The role of silicon in the corrosion of AA6061 aluminium alloy laser weldments

Abstract The galvanic corrosion temporal increase observed on examination of the weld fusion zone (WFZ) of AA6061 laser weldments in 3.5 wt.% NaCl solution cannot be attributed to electron tunnelling as the surface oxide layer is too thick, or the presence of Cl − within the surface layer as this element was not found to be present. Aluminium alloy and WFZ galvanic and surface analyses indicate that the cathodic WFZ corrosion characteristics are due to increases in silicate concentrations in the surface oxide layer, leading to increased ionic and/or p -type semi-conductor conductivity, intermetallic concentrations and surface area.