Influence of ultrasonic impact treatment on stress corrosion of 7075 aluminum alloy and its welded joints
J.T. Wang, J.W. Chen, Y.K. Zhang, Xingchen Xu, Z.G. Wang, Lechun Xie, Maoyong He, Yalin Lü, Kaiyu Luo, M.Z. Wang
Abstract
The effects of ultrasonic impact treatment (UIT) on stress corrosion cracking (SCC) of 7075 aluminum alloy and its welded joints have been investigated. The microstructural evolution, corrosion behavior, and mechanical properties of the UITed and untreated specimens were studied. The results showed that UIT can refine the grains dramatically and induce a compressive residual stress layer with a depth of 50–75 µm on the material surface. The corrosion resistance was also improved, exhibiting that the SCC factors Iσ, Iδ, and SSI of the specimens with double-side treatments decreased by 37 %, 68 %, and 46 %, respectively. The improved SCC resistance of 7075 aluminum alloy and its welded joints subjected to UIT was mainly attributed to the residual compressive stress and grain refinement, which not only enhanced the pitting corrosion resistance but also effectively inhibited the initiation and growth of corrosion cracking.