CN111254317A

CN111254317A - Nickel-based casting alloy and preparation method thereof

Info

Publication number: CN111254317A
Application number: CN202010060594.0A
Authority: CN
Inventors: 袁晓飞; 尹三强; 吴剑涛; 陈兴福; 李维
Original assignee: Gaona Aero Material Co Ltd
Current assignee: Gaona Aero Material Co Ltd
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2020-06-09
Anticipated expiration: 2040-01-19
Also published as: CN111254317B

Abstract

The invention belongs to the technical field of new materials, and provides a nickel-based casting alloy and a preparation method thereof, which are mainly applied to high-temperature bearing structural members of a ramjet engine with the wall surface temperature of 1200 ℃, such as air inlet channel structural members. The alloy comprises the following components in percentage by mass: 0.1-0.25%, Cr: 7.5-10.7%, Co: 8-12%, W: 8-12%, Al: greater than 6.25%, Ti: 0.75-2%, Ta: 2-3%, Hf: 0.8 to 2.5%, Zr: 0.01-0.15%, B: 0 to 0.2 percent of Ni and the balance of impurity elements. The nickel-based casting alloy is produced by adopting an investment casting method, and has higher temperature bearing capacity and durability than the like cast high-temperature alloy after 870 ℃/16h standard heat treatment.

Description

Nickel-based casting alloy and preparation method thereof

Technical Field

The invention belongs to the technical field of new materials, and relates to a nickel-based cast alloy and a preparation method thereof, in particular to a nickel-based cast superalloy with excellent ultrahigh-temperature mechanical property, which is mainly applied to a high-temperature bearing structural member of a ramjet engine with the wall surface temperature of 1200 ℃, such as an air inlet channel structural member.

Background

Since the concept of hypersonic flight was proposed in the sixties of the twentieth century, the world countries compete for the development of hypersonic technology, and the emphasis has been placed on high-temperature components with complex structures, mainly hypersonic ramjets. In order to meet the requirement of continuous upgrading and updating of the thrust-weight ratio of the engine, the structure and the material of the key high-temperature alloy part are greatly changed, the structure is developed towards the direction of integration and hollowness, and the material is required to have higher temperature bearing capacity, better corrosion resistance, longer service life and lower cost. With the continuous development of aviation and aerospace technologies in China, the performance of the engine is increasingly improved, and the requirements on the temperature resistance and high-temperature mechanical properties of structural materials of the engine are increasingly high. Early engine high temperature components were typically repair welded from wrought superalloy sheet materials, commonly used being GH3230 and GH 5188. GH3230 is Ni-Cr-based solid solution strengthening type deformation high-temperature alloy, and the use temperature range is 700-1050 ℃. GH5188 is Co-Ni-Cr-based solid solution strengthening type deformation high-temperature alloy, and is suitable for manufacturing engine parts requiring high strength below 980 ℃. With the continuous development of the stamping engine, the requirements that the long-time service temperature exceeds 1100 ℃, the short-time service temperature exceeds 1200 ℃ and the service time exceeds 2000s are provided, the use requirements of the engine cannot be met by a deformed high-temperature alloy plate welding piece, and the cast high-temperature alloy structural piece with higher temperature bearing capacity and better comprehensive performance needs to be developed.

