Tadakazu Ohnishi1, Kenji Higashi2 and Yoshizo Nakatani1
1College of Engineering, University of Osaka Prefecture, Sakai
In the conventional aging of Al-8%Mg alloy, the hydrogen embrittlement and the decrease of stress corrosion cracking life by hydrogen permeation are markedly produced in the hardening region of aging process. The step aging hardly alters these behaviors, because this treatment brings about an insignificant change in the microstructure. The thermo-mechanical treatment effectively depresses the embrittlement and the decrease of life by hydrogen permeation over the whole range of testing conditions used in this study. This effect seems to be attributable to a depression of precipitation in the grain boundary at the final aging and to an introduction of the dislocation structure by the intermediate deformation. The effect of dislocation structure and the role of dislocation movement in the hydrogen transport to the critical region of cracking are discussed.
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