Joint strength of weld beads produced in thin aluminium sheets by high-speed CO_2 laser welding

摘要

This article has described a study of the joint strength of bead-on-plate and lap welds produced in thin aluminium alloy sheets by high-speed CO_2 laser welding at speeds of more than 10 m/min. The results obtained may be summarised as follows: 1 During bead-on-plate welding of 6N01 alloy, solidification cracking occurs in the weld metal base at a welding speed of more than 12 m/min and fracture occurs in the weld metal. 2 During lap welding of 5182 and 6N01 alloy sheets, the fracture strength decreases with an increasing welding speed. Fracture occurs in the joint. The fracture strength depends on the joint cross-sectional area and there is no effect of cracking occurring in the weld metal. 3 The results obtained during an investigation of the effect of multiple beads show such beads to give a greater fracture strength. The strength, however, is limited by cracking in the weld metal base. 4 At a narrow bead spacing when individual beads join together, the fracture strength is reduced by reduced joint cross-sectional area. 5 In the case of double lap weld beads, a high fracture strength obtained at a welding speed of less than 10 m/min through the weld metal being crack-free and the joint cross-sectional area being increased. At any higher welding speed, however, the fracture strength is limited by cracking in the weld metal.