CN116083753A - Ni-based alloy material for high-temperature blades of 750 ℃ ultra-supercritical steam turbine - Google Patents

Abstract

A Ni-based alloy material for high-temperature blades of a super-supercritical steam turbine at 750 ℃. It belongs to the field of alloy materials. Materials: the composition C comprises the following components in percentage by weight: 0.04 to 0.10 percent, si: less than or equal to 0.60 percent, mn: less than or equal to 0.50 percent, P: less than or equal to 0.015 percent, less than or equal to 0.010 percent of S, cr: 12.00-16.00%, W:5.0 to 8.0 percent, mo:2.0 to 4.0 percent, ti:1.5 to 2.2 percent of Al:2.40 to 3.00 percent, V:0.20 to 1.00 percent of Fe: less than or equal to 5.0 percent and the balance of Ni. According to the invention, through optimizing the alloy element components, the linear expansion coefficient of the alloy is reduced, the high-temperature performance of the material is improved, the use temperature is up to 750 ℃, and the problem of the low linear expansion coefficient Ni alloy material for the high-temperature blade of the ultra-supercritical steam turbine at 750 ℃ is solved. The Ni-based alloy material is suitable for high-temperature blades of ultra-supercritical turbines at 750 ℃.

Description

A Ni-based alloy material that can be used for high-temperature blades of 750°C ultra-supercritical steam turbines

technical field

The invention belongs to the field of alloy materials, and in particular relates to a Ni-based alloy material which can be used for high-temperature blades of 750°C ultra-supercritical steam turbines.

Background technique

At present, the inlet steam temperature of ultra-supercritical steam turbines put into commercial operation at home and abroad has reached 620°C, and domestically, high-efficiency ultra-supercritical steam turbines with a temperature of 650°C or even higher are being developed. High-temperature blades are in direct contact with steam, requiring materials with excellent high-temperature performance and oxidation resistance. At present, high-efficiency ultra-supercritical steam turbines at 650°C and above must be made of Ni-based alloys. Ni-based alloys have excellent high-temperature performance, and the service temperature can generally exceed 700°C. However, the common problem of Ni-based alloy materials is that the linear expansion coefficient is relatively large. The power of high-efficiency ultra-supercritical steam turbines is relatively high, usually above 600MW, which requires that the size of its components is often relatively large, especially the rotor, cylinder, etc. Therefore, the linear expansion coefficient of these components must be as small as possible to avoid damage. Thermal fatigue damage occurs when components operate at high temperatures. Therefore, the linear expansion coefficient of the high-temperature blades matched with the rotor and other components should also be as small as possible.

Contents of the invention

The object of the present invention is to solve the above-mentioned problems in the prior art, and provide a Ni-based alloy material that can be used for high-temperature blades of 750°C ultra-supercritical steam turbines.

A Ni-based alloy material that can be used for high-temperature blades of 750°C ultra-supercritical steam turbines, which is composed of C: 0.04-0.10%, Si: ≤0.60%, Mn: ≤0.50%, P: ≤0.015%, S ≤0.010%, Cr: 12.00～16.00%, W: 5.0～8.0%, Mo: 2.0～4.0%, Ti: 1.5～2.2%, Al: 2.40～3.00%, V: 0.20～1.00%, Fe: ≤5.0 %, the rest is Ni.

The invention can be used for Ni-based alloy materials for high-temperature blades of ultra-supercritical steam turbines at 750°C. By optimizing the composition of alloy elements, the linear expansion coefficient of the alloy is reduced, and the high-temperature performance of the material is improved, so that the service temperature of the material is as high as 750°C, solving the problem of 750°C. Low linear expansion coefficient Ni alloy material for high-temperature blades of ℃ grade high-efficiency ultra-supercritical steam turbines.

In the present invention, the properties and indexes of the Ni-based alloy material that can be used for the high-temperature blade of the ultra-supercritical steam turbine at 750°C are as follows:

Tensile properties at room temperature: Rp0.2≥690MPa, Rm≥1000～1200MPa, A≥12%, Z≥12%;

Room temperature hardness: 290 ~ 350HB;

Tensile properties at 800°C: Rp0.2≥600MPa, Rm≥750MPa, A≥15%, Z≥15%;

Durability: 850℃, 265MPa, ≥55h;

The Ni-based alloy material of the invention is suitable for high-temperature blades of 750°C ultra-supercritical steam turbines.

Description of drawings

Figure 1 is a comparison chart of linear expansion coefficients in the examples, where ■ indicates Ni-based alloy material, ● indicates GH4133, ▲ indicates 12% Cr steel, and ▼ indicates X6CrNiMoTiB17-13.

