高强Al-Zn-Mg-Cu合金静态再结晶模型及组织演变

Static recrystallization model and microstructure evolution of high strength Al-Zn-Mg-Cu alloy

采用Gleeble 3800热模拟试验机对航空用Al-Zn-Mg-Cu合金的热变形行为进行了测试,对变形后的微观组织进行了表征,系统分析了静态软化行为,建立了静态再结晶动力学模型。结果表明:实验用航空Al-Zn-Mg-Cu合金的静态再结晶激活能为129162 J·mol^(-1),静态再结晶体积分数受变形温度、变形程度、变形速率的影响,且变形温度对静态再结晶影响最明显;变形速率一定时,变形温度越高,道次停留时间的影响越不明显;350℃低温变形后,α-Al基体晶粒内部仍存在大量的位错缠结;400℃中温变形后,位错运动能够充分进行,部分晶粒发生了再结晶;450℃高温变形后,基体晶粒基本全部完成了再结晶,基体晶粒内部发现5~25 nm尺寸范围的Al-Zn-Mg-Cu四元相粒子;对于不同热变形条件,模型预测值的误差在0.008~0.0625范围内,动力学模型的计算结果精确度较高。

The hot deformation behaviors of Al-Zn-Mg-Cu alloy for aviation were investigated using Gleeble 3800 thermal simulator.The microstructure after deformation was characterized.The static softening behaviors were analyzed systematically.The static recrystallization dynamic model was established.The results show that the activation energy of static recrystallization of the experimental Al-Zn-Mg-Cu alloy is 129162 J·mol^(-1).The volume fraction of static recrystallization is affected by deformation temperature,deformation degree and deformation rate,and the deformation temperature has the most obvious effect on static recrystallization.When the deformation rate is constant,the higher the deformation temperature is,the less the influence of pass residence time is.After low temperature deformation at 350℃,there are still a large amount of dislocation entanglement inside theα-Al matrix grains.After medium temperature deformation at 400℃,the dislocation movement can be fully carried out,and some grains undergo recrystallization.After high temperature deformation at 450℃,the matrix grains are basically recrystallized,and Al-Zn-Mg-Cu quaternary phase particles with the size range of 5-25 nm are found inside the matrix grains.For different thermal deformation conditions,the error of the model prediction value is in the range of 0.008-0.0625,and the calculation accuracy of the dynamical model is high.