Anomalous Strain Rate Effect in Ultrafine Grained Titanium

An anomalous effect was found in the strain rate dependence of severe plastic deformed commercially pure titanium with ultrafinegrained structure. A maximum tensile strength was obtained for ϵ˙=10−3s−1. This did not allow a single strain rate sensitivity parameter to be defined in the interval from ϵ˙=10−5to10−1s−1. Distinct deformation mechanisms for lower and higher strain rates might be the reason for this anomaly.