Slow strain rate tension test of high-strength aluminum alloy 7075

The stress corrosion cracking (SCC) behavior of aluminum alloy 7075 in air and in 3.5wt% NaCl water solution has been tested using slow strain rate tension (SSRT) technique, and the effect of strain rate and hydrogen on the SCC behavior of the alloy has been studied. The experimental results show that the alloy is susceptible to SCC which can occur in humid air but can′t in dry air. Alloy 7075 with L-T direction is more susceptible to SCC at a strain rate of 1.331×10 -6 s -1 than at that of 6.655×10 -6 s -1 . In humid air, or by anodic polarization in 3.5wt% NaCl water solution, the mechanism of SCC is mainly anodic dissolution. Under the condition of hydrogen pre-permeation or cathodic polarization, hydrogen embrittlement plays a key role during the SCC process. The results also indicate that the SCC resistance of alloy 7075 decreases with increasing the time of hydrogen pre-permeation.