Stress corrosion behavior and microstructure analysis of Al-Zn-Mg-Cu alloys friction stir welded joints under different aging conditions

The friction stir welding joints of Al-Zn-Mg-Cu alloy were prepared, then their stress corrosion evolution during slow strain rate tensile testing was studied by in-situ electrochemical impedance spectroscopy. Slow stress corrosion process can be divided into three stages according to the corrosion trend, the corresponding charge-transfer resistance also shows three evolutionary patterns. Grain boundary precipitates in thermal machine affected zone (TMAZ) of the pre-weld RRA treatment are more discrete and coarser, and have a higher Cu content than those of pre-weld double-stage aging treatment TMAZ, which reducing the potential difference with the surrounding substrate and exhibiting higher stress corrosion resistance.

Automated summary

The stress corrosion evolution of friction stir welding joints of Al-Zn-Mg-Cu alloy was studied during slow strain rate tensile testing using in-situ electrochemical impedance spectroscopy. The slow stress corrosion process can be divided into three stages based on the corrosion trend, with corresponding charge-transfer resistance showing three evolutionary patterns. The grain boundary precipitates in the thermal machine affected zone (TMAZ) of the pre-weld RRA treatment are more discrete and coarser, with a higher Cu content, reducing the potential difference with the surrounding substrate and exhibiting higher stress corrosion resistance.