DYNAMIC FLOW STRESS RESPONSE OF ALUMINIUM TO SUDDEN REDUCTION IN STRAIN RATE AT VERY HIGH STRAIN RATES

摘要

In order to evaluate the effects of the instantaneous strain rate and the structural state reflecting the strain rate history upon the dynamic flow stress, the tests in which the strain rate is suddenly decreased during the dynamic plastic deformation are conducted for high purity polycrystalline aluminium in a strain rate range from about 8000 to 20000 /s. To obtain a sufficiently steep reduction in the strain rate a new apparatus is devised. The results indicate that the instantaneous strain rate plays a more important role than the strain rate history for the dynamic flow stress in such a very high strain rate range in which the steep increase in the strain rate sensitivity of the flow stress is observed.