电偶腐蚀的微观机理及其对材料性能的影响

为探讨应力和电偶双重因素对2A12合金/45钢腐蚀行为的影响，利用专用的加载装置开展了外加应力作用下偶对2A12合金/45钢在3.5% NaCl溶液中的腐蚀行为研究，利用扫描电镜(SEM)和X射线衍射仪等手段观察了试样腐蚀后的微观形貌特征，并采用拉伸试验研究了电偶腐蚀对2A12合金材料力学性能的影响。结果表明，无外加应力时2A12合金表面的宏观腐蚀形态基本为均匀腐蚀。随着外加应力的增大，点蚀面积增大的同时局部腐蚀向基体内部进一步发展。因此，外加应力是通过改变2A12合金表面的细观组织结构和腐蚀形态来加速偶对中阳极材料2A12合金表面腐蚀的，尤其是促进局部腐蚀加剧向基体内部发展。在此基础上，根据不同腐蚀周期内2A12合金的腐蚀特征和失重率，得到了腐蚀材料性能和寿命预测的数学模型。

Micro-mechanism of Galvanic Corrosion Behavior and Its Effects on Materials' Performance

In order to study the effects of the stress and galvanic factors on the corrosion behavior of 2A12 alloy and 45 steel, a special loading device were applied to investigate the galvanic corrosion between 2A12 alloy and 45 steel under applied tensile stress in neutral 3.5% NaCl solution. The morphology changes on the surface of 2A12 alloy was investigated based on electron microscopy (SEM) and X-ray diffraction (XRD), and the effects of galvanic corrosion on the mechanical properties of 2A12 alloy were investigated using the methods of tensile test. The results show that the morphology of corrosion possess characteristics of uniform pitting corrosion macroscopically however that of localize corrosion microscopically without the effects of external stresses. The pitting corrosion develops into larger dimension and the localized corrosion penetrated into the matrix with the external stress increased. The microcosmic structure and corrosion morphology of 2A12 alloy are changed from the external stress, which may evidently accelerate the galvanic corrosion of anode materials 2A12, especially localized corrosion expanded from the surface into the entrails. Based on the characteristics of corrosion metrics and the weight loss ratio of 2A12 in different external stresses and corrosion time, the forecasting model was established to predict the performance and life.