Corrosion-resistant nickel-based superalloy as well as preparation method and application thereof

Abstract

The invention discloses a corrosion-resistant nickel-based superalloy, a preparation method and application thereof, and belongs to the technical field of corrosion-resistant nickel-based alloys, and the corrosion-resistant nickel-based superalloy comprises the following components in percentage by mass: 34%-38% of Cr, 3.5%-5% of Al, 0.5%-10% of Co, 0.01%-0.05% of C, 0.001%-0.006% of B, 0.02%-0.05% of Zr, less than 0.08% of Y, less than 0.08% of La and the balance of Ni. The microstructure comprises equiaxial austenite alloy grains, dispersed spherical a-Cr phases and lamellar structures, wherein the lamellar structures are distributed in an area between the spherical a-Cr phases in a colony manner; and the solid solution state hardness is 150-350 HV, the aging state hardness is 380-750 HV, the tensile strength is 1200-2100 MPa, the yield strength is 800-1800 MPa, and the like. By adding Co, the segregation degree of the alloy is remarkably improved, the homogenization and hot working difficulty is reduced, and the requirements of hot-end components serving in a complex environment can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion-resistant nickel-based alloys, and relates to a corrosion-resistant nickel-based high-temperature alloy, a preparation method and applications thereof. Background Art

[0002] The fuels used in critical equipment such as petroleum refining equipment, thermal power generation equipment, waste-to-energy equipment, gas turbines, and boilers generate highly corrosive combustion ash, causing high-temperature corrosion in critical components. Traditional heat-resistant steels are no longer able to meet the increasingly demanding performance requirements of these critical components, leading to the increasing use of nickel-based superalloys. This is because nickel-based superalloys typically contain a certain amount of chromium to ensure the alloy's excellent oxidation and corrosion resistance. However, traditional nickel-based alloys typically contain only around 15-25% chromium, and their corrosion resistance and strength are no longer sufficient for today's complex and demanding high-temperature, high-corrosion, and high-stress environments. For example, Nimonic 80A and Inconel 625 alloys, widely used in thermal power plants and shipbuilding, no longer meet the required strength and corrosion resistance.

[0003] At present, there are some related patent technologies for the research of corrosion-resistant nickel-based alloys, but there are still certain limitations. The Chinese invention patent application number CN201810457993.3 discloses a "high-cobalt nickel-based high-temperature alloy and its preparation method". The above technology improves the high-temperature mechanical properties of the alloy by adding Co element to the nickel-based alloy. However, the amount of Cr element added in the invention is relatively small, about 18%, which makes it difficult to give the material good corrosion resistance and cannot be applied to complex and harsh high-temperature, high-corrosion, and high-stress environments; the Chinese invention patent application number CN202311737608.8 discloses a "Ni-Cr-Al system nickel-based high-temperature alloy and its preparation". Although a relatively high Cr element (30-45%) is added to the nickel-based alloy in the above technology, which has good corrosion resistance, the alloy has severe segregation, high brittleness, poor high-temperature performance, and a certain amount of Ti element is introduced, which will seriously deteriorate the hot working performance of the alloy.

[0004] Therefore, we need to design a nickel-based high-temperature alloy with higher strength and better corrosion resistance based on traditional nickel-based alloys to meet the increasingly high performance requirements of key components of important equipment such as petroleum refining equipment, thermal power generation equipment, waste power generation equipment, gas turbines and boilers, thereby improving their service life, extending overhaul intervals, and reducing economic losses caused by corrosion problems. Summary of the Invention

[0005] To address the problems of the existing technology, the present invention provides a corrosion-resistant nickel-based high-temperature alloy and its preparation method. The corrosion-resistant nickel-based high-temperature alloy is produced through vacuum induction and electroslag dual melting, homogenization, forging to produce rods, solution treatment, and aging treatment. After various heat treatment processes, the product can exhibit diverse performance characteristics and can be tailored to component requirements, better adapting to the component's service environment. This significantly differs from traditional nickel-based high-temperature alloys. Furthermore, this high-temperature alloy can be used in combustion chamber nozzles and fuel control system components of gas turbines, key combustion chamber components of marine low-speed engines (injector nozzles, exhaust valve stems), and other hot-end components requiring high strength, corrosion resistance, and wear resistance.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A corrosion-resistant nickel-based high-temperature alloy is a new type of high-Cr nickel-based alloy. The nickel-based high-temperature alloy is named TA800, and its components, calculated by mass percentage, include: Cr: 34% to 38%, Al: 3.5% to 5%, Co: 0.5-10%, C: 0.01-0.05%, B: 0.001-0.006%, Zr: 0.02-0.05%, Y: less than 0.08%, La: less than 0.08%, and the balance is Ni.

