AUTHOR=Wang Jian , Zhang Binbin , Xu Weichen , Zhang Jie , Yang Lihui , Peng Zhongbo , Hou Baorong 

TITLE=Microstructure Refinement on Crevice Corrosion of High-Speed Rail Steel U75V Visualized by an In Situ Monitoring System

JOURNAL=Frontiers in Materials

VOLUME=Volume 8 - 2021

YEAR=2022

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2021.820721

DOI=10.3389/fmats.2021.820721

ISSN=2296-8016

ABSTRACT=Rail foot section covered by fastener will suffer from crevice corrosion, leading to thinning and localized attack of crevice interior posing a risk of failure. This work investigated crevice corrosion behavior of a typical pearlitic high-speed rail steel U75V, focusing for the first time on the effect of pearlitic microstructure refinement achieved by heat treatment with different cooling rates 2 °C/s, 5 °C/s and 10 °C/s. Under anodic polarization, localized dissolved spots were presented on as received sample, where crevice corrosion mostly initiated from. For cooling rates 2 °C/s and 5 °C/s, localized dissolved spots were also observed but crevice corrosion was mostly presented as general corrosion instead of from local spots, ascribed to enhanced tendency of uniform dissolution due to microstructure refinement and homogenization. For cooling rate 10 °C/s, crevice corrosion expanded flocculently, ascribed to preferential dissolution of pearlitic nodules with entangled cementite due to over refinement. Crevice corrosion was obviously accelerated by microstructure refinement. Cooling rates 5 °C/s and 10 °C/s led to fastest and slowest expansion of corroded area respectively, while corrosion depth was just the opposite based on same amount of metal loss. This work provides important information regarding effect of pearlitic microstructure refinement on crevice corrosion and introduces a facile method for in-situ monitoring of crevice corrosion.