Liquation Cracking Susceptibility and Mechanical Properties of 7075 Aluminum Alloy GTAW Joints

Abstract

In this work, aluminum alloy 7075-T651 was welded by using customized Al-Cu-Si and Al-Cu-Mg-Zn filler wire during gas tungsten arc welding. The liquation cracking susceptibility of the joints was tested under a circular-patch welding experiment. Besides, the temperature vs. solid fraction curves (T-fS) was calculated for different samples to reveal the formation mechanism of liquation cracking. The joint was susceptible to liquation cracking if (fS)weld > (fS)workpiece during the cooling stage. The results of the circular-patch welding experiment show that the liquation cracking susceptibility of the joint by using ER5356, Al-Cu1.5-Si4.5, Al-Cu3.0-Si2.5, Al-Cu4.5-Si1.5, Al-Cu2.3-Mg2.3-Zn6.6 and Al-Cu2.2-Mg2.0-Zn7.8 filler metal is 22.8%, 8.3%, 2.8%, 2.8%, 3.3% and 1.4%, respectively. The mechanical test shows that the data dispersion of the 7075 gas tungsten arc welding joint can be decreased by eliminating the liquation crack.