High-temperature nickel-based alloy

Abstract

A high-temperature nickel-based alloy consisting of, in wt.%, 0.04 to 0.1% of C, maximum 0.01% of S, maximum 0.05% of N, 24 to 28% of Cr, maximum 0.3% of Mn, maximum 0.3% of S i, 1 to 6% of Mo, 0.5 to 3% of Ti, 0.001 to 0.1% of Nb, maximum 0.2% of Cu, 0.1 to 0.7% of Fe, maximum 0.015% of P, 0.5 to 2% of Al, maximum 0.01% of Mg, maximum 0.01% of Ca, 0.01 to 0.5% of V, maximum 0.1% of Zr, 0.2 to 2% of W, 17 to 21% of Co, maximum 0.01% of B, maximum 0.01% of O, the balance Ni, and impurities resulting from melting.

Description

[0001] This application is a divisional application of patent application number 201880033862.0.

[0002] The invention relates to a high-temperature nickel-based alloy.

[0003] The material C263 (Nicrofer 5120CoTi) is used in particular as a heat shield in turbochargers or vehicle engines. The heat shield separates the compressor side from the turbine side within the turbocharger and the hot exhaust gas flows directly into it. Since the exhaust gas temperature, especially in Otto engines, is constantly increasing, this can lead to failures of the components, for example in the form of deformation, which leads to a significant reduction in the performance of the turbocharger.

[0004] The exhaust gas temperature can be up to 1,050°C, with the temperature reached at the thermal barrier being about 900 to 950°C. At such temperatures the C263 material is no longer creep resistant. The general composition of the material C263 is given as follows (in weight %): Cr 19.0-21.0%, Fe max 0.7%, C 0.04-0.08%, Mn max 0.6%, Si max 0.4%, Cu max 0.2%, Mo 5.6-6.1%, Co 19.0-21.0%, Al 0.3-0.6%, Ti 1.9-2.4%, P max 0.015%, S max 0.007%, B max 0.005%.

[0005] From DE 100 52 023 C1 is known an austenitic nickel-chromium-cobalt-molybdenum-tungsten alloy containing (in mass %): C 0.05-0.10%, Cr 21-23%, Co 10-15%, Mo 10-11%, Al 1.0-1.5%, W 5.1-8.0%, Y 0.01-0.1%, B 0.001-0.01%, Ti max. 0.5%, Si max. 0.5%, Fe max. 2%, Mn max. 0.5%, Ni balance including unavoidable impurities resulting from melting. The material can be used for compressors and turbochargers of combustion engines, parts of steam turbines, parts of gas turbines and steam turbine power plants.

[0006] EP 1 466 027 B1 discloses a high temperature resistant and corrosion resistant Ni-Co-Cr alloy comprising (in weight %): Cr 23.5-25.5%, Co 15.0-22.0%, Al 0.2-2.0%, Ti 0.5-2.5%, Nb 0.5-2.5%, up to 2.0% Mo, up to 1.0% Mn, Si 0.3-1.0%, up to 3.0% Fe, up to 0.3% Ta, up to 0.3% W, C 0.005-0.08%, Zr 0.01-0.3%, B 0.001 to 0.01%, up to 0.05% rare earth elements as mixed metals, Mg+Ca0.005-0.025%, optionally up to 0.05% Y, the remainder Ni and impurities. The material can be used as exhaust valves for diesel engines and pipes for steam boilers in a temperature range between 530 and 820°C.

[0007] US 6,258,317 B1 describes an alloy that can be used for gas turbine components, which are used for temperatures up to 750°C, and which contains (in weight %): Co 10-24%, Cr 23.5-30%, Mo2.4-6%, Fe 0-9%, AI 0.2-3.2%, Ti 0.2-2.8%, Nb 0.1-2.5%, Mn 0-2%, up to 0.1% Si, Zr 0.01-0.3%, B 0.001-0.01%, C 0.005-0.3%, W 0-0.8%, Ta 0-1%, the remainder Ni and unavoidable impurities.

