摘要： 【目的】针对当前车门包边处腐蚀问题日益凸显，锌铝镁镀层钢板在车门内板包边位置频发丝状腐蚀的问题，通过系统评价该镀层钢板的耐腐蚀性，阐明丝状腐蚀的诱发机理并提出高效防控技术方案。【方法】从均匀腐蚀、锐边腐蚀、缝隙腐蚀 3个方面，对锌铝镁镀层钢板开展耐腐蚀性测评；结合实际应用工况，重点分析包边结构特性、材料表面状态及环境作用因素，探究丝状腐蚀的形成原因。【结果】锌铝镁镀层中存在电化学电位差，加上车门包边处折边胶填充不密实的结构缺陷，以及包边空腔内残留酸性电解质，三者在高温高湿环境下共同作用，最终触发丝状腐蚀；采用空腔满胶密封、提升前处理膜层质量、避免使用乙酸、喷涂防腐蜡等组合防护措施，可显著降低该腐蚀问题的发生率。【结论】锌铝镁镀层钢板的耐腐蚀性需通过多维度综合评价界定，其车门内板包边的丝状腐蚀是电化学电位差、折边胶填充缺陷、前处理膜质量、介质残留及环境因素共同作用的结果，采用针对性组合防护技术可有效提升该部位的防腐性与服役寿命。

关键词: 锌铝镁镀层钢板, 车门内板, 缝隙腐蚀, 丝状腐蚀

Abstract: ［Objective］In response to the increasingly prominent corrosion issue at door hemming positions，this study focuses on the frequent filiform corrosion failures of zinc-aluminum-magnesiumcoated steel sheets at the hemming of door inner panels. It aims to systematically evaluate the corrosionresistance of the coated steel sheets，clarify the induction mechanism of filiform corrosion，and propose efficient prevention and control technical schemes.［Methods］ Systematic corrosion resistance assessment of zinc-aluminum-magnesium coated steel sheets was conducted from three core dimensions：uniform corrosion，sharp-edge corrosion，and crevice corrosion. Combined with actual service conditions，the structural characteristics of the hemming，material surface state，and environmental factors were analyzed emphatically to explore the formation path of filiform corrosion in depth.［Results］ There exists an electrochemical potential difference in the zinc-aluminum-magnesium coating. Combined with the structural defect of insufficiently filled hemming adhesive at the door hemming and poor quality of the pretreatment film，acetic acid medium remains in the hemming cavity. These three factors act synergistically in a high-temperature and high-humidity environment，ultimately triggering filiform corrosion. The adoption of combined protective measures such as full-cavity adhesive sealing，improving the quality of the pretreatment film，removing residual acetic acid，and spraying anti-corrosion wax can significantly reduce the incidence of this corrosion problem.［Conclusion］The corrosion resistance of zinc-aluminum-magnesium coated steel sheets should bedefined through multi-dimensional comprehensive evaluation. The filiform corrosion at the hemming ofdoor inner panels is the result of the combined action of electrochemical potential difference，hemming adhesive filling defects，pretreatment film quality，medium residue，and environmental factors. The application of targeted combined protective technologies can effectively improve the corrosion reliabilityand service life of this key position.

Key words: zinc-aluminum-magnesium coated steel plate, door inner panel, crevice corrosion, filiform corrosion

中图分类号: 

• TQ630. 4