Property Comparison of Laser Welded Butt Joint and T-joint of 6156-T4 Al Alloy

The tensile property, fatigue property and fracture morphology of the laser welded butt joint and T-joint of 6156-T4 Al alloy were researched and compared using the tension testing machine, fatigue tester, scanning electron microscope, etc. The results show that the tensile property of the butt joint was close to that of the base metal, while the tensile strength of T-joint decreased to a certain extent comparing to that of the base metal. The fatigue strength of the butt joint was obviously higher than that of the T-joint. The fatigue fracture of the butt joint was in the heat affected zone while that of the T-joint was across the heat affected zone and base metal. The fatigue cracks of the two joints initiated from the weld toe, at which the stress concentration was relatively serious, and then propagated in a shape of approximate semi-ellipse along the plate thickness direction until the joint fracture.