A long-life non-magnetic bearing alloy and preparation method thereof

Abstract

The present invention relates to a long-life non-magnetic bearing alloy, which belongs to the field of alloy steel and solves the problem that the non-magnetic bearing alloy in the prior art has poor performance in comprehensive performance such as service life, hardness, wear resistance, and corrosion resistance. A long-life non-magnetic bearing alloy comprises Cr: 39.00%~41.00%, Al: 2.75%~3.35%, Ti: 0.90%~1.20%, C≤0.30%, Fe≤0.50%, Mn≤0.18%, Si≤0.20%, S≤0.008%, P≤0.010%, O≤0.0010%, N≤0.0050%, Co≤0.01%, and the balance is Ni and unavoidable impurities; and Al+Ti≥3.85%. The present invention realizes that the bearing alloy is superior to the existing non-magnetic bearing alloy in comprehensive performance of performance such as service life, hardness, wear resistance, and corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of alloy steel, and in particular to a long-life non-magnetic bearing alloy and a preparation method thereof. Background Art

[0002] Due to their special physical properties, non-magnetic bearing alloys play an important role in the field of high-tech and industrial applications. For example, for drive mechanisms in strong magnetic field applications (such as reluctance motor drive mechanisms), non-magnetic bearing alloys should be used to prevent the bearing material from being magnetized in a strong magnetic field, resulting in a large amount of wear and corrosion products being adsorbed in the bearing gap, blocking the bearing.

[0003] Non-magnetic alloys mainly include iron-based austenitic alloys, nickel-based alloys and cobalt-based alloys. The typical steel type of iron-based austenitic alloy is 70Mn15Cr2Al3WMoV2 steel. The hardness of this alloy after solid solution aging can reach HRC40, but its hardness is still low and its corrosion resistance is poor. It usually needs to be nitrided before use. However, the nitrided layer is only 0.1~0.2mm, so the bearings made cannot meet the requirements of heavy load and long life. Nickel-based alloys are also non-magnetic materials, but their hardness is usually around HRC40. For example, Hastelloy C, which is sometimes used as a light-load bearing and has an operating temperature above 600℃, has a maximum hardness of only HRC25~30. The hardness of cobalt-based alloys such as Stellite 6 and Stellite 3 after heat treatment is around HRC50, while the hardness of Stellite 20, Stellite 100 and other alloys after heat treatment can reach above HRC58. However, this material is easily nuclear activated, and the activated Co60 is highly radioactive and has a long half-life. In addition, this type of material is extremely difficult to machine.

[0004] With the increasing requirements on load, ambient temperature and service life of driving mechanisms in strong magnetic field applications, the comprehensive performance of existing bearing alloys has been unable to meet the requirements. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a long-life non-magnetic bearing alloy and a preparation method thereof, so as to solve the problem that the non-magnetic bearing alloy in the prior art has poor performance in comprehensive properties such as service life, hardness, wear resistance, and corrosion resistance.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The invention provides a long-life non-magnetic bearing alloy. The chemical composition of the bearing alloy comprises, by mass percentage, Cr: 39.00%-41.00%, Al: 2.75%-3.35%, Ti: 0.90%-1.20%, C≤0.30%, Fe≤0.50%, Mn≤0.18%, Si≤0.20%, S≤0.008%, P≤0.010%, O≤0.0010%, N≤0.0050%, Co≤0.01%, and the balance is Ni and unavoidable impurities; and Al+Ti≥3.85%.

[0008] Furthermore, the contents of the four elements P, S, O and N must satisfy the following conditions: P+S+O+N≤0.020%; and / or, Al+Ti≤4.50%; and / or, 2.5<Al / Ti<3.5.

[0009] Furthermore, the chemical composition of the bearing alloy also includes rare earth elements, and the rare earth element content is 0<≤0.05%; the rare earth elements include one or a combination of Ce, La, and Y.

[0010] Further, Ni+Cr>94.5%; and / or, 58.5%<Ni+Al+Ti<59.5%; and / or, 9<Cr / (Al+Ti)<11.

[0011] The present invention also provides a method for preparing the bearing alloy as described above, comprising the following steps:

[0012] S1. Material preparation: Select raw materials according to the composition requirements of the target alloy;

[0013] S2. Smelting and pouring: using a vacuum induction furnace and a vacuum consumable furnace for smelting and pouring to obtain an alloy consumable steel ingot;

[0014] S3, hot processing technology: after forging and material forming process, the alloy consumable steel ingot obtained in step S2 is processed to obtain a product of desired shape; wherein, the forging mainly includes: using low temperature T 311 ≤600℃Furnace loading and protection, intermediate temperature T 312 =850-950℃ keep warm, then raise the temperature to T 313 =1140~1160℃ keep warm, then forge to get intermediate billet, control final forging temperature T 314 ≥1000℃;

[0015] The forming process mainly includes: heating the intermediate billet to a temperature T 321 =1000~1100℃ and keep warm, then forge and / or roll into finished product, the final forging or final rolling temperature is ≥950℃ to obtain the product;

[0016] S4, heat treatment process: the product obtained in step S3 is subjected to solution treatment and aging treatment in sequence.

[0017] Further, in step S4, the solution treatment mainly includes: heating the product to a temperature T 411 =1185~1220℃, then keep warm and quench in water.

[0018] Further, in step S4, the aging treatment mainly includes: heating the product to a temperature T 421 =600~650℃, then keep warm and air cool.

[0019] Further, in step S3, the forging further includes: post-forging annealing; the post-forging annealing mainly includes: heating the forged intermediate billet to a temperature T 315 = 890~950℃ and keep warm, then cool in the furnace; and / or,

[0020] In step S3, the material forming process further includes: annealing after forging and rolling; the annealing after forging and rolling mainly includes: heating the product to T 322 =870~930℃ and keep warm, then cool in the furnace.

[0021] Further, in step S2, the process of smelting and pouring using a vacuum induction furnace mainly includes: adding the main materials Ni and Cr, evacuating the vacuum and heating to a temperature T 211 =1500~1540℃ until the main material is completely melted, and then refined. Refining time t 211 >60min; after refining, Al and Ti elements are added for alloying, and after sufficient stirring, vacuum casting is performed to obtain a consumable electrode rod; the vacuum casting temperature T 212 =1420~1440℃.

[0022] Furthermore, in step S2, before using the vacuum consumable furnace for smelting, the consumable electrode rod is heated to a temperature T 221 =890~950℃ and keep warm, then cool to T 222 ≤450℃, air-cooled out of furnace.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] (1) The present invention ensures that the bearing alloy has excellent comprehensive properties in terms of high hardness, high temperature resistance, corrosion resistance and non-magnetism by rationally selecting the main alloying elements of the bearing alloy and controlling their content within an appropriate range. At the same time, by strictly controlling the content of impurity elements at a low level, the strength, toughness and fatigue life of the bearing alloy are further improved. Compared with several typical types of existing non-magnetic bearing alloys: iron-based austenitic alloys, nickel-based alloys and cobalt-based alloys, the present invention optimizes a series of chemical compositions to achieve synergistic effects among the alloying elements, thereby surpassing the existing non-magnetic bearing alloys in terms of comprehensive performance in terms of service life, hardness, toughness, corrosion resistance and the like. Specifically, by controlling the content of Cr, Al, Ti, Ni and the compatibility relationship between Al and Ti, as well as controlling the upper limits of the remaining trace elements and impurity elements, the alloy microstructure and grain refinement can be optimized, so that the bearing alloy has more excellent comprehensive properties in terms of fatigue resistance, hardness, strength, corrosion resistance, strength and non-magnetism.

