冷复合长寿命钎焊板材的腐蚀机制研究

Study on corrosion mechanism of cold composite long life brazed plate

通过SWAAT模拟海水盐雾腐蚀试验并结合OM、SEM、EDS、EPMA等测量表征技术,研究了冷复合钎焊铝板的腐蚀穿透过程并分析了其实现长寿命耐腐蚀的机理。结果表明:钎焊时芯材中Cu向残留皮材的Al-Si共晶相扩散使其电位升高,导致腐蚀从焊后残留皮材中α-Al相的点蚀开始并伴随Al-Si共晶相脱落。冷复合后的扩散退火和钎焊过程中皮材和芯材元素的互扩散在皮材芯材结合区域形成了一条电位较低的沉淀析出带,腐蚀区延此区域优先发生横向腐蚀继而芯材发生晶间腐蚀至穿透;对比传统半连续铸造铸锭均质热轧复合的钎焊板材,铸轧料冷轧复合的板材具有更优异的耐腐蚀性能。

Through swaat simulated seawater salt spray corrosion test and combined with OM,SEM,EDS,EPMA and other measurement and characterization techniques,the corrosion penetration process of cold composite brazed aluminum plate was studied and the mechanism of long life corrosion resistance was analyzed.The results show that the diffusion of Cu from the core to the Al Si eutectic phase of the residual skin increases the potential,which leads to the corrosion starting from the pitting of theα-al phase in the residual skin and accompanied by the fall off of the Al Si eutectic phase.In the process of diffusion annealing and brazing after cold compounding,the mutual diffusion of skin and core elements forms a precipitation strip with low potential in the joint area of skin and core,and the corrosion zone is extended in this area,and transverse corrosion takes place preferentially,then intergranular corrosion and penetration take place in the core;compared with the traditional semi continuous casting ingot homogeneous hot rolling composite brazing plate,the cold rolling composite plate of cast rolling stock has more Excellent corrosion resistance.