Fatigue failure properties of injection molded superalloy compacts

Superalloys have been used especially for aerospace and atomic energy applications because of their excellent attributes of high corrosion and oxidation resistance, and high temperature strength. A Inconel 718 is one of representative Ni-base superalloys. However, it is not easy to produce the complicate shaped parts with low cost due to their poor workability. In this study, Metal Injection Molding (MIM) process, one of near net-shape powder forming, has been applied to fabricate the Inconel 718 alloy compacts using two type of powders; gas and water atomized powders. By optimizing the MIM process, their obtained relative density was near full density (98∼99%). However, the fatigue strength of heat treated sintered Inconel 718 compacts showed 65% of heat treated wrought materials due to the remained pores. The effect of remained pores on fatigue strength was discussed by the prediction equation of endurance limit considering the inclusion.