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利用Gleeble-1500热模拟试验机对均匀化7050铝合金在573~723℃和0.000 5~1s-1变形条件下进行热压缩试验。通过线性回归分析计算出均匀化7050铝合金的应变硬化指数以及变形激活能,获得了均匀化7050铝合金热压缩变形条件下的流变应力本构方程。并借助扫描电镜(SEM)、电子背散射衍射(EBSD)和透射电镜(TEM)显微分析,对不同热变形条件下合金的微观组织演变进行研究。结果表明,均匀化7050铝合金在高温压缩变形过程中有动态回复和动态再结晶现象。随着变形温度升高和应变速率下降,合金位错密度降低,流变应力减小。在热变形过程中,合金的主要软化机制由动态回复逐渐演变为动态再结晶,热变形组织由位错亚结构转变为再结晶组织。
The hot compression tests were carried out on the homogenized 7050 aluminum alloy under the deformation of 573 ~ 723 ℃ and 0.000 5 ~ 1s-1 using the Gleeble-1500 thermal simulation machine. The strain hardening index and deformation activation energy of homogenized 7050 aluminum alloy were calculated by linear regression analysis. The flow stress constitutive equation of homogenized 7050 aluminum alloy under hot compression deformation was obtained. The microstructure evolution of the alloy under different hot deformation conditions was studied by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The results show that the homogenized 7050 aluminum alloy has dynamic recovery and dynamic recrystallization during high temperature compression deformation. As the deformation temperature increases and the strain rate decreases, the dislocation density decreases and the flow stress decreases. During the hot deformation process, the main softening mechanism of the alloy gradually evolved from dynamic recovery to dynamic recrystallization, and the hot deformed structure transformed from dislocation substructure to recrystallized structure.