中文摘要：

针对7475-T761航空铝合金中心开裂（MT）试样进行了不同温度、不同应力比条件下的一系列疲劳裂纹扩展试验,得到了相应试验条件下的疲劳裂纹扩展数据与规律,讨论了应力比、环境温度对疲劳裂纹扩展行为的影响,并利用扫描电镜（SEM）观测分析了疲劳断口。结果表明：7475-T761铝合金疲劳裂纹扩展速率随应力比、温度的增加而增加;消除裂纹闭合效应影响后,相同温度不同应力比下的da/dN-ΔKeff可由同一拟合公式描述;高温时弹性模量和材料抗拉强度的下降以及裂纹表面氧化导致裂纹扩展速率较快;对比不同条件下稳定扩展区疲劳条带宽度验证了试验分析结论。

英文摘要：

In order to study the fatigue crack growth behavior of 7475-T761 aluminum alloy under various temperatures and stress ratio （R）, fatigue tests of MT specimens were carried out and fatigue fractures morphology were observed by scanning election microscope（SEM）. The results show that the fatigue crack propagation rate increases as the stress ratio and temperature increase; the da/dN--△Keff data under the same temperature but different stress ratios can be described by the same formula after the elimination of crack closure effect; the crack growth rate gets faster as the decrease in elastic modulus and tensile strength, and due to crack surface oxidation; the conclusion of test data analysis is verified through comparing fatigue striation width on stable propagation region under different conditions.