Investigating crevice corrosion behavior of 6061 Al alloy using wire beam electrode

Abstract

In this work, the non-uniform corrosion behavior of 6061 Al alloy in mass 3.5% sodium chloride solution under a crevice spacing of d = 206 μm was studied by using wire beam electrode (WBE) method. The combined tests of the WBE with dynamic potential polarization (Tafel) and electrochemical impedance spectroscopy (EIS) curves were carried out, together with a scanning electron microscope (SEM) and an X-ray photoelectric spectroscope. The results showed that the crevice corrosion was not obvious at the early stage, and the potential of Al alloy in the crevice area was higher than that outside the crevice. With increasing corrosion time, under the combined action of Al2O3, SiO2 and metal chloride gradually formed on the surface of Al alloy, the crevice area was reversed into the anode area, with corrosion current density of 3.399 × 10−4 A cm−2, which gradually showed the characteristics of crevice corrosion. This phenomenon suggested that the corrosion products and surface oxides of Al alloy determined the difference of corrosion behavior between the inside and outside crevice. Thus, it is well proved that the WBE is a feasible method to study corrosion behavior of crevice.