挤压比对6061铝合金耐腐蚀性能的影响

采用失重法、极化曲线探讨了不同挤压比下6061铝合金在不同环境下的耐腐蚀性能,利用光学显微镜、SEM观察铝合金的显微组织。结果表明:随着挤压比(=18、23、25)的增大,6061铝合金晶粒得到明显细化,经过阳极氧化处理后,铝合金表面形成的阳极氧化膜厚度随着挤压比增大而增加。在3%HCl溶液中,未经阳极氧化处理的铝合金,其耐腐蚀性能随着挤压比的增大而提高;而经过阳极氧化处理后,铝合金表面形成的阳极氧化膜在大的挤压比下更容易破损,耐腐蚀性能反而降低。在3.5%NaCl溶液中,未经阳极氧化处理的铝合金,其耐腐蚀性能随着挤压比增大而降低;经过阳极氧化处理后,挤压比越大,形成的阳极氧化膜越厚,对Cl-的阻挡作用就越明显,耐腐蚀性能也越好。

Effects of Extrusion Ratio on the Corrosion Resistance of 6061 Aluminum Alloy

The effects of extrusion ratio on the corrosion resistance of 6061 aluminum alloy in different condition were studied.The anti-corrosion was evaluated with weight-loss method and potentiodynamic polarization curve,the micro-morphology was analyzed with optical microscope and SEM.The results showed that the grains of 6061 aluminum alloy become finer with the increase of extrusion ratio(=18,23,25).The ply of anodic oxidation film of 6061 aluminum alloy,produced by anodic oxidation,become thicker with the increase of extrusion ratio.After immersion in 3% HCl solution,corrosion resistance of 6061 aluminum alloy,without anodic oxidation process,is improved with he increase of extrusion ratio.The anodic oxidation film of 6061aluminum alloy,produced by anodic oxidation,is much more likely to be damaged in higher extrusion ratio,so the corrosion resistance become worse.In 3.5% NaCl solution,the corrosion resistance of 6061 aluminum alloy,without anodic oxidation process,decreases with he increase of extrusion ratio.The higher extrusion ratio leads to thicker ply of anodic oxidation film of 6061 aluminum alloy,the Cl-can be protected more widely from corroding 6061 aluminum alloy,so the corrosion resistance will increase obviously.