Effects of strain rate on dynamic recrystallization microstructure of 3003 aluminum alloy in process of hot deformation

The isothermal and constant strain rate compression tests of 3003 aluminum alloy were conducted in the strain range of 0.01-10.0 s-1 at 400 ℃ on a Gleeble-1500 thermal simulator.The true stress-true strain curves were obtained in the tests.The results show that the actual deformation temperature of the sample deformed at higher strain rates(≥1.0 s-1) is higher than the preset temperature,resulting in a deformation thermal effect.The critical strain of dynamic recrystallizaion(DRX) increases with strain rate increasing.The serrate flow curves are observed at the higher strain rates(≥1.0 s-1),which indicates that discontinuous dynamic recrystallization(DDRX) occurs.Optical microscope and transmission electron microscopy were employed to analyze the effect of strain rate on the microstructural evolution.The results show that lower strain rates,more easily DRX occurs.Due to the deformation thermal effect,DRX also takes place in the studied alloys at the strain rate of 10.0 s-1.The grain size can be defined obviously with strain rates increasing at the strain rate higher than 0.1 s-1.Recrystallized volume fraction decreases with strain rate increasing at the same strain.Based on the size of DRX grain and uniformity in the microstructure,the strain rate of 0.1 s-1 is preferable to hot working.