Abstract
For 6061-T6 and 7075-T6 aluminum alloy plates, SSRT (slow strain-rate technique) tests in humid air with 90% relative humidity were carried out using a notched tensile specimen to evaluate the susceptibility to hydrogen embrittlement and to appreciate the role of notch in the process of HEAC (hydrogen-environment-assisted cracking). 7075-T6 showed a significant embrittlement due to intergranular cracking more inspired by the existence of notch, while in contrast, 6061-T6 exhibited a trend of an enhanced plastic deformation by hydrogen effects, accompanied with a trace of nonconventional TTS facet in fracture surface and an increase in notch opening displacement in the early stage of still low stress level. The SSRT behaviors of these alloys are explained to result from the mechanism of hydrogen-enhanced localized plasticity, where the process of hydrogen population is supported to include both effects of trapping at microstructural defects such as inclusions and stress-induced diffusion at macroscopic defects such as notch.