[0025] (2) In some preferred embodiments, by precisely controlling the upper limit of the impurity elements P+S+O+N, the upper limit of the alloying elements Al+Ti, the Al / Ti ratio, adding an appropriate amount of rare earth elements, and finely controlling the range of Ni+Al+Ti and the ratio of Cr / (Al+Ti), it helps to further improve the comprehensive performance of the non-magnetic bearing alloy in terms of service life, hardness, wear resistance, corrosion resistance (such as in high temperature and high pressure water media), especially under high load.

[0026] (3) Based on the advantages of the alloy chemical composition in the present invention in improving the comprehensive performance, the present invention also provides a corresponding non-magnetic bearing alloy preparation method, ensuring that its advantages in comprehensive performance can be achieved and maintained in the finished steel, thereby providing solid process support for the application of non-magnetic bearing alloys. Specifically, based on controlling the content and compatibility of Cr, Al, Ti, Ni and the upper limit of other trace and impurity elements, and in conjunction with the control of forging and material forming processes in the preparation method, the alloy microstructure can be further optimized and the grains can be refined, so that the bearing alloy has better comprehensive performance in fatigue resistance, hardness, corrosion resistance, strength, non-magnetic properties, etc.

[0027] (4) In some preferred embodiments, by precisely controlling the temperature of solution treatment and aging treatment, introducing annealing steps into the forging and forming processes and precisely controlling annealing parameters, and precisely controlling the processes and parameters during smelting and casting, it is beneficial to further improve the comprehensive performance of the non-magnetic bearing alloy.

[0028] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components;

[0030] Figure 1 It is a static water corrosion curve diagram of Preparation Example 1-1 of Example 1 of the present invention;

[0031] Figure 2 This is the static water corrosion curve of Comparative Example 1. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0033] G52 # alloy is a non-magnetic, corrosion-resistant and wear-resistant iron-based austenitic deformable alloy. Its magnetic permeability μ≤1.005 Gauss / Oersted, room temperature hardness HRC48~52, unnotched impact toughness ak≥22J / cm 2 , its corrosion resistance in high-temperature water is better than that of 9Cr18, and it can be used for medium-load bearings. However, with the increasing load, ambient temperature, and service life requirements of the drive mechanism, the comprehensive performance of existing bearing alloys is poor and can no longer meet the use requirements. In order to further improve and enhance the comprehensive performance of non-magnetic bearing alloys under various working conditions, especially under more harsh conditions, the present invention optimizes the alloy composition and improves the preparation process, aiming to be superior to existing non-magnetic bearing alloys in terms of comprehensive performance in terms of service life, hardness, wear resistance, high temperature resistance, corrosion resistance, etc., so as to ensure the reliability, stability and safety of non-magnetic bearing products under various working conditions.

[0034] In the first aspect, the present invention provides a long-life non-magnetic bearing alloy. The chemical composition of the bearing alloy includes, by mass percentage, Cr: 39.00%~41.00%, Al: 2.75%~3.35%, Ti: 0.90%~1.20%, C≤0.30%, Fe≤0.50%, Mn≤0.18%, Si≤0.20%, S≤0.008%, P≤0.010%, O≤0.0010%, N≤0.0050%, Co≤0.01%, and the balance is Ni and unavoidable impurities; and Al+Ti≥3.85%.

[0035] The design idea of ​​the chemical composition of the non-magnetic bearing alloy provided by the present invention is as follows: through the alloying design of Ni, Cr, Al and Ti, the main alloying elements of the alloy of the present invention are formed to ensure the high hardness, high wear resistance, high temperature resistance, corrosion resistance and non-magnetic properties of the bearing alloy. Among them, Ni and Cr elements are added to form a Ni-Cr based austenitic alloy to obtain heat resistance, corrosion resistance and non-magnetic properties; Al and Ti elements are added to form γ' (Ni3A1Ti) dispersion precipitation, so that the alloy has high hardness and wear resistance; other inevitable impurities are controlled to ensure that the alloy has a long life.

[0036] Specifically, the functions and proportions of the elements of the present invention are as follows:

[0037] Ni has a face-centered cubic structure and no allotropic transformation. The face-centered cubic austenite structure has non-magnetic properties and good high-temperature strength. Nickel has high chemical stability, is almost not oxidized below 500°C, and is not easily corroded by moisture, water, and certain salt aqueous solutions. Single Ni cannot achieve comprehensive performance requirements such as high hardness, so alloying is required, so the Ni content requirement is a surplus.

[0038] Cr is a ferrite-forming element, forming an α-Cr phase in a Ni-Cr alloy. Although the α-Cr phase has a body-centered cubic structure, it is paramagnetic, so the alloy is not ferromagnetic. An increase in the Cr content can increase the hardness of the alloy, but it will cause the thermoplasticity of the alloy to decrease, so 39% ≤ Cr ≤ 41% is required. Exemplarily, the Cr element content is 39.2%, 39.4%, 39.6%, 39.8%, 40.0%, 40.2%, 40.4%, 40.6%, and 40.8%.

[0039] Al and Ti elements precipitate extremely fine γ' (Ni3A1Ti) after solid solution aging, which is the basis for the alloy to obtain superhardening ability. With the increase of Al+Ti content, the hardness of the alloy increases but the toughness decreases. Therefore, it is required that Al is controlled at 2.75%~3.35%, Ti is controlled at 0.90%~1.20%, and Al+Ti≥3.85%. For example, the Al element content is 2.80%, 2.85%, 2.90%, 2.95%, 3.00%, 3.05%, 3.10%, 3.12%, 3.14%, 3.16%, 3.18%, 3.20%, 3.22%, 3.24%, 3.26%, 3.28%, 3.30%, and 3.32%. Further, Al is controlled at 3.10%~3.35%. For example, the Ti content is 0.92%, 0.94%, 0.96%, 0.98%, 1.00%, 1.03%, 1.06%, 1.09%, 1.12%, 1.15%, and 1.18%. Further, the Ti content is controlled at 0.90% to 0.98%.

[0040] C is an austenite stabilizing element and a strong carbide forming element. Carbides can improve the hardness and wear resistance of the alloy, but the presence of carbides will reduce the corrosion resistance of the steel, so C should be controlled to be ≤ 0.30%. Further, 0.0005% ≤ C ≤ 0.30%; preferably, C < 0.02%. Exemplarily, the C content is 0.0005%, 0.001%, 0.005%, 0.01%, and 0.015%.

[0041] Fe is a body-centered cubic structure at room temperature and a face-centered cubic structure at high temperature, with allotropic transformation. The content of Fe has a direct impact on the microstructure of the alloy, thereby affecting the hardness, corrosion resistance and non-magnetic properties of the alloy. In order to ensure the stability of the alloy performance, Fe should be controlled to be ≤ 0.50%. Further, 0.001% ≤ Fe ≤ 0.50%; preferably, Fe ≤ 0.10%; illustratively, the Fe element content is 0.001%, 0.005%, 0.01%, 0.05%, 0.08%.

