The quasi-static and dynamic material properties

including the strength relation and fracture criterion

from room temperature to 250 益are investigated using a universal testing machine

a torsion testing machine

a split Hopkinson tension bar and the Taylor impact test. The Johnson-Cook constitutive relation with a modification on the strain hardening term and the Johnson-Cook fracture model with a mod- ification on the temperature softening item were proposed to fit the test results. The material constants were calibrated by a combination of experimental tests and numerical simulations. It is concluded that the strain strengthening and temperature softening effect is obvious

while the strain rate hardening effect is not significant; the fracture strain increases with temperature and strain rate and decreases with stress tri- axiality.