湿热环境中汽车板表面腐蚀萌生与表面轮廓特征的关系

目的探究储运过程中深冲用汽车板表面轮廓对其耐蚀性能的影响。方法在模拟的高温高湿腐蚀环境中研究两类无间隙原子钢在其腐蚀初期表面锈点的萌生规律,并采用白光干涉轮廓仪对钢板的表面形貌特征进行表征,探究影响储运过程中汽车板耐蚀性能的表面状态因素。结果仅通过平均粗糙度Sa的差异无法区分具有不同表面轮廓特征的汽车板,因此也无法使用平均粗糙度参数Sa预估汽车板的耐蚀性能。在锈点萌生初期,汽车板表面轮廓的最大高度Sz和最大峰高Sp值的大小直接影响表面电化学活性。在锈点扩展阶段,汽车板表面波峰聚集程度的作用对锈点扩展的影响更为显著。结论 Sz和Sp越大,锈点萌生的速度越快;波峰聚集程度越高,锈点扩展速度越快。该研究结果为提高钢板表面耐蚀性能提供了一条新的思路。

Relationship between Corrosion Initiation and Surface Morphology of Automotive Sheet in High Temperature and Humidity Environment

The work aims to explore the influence of surface morphology on the corrosion resistance of automotive sheet in storage and transportation. The initiation laws of rust points of two kinds of interstitial free (IF) steel exposed to the simulated high-temperature and humidity environment were investigated in the early corrosion stage and the surface morphology of automotive steel sheet was characterized by white-light interferometer to explore the surface factors affecting the corrosion resistance of automotive sheet during storage and transportation. The automotive sheets with different surface morphology features could not be characterized solely by the average roughness parameter Sa. Thus, the corrosion resistance of automotive steel sheet could not be evaluated by Sa. Moreover, the surface electrochemical activity directly depended on the maximum peak height Sp and maximum valley depth Sv of IF steel surface in the initiation stage. In the stage of rust point expansion, the peak aggregation degree on the surface of automotive sheet had a more significant effect on rust point expansion. The larger the values of Sp and Sv are, the greater the speed of rust point initiation is. The higher aggregation degree of peak is, the greater the speed of rust point propagation is. The results are anticipated to provide a new perspective and possibility for enhancing the corrosion resistance of automotive sheet.