Energy absorption in low cycle fatigue in 9Cr1Mo and 304 stainless steels

Abstract

Energy absorption characteristics in slow tensile cyclic deformation within the flow stress are examined as functions of temperature and previous plastic strain. The energy absorption is analysed in terms of thermal activation, and the activation energy is determined by separately determining the activation volume from stress relaxation at stress values below the flow stress. The required internal stress and the dislocation velocity-stress exponent are obtained from instantaneous strain rate change experiments. Some possible mechanisms are considered based on the energy absorption and the activation energy, which have different temperature dependences in the two steels.