[0008] The following is a detailed description of the functions and dosages of the main components in the present invention (all in percentage by mass):

[0009] Co: Co primarily dissolves in the Ni-based solid solution. Due to the atomic size difference with Ni, Co creates lattice distortion, increasing resistance to dislocation motion and providing solid solution strengthening, thereby improving the alloy's strength and hardness. Co also affects phase stability, helping to stabilize the γ phase (a nickel-based solid solution with a face-centered cubic structure) and inhibiting the precipitation of deleterious phases. During high-temperature service, Co reduces the aggregation and growth of the γ' phase (an intermetallic compound phase such as Ni(Al,Ti)), maintaining a finely dispersed γ' phase, thereby maintaining the alloy's excellent high-temperature strength and creep resistance. Regarding its impact on processability, an appropriate amount of Co can improve the alloy's hot working properties, reduce deformation resistance, and enhance its thermoplasticity. The addition of Co significantly reduces the degree of segregation, easing homogenization and hot working difficulties. This makes the alloy easier to form during hot working processes such as forging and rolling, reducing the occurrence of processing defects. However, excessive Co content can lead to the precipitation of deleterious σ phases and increase the alloy's work hardening rate, negatively impacting processability. Therefore, the present invention limits the Co content of the alloy to 0.5-10%.

[0010] Cr: Cr is an indispensable alloying element in nickel-based high-temperature alloys. Its main functions are as follows: (1) Solid solution strengthening: Cr in the γ matrix of the high-temperature alloy causes lattice distortion, produces elastic stress field strengthening, and improves the strength of the γ solid solution; (2) Precipitation strengthening: In this alloy, Cr element exists mainly in the form of lamellar α-Cr phase through appropriate heat treatment. It is one of the important strengthening phases of the alloy and can also form a series of Cr-based carbides with C. In this alloy, M is the main 23 The main carbide is C6 type carbide, which is mainly distributed at the grain boundaries. The granular discontinuous carbides evenly distributed at the grain boundaries can effectively prevent grain boundary slip and migration, thereby improving strength. (3) In the nickel-based alloy, after subsequent solid solution and aging heat treatment, it can be dispersed and evenly distributed in a smaller size (≤3μm) near the grain boundaries, which is beneficial to improving the ductility of the alloy. (4) Oxidation resistance: It can form a Cr2O3 type oxide film with good oxidation resistance, and the higher the Cr content, the better the oxidation resistance. However, as the Cr content increases, a eutectic of γ phase and a-Cr phase will form in the alloy, deteriorating the hot working and use performance. In order to avoid the formation of a eutectic of γ phase and a-Cr phase in the alloy, the Cr content is controlled at 34%~38% in the present invention.

[0011] Al: Al is the primary element for forming the γ′ phase. It forms the γ' phase (Ni3Al) with Ni, which acts as precipitation strengthening. One of the key benefits of Al addition to this alloy is that it promotes the formation of lamellar structures (strengthening phases), increases the rate of lamellar formation, and refines the lamellar structure. Too low an Al content reduces the number of strengthening phases, or even prevents the formation of the critical lamellar strengthening phase, kinetically inhibiting their formation. However, excessive Al leads to the formation of a eutectic phase (γ + αCr), impairing hot workability and performance. Therefore, the Al content in this alloy is strictly limited to 3.5% to 5%.

[0012] C: C in nickel-based alloys mainly affects the mechanical properties of materials by forming MC carbides during solidification and precipitating M23C6 and M6C during heat treatment. The granular discontinuous carbides M23C6 precipitated at the grain boundaries can prevent grain boundary sliding and crack propagation, increase the durability, and improve the durability plasticity and toughness. A higher C content tends to increase the M in high Cr nickel-based alloys. 23 The precipitation of C6 forms large-sized, chain-like carbides and increases the uneven distribution of M23C6 at the grain boundaries, deteriorating the mechanical properties of the alloy. Therefore, in the present invention, the C content is controlled to 0.01-0.05%.

