热变形条件对2124铝合金流变应力和显微组织的影响

Influence of Hot Deformation Condition on Flow Stress and Microstructure of 2124 Aluminum Alloy

采用Gleeble热模拟试验机对2124铝合金进行热压缩试验,通过分析合金在高温塑性变形过程中的流变应力变化规律,以及利用光学显微镜和透射电镜观察合金在热变形过程中的显微组织演变,探讨了不同变形温度和应变速率对合金热塑性变形能力的影响。结果表明,2124铝合金在热变形中的流变应力稳态值随热变形温度的升高或应变速率的减小而增大,可用双曲正弦形式的本构方程来描述热变形条件和流变应力的关系,合金的变形激活能为170.13 k J/mol。在较低变形温度或较高应变速率下,热变形后合金组织中存在大量位错缠结和位错墙,软化机制主要为动态回复。随变形温度的升高或者应变速率的降低,该合金组织中出现了再结晶晶粒,软化机制逐渐向动态再结晶转变。

The hot compression tests of 2124 Al alloy at different temperatures and strain rates were performed on Gleeble thermal simulation machine.The variation of flow stress was investigated.The microstructure evolution during hot deformation was observed by optical microscope and transmission electron microscope.The results show that the flow stress of 2124 Al alloy increases with increasing temperature and strain rate.The relationship between hot deformation and flow stress can be described by constitutive equation in the form of hyperbolic sine.The hot deformation activation energy is170.13 k J/mol.At low temperature or high strain rate,a mass of dislocation tangles and dislocation walls exist in the deformed alloy,thus,the softening mechanism is mainly dynamic recovery.With the increase of deformation temperature or the decrease of strain rate,the recrystallized grains appear in the alloy,which can represent that the softening mechanism of the alloy transforms into dynamic recrystallization.