Detailed ways

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific Embodiment 1: In this embodiment, a Ni-based alloy material that can be used for high-temperature blades of ultra-supercritical steam turbines at 750°C is composed of C: 0.04-0.10%, Si: ≤0.60%, and Mn: ≤0.50% according to weight percentage , P: ≤0.015%, S ≤0.010%, Cr: 12.00～16.00%, W: 5.0～8.0%, Mo: 2.0～4.0%, Ti: 1.5～2.2%, Al: 2.40～3.00%, V: 0.20 ~1.00%, Fe: ≤5.0%, the rest is Ni.

In this embodiment, Cr: Cr is an indispensable alloying element in Ni-based alloy elements, and the main functions of Cr are:

(i) Improve the oxidation resistance and corrosion resistance of steel;

(ii) Solid solution in the matrix plays a role of solid solution strengthening; (iii) Improves the stacking fault energy of the solid solution and improves the high-temperature creep durability.

In this embodiment, W: W is dissolved in the γ matrix and γ' phase in the Ni-based alloy, accounting for 50% each, and the atomic radius of W is larger, 10-13% larger than that of Ni. The main functions of W are:

(i) Solid solution in the matrix plays a role of solid solution strengthening;

(ii) W atoms in the alloy matrix cause significant expansion of the lattice, forming a large long-range stress field, preventing dislocations from running, and significantly improving the yield strength of the alloy;

(iii) W significantly reduces the stacking fault energy of the matrix, effectively improving the high-temperature creep durability of the alloy; (iv) W can reduce the linear expansion coefficient of the alloy.

In this embodiment, Mo: Mo is mostly dissolved in the γ matrix in the Ni-based alloy, accounting for about 25% in the γ' phase, and the atomic radius of Mo is also larger, 9-12% larger than that of Ni. The main functions of Mo are:

(i) Solid solution in the matrix plays a role of solid solution strengthening;

(ii) Mo atoms cause significant lattice expansion in the alloy matrix, forming a large long-range stress field, preventing dislocations from running, and significantly improving the yield strength of the alloy;

(iii) Mo reduces the stacking fault energy of the matrix and effectively improves the high-temperature creep durability of the alloy;

(iv) Form a large number of fine and dispersed M6C carbides, which play a role in precipitation strengthening;

(v) Mo can also refine austenite grains; (vi) Mo can reduce the linear expansion coefficient of the alloy.

Al in this embodiment: In the Ni-based alloy, about 20% of Al enters into the γ matrix to perform solid solution strengthening, while 80% of Al forms Ni3Al with Ni to perform precipitation strengthening.

In this embodiment, Ti: In Ni-based alloys, about 10% Al enters into the γ matrix to act as solid solution strengthening, while 90% of Al enters into the γ' phase to replace Al to form Ni3 (Al, Ti), and carry out Precipitation strengthening.

Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that it consists of C: 0.072%, Si: ≤ 0.06%, Mn: ≤ 0.05%, P: ≤ 0.005%, S ≤ 0.001%. , Cr: 14.83%, W: 6.50%, Mo: 3.6%, Ti: 2.04%, Al: 2.50%, V: 0.47%, Fe: ≤0.43%, and the rest is Ni. Others are the same as in the first embodiment.

Specific embodiment 3: The difference between this embodiment and specific embodiment 1 is that it consists of C: 0.071%, Si: ≤0.05%, Mn: ≤0.06%, P: ≤0.006%, S ≤0.001% according to weight percentage , Cr: 14.82%, W: 6.49%, Mo: 3.50%, Ti: 2.05%, Al: 2.52%, V: 0.48%, Fe: ≤0.45%, and the rest is Ni. Others are the same as in the first embodiment.

Embodiment 4: This embodiment is different from Embodiment 1 in that it can be used for the preparation of Ni-based alloy materials for 750°C ultra-supercritical steam turbine high-temperature blades: according to the design, it can be used for 750°C ultra-supercritical steam turbine high-temperature blades. The formula of the Ni-based alloy material is batched, and the preparation is completed after smelting, rolling and heat treatment. Others are the same as in the first embodiment.

Embodiment 5: This embodiment is different from Embodiment 4 in that the smelting includes vacuum induction and electroslag smelting. Others are the same as in Embodiment 4.

Embodiment 6: This embodiment is different from Embodiment 4 in that the rolling: the temperature is 950-1170°C. Others are the same as in Embodiment 4.

Specific embodiment seven: the difference between this embodiment and specific embodiment four is that the heat treatment:

Solid solution: 1170～1190℃, heat preservation for 2h, air cooling;

Solid solution: 1030～1050℃, heat preservation for 4h, air cooling;

Aging, 780～800℃, heat preservation for 18h, air cooling. Others are the same as in Embodiment 4.

Verify the beneficial effects of the present invention through the following examples:

Example:

A Ni-based alloy material that can be used for high-temperature blades of ultra-supercritical steam turbines at 750°C, which is composed of C: 0.072%, Si: ≤0.06%, Mn: ≤0.05%, P: ≤0.005%, and S≤0.001 %, Cr: 14.83%, W: 6.50%, Mo: 3.6%, Ti: 2.04%, Al: 2.50%, V: 0.47%, Fe: ≤0.43%, and the rest is Ni.