[0013] B: The addition of trace amounts of B strengthens grain boundaries, improves carbide morphology, and enhances the alloy's creep resistance and durability. Furthermore, carbides and borides compete for Cr, and trace additions of B can reduce the formation of continuous Cr-based carbides and improve carbide morphology. However, excessive addition can lead to dense boride precipitation at grain boundaries, embrittle them, and degrade material performance. Therefore, the present invention limits the B content in the alloy to 0.001-0.006%.

[0014] Zr: Zr atoms can segregate to grain boundaries, increasing grain boundary strength, improving carbide morphology and distribution, and inhibiting the formation of secondary carbides M23C6 and M6C, thereby improving the alloy's microstructural stability during prolonged high-temperature thermal exposure. Taking into account factors such as cost, the Zr content in this invention is controlled to 0.02-0.05%.

[0015] Y and La: Adding rare earth elements Y and La effectively absorbs free O and S in the alloy, forming stable rare earth oxides or sulfides, thereby mitigating the harmful effects of O and S, purifying the alloy, and refining the grain size. However, excessive addition can degrade the alloy's performance. In this invention, the Y and La content of the alloy is limited to below 0.08%.

[0016] The corrosion-resistant nickel-based high-temperature alloy has the following structure and properties:

[0017] The nickel-based alloy is a Ni-Co-Cr-Al alloy, which belongs to the category of high-Cr high-temperature alloys. The Cr content is far higher than that of ordinary high-temperature alloys, at more than 30%, giving the alloy material good corrosion resistance, strength and hardness. However, high-Cr alloys are often difficult to hot-process, and are prone to cracking and other phenomena. The root cause is that the segregation of high-Cr alloy elements is relatively serious. The addition of Co content can significantly improve the segregation degree of the alloy, reducing the difficulty of homogenization and hot processing; through the control of solid solution and aging, including the control of temperature, time and cooling method, the alloy can obtain a variety of different special microstructures, and then obtain different strength, hardness and ductility to meet the performance requirements of different components for corrosion-resistant nickel-based alloys. The above-mentioned special microstructure is closely related to the composition and heat treatment process, which is significantly different from traditional nickel-based high-temperature alloys. The details are as follows:

[0018] The microstructure of the nickel-based high-temperature alloy mainly includes equiaxed austenitic alloy grains, dispersed spherical a-Cr phases, and lamellar structures distributed in colonies in the areas between the spherical a-Cr phases. Specifically, the grain size of the equiaxed austenitic alloy grains reaches level 7 or above; the average size of the dispersed spherical a-Cr phases is less than 5 μm, and the phase ratio of the spherical a-Cr phase is less than 16%; the lamellar structure has the following characteristics: the structure of the lamellar structure is composed of α-Cr phase lamellars, γ phase lamellars, and γ' phases; the average spacing between adjacent a-Cr phase lamellar layers in the lamellar structure is less than 300 nm, wherein the α-Cr phase layer thickness is less than the γ phase, the α-Cr phase layer thickness is less than 75 nm, the average γ phase layer thickness is less than 150 nm, and the average size of the γ' phase is less than 75 nm; the lamellar structure is distributed in colonies in the areas between the spherical a-Cr phases, which is defined as lamellar structure colonies (with the same orientation), and the size of the lamellar structure colonies is less than 10 μm. Grain size and lamellar structure give the material extremely high strength. The smaller the grain size and the finer the average interlamellar spacing, the greater the alloy strength. The spherical α-Cr phase acts as a plasticizer, and the greater the ratio of spherical α-Cr phase, the better the ductility. Furthermore, the grain size cannot be too large, otherwise the lamellar structure of the alloy will coarsen, seriously reducing the alloy's ductility. Generally, the grain size should be controlled within 150μm, preferably within 100μm. By controlling the above-mentioned microstructure morphology and ratio through heat treatment, a variety of properties can be achieved.

