Stress relaxation in silver between 300 and 1233 k

Abstract

Evolution of elastic-plastic shock waves in 99.9-% purity silver has been recorded with VISAR for sample thicknesses varied from 0.127 to 2.0 mm at initial sample temperature varied from 296 to 1233 K. The decay of the elastic precursor wave at 933, 1173 and 1233 K temperatures is found to be approximately inversely proportional to the square root of the propagation distance. For the strain rate range from 104 s-1 to 106 s-1 this corresponds to the cubic dependence of the initial plastic strain rate on the shear stress. At the fixed strain rates the flow stress grows linearly with temperature but the dependence becomes stronger than linear near the melting temperature. An analysis of the rise times of the plastic shock waves shows that for the same level of shear stress the plastic strain rate at the shock front is significantly higher than that at the top of the elastic precursor wave.