Effect of ECAP and Heat-treatment on Pitting Corrosion Behavior of Industrial Pure Iron

• Main Authors: ZHANG Liu-yan, MA Ai-bin, JIANG Jing-hua, YU Hai-bin, WU Hui-shu
• Format: Article
• Language: zho
• Published: Journal of Materials Engineering 2016-11-01
• Series: Journal of Materials Engineering
• Subjects: ECAP; heat-treatment; industrial pure iron; pitting corrosion behavior
• Online Access: http://jme.biam.ac.cn/CN/10.11868/j.issn.1001-4381.2016.11.011
• ISSN: 1001-4381; 1001-4381

In order to guide a reasonable application of the bulk ultrafine-grained industrial pure iron, a serious of ultrafine-grained pure iron samples with different microstructures were fabricated by multi-passes ECAP and heat-treatment, and their microstructures and pitting corrosion behaviour were investigated by transmission electron microscopy (TEM), electrochemical polarization and impedance spectroscopy (EIS) techniques, respectively. Results show that:with the increase of ECAP passes, lath-shaped structure with high dislocation density transforms into equiaxed grains with low dislocation density; the dislocation density decreases and the high-angle grain boundaries increase, after the annealing treatment. ECAP passes have less effect on the self-passivation of pure iron, and its open circuit potential (OCP) and polarization resistance are less changed; the pitting corrosion resistance of the ECAPed pure iron is related to the ECAP passes:the pitting potential first decreases and then increases with the increase of ECAP passes; the self-passivation property and pitting corrosion resistance of the ECAPed pure iron are improved after the annealing heat-treatment, the OCP, polarization resistance and pitting potential values increase obviously.