Microstructure and Corrosion Characteristics of Aluminum Alloy High Voltage Isolation Switch Parts Applied in Offshore Environment with SO₂

The microstructure and corrosion characteristics of 2A12-T4 aluminum alloy high voltage isolation switch parts used in offshore environment with SO₂ were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the grains of 2A12-T4 aluminum alloy were elongated along the deformation direction, and a certain number of sub-crystals formed. The main second phase was T phase surrounded by a mass of dislocations. The main corrosion products of 2A12-T4 aluminum alloy were Al(OH)₃ and Al₂(SO₄)₃·14H₂O. The corrosive behavior was mainly controlled by Cl^- and SO₂ in moist environment. Additionally, the deformed elongated grains and the second phase particles accelerated the corrosion.