Study on Galvanic Corrosion Behavior of AH36 Steel and TC4 Alloy Processed by Plasma Electrolytic Oxidation

The plasma electrolytic oxidation (PEO) technology was used to prepare ceramic coating on the surface of titanium alloy to prevent the galvanic corrosion of AH36/TC4(PEO). The results showed that after PEO treatment, ceramic coating with micropores was formed on the substrate surface. When the voltage was low, the pore size was small. With the increase of voltage, the thickness and the pore sizes of the coating increased. After PEO process, the average galvanic corrosion rate was reduced by 60%, and the number of pitting pits on the AH36 surface in the galvanic pair was reduced. The tensile strength and elongation of AH36 coupled with TC4(PEO) decreased by 4.0% and 11.9%, respectively. The contents of the corrosion products Fe 2 O 3 ·H 2 O and FeO(OH) decreased, and the corrosion area of the tensile specimen was evidently reduced. Therefore, the PEO process can effectively reduce the galvanic corrosion susceptibility of AH36/TC4(PEO), alleviate the reduction degree of ductility and toughness of anode AH36, and enhance the corrosion resistance performance.