In the last 60-70 s, Martin Metals, Inc. of America, successively developed Mar-M200, Mar-M246(US3164465, published as 1965, 1 and 5, under the name of Nickel-Base Alloys) and Mar-M002(US3765879, published as 1973, 10 and 16, under the name of Nickel Base Alloys). Among them, the Mar-M200 alloy contains elements such as Nb which easily form an MC type carbide which is unstable, and has a low supersaturation degree, and thereforeThe medium temperature endurance, plasticity and creep property of the alloy are poor due to the low content of the eutectic of the gamma/gamma' phase, for this reason, Nb is removed, Mo and Ta are added, and W content is reduced, so that Mar-M246 alloy is developed, which maintains the original good high temperature property and has improved medium temperature endurance, but because of containing 2.5 wt% of Mo, the alloy forms M at high temperature₆The quantity of the C phase is increased, and the tendency of forming a TCP phase at the temperature of more than 1000 ℃ is increased, so that the alloy composition is further adjusted and improved, Mo is removed, Hf is added, the Ta content is increased, and the nickel-based casting high-temperature alloy Mar-M002 with good medium-high temperature performance and excellent comprehensive performance is formed. As a precipitation strengthening type high W class equiaxed crystal casting high-temperature alloy, the medium-temperature and high-temperature performance level of the Mar-M002 alloy belongs to the highest level of the existing equiaxed crystal casting high-temperature alloy. The alloy has stable structure, good high-temperature oxidation resistance and heat corrosion resistance, is mature to be applied to aeroengine turbine rotor blades and integrally cast turbines, and has long-term use temperature not exceeding 1050 ℃.

Aiming at the requirements of a new generation of ramjet on high-temperature alloy structural members, the trial production of structural members such as an air inlet channel and the like is developed by adopting Mar-M002 alloy in China. However, due to the difference between the working condition and the structure of the Mar-M002 alloy and the difference between the working condition and the structure of an aero-engine, the existing Mar-M002 alloy components, casting process and heat treatment process do not completely meet the use requirements of a high-temperature structural member of a ramjet engine, namely the long-time use temperature exceeds 1100 ℃, the short-time use temperature exceeds 1200 ℃ and the service time exceeds 2000 s. The alloy composition and structure are precisely regulated and controlled according to the mechanical property requirement of the high-temperature part of the ramjet, so that the ramjet has good comprehensive properties.

Disclosure of Invention

The invention aims to provide a low-cost nickel-based cast superalloy with higher temperature bearing capacity. The comprehensive properties of the alloy comprise room-temperature tensile property, ultrahigh-temperature durability and high-temperature oxidation property. The alloy is mainly applied to high-temperature bearing structural members of a ramjet engine with the wall temperature of 1200 ℃, such as air inlet structural members.

To achieve the above object, the present invention provides a nickel-base casting alloy comprising, in weight percent, C: 0.1-0.25%, Cr: 7.5-10.7%, Co: 8-12%, W: 8-12%, Al: greater than 6.25%, Ti: 0.75-2%, Ta: 2-3%, Hf: 0.8 to 2.5%, Zr: 0.01-0.15%, B: 0 to 0.2 percent.

The invention also provides a preparation method of the nickel-based casting alloy, which comprises the following steps: the alloy raw materials are sequentially subjected to mixing melting, refining and casting molding under the vacuum condition.

Compared with the recently developed high-temperature alloy of the same type, the high-temperature mechanical property of the nickel-based casting alloy is obviously improved, and the high-temperature oxidation resistance and the room-temperature tensile property are good. In particular, the high temperature tensile strength and long life of the nickel-base casting alloy of the present invention is higher than that of the commercial alloy Mar-M002 at 1200 ℃. The nickel-based cast superalloy has higher temperature bearing capacity and durability compared with similar superalloy, is a novel ultra-high temperature resistant nickel-based cast superalloy, and can effectively improve the working reliability and performance level of a new generation of ramjet.

Drawings

FIG. 1 is a typical low magnification microstructure of a nickel-based casting alloy according to one embodiment of the present invention;

FIG. 2 is a typical structure of a dendritic dry gamma prime strengthening phase of a nickel-base casting alloy according to one embodiment of the present invention.

Detailed Description

In the present invention, unless otherwise specified, all the contents mentioned in the present invention are contents in weight percentage.

The invention provides a nickel-based casting alloy, which comprises the following components in percentage by weight: 0.1-0.25%, Cr: 7.5-10.7%, Co: 8-12%, W: 8-12%, Al: greater than 6.25%, Ti: 0.75-2%, Ta: 2-3%, Hf: 0.8 to 2.5%, Zr: 0.01-0.15%, B: 0 to 0.2 percent.