[0008] The basic object of the present invention is to modify the composition of a material based on C263 in such a way that the stability of the phase that increases the strength is shifted towards higher temperatures. At the same time, care should be taken to shift the stability limits of other phases (e.g., the Eta phase) towards lower temperatures. Furthermore, an attempt should be made to initiate additional hardening mechanisms.

[0009] This object is achieved by a high temperature nickel-based alloy consisting of (in wt. %):

[0010] C 0.04-0.1%

[0011] S max 0.01%

[0012] N max 0.05%

[0013] Cr 24-28%

[0014] Mn max 0.3%

[0015] S i max 0.3%

[0016] Mo 1-6%

[0017] Ti 0.5-3%

[0018] Nb 0.001-0.1%

[0019] Cu max 0.2%

[0020] Fe 0.1-0.7%

[0021] P max 0.015%

[0022] A l 0.5-2%

[0023] Mg max 0.01%

[0024] Ca max 0.01%

[0025] V 0.01-0.5%

[0026] Zr max 0.1%

[0027] W 0.2-2%

[0028] Co 17-21%

[0029] B max 0.01%

[0030] Omax 0.01%

[0031] The balance of Ni, and impurities arising from the melt.

[0032] Advantageous developments of the alloy according to the invention are revealed in the dependent claims.

[0033] The nickel-based alloy according to the invention should preferably be used for components which are exposed to component temperatures above 700° C., preferably >900° C., in particular >950° C. The goal of shifting the gamma-prime phase to high temperatures is achieved, wherein the stabilization of other phases (smaller than the gamma-prime phase and towards low temperatures) can also be achieved.

[0034] The following are some important application scenarios for the alloy:

[0035] car

[0036] -Exhaust equipment

[0037] -Turbocharger

[0038] -Probe

[0039] -valve

[0040] -pipeline

[0041] -High temperature filters or their parts

[0042] -Seals

[0043] - Spring element

[0044] Turbines for aircraft or stationary use

[0045] -blade

[0046] -Conductive surface

[0047] -Probe

[0048] -pipeline

[0049] -cone

[0050] -case

[0051] power plant

[0052] -pipeline

[0053] -Probe

[0054] -valve

[0055] -Casting parts

[0056] -Turbine

[0057] -Turbine housing

[0058] The components are generally used in hot and highly loaded environments, with permanent component temperatures of sometimes above 900° C. Furthermore, oxygen-containing atmospheres are present, for example from car or truck engines, propellers or gas turbines.

[0059] The alloy according to the invention has high heat resistance and creep resistance, with a high temperature corrosion resistance (for example in the case of exhaust gases) being present at the same time.

[0060] The alloy according to the invention is also fatigue-resistant at high temperatures, in particular above 900° C.

[0061] Possible product forms are:

[0062] -bring

[0063] -plate

[0064] -Silk

[0065] -strip

[0066] -Casting parts

[0067] - Powders for additive manufacturing (e.g. 3D printing) and classic powders (e.g. sintering)

[0068] - Tubes (welded or seamless)

[0069] The following elements may be varied in order to optimize the desired parameters as given below (in weight %):

[0070] Cr 24-26%

[0071] Mo 2-6%, especially 4-6%

[0072] Mo 1.5-2.5%

[0073] Ti 0.5-2.5%, especially 1.5-2.5%

[0074] Al 0.5-1.5%

[0075] V 0.01-0.2%

[0076] W 0.2-1.5%, especially 0.5-1.5%

[0077] Co 18.5-21%

[0078] Advantageously, the sum of Ti+Al (in wt. %) is at least 1%. In certain use cases, it may be convenient if the sum of Ti+Al (in wt. %) is at least 1.5%, in particular at least 2%.

[0079] According to a further aspect of the invention, the Ti / Al ratio should be at most 3.5, in particular at most 2.0.

[0080] By reducing the Ti / Al ratio, no or only a small amount of Eta-Ni3Ti can be formed.

[0081] The high temperature nickel-based alloy of the present invention can preferably be used for large-scale production (>1 t).

[0082] The advantages of the alloy of the present invention will be explained in detail with the help of examples:

[0083] In Table 1 the same reference batch (laboratory) of the prior art (large scale production Nicrofer 5120 CoTi) and various alloy compositions of the present invention are compared.

