On the Softened Zone by MIG Welding Method in a Work-Hardened Corrosion-Resistant Aluminum Alloy

Abstract

When work hardened materials of corrosion-resistant aluminum alloy are welded, the hardness increased by the cold working is softened partially welding heat. and also the mechanical strength locally is reduced and then the joint efficiency falls naturally.
Therefore, in this investigation, the author inquired into the generating condition of softened zone using A2P7-1/4 H work hardened materials of 0.5cm thick plate and simultaneously investigated about the countermeasure for the falling of the strength of the joint by the generation of the softened zone.
The author measured the thermal cycle in each point of heat affected zone and made sure that the softened degree by welding heat was depended upon the degree of the influence of the heating largely on the neak temperature
Consequently, in this experiment the author found that the softening began at about 300°C and proceeded gradually beyond this temperature and then completed perfectly at about 500°C; and also width of softened zone was increased and the strength of the joint was reduced proportionally to the welding heat.
The author made clear that to raise the joint efficiency up to 100 per cent without falling of the strength of the joint in welding the width of the softened zone ought to be kept under 0.8cm; from the relation of the width of the softened zone and the strength of joint.
Next, the author tried an improvement of the strength of the joint by PEENING method, and consequently made clear that this PEENING method was comparatively way.