According to the invention, Al is an important constituent of the nickel-based casting alloy, and is particularly advantageous for increasing the amount and stability of the gamma prime strengthening phase at high temperatures, the Al content of the nickel-based casting alloy being more than 6.25%, preferably less than or equal to 8.75%, such as 6.3%, 6.4%, 6.45%, 6.5%, 6.56%, 6.6%, 6.7%, 6.75%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 8%, 8.2%, 8.4%, 8.5%, 8.6%, 8.7%, 8.75% or any value therebetween.

According to the invention, C is particularly advantageous for improving the high temperature strength and mechanical properties of the nickel-base casting alloy, the content of C in the nickel-base casting alloy being between 0.1 and 0.25%, preferably between 0.13 and 0.17%.

According to the invention, Cr is an indispensable alloying element in superalloys, and the Cr content of the nickel-base casting alloy is 7.5-10.7%, preferably 8-10%.

According to the invention, the content of Co in the nickel-base casting alloy is 8-12%, preferably 9-11%.

According to the invention, W is particularly advantageous for improving the yield strength and creep behaviour of nickel-base casting alloys, in which W is present in an amount of 8-12%, preferably 9-11%.

According to the invention, the Al content of the nickel-base casting alloy is 6.26 to 8.5%, preferably 6.5 to 7%, in particular 6.5 to 6.6%.

According to the invention, the Ti content of the nickel-base casting alloy is between 0.75 and 2%, preferably between 1.25 and 1.75%. According to a preferred embodiment of the invention, the total content of Al and Ti in the nickel-base casting alloy is below 8.5%, in particular 8-8.5%.

According to the invention, Ta is particularly advantageous for improving the strength, creep resistance, hot corrosion resistance and cold and hot fatigue properties of nickel-base casting alloys, the content of Ta in said nickel-base casting alloys being between 2 and 3%, preferably between 2.25 and 2.75%.

According to the invention, the content of Hf in the nickel-base casting alloy is 0.8-2.5%, preferably 1.3-1.7%.

According to the invention, Zr is particularly advantageous for increasing the high-temperature strength and the service life of the nickel-base casting alloy, the Zr content of the nickel-base casting alloy being set to 0.01-0.15%, preferably 0.03-0.08%.

According to the invention, B is particularly advantageous for improving the castability and the microstructure stability of nickel-base casting alloys in which B is present in an amount of 0-0.2% or 0.002-0.2%, preferably 0.01-0.02%.

According to the present invention, the main component of the nickel-based casting alloy is Ni, wherein the content of Ni may be 48 to 65%, preferably 54.5 to 65.5%.

According to the invention, the nickel-based casting alloy generally contains unavoidable impurities, such as, for example, Mo, Fe, V, Mg, Mn, Si, Bi, S, P, Cu, Ag, Pb. Specifically, the nickel-based casting alloy contains Mo: 0.5% or less, Fe: 0.5% or less, V: 0.1% or less, Mg: 0.003% or less, Mn: 0.2% or less, Si: 0.2% or less, Bi: 0.00005% or less, S: 0.01% or less, P: 0.01% or less, Cu: 0.1% or less, Ag: 0.0005% or less, Pb: less than 0.0005%. The trace impurity elements Ag, Pb and Bi in the nickel-based casting alloy are respectively controlled at the magnitude of 5ppm and 0.5ppm, which plays an important role in ensuring the smelting quality of the nickel-based casting alloy and the quality of alloy remelting forming parts.

According to a preferred embodiment of the present invention, the nickel-based casting alloy is composed of Ni, C, Cr, Co, W, Al, Ti, Ta, Hf, Zr, B and inevitable impurities, wherein the contents of C, Cr, Co, W, Al, Ti, Ta, Hf, Zr, B and inevitable impurities may be as described above, and the balance is Ni.

The present invention provides a method of preparing the nickel-based casting alloy as described above, comprising: the alloy raw materials are sequentially subjected to mixing melting, refining and casting molding under the vacuum condition.

In the method of the present invention, the vacuum condition may be a vacuum degree of 10Pa or less (for example, 5 to 10 Pa).

