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| Study on the microstructure and properties of a new type of nickel-based superalloy |
| ZHANG Xiaomin,QIN Heyong,YU Ping,TIAN Qiang,DUAN Ran,ZHANG Wenyun |
| Central Iron and Steel Research Institute, Beijing 100081, China |
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Abstract GH4742 (Russian ЭП742) alloy is a typical high-alloyed hard-to-deform nickel-based superalloy turbine disk material. In this paper, GH4742 alloy is improved by adjusting the composition of Al, Ti and Nb, and a new type of nickel-based superalloy was invented. Use JMatPro to simulate the equilibrium phase diagram, and then use optical metallographic microscope and field emission scanning electron microscope to observe the alloy′s grain structure, carbides and γ′ phase distribution, and at the same time to detect the mechanical properties.The results show that the phase transition of the alloy in the equilibrium state from 1 400 ℃ to 300 ℃ during the cooling process can be summarized as L → L+γ → L+γ+MC →γ+MC+γ′ → γ+γ′+MC+μ → γ+γ′+μ+MC+M23C6 → γ+γ′+μ+MC+M23C6+σ. The volume fraction of γ′ phase precipitated at 780 ℃ is 40.88%. The forging deformation process is γ+γ′ dual phase zone deformation. After solution at 1 120 ℃, the microstructure after standard double aging treatment (850 ℃/6 h/AC+ 780 ℃/6 h/AC) clearly shows two different size grains. Small crystal grains (13 μm) are distributed around large crystal grains (100 μm) in a necklace shape. The carbides in this alloy are mainly MC (NbC, TiC, VC) of large size and irregular shape. The distribution state of the strengthening phase γ′ phase also has two different sizes. The average diameter of γ′I phase is 600 nm, the average diameter of γ′II phase is 150 nm. The good matching of the two sizes of γ′ phase strengthening makes the alloy have high strength and high plasticity at the same time, and excellent mechanical properties. The tensile strength at room temperature is 1 478 MPa, and the durability at 650 ℃/863 MPa is 194 h, which far exceeds the standard of 50 h at 650 ℃/823 MPa for GH4742 alloy.
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Received: 21 July 2021
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| [1] |
Guang‑di Zhao, Xi‑min Zang, Wen‑ru Sun. Role of carbon in modifying solidification and microstructure of a Ni?based superalloy with high Al and Ti contents[J]. JOURNAL OF IRON AND STEEL RESEARCH,INTERNATIONAL, 2021, 28(1): 98-110. |
| [2] |
Bo Xia, Xiao‑ming Zhang, R.D.K. Misra, Ming‑ming Pan, Yu‑qian Wang. Signifcant impact of cold-rolling deformation and annealing on damping capacity of Fe–Mn–Cr alloy[J]. JOURNAL OF IRON AND STEEL RESEARCH,INTERNATIONAL, 2020, 27(5): 566-576. |
| [3] |
Han‑sheng Bao, Gang Yang, Zheng‑zong Chen, Zheng‑dong Liu. Effects of long term aging on microstructure and properties of a tungsten bearing heat resistant alloy[J]. JOURNAL OF IRON AND STEEL RESEARCH,INTERNATIONAL, 2020, 27(4): 477-487. |
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2022, Vol. 40 
