Improvement of ultrasonic weld strength for Al-Mg alloy by adhesion of alcohol - Ultrasonic welding of Al-Mg alloy (2nd report)

In order to improve the ultrasonic weld strength of Aluminum (Al)-Magnesium (Mg) alloy, the effects of pre-heating the specimen and the putting a drop of alcohol on the welding surface on the weldability were examined. Al-4.1 mass% Mg alloy (A5086) with 1.2 mm thickness was lap-welded. The following results were obtained in this study. Pre-heating the specimen increases the strength of the weld. The adhesion of the alcohol on the welding surface causes the specimen temperature during welding to increase by 130 K higher than that without the alcohol adhesion, because the large relative motion between the specimens was induced at the incipient stage of the welding process due to the alcohol adhesion. The amplified relative motion and softening of the specimen because of the temperature rise broken down the Mg-segregated region preventing the faying surface from welding and resulted in increasing the weld strength about twice as high as that without alcohol. Furthermore, the adhesion of the alcohol causes the welding time necessary to achieve the sound welding to shorten below 1 second.