轧制温度对AZ61镁合金耐腐蚀性的影响

Effect of rolling temperature on the corrosion resistance of AZ61 magnesium alloy

  • 摘要: 采用金相显微镜、X射线衍射仪、极化曲线、电化学阻抗谱和浸泡实验对轧后(轧制温度分别为:300、350、380、400 ℃)AZ61镁合金分别进行了微观表征和性能测试。研究了轧制温度对AZ61镁合金微观组织的影响及对耐腐蚀性的遗传效应,明确了轧制温度与耐腐蚀性之间的映射关系。结果表明:随着轧制温度的升高,AZ61镁合金的晶粒尺寸先减小后增大,β相含量先减小后增加再减小,其耐腐蚀性先升高后降低再升高;AZ61镁合金的腐蚀行为呈先局部点蚀,然后以“丝状”扩展为面蚀;当轧制温度为350 ℃时,AZ61镁合金的晶粒尺寸最小且β相含量最少,此时合金具有较好的耐腐蚀性,其极化电阻高达530.970 Ω·cm2,腐蚀电位φcorr为-1.470 V,腐蚀电流密度Jcorr为8.415×10-6 A/cm2,平均腐蚀速率低至1.14×10-4 g/(cm2·h)。

     

    Abstract: The microstructure and properties of AZ61 magnesium alloy after rolling (rolling temperature: 300, 350, 380 and 400 ℃) were characterized and tested by metallographic microscopy, X-ray diffraction, polarization curves, electrochemical impedance spectroscopy and immersion tests, respectively. The influence of the rolling temperature on the microstructure of AZ61 magnesium alloy and the genetic effect of the temperature on the corrosion resistance were studied, and the mapping relationship between its rolling temperature and corrosion resistance was clarified, respectively. The results showed that with increasing rolling temperature, the grain size of the AZ61 magnesium alloy first decreased and then increased, the content of the β phase decreased first, then increased, and then decreased, and its corrosion resistance increased first, then decreased, and then increased. The corrosion behavior of the AZ61 magnesium alloy was first localized pitting corrosion and then extended to surface corrosion. When the rolling temperature was 350 ℃, the grain size of the alloy was the smallest, the content of the β phase was the lowest, and the alloy had the best corrosion resistance at this time. The polarization resistance was as high as 530.970 Ω·cm2, the corrosion potential was -1.470 V, the corrosion current density was 8.415×10-6 A/cm2, and the average corrosion rate was as low as 1.14×10-4 g/(cm2·h).

     

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