7085铝合金热变形的流变应力行为和显微组织

Flow stress behavior and microstructure of 7085 aluminum alloy during hot deformation

采用Gleeble-1500热模拟机进行热压缩实验,研究7085铝合金在变形温度为350-470℃、应变速率为0.001-1 s？1条件下的流变应力变化规律和变形后的显微组织。研究表明：7085铝合金的流变应力随应变速率增大而增大,随变形温度升高而减小。该合金热压缩变形的流变应力行为可用双曲正弦形式的本构方程描述为ε=A[sinh（ασ）]nexp（？Q/RT）,也可用Zener-Hollomon参数来描述,其参数A、α、n以及热变形激活能Q分别为2.722 54×1011s？1、0.016 03 MPa？1、6.259以及176.58 kJ/mol。随着温度升高和应变速率降低,合金的主要软化机制由动态回复逐渐转变为动态再结晶。

The flow stress behavior and the deformation microstructure of 7085 aluminum alloy during hot compression deformation were studied by thermal simulation test using Gleeble-1500 thermal simulation machine,at temperature ranging from 350 ℃ to 470 ℃ and strain-rate from 0.001 s-1 to 1 s-1.The experimental results indicate that the flow stress and peak stress increase with increasing strain rate,and decrease with increasing deformation temperature,which can be described by a constitutive equation in hyperbolic sine function as A[sinh（ασ）]nexp（-Q/RT）,and can also be described by Zener-Hollomon parameters,whose values of related parameters A,α,n and activation energy for hot deformation Q,are 2.722 54×1011 s-1,0.016 03 MPa-1,6.259 and 176.58 kJ/mol,respectively.With increasing the temperature and decreasing the strain rate,the main soften mechanism of the 7085 alloy transforms from dynamic recovery to dynamic re-crystallization.