Assessment of Russian P/M superalloy EP741NP

Abstract

An investigation was undertaken to assess the Russian P/M superalloy EP741NP. This alloy has been reported to be one of the most advanced Russian nickel-base superalloys used in AL31FP turbine engines for the current Sukoi fighters and other applications. Extensive metallographic investigations were undertaken on a sample of this alloy. Material was characterized in the as-received condition and after various thermal cycles. The microstructures and phases observed were not consistent with those expected or reported by others. Detailed metallographic characterization revealed the presence of large gamma-prime grain size and extensive prior particle boundaries (PPB's). These microstructural features appear to significantly impact the primary mechanical properties investigated for this as-HIP and heat treated superalloy disc material. Mechanical property testing was performed to assess the mechanical property capabilities for this alloy. The results of this investigation have shown that this alloy has limited tensile strength capabilities, but may exhibit enhanced creep strength. The measured mechanical property values were compared with various literature values for this and other P/M alloys.