応力破断線図の領域区分によるクリープ破断寿命評価の改善

抄録

Creep deformation and fracture mechanisms are known to change with stress and temperature, as indicated in the deformation and fracture mechanism maps. When creep rupture data are evaluated with a time-temperature parameter (TTP), the data should be divided into several mechanism fields. This idea was applied to creep rupture data difficult to be described by a simple TTP and stress function. It was suggested that, by dividing rupture data, all data can be described by a TTP having only one arbitrary constant and a linear stress function. Within the same field, rupture lives hundred times longer than the longest test duration could be predicted without introducing any appreciable error. Extrapolation across a field boundary, however, caused serious error ; one may not correctly predict a rupture life two times longer than the test duration. Information about field boundaries is necessary for correct extrapolation.