Corrosion Behavior of Q345q Steel with Oxide Scale in Simulated Typical Atmospheric Environmentin Northwest China
Chinese Journal of Materials Research. 2019, 33 (
The structure of the oxide scale on the as received hot-rolled bridge steel Q345q and the corrosion behavior of the steel Q345q with oxide scale in three simulated atmospheric environments in Northwest China were studied by XRD, scanning electron microscopy, electrochemical technique and wet-dry alternating corrosion test. The results show that the hot-rolled oxide scale composes mainly of Fe
3O 4 and Fe 2O 3, which is porous with cracks and other defects. After the dry-wet alternating accelerated corrosion test of the steel Q345q with oxide scale, although the corrosion weight loss is the highest in NaHSO 3 solution, the free-corrosion potential increases with the corrosion time, and the free-corrosion current density decreases in the later stage of corrosion. As far as the morphology of the rust layer and the ratio of γ/ α* are concerned, the rust layer formed on the steel presents good stability; However, in deicing salt solution, the corrosion rate is the smallest, but the steel suffered mainly from Cl --dominated pitting corrosion with the corrosion characteristics of "large cathode and small anode". Its corrosion products contain such as β-FeOOH and HFeCl 4(H 2O) 6, which results in loose rust layer with poor protectiveness and increased free-corrosive current density; In deicing salt+NaHSO 3 solution, both pitting corrosion and general corrosion occur. Due to the synergistic effect of Cl - and HSO 3 -, the autocatalytic effect of a part of Cl - is reduced, but most α-FeOOH is converted from β-FeOOH, which resulted in the poor protective rust layer.
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