粗糙度和金属间化合物粒子对A6111铝合金表面腐蚀的影响

Effect of Roughness and Intermetallic Particles on Surface Corrosion of A6111 Alloy

摘要:

钎焊铝蜂窝夹层结构板常用于高速列车的地板和船舶的甲板。其中四层铝复合板（4343/3003/6111/3003）作为该蜂窝结构的面板常暴露于腐蚀性环境中。经过成分优化的6111铝合金作为四层铝复合板的主要支撑层材料，其组织结构和表面状态对腐蚀 性能有很大影响。采用不同粒度的砂纸磨削6111铝合金，研究了不同程度磨削后6111铝合金的微观组织和表面腐蚀行为。结果表明：6111合金中的AlFeSi(Mn, Cu)相的电位高于基体电位，这种相作为阴极与相邻基体形成多级体系，加剧了表面腐蚀。同时，较光滑的表面具有更好的耐腐蚀性。当表面粗糙度从18.03 μm降至0.92 μm时，表面几何体积由0.629 mm³减少至0.029 mm³，金属间化合物AlFeSi(Mn，Cu)粒子的平均数量由1631 mm^-2减少至917 mm^-2，其面积分数由3.93%降至0.92%。相应地，平均腐蚀深度由237 μm降至95 μm。

Abstract:

Four-layer aluminum brazing sheets (4343/3003/6111/3003) with honeycomb sandwich structure are used as candidates for floor of high-speed train and ship deck, which are often exposed to corrosive environments. Microstructure and surface conditions of optimized 6111 aluminum alloy, which serves as the main support layer of this four-layer brazing sheet, have a great effect on the corrosion properties, which were investigated by a set of 6111 aluminum alloy ground with sandpaper of different grits. The results show that the AlFeSi(Mn, Cu) phase acts as cathode, due to its higher potential than that of the matrix, and forms a multi-stage system with adjacent matrix, which aggravates the surface corrosion. A smoother surface exhibits better corrosion resistance. Specifically, when lowering surface roughness from 18.03 μm to 0.92 μm, the surface volume decreases from 0.629 mm³ to 0.029 mm³, and the average number of intermetallic particles AlFeSi (Mn, Cu) is reduced from 1631 mm^-2 to 917 mm^-2, with area fraction decreasing from 3.93% to 0.92%. As a consequence, the average corrosion depth decreases from 237 μm to 95 μm.