Abstract
Al-Zn-Mg and Al-Cu-Mg alloys have been known to be susceptible to stress corrosion cracking, which is based on intergranular cracking. The crack propagation mechanism depends on alloy system. In Al-Zn-Mg alloys, the crack propagates due to hydrogen embrittlement. In Al-Cu-Mg alloys, anodic dissolution along grain boundaries is suggested to be the crack propagation mechanism, not to be hydrogen embrittlement. It has reported that the peak-aged Al-Zn-Mg alloy showed a loss of elongation resulting from hydrogen embrittlement when tensile testing was performed in humid air at a low strain rate, while the peak-aged Al-Cu-Mg alloy did not show a loss of ductility. To reveal the mechanism of high-resistance to hydrogen embrittlement in the Al-Cu-Mg alloy is important for the elucidation of the hydrogen embrittlement mechanism in aluminum alloys. In this study, an Al-Cu-Mg alloy was subjected to the artificial aging where the aging temperature was lower than usual condition in order to obtain fine and high-density distribution grain boundary precipitates. Hydrogen embrittlement sensitivity was evaluated by means of the slow strain rate tensile testing in humid air and fracture surface observation with a scanning electron microscopy.
