不同淬火介质下7055铝合金厚板淬火内应力测试

摘要

7xxx系铝合金在淬火后会产生较大的残余应力,且淬火介质对淬火残余应力的水平与分布影响显著.通过裂纹柔度法研究不同淬火介质种类、温度和浓度对淬火残余应力的影响规律.结果表明:淬火残余应力符合典型的"外压内拉"分布,淬火残余应力水平随水温升高先缓慢降低后急速降低,随PAG浓度升高先迅速降低后缓慢降低.各淬火介质下应力水平由高到低的顺序依次为5%NaCl+5%KNO3溶液(质量分数)、20 ℃水、5%PAG溶液(体积分数).在80 ℃水和15%PAG溶液(体积分数)淬火后,残余应力水平降低比例最大均达到60%以上,抑制残余应力效果明显.%Large residual stress produces after quenching in 7xxx series aluminum alloy and quenching medium influences the quenching residual stress obviously. In this work, the effects of quenching medium type, temperature, concentration on quenching residual stress were studied by using the crack compliance method. The results show that the quenching residual stress with typical distribution decreases slowly at first and then decreases rapidly with water temperature rising, while decreases rapidly at first and then decreases slowly with the increasing of PAG concentration. The stress level of each quenching medium from high to low is as follows: 5%NaCl+5%KNO3solution (mass fraction), 20 ℃ water, 5%PAG solution (volume fraction). After quenching at 80 ℃ water or 15%PAG solution (volume fraction), the reduction ratio of residual stress level is above 60%, thus the reduction of quenching residual stress is obvious.