Non-metallic inclusions have the potential to significantly degrade the low-cycle-fatigue (LCF) life of nickel-base disk alloys. Ceramic inclusions in powder metallurgy (PM) disk alloys are inherent defects produced as by-products of powder processing techniques. Contamination of the powder can occur in the melt, during powder atomization, or during any of the various handling processes through consolidation. In modern nickel disk powder processing facilities, the levels of inclusion contamination can be reduced to less than 1 part per million by weight. However, despite this low probability of occurrence, the effect of inclusions on component reliability must be considered by the metallurgist and designer. The objective of this study is to investigate the effects of forging strain on ceramic inclusions. Since natural inclusions occur so infrequently, it was necessary to introduce elevated levels of inclusions in a powder metallurgy, nickel-base superalloy. The seeded material was conventionally hot compacted, extruded, and forged. Extensive metallographic analyses were performed to quantify inclusion size, shape, orientation, and extent of breakup. This information was later correlated with forging strains.
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