On the use of tensile test time to adjust the time to rupture term in creep rupture life models whose stress term is normalized by tensile strength

Abstract

Creep life models which normalize stress by an ultimate tensile strength (UTS), such as the Wilshire equation, have a mathematical structure which results in the time to rupture being zero when the applied stress equals the UTS. However, the duration of a standard tensile test used to determine UTS is finite. Recently, two very different approaches to address this issue have appeared in the literature. In this study, these approaches are quantitatively compared by correlating them to the same set of creep rupture data with the Wilshire equation. Predicted times to rupture of each model are also compared with equivalent times to creep rupture of slow and fast constant strain rate tests performed on the same alloy, and the preferred method to account for finite tensile test times is identified.