[0019] In terms of the performance of the nickel-based high-temperature alloy, the solid solution hardness ranges from 150 to 350 HV, and the aged hardness ranges from 380 to 750 HV. The good solid solution softening effect makes the alloy easy to process high-precision components, reducing the processing difficulty. The alloy has high hardness and good red hardness in the aged state; the tensile strength ranges from 1200 to 2100 MPa, the yield strength is 800 to 1800 MPa, the elongation is 2 to 30%, and the cross-sectional reduction rate is 5 to 60%. After different heat treatment processes, the alloy can have various performance characteristics and can be tailored according to component requirements to better adapt to the service environment of the component. This is significantly different from traditional nickel-based high-temperature alloys.

[0020] A method for preparing a corrosion-resistant nickel-based high-temperature alloy comprises the following steps:

[0021] The first step is TA800 alloy smelting:

[0022] High-purity component raw materials were prepared according to mass percentage (wt. %), and the ingredients were processed by a dual melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots.

[0023] The second step is homogenization treatment of TA800 alloy:

[0024] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 2-4°C / min to 1100-1180°C, keep at this temperature for 16-28 hours, then take out and air cool.

[0025] Step 3: TA800 alloy forging:

[0026] Forging process: The billet is fed into the furnace at 700°C, held for 3-7 hours, then heated at a rate of 2-4°C / min to 1100-1150°C. After holding for 4-8 hours, the billet is removed from the furnace and forged. Open forging is performed using an air hammer forging method with axial drawing. The final forging temperature is no less than 900°C. Each reheat is held at 1100-1150°C for no less than 40 minutes. The billet is forged several times using this process to produce forged bars. TA800 alloy is rolled into billets: For forged bars with a diameter ≥50mm and a length ≥2000mm, the TA800 alloy is hot-rolled and drawn after billet forging. The process involves heating the bars in a furnace at 700°C at a rate of approximately 2.5°C / min to 1130°C, holding for 3 hours, and then rolling them out of the furnace. Rolling is performed in two heats: the first heat consists of 9-12 passes with a feed of 5mm per pass (on both sides), and the second heat consists of 5-8 passes with a feed of 2mm per pass (on both sides). The rolled bar specifications are selected based on the diameter of the exhaust valve forging bar (polished bar). Generally, the rolled bar diameter allowance is 3-4mm per side, resulting in a black-skinned forged bar.

[0027] An application of a corrosion-resistant nickel-based high-temperature alloy, wherein the corrosion-resistant nickel-based high-temperature alloy is a high-strength, high-corrosion-resistance, high-wear-resistance, non-magnetic, low-density (7.8g / cm 3 ) nickel-based high-temperature alloy, which can meet the needs of hot-end components serving in complex environments, can be used in gas turbine combustion chamber nozzles and fuel control system related components, key components of marine low-speed engine combustion chambers (injector nozzles, exhaust valve stems) or other hot-end components requiring high strength, corrosion resistance and wear resistance.

[0028] The beneficial effects of the present invention are:

[0029] (1) The nickel-based alloy described in the present invention is a Ni-Co-Cr-Al alloy, which belongs to the category of high-Cr high-temperature alloys. The Cr content is far higher than that of ordinary high-temperature alloys, exceeding 30%, which gives the alloy material good corrosion resistance, strength and hardness. However, high-Cr alloys are often difficult to hot-work and are prone to cracking. The root cause is that the segregation of high-Cr alloy elements is relatively severe. The addition of Co can significantly improve the degree of segregation of the alloy, reducing the difficulty of homogenization and hot working.

[0030] (2) The present invention can obtain a variety of special microstructures of the alloy through the control of solid solution and aging, including the control of temperature, time and cooling method, and thus obtain different strengths, hardness and ductility to meet the performance requirements of different components for corrosion-resistant nickel-based alloys. The above special microstructures are closely related to the composition and heat treatment process, which is significantly different from traditional nickel-based high-temperature alloys. It has diverse performance characteristics and can be tailored according to the needs of the components to better adapt to the service environment of the components. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a comparison chart of the yield strength of the TA800 alloy obtained in Example 1 and traditional representative corrosion-resistant materials;

[0032] Figure 2 This is a comparison chart of the S and V corrosion resistance of the TA800 alloy obtained in Example 1 and typical corrosion-resistant alloys;

[0033] Figure 3 This is a metallographic photograph of the TA800 alloy obtained in Example 1 after solution treatment;