[0042] Si and Mn elements can improve the strength and hardness of the alloy through solid solution strengthening, but too high will affect the plasticity and toughness of the alloy, so Si≤0.20%, Mn≤0.18%, and the above appropriate Si and Mn content are also conducive to deoxidation. Exemplarily, the Si element content is 0.001%, 0.005%, 0.01%, 0.02%, 0.05%, 0.08%, 0.10%, 0.16%, and 0.18%. Exemplarily, the Mn element content is 0.001%, 0.005%, 0.01%, 0.02%, 0.05%, 0.08%, 0.10%, 0.12%, and 0.15%. Further, 0.08%≤Si≤0.13%, 0.02%≤Mn≤0.10%.

[0043] S and P elements are low melting point elements, which have an adverse effect on the thermoplasticity of the alloy, so S≤0.008%, P≤0.010%. Exemplarily, the S content is 0.00001%, 0.00005%, 0.0001%, 0.0005%, 0.0008%, 0.0010%, 0.0020%, 0.0030%, 0.0040%. The P content is 0.00001%, 0.00005%, 0.0001%, 0.0005%, 0.0008%, 0.0010%, 0.0020%, 0.0030%, 0.0040%. Further, S≤0.005%, P≤0.005%.

[0044] O and N elements are very likely to form oxide and nitride inclusions with Al and Ti in the alloy, affecting the toughness, corrosion resistance and fatigue properties of the alloy, so O≤0.0010%, N≤0.0050%. For example, the O content is 0.00001%, 0.00005%, 0.0001%, 0.0005%, 0.0008%. The N content is 0.00001%, 0.00005%, 0.0001%, 0.0005%, 0.0008%, 0.0010%, 0.0020%, 0.0030%, 0.0040%. Further, 0.0001%<O≤0.0010%, 0.0001%<N≤0.0050%.

[0045] The addition of Co element can usually play a role in solid solution strengthening, improving the strength and temperature resistance of the material. However, Co element is easy to be nuclear activated, and the activated Co60 is highly radioactive and has a long half-life. The present invention is based on the idea of ​​Al / Ti composite strengthening, and considers the need to be applied to specific fields (such as under strong magnetic field conditions), so Co≤0.01%. Exemplarily, the Co element content is 0.0001%, 0.0005%, 0.001%, 0.003%, 0.006%, 0.007%; further, 0.001%<Co≤0.01%.

[0046] Compared with the prior art, the present invention ensures that the bearing alloy has excellent comprehensive performance in terms of high hardness, high temperature resistance, corrosion resistance, and non-magnetism by rationally selecting the main alloying elements of the bearing alloy and controlling their content within an appropriate range. At the same time, by strictly controlling the content of impurity elements at a low level, the strength, toughness, and fatigue life of the bearing alloy are further improved. Specifically, compared to several typical types of existing non-magnetic bearing alloys: iron-based austenitic alloys, nickel-based alloys, and cobalt-based alloys, the present invention optimizes a series of chemical compositions to achieve a synergistic effect among the alloying elements, thereby surpassing existing non-magnetic bearing alloys in terms of comprehensive performance in terms of service life, hardness, wear resistance, toughness, and corrosion resistance. Specific optimization measures include:

[0047] (1) By controlling the Cr content to form a high-hardness α-Cr phase, the hardness and wear resistance of the material are improved, which helps to solve the problem of insufficient hardness and wear resistance of non-magnetic bearing alloys in the prior art. If the Cr content is too high (>41%), the thermoplasticity of the material will be reduced, making it impossible to form the material by hot working or difficult to form; on the contrary, if the Cr content is too low (less than 39%), the α-Cr phase cannot be effectively formed, and the hardening effect of chromium cannot be fully utilized, which affects the hardness and wear resistance of the material.

[0048] (2) By controlling the content of added Al and Ti elements, γ' (Ni3A1Ti) is dispersed and precipitated, so that the material has superhardening ability and heat and wear resistance. As the Al+Ti content increases, the hardness of the alloy increases. When Al+Ti ≥ 3.85%, sufficient precipitation of γ' (Ni3A1Ti) is guaranteed to achieve a significant increase in hardness. For example, the room temperature hardness is guaranteed to be ≥ 58HRC, which helps to solve the problem that one or more of the hardness, wear resistance, and temperature resistance of non-magnetic bearing alloys in the prior art are insufficient.

[0049] (3) By controlling the Cr content, not only the hardness and wear resistance can be improved, but also Cr and the remaining Ni can form a Ni-Cr based austenitic alloy, making the material non-magnetic and improving the high temperature performance, corrosion resistance and oxidation resistance of the alloy, which helps to solve the problems of high magnetic permeability, temperature resistance and corrosion resistance of the non-magnetic bearing alloy in the prior art.

[0050] (4) By adding an appropriate amount of chromium, the strength of the alloy can be improved while taking into account its toughness and plasticity, making it perform well in a variety of applications.

[0051] (5) By strictly controlling the upper limits of other trace elements, such as C, Fe, Mn, Si, S, P, O, N, and Co, an optimized balance of high hardness and wear resistance, corrosion resistance, high strength and toughness, and long life can be achieved while ensuring that the material has no magnetic properties.

[0052] In some preferred embodiments, the contents of the four elements P, S, O, and N must satisfy: P+S+O+N≤0.020%. By precisely controlling the sum of the contents of the impurity elements phosphorus (P), sulfur (S), oxygen (O), and nitrogen (N) not exceeding the set upper limit, not only can the thermoplasticity of the alloy material be significantly improved, thereby facilitating processing and forming, but also the formation of inclusions such as oxides and nitrides can be effectively reduced. The reduction of these inclusions is crucial to improving the purity and structural uniformity of the alloy material. The improvement in purity helps to reduce the stress concentration points inside the material, while the structural uniformity ensures that the material has consistent performance in different parts. These two factors work together to significantly improve the contact fatigue life of the alloy material, that is, the durability of the material under repeated loads. This is particularly important for the manufacture of high-performance bearings, gears, and other key mechanical components, because these components need to maintain long-term stable operation under high loads and harsh environments, and have high requirements for the fatigue resistance of the material.

[0053] In some preferred embodiments, Al+Ti≤4.50%. The higher the total content of Al and Ti, the worse the impact performance of the alloy, so controlling Al+Ti≤4.50% helps to maintain the impact toughness of the alloy. Good toughness means that the alloy material is easier to deform and process at high temperatures, reducing cracking and defects during processing, and improving the processing qualification rate of the product. Moreover, this control is also important for improving the service life of the alloy under high load and complex working conditions.

[0054] In some preferred embodiments, 2.5<Al / Ti<3.5. By maintaining the Al / Ti ratio between 2.5 and 3.5, it is possible to ensure a more complete precipitation of the γ' phase in the alloy, while further improving the thermoplasticity of the material, thereby obtaining better mechanical properties, for example, achieving an optimized balance of hardness, strength, and toughness-plasticity. Exemplarily, Al / Ti=2.6, 2.7, 2.8, 2.9, 2.95, 3.0, 3.05, 3.1, 3.2, 3.3, 3.4. Further, 2.85≤Al / Ti≤3.15.

