In order to evaluate the susceptibility to hydrogen embrittlement(HE) of aluminum alloys 6061-T6 and 7075-T6 as candidate materials for high pressure-hydrogen container liner, SSRT (slow strain-rate technique) tests under wet air with 90% relative humidity have been carried out in a range of strain rate 3.47×10^<-7>〜1.39×10^<-5>/s by using smooth-and notched-plate specimens. 7075-T6 showed a significant susceptibility to HE, resulting in intergranular fracture, while in contrast, 6061-T6 exhibited a superior resistance, accompanying rather a trend to enhanced plasticity. Difference in form of crack extension between smooth-and notched-specimens of 7075-T6 was found. The observation supports the HE process includes both effects of plastic deformation and hydrostatic stress gradient on hydrogen transport.