[0084] In Table 2, several large scale production batches of the prior art are compared (large scale production Nicrofer 5120 CoTi).

[0085] Table 1

[0086]

[0087]

[0088] Table 1 (continued)

[0089]

[0090]

[0091] Table 2

[0092]

[0093]

[0094] 8 kg of initial material was used for each melt (Table 1). After casting, the samples were subjected to spectrogram analysis. The samples were subsequently rolled to a thickness of 6 mm. By further rolling (with intermediate annealing) on ​​a laboratory rolling mill, the samples were rolled to a final thickness of 0.4 mm.

[0095] Solution annealing was performed at 1,150 °C for 30 min, followed by water quenching.

[0096] Precipitation hardening was performed at 800, 850, 900 and 950°C for 4 / 8 / 16 hours followed by water quenching.

[0097] Variants 250575 to 250577 show a very high hardness level compared to the prior art (in each case compared to variants 250573 and 250574). This means that the phase that increases the strength (here the gamma-based phase) is still stable.

[0098] For large-scale applications (Table 2), the material is produced in a medium-frequency induction furnace and then cast as a continuous casting in the form of a thick plate (Brammenform). The thick plate is then remelted in an electric slag remelting furnace to form another thick plate (correspondingly a strip). The corresponding thick plate is then hot-rolled to produce a strip material with a thickness of about 6 mm. This is followed by a cold rolling process in which the strip material is rolled to a final thickness of about 0.4 mm.

[0099] Thus, there is now a starting material for a deep-drawn or stamped product. Depending on the requirements, a further heat treatment can be carried out, depending on the product.

[0100] The following manufacturing routes are suitable for producing parts for aircraft:

[0101] VIM-VAR

[0102] The product form after VAR can be either slabs or strips.

[0103] The forming can be performed by rolling or forging.

[0104] The following preparation routes are also suitable for producing components for power plants or automobiles:

[0105] VIM-ESU

[0106] Forming by forging or rolling is also conceivable here.

[0107] Figure 1 The time-dependent creep elongation of different materials at a typical application temperature of 900°C and a load of 60 MPa is shown. Materials C-263 standard (Nicrofer 5120CoTi), C-264 variant 76 (Batch 250576) and C-264 variant 77 (Batch 250577) are shown.

[0108] In standard form it can be seen that at a predetermined temperature and load, the material fails after less than 100 hours.

[0109] The other two variants showed service lives of approximately 400 hours and approximately 550 hours, respectively.

[0110] Variants 76 and 77 show an improved service life, which results in a higher creep resistance and thus much smaller component deformations under operating conditions.

Claims

1. Use of a high-temperature nickel-based alloy as a component of a turbocharger, a component for a floating or stationary turbine, especially a steam turbine, a blade or a conducting element for a floating or stationary turbine, especially a steam turbine, the nickel-based alloy consisting of the following, expressed in % by weight: The minimum sum of Ti+Al is 2wt%, The maximum ratio of Ti / Al is 2.

0.

2. Use according to claim 1, wherein the nickel-based alloy has 24-26% Cr in weight %.

3. The use according to claim 1 or 2, wherein the nickel-based alloy has 2-6% Mo in weight %.

4. The use according to claim 1 or 2, wherein the nickel-based alloy has 1.5-2.5% Mo in weight %.

5. Use according to claim 1 or 2, wherein the nickel-based alloy has 4-6% Mo in weight %.

6. The method according to claim 1, wherein the nickel-based alloy has 0.5-1.5% Al in wt%.

7. The use according to any one of claims 1 to 6, wherein the nickel-based alloy has 0.01-0.2% V in weight %.

8. The use according to any one of claims 1 to 7, wherein the nickel-based alloy has 0.5-1.5% W in weight %.

9. Use according to one of claims 1 to 8, wherein the nickel-based alloy can be used for components which are exposed to component temperatures of >700°C, in particular >900°C, or more precisely >950°C.

10. The method according to claim 1, wherein the method is used as a component in a power plant.

11. The use according to claim 10, which can be used for pipes or sensors in power plants.

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