A revisit with a classical rate-theory-based deformation-rate law and its use in engineering application

In this paper, a deformation law based on the classical chemical-rate theory is examined. The approach is to apply this well-known formalism in the simplest way possible to describe the steady-state deformation-rate behavior of metals. In addition to general aspects of the stress and temperature dependence of plastic flow, the behavior of an important commercial alloy (type 316 stainless steel) in engineering application is studied and compared with experiment. In this context, it is shown how this single rate-equation can, with unaltered parameters, be used to describe quantitatively deformation-rate-related behavior over a very wide range of stress and temperature, transcending a variety of mechanical tests. In this formulation, the stress dependence of the plastic strain-rate is characterized via a stress-independent activation volume, Ω. The temperature dependence of Ω is extracted from the stress dependence of the activation entropy, determined by application of the theory of thermo-elasticity. The resulting rate equation simulates a power-law stress dependence in the intermediate creep range, but describes other deformation rate regimes rather well without alteration of parameters. (author)