两种典型大气环境下7A85铝合金的腐蚀行为研究

Corrosion Behavior of 7A85 Aluminum Alloy in Two Typical Atmospheric Environments

目的研究湿热海洋、干热沙漠两种典型大气环境对7A85铝合金腐蚀行为的影响。方法在万宁、敦煌两种典型环境中开展7A85铝合金大气暴露试验,利用金相显微镜分析7A85铝合金在我国两种典型大气环境中的腐蚀特征,定期测试该材料的拉伸强度和腐蚀深度。结果暴露3 a,7A85铝合金湿热海洋、干热沙漠两种典型大气环境中的最大腐蚀深度分别为254、90μm,抗拉强度分别下降了18%和5%,断后伸长率分别下降了72%和22%。结论 7A85铝合金暴露于相对湿度较低的干热沙漠环境,表面形成的腐蚀产物膜会阻止腐蚀的进一步发生;暴露于湿热海洋大气环境,随暴露时间的延长,7A85铝合金腐蚀逐渐加深。

The paper aims to research influences of two typical atmospheric environments of damp hot ocean and dry-heat desert on corrosion behavior of 7 A85 aluminum alloy. Atmospheric exposure tests of 7 A85 aluminum alloy were carried out in Wanning and Dunhuang. The corrosion characteristics of 7 A85 aluminum alloy in two typical atmospheric environments were investigated by metallographic microscope. The tensile strength and corrosion depth of the material were tested regularly. After 7 A85 aluminum alloy was exposed for 3 years in damp hot ocean atmospheric environment and dry heat desert atmospheric environment, the maximum corrosion depth was 254 μm and 90 μm respectively;the tensile strength was reduced by 18% and 5% respectively;and the elongation after fracture was reduced by 72% and 22% respectively. If 7 A85 aluminum alloy is exposed in dry-heat desert environment with low relative humidity, the further corrosion would be prevented by the corrosion product film formed on the surface. The corrosion of 7 A85 aluminum alloy exposed to the damp hot ocean environment will be gradually deepened with the extension of the exposure time.