7075 Aluminum Alloy To Control The Experimental Simulation Of The Rolling Process

Control rolling process was systematically tested on Gleeble-1500 thermal -mechanical machine through a series of multi-pass hot compression tests. The microstructure and mechanical properties were analyzed by observation of OM and TEM, and by measurement of hardness of deformed samples. Afterwards, the curve of flow stress of 7075 aluminum alloy during compression was studied. The results are shown as following:1) The flow stress is controlled by both strain rate and deforming temperature, the flow stress decreases with the increase of temperature, while increases with the increases with strain rate. The flow stress of 7075 aluminum alloy can be presented by the Zener-Hollomon Parameter in exponential form.2) The continuous dynamic recrystallization (CDR) phenomena was observed during multi-pass hot compression of 7075 aluminum alloy, and the high strain rate was thought to cause the dynamic recrystallization.3) There is no obvious hardening effects of the stable phase η precipitated in a high temperature which is instead generally associated with the decrease of the hardness of alloy during the process of multi-pass hot compression; After a treatment of solution and ageing, the hardness of deformed sample obviously increased, and a more stable and dispersed hardening phase η.' and thus a larger hardness were obtained when the deformation temperature of final pass is high than 340℃.4)An obvious drop in the flow stress was observed after the interval during multi-pass deformation, the softening fraction (FS) increased as the holding time prolonged and the temperature of deformation increased. Strain rate and cumulative strain has an obvious effect on the softening fraction. Even the holding temperature was low and the holding time was short, a high softening fraction can be obtained in the condition of high strain rate and strains.