In the method of the present invention, the mixed melting and refining may be carried out in a conventional manner, but preferably, the mixed melting and refining is carried out in a manner that: and (3) starting power transmission when the vacuum degree is lower than 10Pa, wherein the transmitted power is 25-35KW, reducing the power to 15-25KW after the alloy raw materials are completely melted, refining until the surface of the molten steel is clean and free of films, and cutting off the power and measuring the temperature when the temperature of the molten steel is higher than the alloy pouring temperature by about 20-30 ℃. The mixing melting and refining may be performed in a vacuum induction furnace crucible.

In the method of the present invention, the casting molding can be performed by a conventional method, but preferably, the casting molding is performed by: the transmitted power is 5-15KW, the casting temperature is 1450-.

In the method of the present invention, in order to further improve the performance of the nickel-based casting alloy of the present invention, the method may further comprise heat-treating the cast material at 850-900 ℃ for 15-20 h.

Methods of selecting the composition of the alloy feedstock to yield a nickel-base casting alloy having a desired composition are well known to those skilled in the art and will not be described in detail herein.

The nickel-based casting alloy or the nickel-based casting alloy prepared by the method has obviously improved high-temperature mechanical property, and is particularly suitable for high-temperature bearing structural members of the ramjet with the wall temperature of 1200 ℃, such as air inlet structural members. Therefore, the invention also provides the application of the nickel-based casting alloy in preparing a high-temperature bearing structural part (such as an air inlet passage structural part) of a ramjet engine with the wall temperature of 1200 ℃.

The present invention is illustrated in more detail by the following examples so that those skilled in the art can understand the advantages and features of the present invention. However, the present invention is not limited to these examples.

Examples 1 to 3

(1) Preparing alloy raw materials according to the compositions shown in the table 1;

(2) putting the prepared alloy raw material into a crucible of a vacuum induction furnace, vacuumizing to below 10Pa, starting to transmit power, wherein the transmitted power is 30KW, reducing the power to 20KW after the alloy raw material is completely melted, refining until the liquid level of steel is clean and has no film, cutting off the power and measuring the temperature when the temperature of the molten steel is higher than about 25 ℃ of the alloy pouring temperature, and performing pouring forming at the transmitted power of 10KW, wherein the pouring forming temperature is 1480 ℃ and the shell temperature is 900 ℃; heat treatment is carried out for 16 hours at 870 ℃, and the nickel-based casting alloy ingot can be obtained. Fig. 1 is a typical low power (× 200 times) microstructure of the alloy obtained in example 1, and fig. 2 is a typical structure of dendrite dry γ' strengthening phase of the alloy obtained in example 1, which is observed by a field emission scanning electron microscope.

Mar-M002 is a nickel-based cast equiaxed superalloy as described in US 3765879.

TABLE 1

	Example 1	Example 2	Example 3	Mar-M002
					Ni	Bal.	Bal.	Bal.	Bal.
Al	6.56	6.74	6.98	5.48
					Ti	1.50	1.49	1.48	1.48
Cr	8.86	8.94	8.89	8.82
					Ta	2.53	2.43	2.40	2.48
Co	10.02	9.59	9.62	10
					Hf	1.52	1.59	1.60	1.48
W	10.02	10.03	10.07	9.98
					B	0.015	0.016	0.016	0.015
Zr	0.045	0.055	0.055	0.047
					C	0.14	0.14	0.14	0.15
Mo	0.057	0.038	0.037	0.072
					Fe	0.31	0.083	0.084	0.36
V	0.0071	＜0.005	＜0.005	0.011
					Mg	＜0.001	＜0.001	＜0.001	＜0.001
Mn	＜0.005	＜0.005	＜0.005	＜0.005
					Si	0.053	0.023	0.024	0.058
Bi	＜0.00001	＜0.00001	＜0.00001	＜0.00001
					S	0.0015	0.0012	0.0012	0.0013
P	＜0.005	＜0.005	＜0.005	＜0.005
					Cu	0.0075	0.001	0.001	0.0018
Ag	＜0.0001	＜0.0001	＜0.0001	＜0.0001
					Pb	＜0.0001	＜0.0001	＜0.0001	＜0.0001

Test example 1

The properties of the nickel-base casting alloy were evaluated as follows.

