在变形温度为653～733 K、应变速率为0.01～0.1 s^-1、变形道次间停留时间为30～240 s下，对Al-Mg-Si-Cu合金进行双道次等温热压缩试验，定量分析了合金的动态与静态软化行为，探讨了合金的流变软化行为机理。结果表明：合金在第一道次变形时的动态软化率均不低于10%，流变软化程度随着应变速率的增大和变形温度的升高而减小，软化机制为动态回复与再结晶相结合；变形道次间停留阶段的软化行为显著，最大软化率可达97.82%，静态软化程度随变形温度的升高、应变速率的增大和道次间停留时间的延长而增大，软化行为由静态回复与再结晶共同主导；合金在第二道次变形时的流变应力峰值较低且软化率均不高于5%，软化行为由再结晶与回复共同主导。

Two-pass isothermal compression tests of Al-Mg-Si-Cu alloy were conducted under deformation temperature of 653-733 K, strain rate of 0.01-0.1 s^-1 and inter-pass holding time of 30-240 s. The dynamic and static softening behavior of the alloy was quantitatively analyzed and the flow softening behavior mechanism of the alloy was investigated. The results show that the flow softening ratio of the alloy at the first deformation pass was no less than 10%; the flow softening degree decreased with increasing strain rate and deformation temperature; the softening mechanism was a combination of dynamic recovery and recrystallization. During the inter-pass periods, the flow softening behavior was obviously observed and the softening ratio reached up to 97.82%; the static softening degree increased with the deformation temperature, the strain rate and the inter-pass holding time. The softening behavior was dominated by the static recovery and recrystallization. The peak values of flow stress during the second deformation pass were relatively low and the softening ratios were no more than 5%; the softening behavior was dominated by the recrystallization and recovery.