Q235钢结构件表面热镀锌层的应力腐蚀及其机理  

Stress Corrosion and Its Mechanism of Hot-dip Galvanized Coating on Q235 Steel Structure

作　　者：赵骞 张洁 毛锐锐 缪春辉 卞亚飞 滕越 汤文明[2] ZHAO Qian;ZHANG Jie;MAO Ruirui;MIAO Chunhui;BIAN Yafei;TENG Yue;TANG Wenming(Electric Power Research Institute,Anhui Electric Power Co.,Ltd.,State Grid,Hefei 230601,China;School of Materials Science and Engineering,Hefei University of Technology,Hefei 230009,China)

机构地区：[1]国网安徽省电力有限公司电力科学研究院,合肥230601 [2]合肥工业大学材料科学与工程学院,合肥230009

出　　处：《中国腐蚀与防护学报》2024年第5期1305-1315,共11页Journal of Chinese Society For Corrosion and Protection

基　　金：国网安徽省电力有限公司科技项目(B3120522001G)。

摘　　要：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Zn_(5)(OH)_(8)Cl_(2)·H_(2)O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E_(corr)降低,I_(corr)增大,电化学阻抗减小,应力腐蚀程度增加,形成更多Zn_(5)(OH)_(8)Cl_(2)·H_(2)O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-FeZn_(13)/η-Zn界面扩展,加剧镀锌层的电化学腐蚀过程。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 solution while applied bending stress with a home-made three-point bending stress loading device.The results 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 Zn_(5)(OH)_(8)Cl_(2)·H_(2)O.As the applied stress increased,the E_(corr) was decreased,but the I_(corr) 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 corrosion product Zn_(5)(OH)_(8)Cl_(2)·H_(2)O,which induced the formation of cracks at the stress concentrated sites beneath the corrosion product,i.e.,the corrosion pits inη-Zn layer.The cracks then penetrated through theη-Zn layer,and extended along the interfaceζ-FeZn_(13)/η-Zn.As a result,electrochemical corrosion of the galvanized coating was accelerated.

关 键 词：Q235钢结构 热镀锌层 应力腐蚀 显微组织 腐蚀机理 

分 类 号：TG174.3[金属学及工艺—金属表面处理]