通过测定时间-温度-硬度曲线并采用透射电镜研究7055铝合金的淬火敏感性.研究结果表明:7055铝合金的淬火敏感温度区间为235~415℃,鼻尖温度约为355℃;7055铝合金的过饱和固溶体在355℃保温时快速分解,析出大量无强化作用的粗大η相,减小基体中溶质原子浓度,降低时效强化效果;该合金较佳的淬火制度为:适当减小高温区间的冷却速率,加大淬火敏感温度区间235~415℃的冷却速率.在此淬火制度下,既可减小铝合金残余应力,又可保证其较佳的力学性能.
The quench sensitivity of 7055 aluminum alloy was studied with time-temperature- hardness curve evaluated via interrupted quenching and transmission electron microscopy. The results show that the critical temperature range is 235 -415 ℃ with the nose temperature of 355 ℃. Fast decomposition of the supersaturated solid solution held at 355 ℃ is observed and large η phase is primarily formed on dispersoids, which leads to the loss of solutes and decrease of aging hardening effect. The optimum quenching condition for the alloy is as follows, rapid cooling in the critical temperature range of 235 -415 ℃ and slower cooling in the high temperature range, which can lead to high mechanical properties and low residual stress can be obtained.