首页|Q235钢结构件表面热镀锌层的应力腐蚀及其机理

Q235钢结构件表面热镀锌层的应力腐蚀及其机理

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采用自制的三点弯曲应力加载装置及浸泡腐蚀实验方法,开展电网设备常用的Q235镀锌钢结构件表面镀锌层应力腐蚀行为的研究.结果表明,Q235钢板镀锌层表面应力腐蚀是ZnO、Zn(OH)2和Zn5(OH)8Cl2·H2O等腐蚀产物的形成(明显的腐蚀坑)、脱落(无明显腐蚀坑)、再形成、再脱落的过程.随着外加应力的增大,Q235钢板镀锌层腐蚀表面的Ecorr降低,Icorr增大,电化学阻抗减小,应力腐蚀程度增加,形成更多Zn5(OH)8Cl2·H2O腐蚀产物.建立了Q235钢板镀锌层应力腐蚀模型,阐明其应力腐蚀过程及机理.外加应力在η-Zn层中腐蚀坑应力集中部位诱发应力腐蚀裂纹,突破η-Zn层,并沿ζ-FeZn13/η-Zn界面扩展,加剧镀锌层的电化学腐蚀过程.
Stress Corrosion and Its Mechanism of Hot-dip Galvanized Coating on Q235 Steel Structure
The corrosion behavior of hot-dip galvanized coating on the Q235 steel plates commonly-used in grid equipment by applied bending stress was studied via immersion test in 0.05 mol/L NaCl solu-tion while applied bending stress with a home-made three-point bending stress loading device.The re-sults showed that by the applied bending stress,the corrosion of the hot-dip galvanized coating on Q235 steel plate was a process of repeated formation and spallation of corrosion products,of which the former involves apparently the occurrence of corrosion pits,while the later does not.The corrosion products were mainly composed of ZnO,Zn(OH)2 and Zn5(OH)8Cl2·H2O.As the applied stress increased,the Ecorr was decreased,but the Icorr and the electrochemical impedance were increased for the hot-dip galvanized coating on Q235 steel plate.A corrosion model was established to illustrate the corrosion process and the relevant mechanism for the corrosion of the hot-dip galvanized coating/Q235 steel plate.That is,the corrosion of the hot-dip galvanized coating was speeded by the applied bending stress to form more cor-rosion product Zn5(OH)8Cl2·H2O,which induced the formation of cracks at the stress concentrated sites beneath the corrosion product,i.e.,the corrosion pits in η-Zn layer.The cracks then penetrated through the η-Zn layer,and extended along the interface ζ-FeZn13/η-Zn.As a result,electrochemical corrosion of the galvanized coating was accelerated.

Q235 steel structurehot-dip galvanized layerstress corrosionmicrostructurecorro-sion mechanism

赵骞、张洁、毛锐锐、缪春辉、卞亚飞、滕越、汤文明

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国网安徽省电力有限公司电力科学研究院 合肥 230601

合肥工业大学材料科学与工程学院 合肥 230009

Q235钢结构 热镀锌层 应力腐蚀 显微组织 腐蚀机理

国网安徽省电力有限公司科技项目

B3120522001G

2024

中国腐蚀与防护学报
中国腐蚀与防护学会 中国科学院金属研究所

中国腐蚀与防护学报

CSTPCD北大核心
影响因子:0.819
ISSN:1005-4537
年,卷(期):2024.44(5)