Deformation behavior and microstructure evolution of 7050 aluminum alloy during high temperature deformation

Deformation behavior and microstructure evolution of 7050 aluminum alloy were investigated by tensile tests conducted at different temperatures (340, 380, 420, and 460 degrees C) with different strain rates of 1.0 x 10(-4), 1.0 x 10(-3), 1.0 x 10(-2) and 0.1 s(-1). The results show that the stress level of the alloy can be presented by a Zener-Holloman parameter in a hyperbolic sine-type equation with the hot activation energy of 256.6 kJ/mol. Ductile transgranular fracture transforms progressively into ductile intergranular (or inter-subgranular) fracture with the decrease of Z value. At the same time, the soften mechanism of the alloy during high temperature deformation transforms from dynamic recovery to continuous dynamic recrystallization with decreasing Z value. The main deformation mechanism is usual slipping when the alloy was deformed at high Z value. Grain boundaries sliding takes part in deformation with low Z value. Grain boundaries migration plays the role with medium Z value. (C) 2007 Elsevier B.V. All rights reserved.