Crevice corrosion of U75V high-speed rail steel with varying crevice gap size by in-situ monitoring
Weichen Xu, Yu Deng, Binbin Zhang, Jie Zhang, Zhongbo Peng, Baorong Hou, Jizhou Duan
Abstract
Crevice corrosion of high-speed rail steel U75V was studied with varying gap size by using self-designed device. Increasing gap size inhibited exterior cathodic reduction reaction of oxygen, inducing decrease of potential difference between interior and exterior. Gap size decrease after increase induced increase of potential difference after decrease, not completely reversible because rust kept expanding, acting as weaker depolarizer than oxygen. Anodic dissolution of interior was under ohmic-control, fastest near crevice mouth and slowest near but not at deepest site. Corrosion initiation was observed, closely related to pearlite nodules with larger interlamellar spacing and different lamellar directions, inducing deep attack.