(1) Room temperature and high temperature tensile properties

Cutting the sample, machining into a standard round bar tensile sample with the gauge length of 25mm and the diameter of 5mm, and respectively carrying out room temperature tensile tests according to the GB/T228.1-2010 standard and carrying out high temperature tensile tests at 1100 ℃ and 1200 ℃ according to the GB/T4338-2006 standard.

(2) High temperature durability

Cutting the sample, machining the sample into a standard round bar durable sample with the gauge length of 25mm and the diameter of 5mm, and performing a high-temperature durable experiment at 1100 ℃/100MPa and 1200 ℃/30MPa according to GB/T2039-.

(3) High temperature oxidation resistance

The sample was cut and processed into 30X 10X 1.5mm thin pieces, which were polished and then placed in a crucible for weighing, followed by being placed in a heat treatment furnace. The oxidation weight increase value of the alloy after the test at different temperatures and times is measured by adopting a weight increase method according to the standard HB 5258-2000 for evaluating the oxidation resistance of the alloy. The total test time at 1100 ℃ was 100h, and samples were taken and weighed every 25 h.

Table 2 shows the results of the evaluation of the properties of the example and commercial alloy Mar-M002. It can be seen that the high temperature strength of the examples at 1200 ℃ is significantly better than that of the Mar-M002 alloy.

TABLE 2

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A nickel-base casting alloy, comprising, in weight percent, C: 0.1-0.25%, Cr: 7.5-10.7%, Co: 8-12%, W: 8-12%, Al: greater than 6.25%, Ti: 0.75-2%, Ta: 2-3%, Hf: 0.8 to 2.5%, Zr: 0.01-0.15%, B: 0 to 0.2 percent.

2. The nickel-base casting alloy of claim 1, wherein the content of Al in the nickel-base casting alloy is 8.75% or less.

3. The nickel-base casting alloy of claim 1, wherein the nickel-base casting alloy comprises C: 0.13-0.17%, Cr: 8-10%, Co: 9-11%, W: 9-11%, Al: 6.26-8.5%, Ti: 1.25-1.75%, Ta: 2.25-2.75%, Hf: 1.3-1.7%, Zr: 0.03-0.08%, B: 0.01 to 0.02 percent.

4. The nickel-base casting alloy according to claim 1 or 3, wherein the content of Al in the nickel-base casting alloy is Al: 6.5 to 7 percent.

5. The nickel-base casting alloy according to any of claims 1 to 3, wherein the nickel-base casting alloy contains Mo: 0.5% or less, Fe: 0.5% or less, V: 0.1% or less, Mg: 0.003% or less, Mn: 0.2% or less, Si: 0.2% or less, Bi: 0.00005% or less, S: 0.01% or less, P: 0.01% or less, Cu: 0.1% or less, Ag: 0.0005% or less, Pb: less than 0.0005%.

6. The nickel-base casting alloy according to claim 1 or 3, wherein the total content of Al and Ti in the nickel-base casting alloy is 8.5% or less.

7. A method of making the nickel-base casting alloy of any of claims 1-4, comprising: the alloy raw materials are sequentially subjected to mixing melting, refining and casting molding under the vacuum condition.

8. The method of claim 7, wherein the mixing melting and refining is by: and (3) starting power transmission when the vacuum degree is lower than 10Pa, wherein the transmitted power is 25-35KW, reducing the power to 15-25KW after the alloy raw materials are completely melted, refining until the surface of the molten steel is clean and free of films, and cutting off the power and measuring the temperature when the temperature of the molten steel is 20-30 ℃ higher than the alloy pouring temperature.

9. The method of claim 7, wherein the conditions of the cast molding include: the transmitted power is 5-15KW, the casting temperature is 1450-.

10. The method as claimed in any one of claims 7 to 9, wherein the method further comprises heat treating the cast material at 850-900 ℃ for 15-20 h.