2297-T87铝锂合金用于大气腐蚀性的比较

目的利用铝锂合金的大气腐蚀试验结果评价大气腐蚀性。方法对第三代铝锂合金2297-T87在6个自然环境试验站户外暴露后的腐蚀质量损失、腐蚀速率、腐蚀深度、拉伸性能进行分析,综合评价各地区大气腐蚀性。结果2297-T87铝锂合金在团岛、万宁、永兴岛暴露1年后出现显著腐蚀,腐蚀质量损失和腐蚀速率约为江津的2倍、西双版纳的4倍,北京的腐蚀质量损失和腐蚀速率最低。合金最大腐蚀深度的变化趋势与腐蚀质量损失和腐蚀速率的变化趋势一致。观察横截面发现,在万宁、永兴岛、江津暴露后,合金发生严重的点蚀,在腐蚀产物覆盖区域下方形成不规则蚀坑,而在团岛暴露后,合金内部发生晶间腐蚀。合金在江津、永兴岛、万宁、团岛暴露后的拉伸性能仍比较接近,且拉伸强度保持率在90%以上。结论将2297-T87铝锂合金暴露1年后的腐蚀质量损失、腐蚀速率、腐蚀深度作为表征指标,获得各试验站的大气腐蚀性顺序为:北京<西双版纳<江津<永兴岛<万宁<团岛。

Comparison of Atmospheric Corrosivity of 2297-T87 Al-Cu-Li Alloy

The paper aims to evaluate the atmospheric corrosivity by the results of atmospheric corrosion testing of Al-Cu-Li alloy. Corrosion weight loss, corrosion rate, corrosion depth and tensile properties of a 3rd generation Al-Cu-Li alloy 2297-T87 after outdoor exposure in six natural environmental test sites were analyzed to systematically evaluate the atmospheric corrosivity in different regions. Corrosion was evident in 2297-T87 Al-Cu-LI alloy after exposure in Tuandao, Wanning and Yongxing Island. The corresponding corrosion weight loss and corrosion rate were approximately 2 times of those in Jiangjin, and 4 times of those in Xishuangbanna. Corrosion weight loss and corrosion rate in Beijing were the lowest. The changing trend of maximum corrosion depth of the alloy was in line as the corrosion weight loss and corrosion rate. Cross-sectional examination revealed severe pitting in the alloy after exposure in Wanning, Yongxing Island and Jiangjin with irregular pits formed underneath the corrosion product region. Intergranular corrosion was evident in the alloy after exposure in Tuandao. The tensile properties of alloy in Jiangjin, Yongxing Island, Wanning and Tuandao were similar and the tensile stress retention was over 90%. Using corrosion weight loss, corrosion rate and corrosion depth as characterization index, the sequence of atmospheric corrosivity in different test sites is determined as Beijing < Xishuangbanna <Jiangjin < Yongxing Island < Wanning < Tuandao.