by fiber laser. The microstructure, mechanical properties and fracture morphology of the joint was tested and observed by Optical Microscope, material testing machines and Scanning Electron Microscope, thus the failure and fracture mechanism of the welded joint are analyzed. The results showed that good shape of weld was achieved under the optimal welding parameters. Equiaxial as-cast microstructures exist in the welding center and the columnar grains are formed near the fusion line in the WZ (weld zone). The hardness of weld zone is the lowest in the joint, which is about 72 HV, about 57% of that of BM (base metal). The tensile shear strength of the joint is 96Mpa, about 25% of tensile strength of BM. The fracture is happened in the WZ and the brittle fracture mode is dominated with shear dimples and shear planes. © 2019 Trans Tech Publications Ltd, Switzerland.