[0055] In some preferred embodiments, the chemical composition of the bearing alloy also includes rare earth elements, and 0<rare earth element content ≤ 0.05%; the rare earth elements include one or a combination of Ce, La, and Y. By adding rare earth elements, the grain boundaries can be purified, the thermoplasticity can be improved, the grains can be refined, and the corrosion resistance and fatigue life can be improved. However, if the amount of rare earth added is too large, rare earth inclusions will be formed, distributed along the grain boundaries, and the impact toughness of the material will be reduced. Therefore, the rare earth element content is controlled at 0<rare earth element ≤ 0.05%. Exemplarily, the rare earth element content is 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, and 0.04%. Further, 0.001%≤rare earth element≤0.05%.

[0056] In some embodiments, Ni+Cr>94.5%. By controlling the sum of the contents of nickel (Ni) and chromium (Cr) to be greater than 94.5%, it is possible to ensure that the Ni-Cr based austenitic alloy is fully formed, thereby utilizing the stable austenitic structure of Ni-Cr to further improve the heat resistance and corrosion resistance of the alloy material and ensure the non-magnetic properties. Furthermore, Ni+Cr≥95.5%.

[0057] In some embodiments, 58.5%<Ni+Al+Ti<59.5%. By controlling the range of the sum of the contents of nickel (Ni), aluminum (Al) and titanium (Ti), it is possible to ensure that γ' (Ni3AlTi) is dispersed and precipitated more fully, thereby utilizing γ' (Ni3AlTi) to further improve the hardness, temperature resistance and wear resistance, and high temperature oxidation resistance of the alloy material, while maintaining the interface between the matrix and the γ' phase stable, thereby further improving the contact fatigue life of the alloy material.

[0058] In some embodiments, 9<Cr / (Al+Ti)<11. By precisely controlling the ratio of Cr, Al and Ti, the comprehensive properties of the alloy material can be optimized to achieve the best balance of properties such as fatigue resistance, hardness, wear resistance, temperature resistance, strength and toughness. This fine proportion control allows the alloy to maintain high hardness and excellent wear resistance while also exhibiting good high temperature stability and sufficient plasticity and toughness, thereby meeting the needs of various working conditions, especially harsh application environments. For example, Cr / (Al+Ti)=9.2, 9.4, 9.6, 9.8, 10, 10.2, 10.4, 10.6, 10.8; further, 9.5≤Cr / (Al+Ti)≤10.5.

[0059] The present invention controls the content and / or compatibility of elements such as Cr, Al, Ti, Ni, and strictly controls impurity elements, and adds an appropriate amount of rare earth elements to obtain the following alloy microstructure: the organization is Ni-Cr austenite matrix + α-Cr + γ′(Ni3AlTi) + γ″(Ni3AlTi), and the grain size is 4-8 levels, so that the bearing alloy has good fatigue resistance, hardness, wear resistance, corrosion resistance, non-magneticity, etc., so that the bearing alloy has a longer fatigue life, especially a fatigue life under high load, and the bearing alloy has a higher hardness, especially a hardness under high temperature; and has a higher tensile strength.

[0060] The long-life non-magnetic bearing alloy of the present invention has a structure of Ni-Cr austenite matrix + α-Cr + γ′(Ni3AlTi) + γ″(Ni3AlTi); the grain size is 4-8. Fatigue performance: contact fatigue life L under maximum contact stress 4150MPa 10 ≥4.8×10 6 Times, L 50 ≥33×10 6 Contact fatigue life L under maximum contact stress 3500MPa 10 ≥19.6×10 6 Times, L 50 ≥61.8×10 6 Hardness: room temperature hardness ≥58HRC, high temperature hardness at 350℃ ≥53HRC; toughness and plasticity: unnotched impact toughness Ak≥22J; tensile strength: Rm≥2000Mpa; corrosion resistance: in high temperature and high pressure water medium, the test time is ≥4 months, and the corrosion weight gain is ≤23mg / dm 2 ; Non-magnetic: magnetic permeability ≤1.0005 Gauss / Oersted.

[0061] In a second aspect, the present invention further provides a method for preparing the bearing alloy as described above, comprising the following steps:

[0062] S1. Material preparation: Select raw materials according to the composition requirements of the target alloy;

[0063] Exemplarily, the raw material is a high-purity metal or alloy containing Ni, Cr, Al, or Ti;

[0064] S2, smelting and pouring: using a vacuum induction furnace and a vacuum consumable furnace to smelt and pour the raw materials described in step S1 to obtain an alloy consumable steel ingot;

[0065] S3, hot processing technology: after forging and material forming process, the alloy consumable steel ingot obtained in step S2 is processed to obtain a product of desired shape; wherein, the forging mainly includes: using low temperature T 311 ≤600℃Furnace loading and protection, intermediate temperature T 312=850-950℃ insulation, and control the higher final forging temperature T 314 ≥1000℃, intermediate billet is obtained after forging;

[0066] The material forming process mainly includes: heating the forged intermediate billet to a temperature T 321 =1000~1100℃ and keep warm, then forge and / or roll into finished product, the final forging or final rolling temperature is ≥950℃ to obtain the product;

[0067] S4, heat treatment process: the product obtained in step S3 is subjected to solution treatment and aging treatment in sequence.

[0068] Based on the advantages of the alloy chemical composition in the present invention in improving comprehensive performance, the present invention also provides a corresponding method for preparing the non-magnetic bearing alloy as above, ensuring that its advantages in comprehensive performance can be realized and maintained in the final finished steel, thereby providing solid process support for the application of non-magnetic bearing alloys.

[0069] (1) Forging process: For the bearing alloy involved in the present invention, due to its high chromium (Cr) content, the thermoplasticity is reduced. In order to ensure the smooth progress of hot processing such as alloy forging / rolling and improve the yield of the material, it is crucial to take the following measures: first, use low-temperature furnace loading to avoid too fast heating speed; second, carry out intermediate temperature insulation to maintain temperature uniformity; finally, ensure that the final forging temperature is high to prevent thermal stress cracking caused by too low final forging temperature. These temperature control strategies help maintain the temperature and structural uniformity of the alloy during the forging process, reduce the impact of thermal stress, and thus improve the processing performance of the alloy and the quality of the final product. Through the careful control of these forging processes, it can be ensured that the comprehensive performance of the bearing alloy in terms of long life, high hardness, high wear resistance, high temperature resistance, corrosion resistance and strength can surpass the existing non-magnetic bearing alloys and meet the strict standards of high-end applications.

[0070] (2) Finishing process: After the cast structure of the forged alloy is crushed, its thermoplasticity is improved. On this basis, the use of a lower forging and / or rolling temperature of 1000~1100℃ in the finishing process helps to ensure that the alloy obtains a refined and uniform microstructure. This refined and uniform structure is crucial to improving the strength of the alloy while taking into account toughness, because finer grains can more effectively hinder dislocation movement and enhance the strength of the material. At the same time, the increase in grain boundaries helps to absorb and disperse stress, thereby taking into account better toughness. The improvement of the strength and toughness of the alloy material in the finishing process can provide a solid process guarantee for the manufacture of high-performance bearings, ensuring that the final bearing has excellent comprehensive performance.

[0071] Specifically, step S4 includes: step S41, solution treatment; step S42, aging treatment.

[0072] In some embodiments, in step S4, the solution treatment mainly includes: heating the product to a temperature T 411 =1185~1220℃, then keep warm, and then quench in water; preferably, in the solution treatment, the holding time t 411 ≥50min. For example, t 411 =50-60min. For example, T 411 =1190℃, 1195℃, 1200℃, 1205℃, 1210℃, 1215℃.

