The Role of the Direct Current Electric Field in Enhancing the Protective Rust Layer of Weathering Steel

This study aims to generate a protective rust layer for weathering steel (WS) via controlling the direct current electric field (DCEF). The results show that the DCEF accelerates the corrosion kinetics for WS which can be segmented into three stages: the corrosion rate sharp increase stage, the corrosion rate reduction stage, and the corrosion rate tends to be stable stage. For the corrosion process, the DCEF promotes the migration of ions and shifts the electrode potential negatively to accelerate the corrosion reaction in the initial stage. Meanwhile, the DCEF promotes the growth of γ -FeOOH and inhibits the transition of γ -FeOOH to α -FeOOH. When the DCEF is removed in a certain corrosion process, the corrosion rate rapidly steps into the corrosion rate reduction stage to generate a protective rust layer which develops a new green pre-rusting method for WS engineering application.