Flow Stress Behavior of 7AXX Aluminum Alloy during Hot Compression

The research of hot deformation behavior of 7AXX aluminum alloy has important significance to improve forging performance and avoid hot cracking phenomenon. The flow stress behavior of 7AXX aluminum alloy during hot deformation was investigated by isothermal compression tests using Gleeble-3500 system in the temperature range from 360 ℃ to 460 ℃ and at strain rate range from 0.001 s^-1 to 1 s^-1. The relationship between the flow stress and parameters of hot deformation was studied. The flow stress of 7AXX aluminum alloy was fitted by hyperbolic sine equation containing Zener Hollomon parameter. The constitutive equation and the processing maps were evaluated by linear regression analysis. The results demonstrate that the flow stress of 7AXX aluminum alloy is significantly influenced by deformation temperature and strain rate, and the steady state flow stress decreases with the increase of temperature and increases with strain rate. The deformation activation energy of 137.31 kJ/mol and stress exponent of 3.21 were determined to be characteristic parameters of 7AXX aluminum alloy in hot deformation behavior. The area with deformation temperature of 385-450 ℃ and strain rate of 0.01-0.1 s^-1 is processing safety area for hot deformation of 7AXX aluminum alloy.