[0073] It should be noted that by controlling the solid solution temperature range and further ensuring sufficient solid solution holding time, the microstructure and macroscopic properties of the alloy can be significantly improved, and an optimized balance of high hardness, high wear resistance, and high toughness can be achieved. The solid solution temperature is not less than 1185°C, which can better ensure that the hardness of the alloy after aging is greater than 58HRC; but with the increase of the solid solution temperature, the structure of the alloy coarsens, and the impact toughness and wear resistance decrease, so the maximum solid solution temperature is controlled below 1220°C. The holding time ≥50min is to ensure that the alloy can be fully dissolved, so as to ensure that Ni3AlTi can be fully precipitated during aging after solid solution, so as to obtain high hardness.

[0074] In some embodiments, in step S4, the aging treatment mainly includes: heating the product to a temperature T 421 = 600~650℃, then keep warm, and then air cool. Preferably, in the aging treatment, the holding time t 421 ≥5h. For example, t 421 =5-6h. For example, T 421 =610℃, 620℃, 630℃, 640℃.

[0075] It should be noted that by controlling the temperature range of the aging treatment and further ensuring sufficient aging holding time, the microstructure and macroscopic properties of the alloy can be significantly improved, and an optimized balance of high hardness, high wear resistance, strong toughness and other properties can be achieved. In the alloy of the present invention, Ni3AlTi begins to precipitate in large quantities above 600°C, thereby improving the hardness of the alloy; while when the aging temperature is greater than 650°C, the precipitated phase coarsens and the hardness begins to decrease, so the aging temperature is controlled to be no greater than 650°C. Such an aging temperature control strategy helps to avoid excessively coarsened precipitated phases while maintaining the hardness of the alloy, ensuring that the comprehensive performance of the alloy is optimized.

[0076] In some embodiments, in step S3, the forging mainly includes:

[0077] S311, using low temperature T 311 ≤600℃ furnace installation and thorough protection;

[0078] S312, heating to the intermediate temperature T312 =850-950℃ insulation, insulation time t 312 ≥2h; preferably, T 312 =890-910℃;

[0079] S313, then raise the temperature to T 313 =1140~1160℃ insulation, insulation time t 313 ≥20h; then forge to obtain the intermediate billet, control the final forging temperature T 314 ≥1000℃.

[0080] It should be noted that in step S313, heating is performed in a narrow temperature range of 1140~1160℃, with the aim of heating the alloy in the optimal plastic zone to ensure that the steel ingot does not overheat or underheat the structure to affect the alloy performance; further, long-term insulation of 20h or more is used, with the aim of performing high-temperature homogenization treatment, homogenizing the cast structure while improving the thermoplasticity of the alloy, thereby improving the processability of subsequent processes and further improving product quality and comprehensive performance.

[0081] In some preferred embodiments, in step S3, the material forming process mainly includes: heating the forged intermediate billet to a temperature T 321 =1040~1060℃ and keep warm, holding time t 321 ≥1h, and then forged and / or rolled into finished products. For example, the holding time t 321 =1~2h.

[0082] In some embodiments, in step S3, the forging further includes: post-forging annealing; the post-forging annealing mainly includes: heating the intermediate billet obtained by forging to a temperature T 315 = 890~950℃ and keep warm, then cool in the furnace. Preferably, in the post-forging annealing, the holding time t 315 ≥8h, for example, t 315 = 8-10h. For example, T 315 =900°C, 915°C, 925°C, 930°C, 940°C. Preferably, T 315 =910~930℃.

[0083] It should be noted that the purpose of the post-forging annealing process is to soften the alloy to facilitate turning processing and to grind the intermediate billet obtained by forging, which is beneficial to further improve the surface quality of the products obtained by the subsequent material processing. In addition, post-forging annealing can also optimize the microstructure of the alloy, which is beneficial to further improve the comprehensive performance of the non-magnetic bearing alloy.

[0084] In some embodiments, in step S3, the material forming process further includes: annealing after forging and rolling; the annealing after forging and rolling mainly includes: heating the product to T 322= 870~930℃ and keep warm, then cool in the furnace. Preferably, in the annealing after forging and rolling, the holding time t 322 ≥6h; for example, t 322 = 6~8h. For example, T 322 =880°C, 895°C, 900°C, 905°C, 920°C. Preferably, T 322 =890~910℃.

[0085] It should be noted that adding an annealing process after forging and controlling its temperature can help release the internal stress generated during forging and / or rolling, reduce the risk of material deformation and cracking, and optimize the microstructure and improve the uniformity of the structure, thereby further improving the comprehensive performance of the non-magnetic bearing alloy.

[0086] In some embodiments, in step S2, the process of smelting and pouring using a vacuum induction furnace mainly includes: adding the main materials Ni and Cr, evacuating the vacuum and heating to a temperature T 211 =1500~1540℃ until the main material is completely melted, and then refined. Refining time t 211 >60min; after refining, Al and Ti elements are added for alloying, and after sufficient stirring, vacuum casting is performed to obtain a consumable electrode rod; the vacuum casting temperature T 212 =1420~1440℃.

[0087] In order to further improve the smelting effect of the vacuum induction furnace, the following preferred implementation is adopted:

[0088] Preferably, T 211 =1510~1530℃; further, T 211 =1515~1525℃.

[0089] Preferably, the vacuum degree of the refining is ≤2.7Pa.

[0090] It should be noted that high temperature (T 211 ) Rapid melting can reduce the contamination of raw materials. At the same time, low vacuum (≤2.7Pa) and long time (>60min) melting during the refining period can fully remove gases and low melting point metals.

[0091] Preferably, the main ingredients Ni and Cr are added, and the vacuum is evacuated to 30-50Pa. When melting begins, a relatively high vacuum degree is achieved, which can achieve energy-saving and efficient removal of harmful elements such as gases.

[0092] It can be understood that Al and Ti are active and easily burned elements, so they are added before steelmaking, and sufficient stirring is performed to ensure uniform distribution of each element in the molten steel.

[0093] It should be noted that accurately controlling the tapping temperature within the range of 1420°C to 1440°C helps to ensure a stable low superheat, thereby making the microstructure of the consumable electrode rod uniform, which is conducive to the subsequent preparation of uniform and consistent alloy materials. By optimizing the microstructure, the performance stability of the non-magnetic bearing alloy can be ensured, thereby improving its overall performance, including key characteristics such as fatigue stability. For example, T 212 =1425℃、1430℃、1435℃.

[0094] In some embodiments, in step S2, before using the vacuum consumable furnace for smelting, the consumable electrode rod is heated to a temperature T 221 =890~950℃ and keep warm, then cool to T 222 ≤450℃, air-cooled out of furnace.

[0095] It should be noted that by cooling to a lower temperature (≤450℃) before taking out of the furnace, the consumable electrode rod can be prevented from cracking, providing good conditions for subsequent processing and treatment, and ensuring that the overall performance of the product is improved.

[0096] Preferably, before the vacuum consumable furnace is used for smelting, the consumable electrode rod is annealed and peeled. The main steps of the annealing include: heating the consumable electrode rod to a temperature T 221 =910~930℃ and keep warm, holding time t 221 ≥8h, then cool the furnace to T 222 ≤450℃, air-cooled. 221 =8-10h.

[0097] Preferably, the process of smelting and pouring in the vacuum consumable furnace mainly includes: under a vacuum degree of ≤1.33Pa, the melting rate is controlled at 3-4kg / min, and the alloy consumable steel ingot is obtained by smelting and pouring. Exemplarily, the melting rate is 3.6kg / min and 3.8kg / min.

