预变形量对2519铝合金抗剥落腐蚀性能的影响

Effect of predeformation amount on exfoliation corrosion resistance of 2519 aluminium alloy

采用金相观察、硬度测试与透射电镜等方法,研究了时效前冷轧预变形量对2519铝合金晶界无沉淀带及析出相大小、分布和抗剥蚀性能的影响。结果表明当预变形量由0%增至25%时,合金的硬度值增加且到达峰值时效时间缩短,晶界无沉淀带宽度减小,晶内析出相尺寸相应减小并趋于弥散分布。同时合金抗剥落腐蚀性能呈先下降后上升的趋势,其中预变形量为5%与15%的合金在晶粒扁平度增大以及不溶产物产生的楔应力共同作用下,抗剥蚀性能最差,剥蚀等级为E-C级,25%的合金次之(EB+),0%变形量的合金剥蚀等级为EB-。

By means of hardness tests, optical microscopy(OM) and transmission electron microscopy(TEM),effect of the amount of deformation before ageing on microstructure and exfoliation corrosion resistance of 2519 alloy was investigated.The results show that with increasing predeformation amount, the hardness is enhanced and time to peak ageing is shortened due to the decreasing width of precipitation free zones (PFZ) along grain boundaries and the decrease of size of homogeneous distributed precipitates in the matrix. Meanwhile ratings of exfoliation corrosion of specimens are reduced first and then increased. Specimens with deformation reduction 5% and 15% have the worst resistance to exfoliation corrosion resulting from co-effects of higher grain aspect ratio and wedge force from insoluble corrosion products, while a better resistance against exfoliation corrosion can be expected for speciment with rolling reduction 25% and the best anti-corrosion performance is observed for the specimen with 0% predeformation.