Method for controlling precipitation of delta phase in Nb-containing nickel-based superalloy

A technology for nickel-based superalloys and alloys, which is applied in the field of controlling the precipitation of δ phases in nickel-based superalloys containing Nb, and in the field of ultra-supercritical units. It can solve the problems of excessive number of needle-like δ phases and cracks, and achieve the increase of precipitation-strengthening phases. , improve the lasting life and reduce the effect of segregation

Active Publication Date: 2021-06-11
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Abstract
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  • Application Information

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Problems solved by technology

[0006] The object of the present invention is to provide a method for controlling the precipitation of δ phases in nickel-based superalloys containing Nb, which solves the long-term problems caused by the excessive amount of acicular δ phases in such alloys by controlling the number and positions of the δ phases. The problem of cracks during service

Method used

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  • Method for controlling precipitation of delta phase in Nb-containing nickel-based superalloy
  • Method for controlling precipitation of delta phase in Nb-containing nickel-based superalloy
  • Method for controlling precipitation of delta phase in Nb-containing nickel-based superalloy

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Experimental program
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Effect test

Embodiment 1

[0041] Alloy composition (wt.%) of this example: C0.04%, Cr21.5%, Mo9.0%, Nb3.7%, Fe<5.0%, Mn<1.0%, Si<1.0%, Al1.2% , Ti0.6%, B0.005%, Hf0.4%, and the rest is Ni;

[0042] The metallographic structure of the obtained alloy after heat treatment is as follows: figure 1 Shown, MC carbide and M 23 C 6 The carbides are distributed on the matrix or grain boundaries, and the spherical γ′ strengthening phase is evenly distributed on the matrix.

[0043] The metallographic structure of the alloy after long-term aging at 700℃ for 1000-7000h is shown in figure 2 , it can be seen from the figure that the δ phase precipitated in the alloy structure is controlled to precipitate a small amount near the grain boundary region.

[0044] The properties of the alloy of this embodiment at 700°C are as follows:

[0045] Standard heat treatment: σ b =400MPa, σ 0.2 =205MPa, δ=46.0%, ψ=59.0%. Aging at 650°C for 1000 hours: σ b =530MPa, σ 0.2 =410MPa, δ=36.0%, ψ=43.0%. Aging at 650°C for 30...

Embodiment 2

[0053] Alloy composition (wt.%) of this example: C0.02%, Cr21.5%, Mo9.0%, Nb3.7%, Fe<5.0%, Mn<1.0%, Si<1.0%, Al1.2% , Ti0.6%, B0.005%, Hf0.8%, and the rest is Ni;

[0054] The tensile properties of the alloy at 700°C are as follows

[0055] Standard heat treatment: σ b =360MPa, σ 0.2 = 170MPa, δ = 62.0%, ψ = 64.0%, aging at 650°C for 1000 hours: σ b =600MPa, σ 0.2 =450MPa, δ=37.0%, ψ=31.0%. Aging at 650°C for 3000 hours: σ b =635MPa, σ 0.2 =420MPa, δ=25.0%, ψ=12.0%. Aging at 700°C for 1000 hours: σ b =608MPa, σ 0.2 =495MPa, δ=20.0%, ψ=27.0%. Aging at 700°C for 3000 hours: σ b =705MPa, σ 0.2 =520MPa, δ=26.0%, ψ=28.0%. Aging at 750°C for 1000 hours: σ b =930MPa, σ 0.2 =565MPa, δ=19.0%, ψ=21.0%. Aging at 750°C for 3000 hours: σ b =575MPa, σ 0.2 =500MPa, δ=5.0%, ψ=20.0%.

[0056] Durability performance: aging at 700°C for 1000h, and the durability life at 700°C / 350MPa is >299.95h.

Embodiment 3

[0058] Alloy composition of this example: C0.03%, Cr21.5%, Mo9.0%, Nb3.7%, Fe<5.0%, Mn<1.0%, Si<1.0%, Al0.9%, Ti0.6% , B0.005%, Hf0.5%, and the rest are Ni;

[0059] The tensile properties of the alloy at 700°C are as follows

[0060] Standard heat treatment: σ b =400MPa, σ 0.2 =195MPa, δ=59.0%, ψ=57.0% 650°C aging for 1000 hours: σ b =480MPa, σ 0.2 =375MPa, δ=40.0%, ψ=64.0%. Aging at 650°C for 3000 hours: σ b =585MPa, σ 0.2 =480MPa, δ=22.0%, ψ=35.0%. Aging at 700°C for 1000 hours: σ b =640MPa, σ 0.2 =456MPa, δ=32.0%, ψ=38.0%. Aging at 700°C for 3000 hours: σ b =665MPa, σ 0.2 =485MPa, δ=25.0%, ψ=31.0%. Aging at 750°C for 1000 hours: σ b =693MPa, σ 0.2 =445MPa, δ=22.0%, ψ=26.0%. Aging at 750°C for 3000 hours: σ b =775MPa, σ 0.2 =485MPa, δ=18.0%, ψ=32.0%.

[0061] Durability performance: aging at 700°C for 1000h, and the durability life at 700°C / 350MPa is >299.95h.

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Abstract

The invention discloses a method for controlling precipitation of a delta phase in a Nb-containing nickel-based superalloy, and belongs to the technical field of superalloy materials. The method comprises the steps of burdening, casting and heat treatment, Al, Ti and microelements B and Hf are added on the basis of original material chemical components, and according to experimental verification, when the addition amount of Al is 0.5-1.5 wt%, the addition amount of Ti is 0.2-1.0 wt%, the addition amount of B is 0.0010-0.0075 wt% and the addition amount of Hf is 0.1-1.00 wt%, the effects of controlling precipitation of the delta phase in a grain boundary area, reducing a gamma" metastable phase, inhibiting conversion from gamma" to the delta phase, and promoting the precipitation of a stable precipitation strengthening phase are achieved. Therefore, the endurance life, the strength and the structure stability of the materials are remarkably improved.

Description

technical field [0001] The invention relates to the technical field of superalloy materials, in particular to a method for controlling the precipitation of delta phase in a nickel-based superalloy containing Nb, and the nickel-based superalloy containing Nb is applied to an ultra-supercritical unit. Background technique [0002] As countries around the world increase their requirements for improving energy efficiency and reducing pollution emissions, in order to increase the steam temperature of ultra-supercritical coal-fired power generation units from the current 600 °C successfully used to 700 °C in the future, it is necessary to use temperature-bearing capacity Higher nickel-based, nickel-cobalt-based and nickel-iron-based superalloys replace traditional ferritic and austenitic heat-resistant steels. [0003] Ultra-supercritical steam turbine unit rotors, cylinders and other components have large ingot shapes, use a large number of high-temperature alloys, and can weigh ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C19/05C22C1/03C22F1/10
CPCC22C19/055C22C1/023C22C1/03C22F1/10C22F1/002Y02P10/25
Inventor 侯介山李林子杨飞王常帅秦学智周兰章
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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