[0098] It should be noted that through high vacuum (≤1.33Pa) stable low melting rate (3-4kg / min) smelting, the uniform structure of the consumable steel ingot can be ensured, providing good conditions for subsequent processing and treatment, and ultimately ensuring that the comprehensive performance of the product is improved.

[0099] By controlling the compatibility of Cr, Al, Ti, Ni, etc. and finely controlling the forging, forming and solution aging treatment processes in the preparation method, the alloy microstructure can be further optimized, including optimizing the proportion of each phase of Ni-Cr austenite matrix + α-Cr + γ′(Ni3AlTi) + γ″(Ni3AlTi) in the organization, and obtaining a suitable grain size, so that the bearing alloy has better comprehensive properties such as fatigue resistance, hardness, corrosion resistance, strength, and non-magnetic properties.

[0100] The structure and properties of the bearing alloy of the present invention are as follows:

[0101] a) The structure is Ni-Cr austenite matrix + α-Cr + γ′(Ni3AlTi) + γ″(Ni3AlTi); the grain size is 4-8;

[0102] b) Fatigue performance: Contact fatigue life L under maximum contact stress 4150MPa 10 ≥4.8×10 6 Times, L 50 ≥33×10 6 Contact fatigue life L under maximum contact stress 3500MPa 10 ≥19.6×10 6 Times, L 50 ≥61.8×10 6 Second-rate;

[0103] c) Hardness: room temperature hardness ≥ 58HRC, high temperature hardness at 350℃ ≥ 53HRC;

[0104] d) Toughness and plasticity: unnotched impact toughness Ak ≥ 22J;

[0105] e) Tensile strength: Rm ≥ 2000Mpa;

[0106] f) Corrosion resistance: In high temperature and high pressure water medium, the test time is ≥ 4 months, and the corrosion weight gain is ≤ 23 mg / dm 2 ;

[0107] g) Non-magnetic: magnetic permeability ≤ 1.0005 Gauss / Oersted.

[0108] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and comparative examples.

[0109] A. Examples 1 to 6

[0110] The present invention provides 6 embodiments of the non-magnetic bearing alloy, whose chemical composition is shown in Table 1, and the balance is Ni (not shown in Table 1); Embodiments 1-6 are prepared according to the mass ratio of the main alloy elements shown in Table 1, and are smelted using a vacuum induction furnace + a vacuum consumable furnace.

[0111] Table 1: Composition of alloys of Examples 1-6 (wt%)

[0112]

[0113] B. Preparation examples of 6 embodiments under the same preparation process (Preparation Example 1-1 to Preparation Example 6-1)

[0114] The present invention also provides the above six examples of preparation 1-1 to preparation 6-1, the difference between which is that the raw material element ratios used are different, and the remaining steps S2-S4 are basically the same. Taking Example 1 as an example, its preparation example 1-1 includes the following steps:

[0115] S1. Material preparation: prepare high-purity raw materials according to the following element ratios by mass percentage: Cr: 39.0%, Al: 2.75%, Ti: 1.1%, and the balance is Ni;

[0116] S2. Smelting and pouring: Use vacuum induction furnace + vacuum consumable furnace to smelt and pour the prepared raw materials to obtain alloy consumable steel ingots;

[0117] S21. Use vacuum induction furnace for smelting and pouring: add main materials Ni and Cr, evacuate to 30-50Pa, and heat to temperature T 211 =1520℃ until the main material is completely melted, continue to evacuate to a vacuum degree of ≤2.7Pa for refining, refining time t 211 = 65min; after refining, add Al and Ti elements for alloying, stir thoroughly, and then vacuum cast at 1430℃ to obtain a consumable electrode rod;

[0118] S22, using a vacuum consumable furnace for smelting and casting: annealing and peeling the consumable electrode rod, the main steps of the annealing include: heating the consumable electrode rod to a temperature T 221 = 920℃ and keep warm for 8h, then cool to T 222 =450℃, take out of the furnace and air cool; after annealing and peeling, under vacuum degree ≤1.33Pa, the melting rate is controlled at 3.8kg / min, and alloy consumable steel ingots are obtained by smelting and pouring.

[0119] S3, hot processing process: through forging and material forming processes, the alloy consumable steel ingot obtained in step S2 is processed to obtain a product of a desired shape;

[0120] S31, forging; its main steps include:

[0121] S311, using low temperature T 311 ≤600℃ furnace installation and thorough protection;

[0122] S312, heating to the intermediate temperature T 312 =850℃ insulation, insulation time t 312 =2h;

[0123] S313, then raise the temperature to T 313 =1150℃ and keep warm, holding time t 313 = 20h; then forge to obtain the intermediate billet, the final forging temperature T 314 ≥1000℃.

[0124] S32, the material forming process; its main steps include: heating the intermediate billet to a temperature T 321 =1000℃ and keep warm t 321 =1h, then forged and rolled into a product, the final rolling temperature is ≥950℃.

[0125] S4, heat treatment process: the product obtained in step S3 is subjected to solution treatment and aging treatment in sequence;

[0126] S41, solution treatment: heat the product to temperature T 411 =1185℃ after heat preservation t 411 = 50min, then water quench;

[0127] S42, aging treatment: heat the product to temperature T 421 =650℃ after heat preservation t 421 = 5h, then air cool.

[0128] Preparation Example 1-2

[0129] The difference between this preparation example and preparation example 1-1 is that after step S313, step S314 is further included: heating the forged intermediate billet to a temperature T 315 =920℃ and keep warm t 315 = 8h, then furnace cooling. The remaining steps and parameters are basically the same as those in Preparation Example 1-1.

[0130] Preparation Example 1-3

[0131] The difference between this preparation example and preparation example 1-2 is that S32, a material forming process; its main steps include: heating the intermediate billet to a temperature T 321 =1000℃ and keep warm t 321 = 1h, then forged and rolled to obtain products, the final rolling temperature ≥ 950℃; annealing after forging and rolling: the product is heated to T 322 =900℃ and keep warm t 322 = 6h, then furnace cooling. The remaining steps and parameters are basically the same as those in Preparation Example 1-2.

[0132] Preparation Example 1-4

[0133] The difference between this preparation example and preparation examples 1-3 is that in step S41, the solution temperature T 411 = 1210° C. The remaining steps and parameters are basically the same as those of Preparation Example 1-3.

[0134] Preparation Example 1-5

[0135] The difference between this preparation example and preparation examples 1-4 is that S42, aging treatment: heating the product to a temperature T 421=600~620℃ after heat preservation t 421 = 9h, and then air-cooled. The remaining steps and parameters are basically the same as those of Preparation Example 1-4.

[0136] Comparative Example 1

[0137] The G52# non-magnetic bearing alloy smelted and produced by the electroslag remelting process has the following chemical compositions by mass percentage: C: 0.10~0.17%, Cr: 22.0~24.0%, Ni: 27.0~29.0%, Mo: 4.50~5.00%, V: 0.40~0.60%, Ti: 2.70~3.30%, Al: 0.80~1.20%, Mn≤0.50%, Si≤0.80%; the heat treatment process of the G52# non-magnetic bearing alloy is to keep it at 1120℃ for 50min, then cool it down to 900℃ for 3h, and then cool it down to 720℃ for 10h.

