Abstract
The tensile and stress corrosion tests were made on the Al-8%Mg alloy aged at 200°C for various periods after aging at 150°C for 24hr followed cold rolling by 0.30 and 50%. The stress corrosion behavior was tested in the 3.5% NaCl solution by loading of 80% of 0.2% proof stress of the alloy with the anodic current of 5mA/cm2. The two-step aging is not effective, but the thermomechanical treatment is effective in strengthening of the alloy. The effect of thermomechanical treatment is due to a synergetic effect of refining the structure of precipitates and presence of dislocations. The stress corrosion susceptibility is improved especially in the overaging state. This is also due to refinement of the precipitates in the matrix. It seems that presence of stabilized dislocation structure slows down propagation of cracks by affecting the mechanism of embrittling of the grain boundary area.
