The 7xxx series of aluminium alloys are sensitive to intergranular hydrogen environmentally assisted cracking (HEAC) in moist air environments. A new generation of 7xxx alloys used in aircraft components (including AA7449) have been found to be more sensitive to HEAC. This investigation aims to quantify the HEAC crack growth rates of AA7449-T7651 in moist air at different temperatures. Double cantilever beam specimens were loaded at a constant displacement and placed in moist air (80–85% relative humidity) at temperatures between 25 and 80 $°$C. Regular measurements of crack length permitted the determination of the crack growth rate as a function of the stress intensity factor ($K_I$) during stage I (high $K_I$ dependence of growth rate) and stage II (low $K_I$ dependence of growth rate). Increasing the temperature was found to increase the crack growth rate during stage II cracking, following Arrhenius kinetics. The activation energy for the stage II crack growth rate at a stress intensity factor of 14.5 MPa$\sqrt{\mathrm{m}}$ was estimated as 84.7 kJ/mol. Additionally, the threshold stress intensity factor for HEAC was found to decrease with increasing temperature. This was attributed to a higher hydrogen solubility at higher temperatures. The crack growth rate of AA7449-T7651 at room temperature was similar to that of overaged AA7050 and AA7075-T7651, ranging between 1.3 and 2.1 $\times$ 10${}^{-7}$ mm/s. It was inferred that the alloy temper has more influence than the composition during stage II cracking at room temperature.

7xxx系列铝合金对潮湿空气环境中的晶间氢环境辅助开裂（HEAC）敏感。发现用于飞机部件（包括AA7449）的新一代7xxx合金对HEAC更为敏感。这项研究旨在量化AA7449-T7651在潮湿空气中不同温度下HEAC裂纹的生长速率。双悬臂梁试样以恒定位移加载，并置于温度介于25至80之间的潮湿空气（相对湿度80-85％）中 $°$C.定期测量裂纹长度可以确定裂纹扩展速率与应力强度因子的关系（${ķ}_{\mathrm{一世}}$）在第一阶段（高 ${ķ}_{\mathrm{一世}}$ 增长率的依赖性）和第二阶段（低 ${ķ}_{\mathrm{一世}}$增长率的依赖性）。人们发现，随着阿伦尼乌斯动力学的发展，温度升高会提高第二阶段开裂期间的裂纹扩展速率。应力强度因子为14.5 MPa时第二阶段裂纹扩展速率的活化能$\sqrt{\mathrm{米}}$估计为84.7 kJ / mol。此外，发现HEAC的阈值应力强度因子随温度升高而降低。这归因于在较高温度下较高的氢溶解度。室温下AA7449-T7651的裂纹扩展速率与过时的AA7050和AA7075-T7651的裂纹扩展速率相似，范围为1.3至2.1。 $\times$ 10${}^{-7}$ 毫米/秒 可以推断，在室温下第二阶段开裂期间，合金的回火比其成分具有更大的影响。