[0138] Comparative Example 2~Comparative Example 4

[0139] The alloy composition of Comparative Examples 2-4 is shown in Table 2. The preparation method is as follows: a 1-ton vacuum induction furnace and an 8-ton vacuum consumable furnace are used for double vacuum smelting, and then the consumable ingots are forged, hot rolled and heat treated to obtain high-hardness nickel-based alloy bars for non-magnetic bearings. The specific process is as follows:

[0140] (1) 1 ton vacuum induction furnace smelting;

[0141] Select high-purity metal Ni and Cr, remove rust from the surface of raw material blocks, clean and oil-free. Main raw material elements Ni and Cr are added according to the target composition, and special attention is paid to the substitution of Si, Mn, Cu, S and P in the raw materials.

[0142] The vacuum induction furnace is evacuated to below 2.7Pa, and then the main material Ni plate is added, and the power is increased and the power is controlled at 300-600kw. After the Ni plate is completely melted, the power is kept unchanged and the high vacuum is maintained. The N content in the molten steel is controlled within 60ppm. At this time, the main material metal Cr block is added, the power is increased to 600-800kw, and the temperature is increased to 1430-1480℃ for refining. The refining time is about 30-60min. After the metal Cr block is melted, the N content is detected. When the N content is ≤50ppm, alloying elements Al and Ti are added for alloying smelting, and the power value is reduced to 200-600kw, and the temperature of the molten steel is reduced to 1450-1465℃. After that, the composition of the molten steel is analyzed. When the content of the alloying elements (Ni, Cr, Al, Ti, etc.) meets the technical agreement standard (that is, after the target composition requirements), steel is tapped and the electrode is cast. The tapping temperature is ≥1420℃.

[0143] (2) 8 tons of vacuum consumable smelting;

[0144] Place the end of the electrode with the shrinkage hole upward for vacuum consumable smelting, and the electrode surface must be cleaned without rust, oil and other pollutants. During vacuum consumable smelting, the melting rate is set at 2.0-3.5 kg / min. After 120 minutes of vacuum consumable smelting, hot annealing is performed. During this process, the surface temperature of the consumable ingot must not be lower than 500°C to prevent cracks.

[0145] (3) Forging;

[0146] Fast forging + diameter forging, after the consumable ingot is finished, it is heated in the heating furnace, the heating temperature is slowly increased from 580-620℃ to 1130-1170℃, the total heating time is ≥16h, the two-pier and two-draw process is adopted, the ingot is upset to 1 / 2-2 / 3 of the original height, the forging ratio is increased to break the internal structure of the ingot as much as possible, and the octagonal billet with a specification of 200mm-230mm is forged after multiple forgings; then the forged octagonal billet is wrapped with asbestos and sent to the heating furnace for further reheating treatment, the heating temperature is 1120-1200℃, the holding time is ≥4h, and the diameter of the billet is forged into a square billet with a specification of 120mm; the start forging temperature is ≥1050℃, and the stop forging temperature is ≥950℃. The edges and corners of the intermediate billet need to be ground to ensure a smooth transition to avoid cracking on the surface of the rolled bar due to the low temperature at the edges and corners of the square billet during the rolling process.

[0147] (4) Rolling;

[0148] Heat the billet to 1150-1220℃, keep it warm for ≥3h, and use one-fire hot rolling process. During the rolling process, all water cooling needs to be turned off to prevent cracking on the surface of the bar.

[0149] (5) Heat treatment;

[0150] Solution treatment: The bar is solution treated at 1160-1200°C and then quickly quenched in water;

[0151] Aging heat treatment: Heat the solution treated rod to 630-700°C, keep it at this temperature for 4-8 hours, then take it out of the furnace and air cool it to room temperature to obtain a high hardness nickel-based alloy rod for non-magnetic bearings.

[0152] Table 2: Alloy composition of comparative examples 2-4 (wt%)

[0153]

[0154] Performance test and result comparison of the embodiment and the comparative example: The test samples were taken from After solution aging heat treatment, the 60mm round bar was tested and analyzed for contact fatigue life, room temperature and high temperature hardness, impact and tensile properties, and corrosion resistance in high temperature and high pressure water media.

[0155] 1. Contact fatigue life

[0156] Table 3: Contact fatigue life of preparation examples and comparative examples

[0157]

[0158] In addition, the contact fatigue life of the remaining preparation examples of the present invention (i.e., Preparation Example 1-2 to Preparation Example 1-5 and Preparation Example 2-1 to Preparation Example 6-1) is better than that of Preparation Example 1-1, specifically, the contact fatigue life L under the maximum contact stress of 4150 MPa is 10 >4.9×10 6 Times, L 50 >33.7×10 6 times; contact fatigue life L under maximum contact stress 3500MPa 10 >19.7×10 6 Times, L 50 >61.9×10 6 It can be seen that based on the alloy composition and preparation method disclosed in the present invention, the contact fatigue life of the non-magnetic bearing alloy can be significantly extended, thereby better meeting the long-life use requirements of the non-magnetic bearing.

[0159] 2. Hardness

[0160] Table 4: Hardness (HRC) of Preparation Examples and Comparative Examples

[0161]

[0162] Table 5: Hardness (HV) of Preparation Examples and Comparative Examples

[0163]

[0164] Table 6: Comparison of room temperature hardness and high temperature hardness of preparation examples and comparative examples (HRC)

[0165]

[0166] It can be seen from Tables 4-5 that compared with the currently disclosed G52# non-magnetic bearing alloy with good comprehensive performance (i.e., Comparative Example 1), the hardness (HRC and HV evaluation indicators) of Preparation Example 1-1 of the present invention from 28°C to 550°C is higher than that of Comparative Example 1, which shows that the alloy composition and preparation method provided by the present invention can significantly improve the hardness of the non-magnetic bearing alloy, including the hardness at room temperature and high temperature. According to the data in Table 6, the hardness of all preparation examples of the present invention at room temperature significantly exceeds that of Comparative Examples 2-4. At the same time, it can be understood that under high temperature conditions, the hardness of Comparative Examples 2-4 is further reduced and lower than its hardness at room temperature.

[0167] In addition, it can be seen from Table 6 that the remaining preparation examples of the present invention (Preparation Examples 1-2 to 1-5 and 2-1 to 6-1) have further improvements in room temperature hardness and high temperature hardness compared to Preparation Example 1-1, which shows that by optimizing the alloy composition and preparation method of the present invention, the hardness of the non-magnetic bearing can be further improved, including the hardness at room temperature and high temperature.

[0168] 3. Tensile properties and impact toughness;

[0169] Table 7: Tensile properties and impact toughness of preparation examples and comparative examples

[0170]

[0171] In addition, Rp of Preparation Example 1-1 of the present invention 0.2 =2033Mpa, Rp of Preparation Example 1-2 0.2 =1833Mpa.

[0172] According to the data in Table 7, the bearing alloys obtained in all the preparation examples of the present invention exhibit good toughness and can meet the toughness requirements of high-end equipment for non-magnetic bearing materials. Compared with comparative examples 1-4, the bearing alloys prepared in the present invention have significantly improved strength, enabling them to better adapt to various working conditions, especially to maintain normal operation in more complex and harsh environments such as high loads.

