Influence of Initial Microstructure on Rheology of Al-Zn-Mg-Cu Alloy during Thermal Compression
The rheological behavior of two kinds Al-Zn-Mg-Cu aluminum alloy with different extrusion ratio was studied by thermal compression in 300°C~450°C and in strain rate range of 0.01 s-1~10s-1 on Gleeble1500D simulator. The results show that: (1)the flow stress increases with deSuperscript textcreasing deformation temperature and increasing strain rate, and the initial microstructure influence the rheological behavior, the flow stress with fine grain is higher than that with coarse one except in strain rate 0.01s-1 and 0.1s-1 in 450°C owing to deformation easily with more grain boundary sliding in high temperature and low strain rate.(2)The flow stress of Al-Zn-Mg-Cu aluminum alloy during hot compression can be expressed as hyperbolic sine constitutive equation with Arrhenius parameter, the apparent steady state activation energy for hot compression with coarse grain is of 181.51kJ/mol, while that with fine grain is of 203.02kJ/mol.(3) The apparent steady state activation energy decreases with increasing temperature and strain rate, and the value of fine initial microstructure is higher than the low extrusion ratio rod commonly.
L. Xu et al., "Influence of Initial Microstructure on Rheology of Al-Zn-Mg-Cu Alloy during Thermal Compression", Advanced Materials Research, Vols. 314-316, pp. 506-510, 2011