Effect of microstructure (and heat treatment) on the 649°C properties of advanced P/M superalloy disk materials

Abstract

A statistically based approach was completed to assess the effect of microstructural (and associated heat treatment processing parameters) on the 649°C capability of two advanced powder metallurgy (P/M) superalloys. The results showed that microstructure and processing play a key role in achieving a balance of mechanical properties. For a desired combination of good high temperature capability the results indicate that a supersolvus heat treatment followed by a fast cooling rate is desired. In addition, selection of a stabilization heat treat cycle would depend upon the balance of creep and crack growth capability desired. The process described above would nominally produce an ASTM 6 grain size with reasonably fine cooling γ′and aging γ′as defined by the stabilization cycle.