[0173] 4. Corrosion resistance;

[0174] The test conditions for corrosion resistance are: temperature: 300±2℃; pressure: 8.6±0.5MPa; medium: conductivity <200μs / m, pH=6~8; chloride ion: ≤0.1mg / kg; dissolved oxygen: ≤0.1mg / kg; suspended matter: ≤1.0mg / kg; sulfate ion: ≤0.1mg / kg; fluoride ion: ≤0.1mg / kg.

[0175] The static water corrosion curves of Preparation Example 1-1 of Example 1 of the present invention and Comparative Example 1 are as follows: Figure 1 and Figure 2 shown. Figure 1 and Figure 2 The vertical axis is mg / dm 2 Under the above corrosion performance test conditions, the preparation examples of the present invention all meet the following requirements: when the test time is ≥ 4 months, the corrosion weight gain is ≤ 23 mg / dm 2 This shows that the embodiments of the present invention and the preparation examples thereof have excellent corrosion resistance and can better adapt to various working conditions, especially to keep the bearing working normally in more complex and harsh environments such as high temperature and high pressure.

[0176] 5. Magnetic permeability (Gauss / Oersted)

[0177] The magnetic permeability of each embodiment of the present invention and its preparation examples is ≤1.00050 Gauss / Oersted, which meets the requirement of "completely non-magnetic (relative magnetic permeability is less than 1.001 Gauss / Oersted) bearing" in the art.

[0178] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A long-life non-magnetic bearing alloy, characterized in that: In terms of mass percentage, the chemical composition of the bearing alloy includes Cr: 39.2%~40.8%, Al: 3.16%~3.35%, Ti: 0.90%~1.20%, 0.0005%≤C<0.02%, Fe≤0.50%, 0.02%≤Mn≤0.08%, 0.08%≤Si≤0.20%, S≤0.008%, P≤0.010%, O≤0.0010%, N≤0.0050%, 0.001%<Co≤0.01%, and the balance is Ni and unavoidable impurities; The method for preparing the bearing alloy comprises the following steps: S1. Material preparation: Select raw materials according to the composition requirements of the target alloy; S2. Smelting and pouring: using a vacuum induction furnace and a vacuum consumable furnace for smelting and pouring to obtain an alloy consumable steel ingot; S3, hot processing technology: after forging and material forming process, the alloy consumable steel ingot obtained in step S2 is processed to obtain a product of desired shape; wherein, the forging mainly includes: using low temperature T 311 ≤600℃Furnace loading and protection, intermediate temperature T 312 =850-950℃ keep warm, then raise the temperature to T 313 =1140~1160℃ insulation, insulation time t 313 ≥20h; then forge to obtain the intermediate billet, control the final forging temperature T 314 ≥1000℃; the forging also includes: post-forging annealing; the post-forging annealing mainly includes: heating the intermediate billet obtained by forging to a temperature T 315 =890~950℃ and keep warm, holding time t 315 ≥8h, then furnace cool; The forming process mainly includes: heating the intermediate billet to a temperature T 321 =1040~1060℃ and keep warm, then forge and / or roll into product, the temperature of final forging or final rolling is ≥950℃, and the product is obtained; the product forming process also includes: annealing after forging and rolling; the annealing after forging and rolling mainly includes: heating the product to T 322 =870~930℃ and keep warm, holding time t 322 ≥6h, then cool in the furnace; S4, heat treatment process: the product obtained in step S3 is subjected to solution treatment and aging treatment in sequence; The long-life non-magnetic bearing alloy has a structure of Ni-Cr austenite matrix + α-Cr + γ′(Ni3AlTi) + γ″(Ni3AlTi); a grain size of 4-8; fatigue performance: a contact fatigue life of L under a maximum contact stress of 4150MPa 10 ≥4.8×10 6 Times, L 50 ≥33×10 6 times; contact fatigue life L under maximum contact stress 3500MPa 10 ≥19.6×10 6 Times, L 50 ≥61.8×10 6 times; Hardness: Room temperature hardness ≥58HRC, high temperature hardness at 350℃ ≥53HRC; Toughness and plasticity: Unnotched impact toughness Ak≥22J; Tensile strength: Rm≥2000Mpa; Non-magnetic: Magnetic permeability ≤1.0005 Gauss / Oersted.

2. The bearing alloy according to claim 1, characterized in that: The contents of the four elements P, S, O and N must satisfy the following requirements: P+S+O+N≤0.020%; and / or, Al+Ti≤4.50%; and / or, 2.5<Al / Ti<3.

5.

3. The bearing alloy according to claim 1, characterized in that: The chemical composition of the bearing alloy also includes rare earth elements, and the rare earth element content is 0<≤0.05%; the rare earth elements include one or a combination of Ce, La, and Y.

4. The bearing alloy according to claim 1, characterized in that: Ni+Cr>94.5%; and / or, 58.5%<Ni+Al+Ti<59.5%; and / or, 9<Cr / (Al+Ti)<11.

5. A method for preparing a bearing alloy according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Material preparation: Select raw materials according to the composition requirements of the target alloy; S2. Smelting and pouring: using a vacuum induction furnace and a vacuum consumable furnace for smelting and pouring to obtain an alloy consumable steel ingot; S3, hot processing technology: after forging and material forming process, the alloy consumable steel ingot obtained in step S2 is processed to obtain a product of desired shape; wherein, the forging mainly includes: using low temperature T 311 ≤600℃Furnace loading and protection, intermediate temperature T 312 =850-950℃ keep warm, then raise the temperature to T 313 =1140~1160℃ insulation, insulation time t 313 ≥20h; then forge to obtain the intermediate billet, control the final forging temperature T 314 ≥1000℃; the forging also includes: post-forging annealing; the post-forging annealing mainly includes: heating the intermediate billet obtained by forging to a temperature T 315 =890~950℃ and keep warm, holding time t 315 ≥8h, then furnace cool; The forming process mainly includes: heating the intermediate billet to a temperature T 321 =1040~1060℃ and keep warm, then forge and / or roll into product, the temperature of final forging or final rolling is ≥950℃, and the product is obtained; the product forming process also includes: annealing after forging and rolling; the annealing after forging and rolling mainly includes: heating the product to T 322 =870~930℃ and keep warm, holding time t 322 ≥6h, then cool in the furnace; S4, heat treatment process: the product obtained in step S3 is subjected to solution treatment and aging treatment in sequence.

6. The preparation method according to claim 5, characterized in that: In step S4, the solution treatment mainly includes: heating the product to a temperature T 411 =1185~1220℃, then keep warm and quench in water.

7. The preparation method according to claim 5, characterized in that: In step S4, the aging treatment mainly includes: heating the product to a temperature T 421 =600~650℃, then keep warm and air cool.

8. The preparation method according to claim 5, characterized in that: In step S2, the process of smelting and pouring using a vacuum induction furnace mainly includes: adding the main materials Ni and Cr, evacuating the vacuum and heating to a temperature T 211 =1500~1540℃ until the main material is completely melted, and then refined. Refining time t 211 >60min; after refining, Al and Ti elements are added for alloying, and after sufficient stirring, vacuum casting is performed to obtain a consumable electrode rod; the vacuum casting temperature T 212 =1420~1440℃.

9. The preparation method according to claim 8, characterized in that: In step S2, before using the vacuum consumable furnace for smelting, the consumable electrode rod is heated to a temperature T 221 =890~950℃ and keep warm, then cool to T 222 ≤450℃, air-cooled out of furnace.

Images