Analogy between creep cycles and stress relaxation series for activation volume measurement

Two techniques that are commonly used to measure the activation volume in the course of constant strain rate deformation experiments consists of performing either strain rate jump or stress relaxation tests. In this paper, a new method based on repeated creep tests is presented. It is demonstrated that, as for the technique of stress relaxation series, this new procedure allows the measurement of the apparent activation volume and the corresponding strain hardening correction term, which yield the effective activation volume. Only this last parameter is relevant for characterizing the thermally activated processes that control plastic flow.