Low cycle fatigue life prediction - A new model

A new creep-fatigue life prediction method has been developed in this paper to correlate high temperature low cycle fatigue (HTLCF) data on Cr-Mo steels. The new method has been developed within the premise that with the application of cyclic loading, which is plastic strain dominated under HTLCF conditions, damage accrues by means of viscous flow. Concepts of dynamic viscosity were used to describe such a flow behavior and assumed as damage parameter. When the ability of a material to accommodate viscous flow ceases, failure occurs. When these two terms namely; dynamic viscosity and material toughness, equated, produce a life prediction expression, that has been derived in this paper. The assessments of HTLCF data were performed with the new model developed in this paper 1Cr-Mo-V, 2.25Cr-Mo, and 9Cr-1Mo steels. Numerous test conditions were employed by the National Research Institute for Metals, Tokyo, Japan, in generating HTLCF data where the assessments show that the new method correlates the data. Copyright (C) 1997 Elsevier Science Ltd.