GENERAL CREEP-TIME EQUATION. TECHNICAL NOTE

The creep behavior of metallic materials is frequently studied using creep tests carried out under constant load and constant temperature conditions. This technical note presents a general equation that precisely describes the creep-time relationship in such conditions in a succinct format. The equation allows all three classical stages of creep, primary, secondary, and tertiary, to be represented. It expresses creep strain explicitly in terms of real time in a single smooth, continuous curve. It uses six parameters; each independently describes a physical feature of the creep curves. The equation is useful for characterizing experimental results as well as for developing a creep model that can be incorporated into analysis models. Comparison with experimental results shows that the equation closely fits the creep curves of steel at various temperatures and stress levels.