ZL270LF铝合金的热变形行为与组织演变

Hot Deformation Behavior and Microstructural Evolution of ZL270LF Aluminum Alloy

通过热压缩实验研究了ZL270LF铝合金在变形量为70%,温度为300~550℃,应变速率为0.01~10 s^(-1)范围的热变形行为,建立了流变应力本构方程模型,绘制出了二维热加工图,确定了最佳热加工区域,采用电子背散射衍射(EBSD)和透射电子显微镜(TEM)技术研究了该合金的组织演变规律。结果表明:ZL270LF铝合金的流变应力随变形温度的升高和应变速率的降低而降低,热变形激活能为309.05 kJ/mol,最优热加工区为温度470~530℃、应变速率为0.01~1 s^(-1)。该合金在热变形过程中存在3种不同的DRX机制,即连续动态再结晶(CDRX)、不连续动态再结晶(DDRX)和几何动态再结晶(GDRX),其中CDRX是ZL270LF铝合金动态再结晶的主要机制。

The hot deformation behavior of ZL270LF aluminum alloy under a strain of 70%,deformation temperatures ranging from 300°C to 550°C,and strain rate ranging from 0.01 s^(-1) to 10 s^(-1) was studied by hot compression tests.A constitutive equation for flow stress was constructed,and the hot processing map was drawn,thus determining the optimal hot processing region.An electron back scattered diffractometer(EBSD)and a transmission electron microscope(TEM)were used to explore microstructural evolution of the alloy.The results show that the flow stress of ZL270LF Al alloy decreases with increasing deformation temperature and decreasing strain rate.The deformation activation energy is 309.05 kJ/mol,and the optimal processing region is the area where the temperature is from 470°C to 530°C and the strain rate is from 0.01 s^(-1) to 1 s^(-1).Three different dynamic recrystallization(DRX)mechanisms are involved in the hot deformation process of the alloy,namely continuous dynamic recrystallization(CDRX),discontinuous dynamic recrystallization(DDRX),and geometric dynamic recrystallization(GDRX).Among them,CDRX is the main DRX mechanism of ZL270LF Al alloy.