Combined effects of carbide, cavitation and thin-section size on the creep rupture properties of a nickel-base superalloy

Abstract

The combined effects of thin-section size, carbide and cavitation dispersion on the creep rupture characteristics of the conventionally cast MAR-M002 superalloy have been studied at 1173 K/300 MPa. It was shown experimentally that the creep rupture life of the alloy is controlled by the (a<inf>c</inf>/a<inf>o</inf>)/D ratio, where a<inf>c</inf> is the cavity size, a<inf>o</inf> the carbide particle size and D the diameter of the gauge section of specimen. Below a critical value (? 100 × 10-6 ?m-1) of this ratio the rupture life extends rapidly, whereas above the critical value of the ratio there is a slow increase in the rupture life. The effect of the (a<inf>c</inf>/a<inf>o</inf>)/D ratio on the rupture life has been described using the existing theories which were developed for the prediction of stress concentrations at grain boundary particles.