抄録
Laser welding process has significant advantages in terms of low heat input, low distortion, high welding speed, and ease to automation compared with the conventional welding process. In particular, there is considerable interest in welding heat treated alloys, such as Al-Mg-Si alloy, since low heat input makes the softened region of welds minimize.
In the previous study, weldabilities and solidification crack susceptibilities of Al-Mg-Si alloys have been reported using 5kW CO2 laser. Solidification cracking in the weld metal has been prevented by using Al-Si alloy filler wire enriched with Si. However, tensile strengths of welds were lower compared to the base metal because of softening of welds.
In the present study, the behaviors of hardness values of welds of Al-Mg-Si alloy, 6N01-T5, by natural and artificial aging treatment were investigated. Hardness values of the softened region and weld metal were fully recovered to those of the base metal after an artificial aging treatment at 463 K for 28.8 ks without solution annealing. It was caused by the precipitation of Al-Si eutectic in weld metals and the precipitation of G.P. zones in weld metals and heat-affected zones Tensile strengths of welds after the postweld artificial aging treatment had equivalent tensile strengths to those of base metal.
