Interrelation between Damage Variables of Continuum Damage Mechanics and Metallographical Parameters in Creep Damage

Abstract

Identification of the evolution of the damage variable, D, in continuum creep damage theory was developed directly from the metallographical A-parameter. As the observed fraction of cavitated grain boundaries on the observation plane, A-parameter was first related to the cavity area fraction on the grain boundary facet planes by perform ing a probability analysis. Then, two specific A-D relations were obtained corresponding to the instantaneous and continuous nucleation of cavities, respectively. An A-D relation of more generality was also derived from one of the proposed A-D relations by using the Kachanov-Rabotnov creep damage theory. Finally, the creep damage behavior of a practi cal alloy was identified from A-parameter by using the developed A-D relations in addition to the previous one. Some comparisons and discussions were made based on the test results of this alloy.