Mechanical properties of A6082 welded joints with Nd–YAG laser

Abstract

Weldability of A6082 with Nd–YAG laser was investigated to explain the advantages over the conventional MIG process. It is concluded that rapid cooling rate in heat-affected zone (HAZ) contributes to increasing joint strength and improvement durability against liquation cracking in HAZ during Nd–YAG laser welding. This is why rapid cooling rate is enough to prevent crossing the C-curve for precipitation of β′ and small volume of weld metal is enough to reduce shrinkage strain during solidification. And the joint strength increased with an increase of manganese content in the base metal, but by contraries the minimum hardness in HAZ where the fracture occurred in the tensile test decreased. This may be attributed to the prevention of intercrystalline embrittlement due to the addition of manganese in case of Al–Mg–Si series alloys with excessive Si content.

Keywords:

• 6082
• YAG laser
• joint strength
• liquation cracking
• manganese

Acknowledgements

Alloys used in this study were first produced during the Development of New Structural aluminium alloys project carried out by the Japan Aluminium Association Production Discussion Group and were then kept by Professor Okubo of the College of Industrial Technology, Nihon University, and we would like to express our thanks to him for kindly presenting them to us.