Macro and microgalvanic interactions in friction stir weldment of AA2198-T851 alloy

Abstract

The galvanic interactions within and between the friction stir weld zones of the AA2198-T851 alloy have been investigated using electrochemical and microscopy techniques. The parent material (PM) was the most anodic region and exhibited pronounced severe localized corrosion (SLC) both when coupled and isolated. The stir zone was the most resistant to corrosion and exhibited no SLC when coupled, but exhibited SLC when isolated. Profiles associated with dissolved oxygen consumption and hydrogen generation currents across the weldment were inversely related because the anodic (PM) region produced higher hydrogen bubbles and, interestingly, consumed more dissolved oxygen compared with the other regions. Keywords: Aluminium, Polarization, SEM, Pitting corrosion, Oxygen reduction, Friction stir welding