2441 Strain Rate Dependence of Dynamic Flow Stress of TB270 at Very High Strain Rates

Abstract

Strain rate sensitivity "dσ/dlogε" in metals is known to increase dramatically when the strain rate exceeds about 1×10^3s^<-1>. In order to evaluate. the "dσ/dlogε" of a pure titanium at very high strain rates, constant strain rate tests and strain rate reduction tests are conducted for TB270 in the strain rate range from about 1×10^3s^<-1> to 3×10^4s^<-1>. The flow stress increases linearly with increasing logarithum of strain rate' and the "dσ/dlogε" is very high in comparison to that of fcc metals. The flow stress at very high strain rates is controlled mainly by a instantaneous strain rate but the effect of a strain rate history on the flow stress remains considerably.