Variations of galvanic currents and corrosion forms of 2024/Q235/304 tri-metallic couple with multivariable cathode/anode area ratios: Experiments and modeling

• DOI: 10.1016/j.electacta.2020.136947
• Publication Date: 2020-08-15T12:35:21Z
• Authors: Linjun Shi; Yingwei Song; Pingping Zhao; Haitao Wang; Kaihui Dong; Dayong Shan; En-Hou Han
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract Tri-metallic galvanic corrosion is inevitable in practical applications, but relevant investigations are far from sufficient. In this study, a mathematical model based on the Butler-Volmer equation and a finite element model (FEM) of tri-metallic galvanic corrosion were built and validated, which can reasonably predict galvanic corrosion of tri-metallic couples. Simulation and experimental results indicate that galvanic current density and galvanic potential of the tri-metallic couple of 2024 aluminum alloy/Q235 carbon steel/304 stainless steel change with the cathode/anode area ratios in a power function relationship and logarithmic relationship, respectively in 3.5 wt% NaCl. Besides, galvanic corrosion not only accelerates the dissolution of 2024 Al alloy but also transforms its corrosion form. The uncoupled 2024 Al alloy presents pitting corrosion, but the coupled 2024 Al alloy shows typical intergranular corrosion (IGC) morphology.