The temperature and strain-rate dependence of the shear strength of mild steel

Abstract

An account is given of experiments in which the shear flow stress of mild steel was measured at temperatures from 195 to 713°K and strain rates from 10⁻³ to 4 × 10⁴ sec⁻¹. The experimental results obtained at room temperatures are compared with those of earlier tension tests. The rate sensitivity of the flow stress, (∂τ/∂ In γ) _T , is found to be a decreasing function of temperature, except at the highest strain rates; at these rates a large increase in the rate sensitivity is observed, the flow stress at constant temperature varying approximately linearly with strain rate. The data are interpreted in terms of thermal activation rate theory and the theory of the damping of dislocation motion by phonon viscosity.