Improvement of Fatigue Properties of Ni Based René95 Superalloy by Metal Injection Molding

Abstract

Superalloys are widely used in gas-turbine components of aircrafts and power generating plants, and many other parts which need high temperature strength. However, there are issues to be overcome in conventional manufacturing methods; poor material yield and high processing cost. Metal injection molding (MIM) is expected to realize more complex near-net-shaping technique with significant cost savings. In our previous studies, MIM process was applied to Ni – based superalloy of René 95. By optimizing the process conditions, higher than 99 % of relative density was obtained and their tensile strengths at room and high temperature showed almost the same as those of wrought Inconel718. However, their dynamic properties at room temperature showed quite low level. The objective of this work is to improve the dynamic properties of René95 fabricated by MIM process. The effects of grain size, precipitated phase and remained pores on the properties were investigated. Finally, the fatigue strength of 443 MPa was obtained, which was almost as same as that of heat treated wrought Inconel718.