Damage of low-alloy high temperature steels loaded by low-cycle fatigue and creep

Abstract

Present-day models used for calculations of life at combinations of low-cycle fatigue loading and creep mostly work with experimental curves of life at constant amplitude of deformation. However, during such a type of loading, a relative proportion of damage caused by low-cycle fatigue and creep is changed. On the basis of large-extension experimental measurement made on low-alloy CrNiMoV and CrMoV steels, a model describing life of steels at combination of low-cycle fatigue and creep was proposed. The model is suitable for a wide temperature interval, different loading amplitudes and different values of maximum load during the cycle, when creep occurs. The model enables to specify not only the damage, but also values of deformation at all stadia of creep and it is suitable for an evaluation of the life curves on the basis of the three-parameters rain-flow method.