Crevice–galvanic coupling corrosion behavior and mechanism of QC-10 aluminum alloy in chloride-containing solutions

Abstract

The aluminum alloy–steel hybrid structures offer numerous advantages, including lightweight and flexibility. However, the contact between aluminum alloy and steel is prone to cause serious local corrosion. To further reveal the corrosion mechanism at the contact region of aluminum alloy/steel, this paper investigates the crevice corrosion of QC-10 aluminum alloy and the crevice–galvanic coupling corrosion of QC-10 aluminum alloy/S50C steel, explores the synergistic effect of different crevice height, pH and Cl⁻ concentration on the corrosion behavior of QC-10 aluminum alloy by electrochemical experiments, immersion corrosion experiments and microscopic morphology characterization. The results demonstrate that the crevice corrosion of aluminum alloy decreases with the increase of crevice height, and there exists a critical crevice height for the occurrence of crevice corrosion. In the aluminum alloy–steel hybrid structure, the galvanic effect accelerates the crevice corrosion of aluminum alloy, and the corrosion products of steel embedded in the aluminum alloy oxide film decrease the corrosion resistance of the aluminum alloy. Additionally, the corrosion products of steel alter the crevice solution compositions, while intensifying the crevice corrosion of aluminum alloy. It is concluded that reasonable control of the crevice height and the inhibition of the corrosion of steel are effective methods to improve the corrosion resistance of aluminum alloy–steel hybrid structures.