Influence of ultrasonic impact treatment on stress corrosion of 7075 aluminum alloy and its welded joints

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 mu m on the material surface. The corrosion resistance was also improved, exhibiting that the SCC factors I sigma, I delta, and SSI of the specimens with doubleside 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.

Automated summary

The effects of ultrasonic impact treatment (UIT) on stress corrosion cracking (SCC) of 7075 aluminum alloy and its welded joints were investigated. UIT significantly refined the grains and induced a compressive residual stress layer with a depth of 50-75 μm on the material surface. The corrosion resistance was improved, with decreases of 37%, 68%, and 46% in SCC factors I sigma, I delta, and SSI, respectively, for the specimens with doubleside UIT treatments. The improved SCC resistance was mainly attributed to the residual compressive stress and grain refinement, which enhanced pitting corrosion resistance and inhibited the initiation and growth of corrosion cracking.