Effect of Cu addition on laser welding performance of Al–Mn–Mg alloy sheets

Abstract

The present study investigated the effect of Cu addition on the tensile properties and laser welding performance of Al (1·3 mass-%)–Mn (0·5 mass-%)–Mg alloy sheets. It was found that the addition of Cu in the Al–Mn–Mg alloy sheets increased the ultimate tensile strength; however, the laser welding performance deteriorated. The addition of Cu up to 0·45 mass-% induced the laser welding cracking. Observations of the microstructure indicated that residual Cu bearing eutectic phases existed along the grain boundaries in the alloy with 0·45 mass-%Cu, which decreased the ductility of the grain boundaries and resulted in the formation of cracks along the grain boundaries during the solidification process after laser welding.

Keywords:

• Al–Mn–Mg alloy
• Cu addition
• Laser welding performance