目的 改善7050铝合金在湿空气中氢致延迟开裂敏感性高的问题，以延长其使用寿命。方法 采用微弧氧化工艺在铝合金表面生成微弧氧化膜，研究微弧氧化膜对高强铝合金氢致局部塑性变形的影响。通过双悬臂梁（DCB）试样恒位移试验，评价微弧氧化膜对7050铝合金应力腐蚀敏感性的影响，通过读数显微镜原位观察和记录裂纹扩展情况。利用扫描电镜观察断口形貌，采用定氢仪分析氢含量。结果 经过微弧氧化处理后，7050铝合金氢致局部塑性变形行为明显下降。测得有微弧氧化膜试样的应力腐蚀开裂门槛值KISCC为23.340 MPa?m1/2，而无微弧氧化膜试样的KISCC为16.934 MPa?m1/2。有膜的裂纹扩展速率为6.378× 10–6 m/s，无膜的裂纹扩展速率为1.3612×10–5 m/s。同时微弧氧化膜使铝合金DCB试样中氢的体积分数从0.281×10–6下降到0.163×10－6。结论 微弧氧化膜可以降低铝合金裂纹尖端的氢含量，从而抑制铝合金的氢致局部塑性变形。

The work aims to solve the problem of high susceptibility of 7050 aluminum alloy to hydrogen induced delayed cracking in humid air, so as to extend its service life. Micro-arc oxidation (MAO) coating was formed on the surface of 7050 aluminum alloy by micro-arc oxidation process to study the effect of MAO coating on hydrogen induced local plastic deformation in high-strength aluminum alloy. Through the double-cantilever beam (DCB) sample constant displacement test, the effect of the MAO coating on the stress corrosion susceptibility of 7050 aluminum alloy was evaluated, and the crack propagation was in-situ observed and recorded by metallographic microscope and reading microscope. The morphology of the fracture was observed by a scanning electron microscope (SEM), and the hydrogen content was analyzed with a hydrogen analyzer. After MAO treatment, the behavior of hydrogen induced local plastic deformation in 7050 aluminum alloy decreased significantly. The stress corrosion cracking threshold KISCC of the sample with MAO coating was 23.340 MPa?m1/2, while the KISCC of the sample without MAO coating was 16.934 MPa?m1/2. The crack growth rate of the MAO coating sample was 6.378×10–6 m/s, while that of the sample without MAO coating was 1.3612×10–5 m/s. Meanwhile, the hydrogen content in the DCB sample with MAO coating reduced from 0.281×10–6 to 0.163×10–6. The MAO coating can reduce the hydrogen content at the crack tip of aluminum alloy, thus restraining the hydrogen induced local plastic deformation.