Characterization of hot compression behavior of a new HIPed nickel-based P/M superalloy using processing maps

Isothermal forging was a critical step process to fabricate the high-performance nickel-based superalloy. The temperature and strain rate served the most critical role in determining its microstructure and mechanical properties. In this article, we employed the hot compression to simulate the isothe...

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Veröffentlicht in:Materials & design 2015-12, Vol.87, p.256-265
Hauptverfasser: He, Guoai, Liu, Feng, Si, Jiayong, Yang, Chuan, Jiang, Liang
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Sprache:eng
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Zusammenfassung:Isothermal forging was a critical step process to fabricate the high-performance nickel-based superalloy. The temperature and strain rate served the most critical role in determining its microstructure and mechanical properties. In this article, we employed the hot compression to simulate the isothermal forging process upon the temperature ranging from 1000°C to 1100°C in combination with a strain rate of 0.001–1.0s−1 for a new P/M nickel-based alloy. The activation energy was determined as 903.58kJ/mol and the processing maps at a strain range of 0.4–0.7 were developed. The instability domains were more inclined to occur at strain rates higher than 0.1s−1 and manifested in the form of adiabatic shear bands. The map further demonstrated that the regions with peak efficiency of 55% were located at 1080°C/0.0015s−1 and 1095°C/0.014s−1, respectively. Obvious dynamic recrystallization could be detected at the strain rate 0.01s−1 leading to a significant flow stress drop and the grain growth was remarkably triggered under 1100°C. The findings can shed light on the forging processing optimization of the new nickel-based superalloy. Compression behavior and microstructure evolution of a PM nickel-based superalloy. (a) Compression true stress–strain plots upon strain rate 1.0s−1 in a wide range of temperature from 1000°C–1100°C, showing the relationship between temperature and stress. (b) The processing map based on true stress–strain at different temperatures and strain rates demonstrating the instability domains and stability regions. (c) Post-mortem compression morphologies under different deformation conditions. (d) At 1050°C/1s−1, EBSD micrograph showing the microstructure of recrystallization. (e) A closer-up microscopic examination further demonstrates that the necklace-like grain boundary structure is developed due to the recrystallization stimulus. [Display omitted] •The hot flow behavior of a new designed P/M Ni-base superalloy was investigated.•EBSD micrographs were used to support the established processing maps.•High-magnification EBSD micrographs were adopted to characterize microstructural features.•The potential pathways to optimize hot working were proposed for a new alloy.
ISSN:0264-1275
1873-4197
DOI:10.1016/j.matdes.2015.08.035