In this embodiment, it can be used as a Ni-based alloy material for high-temperature blades of ultra-supercritical steam turbines at 750°C. The ingredients are prepared according to the above formula, and the preparation is completed after smelting, rolling and heat treatment.

The smelting: vacuum induction and electroslag process smelting.

The rolling: the temperature is 1050°C.

The heat treatment:

Solid solution: 1150℃, keep warm for 2h, air cooling;

Solid solution: 1050°C, heat preservation for 4 hours, air cooling;

Aging, 800°C, heat preservation for 18h, air cooling.

In this embodiment, the properties of Ni-based alloy materials that can be used for 750°C ultra-supercritical steam turbine high-temperature blades:

Tensile properties at room temperature: Rp0.2, 715MPa, Rm, 1150MPa, A, 15%, Z, 16%;

Room temperature hardness: 343HB;

Tensile properties at 800°C: Rp0.2, 675MPa, Rm, 845MPa, A, 20%, Z, 18%;

Durability: 850℃, 265MPa, 85h;

In this example, it can be used for Ni-based alloy materials for high-temperature blades of ultra-supercritical steam turbines at 750°C. As shown in Table 1 and Figure 1, it can be seen that 12% Cr steel is only used below 600°C, so its performance at 600°C is not assessed. The above linear expansion coefficient, compared with the X6CrNiMoTiB17-13 material commonly used in the European Union and the national high-temperature alloy material grade GH4133 in this example, the Ni-based alloy has a relatively slow change in the linear expansion coefficient, and has a lower linearity at 600°C-900°C Coefficient of expansion.

Table 1 Comparison of linear expansion coefficients

material Ni-based alloy material GH4133 12%Cr steel X6CrNiMoTiB17-13 20°C — — — — 100°C 12.5 12.0 10.72 — 200℃ 12.7 12.9 10.58 17.0 300℃ 12.9 13.5 10.98 — 400°C 13.1 13.9 11.52 18.0 500℃ 13.4 14.6 11.94 — 600°C 13.8 15 12.32 — 700°C 14.3 15.8 — — 800℃ 14.9 16.6 — 19.0 900°C 15.6 17.6 — —

Claims (7)

1. A Ni-based alloy material that can be used for high-temperature blades of ultra-supercritical steam turbines at 750°C, characterized in that it is composed of C: 0.04-0.10%, Si: ≤0.60%, Mn: ≤0.50%, P: ≤0.015%, S≤0.010%, Cr: 12.00～16.00%, W: 5.0～8.0%, Mo: 2.0～4.0%, Ti: 1.5～2.2%, Al: 2.40～3.00%, V: 0.20～1.00% , Fe: ≤5.0%, the rest is Ni. 2. A Ni-based alloy material that can be used for high-temperature blades of 750°C ultra-supercritical steam turbines according to claim 1, characterized in that it is composed of C: 0.072%, Si: ≤0.06%, Mn: ≤ 0.05%, P: ≤0.005%, S ≤0.001%, Cr: 14.83%, W: 6.50%, Mo: 3.6%, Ti: 2.04%, Al: 2.50%, V: 0.47%, Fe: ≤0.43%, The rest is Ni. 3. A Ni-based alloy material that can be used for 750°C ultra-supercritical steam turbine high-temperature blades according to claim 1, characterized in that it is composed of C: 0.071%, Si: ≤0.05%, Mn: ≤ 0.06%, P: ≤0.006%, S ≤0.001%, Cr: 14.82%, W: 6.49%, Mo: 3.50%, Ti: 2.05%, Al: 2.52%, V: 0.48%, Fe: ≤0.45%, The rest is Ni. 4. A kind of Ni base alloy material that can be used for 750 ℃ of ultra-supercritical steam turbine high-temperature blades according to claim 1, is characterized in that the preparation of this material: can be used for 750 ℃ of ultra-supercritical steam turbine high-temperature blades by design The formula of the Ni-based alloy material is batched, and the preparation is completed after smelting, rolling and heat treatment. 5. A Ni-based alloy material that can be used for high-temperature blades of 750°C ultra-supercritical steam turbines according to claim 4, characterized in that the smelting includes vacuum induction and electroslag smelting. 6. The Ni-based alloy material for high-temperature blades of ultra-supercritical steam turbines at 750°C according to claim 4, characterized in that the rolling temperature is 950-1170°C. 7. A kind of Ni-based alloy material that can be used for 750 ℃ ultra-supercritical steam turbine high-temperature blades according to claim 4, characterized in that the heat treatment: Solid solution: 1170～1190℃, heat preservation for 2h, air cooling; Solid solution: 1030～1050℃, heat preservation for 4h, air cooling; Aging, 780～800℃, heat preservation for 18h, air cooling.

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