Structure, mechanical properties, and thermal stability of the high-temperature nickel pelletized alloy �P741NP

Grits, N. M.; Eremenko, V. I.; Fedorenko, E. A.

doi:10.1007/bf00777163

Cited by 3 publications

(2 citation statements)

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“…[11] EP741NP, a P/M superalloy manufactured by direct HIP, is widely used in turbine engines. [7,[12][13][14] The main disadvantage of superalloys made by HIP is the formation of a prior particle boundary (PPB) containing oxides, carbides, and γ 0 , which is detrimental to the material's mechanical properties. [15] The EP741NP superalloy overcomes the PPB problem through a specially tuned composition and a supersolvus HIP process with coarse powder (53-150 μm).…”

Section: Introductionmentioning

confidence: 99%

“…To avoid excessive grain growth, hot deformation is usually operated at the γ þ γ 0 duplex phase field. However, the high Al, Ti, and Nb content (Al þ Ti þ Nb % 9.3 wt%) of EP741NP alloys results in a large volume fraction of γ 0 up to 60%, and high γ 0 solvus temperature up to 1185 C. [13] This can cause rapid age hardening as a result of cooling during processing, and significantly increase resistance to deformation. Several studies have assessed the hot deformation of γ 0 strengthened superalloys, including γ 0 evolution mechanisms, recrystallization mechanisms, and their interactions.…”

Section: Introductionmentioning

confidence: 99%

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Hot Deformation Behavior of a Powder Metallurgy Superalloy with High γ′ Content

Zhang

Liang³

et al. 2021

Adv Eng Mater

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The hot deformation behavior of a powder metallurgy superalloy EP741NP is studied using isothermal compression testing on a Gleeble‐3500 thermomechanical simulator. Constitutive equations and processing maps are then constructed based on the experimental stress–strain data, and microstructural changes are analyzed by sectioning the compressed samples. The results show that most stress–strain curves are characterized by rapid work hardening and slow flow softening. Steady‐state flow stress is achieved under low strain rates and at high temperatures. Based on experimental stress–strain data, a constitutive equation compensated by strain is constructed, which provides an accurate prediction of flow stress behavior. Due to the dissolution of γ′, the effects of temperature on the processing map are more significant than strain rate and strain. The recrystallization rate at low temperature is limited by the γ + γ′ nucleation mechanism around grain boundaries and prior particle boundaries (PPBs), forming a unique necklace structure. The optimal processing conditions for the EP741NP superalloy are at temperatures of 1150–1170 °C and strain rates of 0.005–0.02 s−1, which produces a significantly refined microstructure free from PPB.

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