APPLICATION OF POTENTIOSTATIC AND GALVANOSTATIC TECHNIQUES TO THE STUDY OF INTERGRANULAR CORROSION IN HIGH STRENGTH ALUMINUM ALLOYS.

The effect of slow quenching following solution heat treatment on naturally aged Al-Cu-Mg alloy can be detected by corrosion potentials and accelerated corrosion tests for intergranular corrosion and stress corrosion susceptibility. Faster quenching rates give no indication of the existence of any continuous anodic paths until a stress is applied. A possible mechanism for this is proposed based on the electrochemical effect of stress which is believed to be the result of strain induced depolarization of the anodic phase or phases and stress induced increase in the surface activity of hydrogen ions. Author