Investigation of the Affected Area of Galvanic Corrosion by Current Measurement Between Sus and Sm/Sma

The ends of steel bridge girders are exposed to severe corrosion environments, such as leakage from the deck, high humidity, and salt deposition. To prevent corrosion, using stainless steel (SUS), which has superior corrosion resistance but is more expensive than mild steel (SM) and weathering steel (SMA), in the girder ends and combined with SM/SMA is considered. However, there is concern about the galvanic corrosion due to contact between SUS and SM/SMA. This study investigates the affected area of galvanic corrosion by measuring electric currents on steel specimens. In addition, rust thickness was measured to clarify the corrosion acceleration and affected areas. The results from the electric current measurements of SUS-SM welded specimens show that electric current was detected between SUS and SM only during the high-humidity cycle. Furthermore, from the current and rust thickness measurements, galvanic corrosion occurred in the SM part next to the welding area. The welding area itself acted as a cathode to the SM part and as an anode to the SUS part. Further research is required to clarify the role of the welding area in the corrosion behavior.