Study of the effects of inclusion on creep life and creep damage distribution of PM materials under constant loading

Numerical calculations with the K-R (Kachanov-Rabotnov) damage law have been performed to study the creep damage development in the compact tension (CT) specimens including inclusions under constant loading. Emphasis is placed on the roles of the failure mode between inclusion and matrix, inclusion size and shape. The numerical results show that the maximum creep damage of matrix lies around the notch when the inclusion adheres perfectly with matrix and around the inclusion when the inclusion cracks middle to form a void or debonds from the matrix to form a void. The void shortens specimen's creep life largely. For all failure modes, the specimen containing round inclusion is longer than that containing elliptical inclusion. The inclusion size and aspect ratio of elliptical inclusion influence specimen's creep life in different ways for different failure modes.