Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variant
The effects of heat treatment on the microstructure and creep properties of a modified variant of Inconel 740H alloy were studied. This variant was tuned to have a refined composition, reducing C, Cr, and Co contents while increasing the Ti/Al ratio and Mo content to enhance creep resistance. Two he...
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Elsevier
2025-01-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785424030217 |
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| author | Cheol-Hyeok Yang Chiwon Kim Siyeon Kim Hi-Won Jeong Hyungsoo Lee Dae Won Yun Hyun-Uk Hong |
| author_facet | Cheol-Hyeok Yang Chiwon Kim Siyeon Kim Hi-Won Jeong Hyungsoo Lee Dae Won Yun Hyun-Uk Hong |
| author_sort | Cheol-Hyeok Yang |
| collection | DOAJ |
| description | The effects of heat treatment on the microstructure and creep properties of a modified variant of Inconel 740H alloy were studied. This variant was tuned to have a refined composition, reducing C, Cr, and Co contents while increasing the Ti/Al ratio and Mo content to enhance creep resistance. Two heat treatments were compared: 1) single-aged (SAG: 800 °C/16 h) and 2) stabilization prior to SAG (STBG: 1060 °C/2 h + SAG). Both treatments resulted in a γ-matrix with uniformly distributed γʹ particles (∼35 nm) and a grain size of 90–100 μm. However, the SAG sample showed densely distributed fine granular carbides (M23C6 and MC) at the grain boundaries, whereas the STBG sample had fewer carbides, leaving ∼38% of grain boundaries undecorated. After thermal exposure at 750 °C for 5000 h, both samples exhibited γʹ coarsening and similar degradation in microhardness and tensile properties. However, the SAG sample demonstrated superior creep resistance. During creep, both samples showed Orowan bypassing dislocations around γʹ particles, but only the STBG sample exhibited coarse, nodule-like γʹ precipitation at carbide-free grain boundaries, leading to easier intergranular cracking. The higher fraction of grain boundary carbides in the SAG sample effectively suppressed nodule-like γʹ formation and reduced creep damage by strengthening the grain boundaries, preventing dislocation impingement. Consequently, the SAG treatment offered better protection against creep degradation. |
| format | Article |
| id | doaj-art-e72d211912ca4d4ba7fbde75686a7459 |
| institution | Kabale University |
| issn | 2238-7854 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Elsevier |
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| series | Journal of Materials Research and Technology |
| spelling | doaj-art-e72d211912ca4d4ba7fbde75686a74592025-01-19T06:25:51ZengElsevierJournal of Materials Research and Technology2238-78542025-01-013424122429Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variantCheol-Hyeok Yang0Chiwon Kim1Siyeon Kim2Hi-Won Jeong3Hyungsoo Lee4Dae Won Yun5Hyun-Uk Hong6Department of Materials Convergence and System Engineering, Changwon National University, 20 Changwondaehak-ro, Changwon, Gyeongnam, 51140, Republic of KoreaDepartment of Materials Convergence and System Engineering, Changwon National University, 20 Changwondaehak-ro, Changwon, Gyeongnam, 51140, Republic of Korea; Extreme Materials Research Institute, Korea Institute of Materials Science 797 Changwondaero, Changwon, Gyeongnam, 51508, Republic of KoreaDepartment of Materials Convergence and System Engineering, Changwon National University, 20 Changwondaehak-ro, Changwon, Gyeongnam, 51140, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science 797 Changwondaero, Changwon, Gyeongnam, 51508, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science 797 Changwondaero, Changwon, Gyeongnam, 51508, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science 797 Changwondaero, Changwon, Gyeongnam, 51508, Republic of KoreaDepartment of Materials Convergence and System Engineering, Changwon National University, 20 Changwondaehak-ro, Changwon, Gyeongnam, 51140, Republic of Korea; Corresponding author. Changwon National University, Changwon, 51140, Republic of Korea.The effects of heat treatment on the microstructure and creep properties of a modified variant of Inconel 740H alloy were studied. This variant was tuned to have a refined composition, reducing C, Cr, and Co contents while increasing the Ti/Al ratio and Mo content to enhance creep resistance. Two heat treatments were compared: 1) single-aged (SAG: 800 °C/16 h) and 2) stabilization prior to SAG (STBG: 1060 °C/2 h + SAG). Both treatments resulted in a γ-matrix with uniformly distributed γʹ particles (∼35 nm) and a grain size of 90–100 μm. However, the SAG sample showed densely distributed fine granular carbides (M23C6 and MC) at the grain boundaries, whereas the STBG sample had fewer carbides, leaving ∼38% of grain boundaries undecorated. After thermal exposure at 750 °C for 5000 h, both samples exhibited γʹ coarsening and similar degradation in microhardness and tensile properties. However, the SAG sample demonstrated superior creep resistance. During creep, both samples showed Orowan bypassing dislocations around γʹ particles, but only the STBG sample exhibited coarse, nodule-like γʹ precipitation at carbide-free grain boundaries, leading to easier intergranular cracking. The higher fraction of grain boundary carbides in the SAG sample effectively suppressed nodule-like γʹ formation and reduced creep damage by strengthening the grain boundaries, preventing dislocation impingement. Consequently, the SAG treatment offered better protection against creep degradation.http://www.sciencedirect.com/science/article/pii/S2238785424030217SuperalloysHeat treatmentMicrostructure stabilityCreepLamellae γʹ |
| spellingShingle | Cheol-Hyeok Yang Chiwon Kim Siyeon Kim Hi-Won Jeong Hyungsoo Lee Dae Won Yun Hyun-Uk Hong Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variant Journal of Materials Research and Technology Superalloys Heat treatment Microstructure stability Creep Lamellae γʹ |
| title | Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variant |
| title_full | Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variant |
| title_fullStr | Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variant |
| title_full_unstemmed | Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variant |
| title_short | Intergranular creep resistance affected by grain boundary carbides to suppress lamellae γʹ precipitation in a specially designed inconel 740H variant |
| title_sort | intergranular creep resistance affected by grain boundary carbides to suppress lamellae γ precipitation in a specially designed inconel 740h variant |
| topic | Superalloys Heat treatment Microstructure stability Creep Lamellae γʹ |
| url | http://www.sciencedirect.com/science/article/pii/S2238785424030217 |
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