[0034] Figure 4 This is the IPF diagram of the structure of the TA800 alloy after solution treatment obtained in Example 1;

[0035] Figure 5 The metallographic and scanning electron microscope images of the TA800 alloy obtained in Example 1 after solution aging treatment are shown;

[0036] Figure 6 This is a transmission electron microscope photograph of the structure of the TA800 alloy obtained in Example 1 after solution aging treatment;

[0037] Figure 7 The EBSD grain analysis and precipitation phase analysis results of the TA800 alloy after solution aging treatment obtained in Example 1; Figure 7 (a) is ebsd grain analysis, Figure 7 (b) is the analysis result of the precipitated phase;

[0038] Figure 8 Graph showing the relationship between the hardness of the TA800 alloy obtained in Example 2 and the solution and aging treatment temperatures;

[0039] Figure 9 The EBSD grain analysis results of the TA800 alloy obtained in Example 3;

[0040] Figure 10 The EBSD grain analysis results of the TA800 alloy obtained in Example 4 are as follows;

[0041] Figure 11The EBSD grain analysis results of the TA800 alloy obtained in Example 5 are as follows;

[0042] Figure 12 This is a metallographic photograph of the as-cast structure of the TA800 alloy obtained in Example 6;

[0043] Figure 13 This is a metallographic photograph of the as-cast structure of the TA800 alloy obtained in Example 7;

[0044] Figure 14 This is a metallographic photograph of the as-cast structure of the TA800 alloy obtained in Example 8;

[0045] Figure 15 This is a metallographic photograph of the homogenized state of TA800 alloy obtained in Comparative Example 1;

[0046] Figure 16 This is a metallographic photograph of the homogenized state of TA800 alloy obtained in Example 6;

[0047] Figure 17 This is a metallographic photograph of the homogenized state of TA800 alloy obtained in Example 7. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0049] Example 1

[0050] The TA800 alloy in this embodiment is a nickel-based alloy with a high Cr content. Specifically, the high-temperature alloy composition, in percentage by mass, includes: Cr: 37%, Al: 4.3%, Co: 4%, C: 0.02%, B: 0.004%, Zr: 0.03%, and the balance is Ni. The preparation process of this embodiment includes the following steps:

[0051] The first step is TA800 alloy smelting:

[0052] High-purity component raw materials were prepared according to mass percentage (wt. %), and the ingredients were processed by a dual melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 200 mm.

[0053] The second step is homogenization treatment of TA800 alloy:

[0054] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 3°C / min to 1140°C, keep at this temperature for 24 hours, then take it out and air cool it.

[0055] Step 3: TA800 alloy forging:

[0056] Forging process: The billet is fed into the furnace at 700°C, held at this temperature for 7 hours, then heated at a rate of 3°C / min to 1130°C, held for 4 hours, and then removed from the furnace for open forging. The open forging method is air hammer open forging with axial stretching, and the final forging temperature is not less than 900°C. The return temperature for each heat is 1130°C and the holding time is 50 minutes. According to the above process, the billet is open forged three times. After the open forging is completed, the forging ratio is 3, and the open bar is obtained. The billet is placed in the furnace at 700°C, heated at a rate of 2.5°C / min to 1130°C, held for 3 hours, and then removed from the furnace for rolling. The rolling is carried out in two heats: the first heat has 9 passes, with a feed of 5mm per pass (on both sides), and the second heat has 6 passes, with a feed of 2mm per pass (on both sides). The specifications of the rolled bar are selected based on the diameter of the exhaust valve forging bar (polished bar). In this embodiment, the diameter allowance of the rolled bar is 2.5 mm on one side, and the final hot-rolled bar has a diameter of 65 mm and a length of 2450 mm.

[0057] The black-skinned forged bars of the alloy of Example 1 were prepared by the above preparation process, and then solution and aging heat treatment were performed to evaluate their microstructure characteristics and mechanical properties. The TA800 alloy bars were subjected to solution + aging heat treatment. The solution heat treatment system was 1080°C for 1 hour and then water cooling. The aging heat treatment temperature was 810°C for 24 hours, and air cooling was performed after aging heat treatment.

[0058] Table 1, Mechanical properties and hardness test results

[0059]

[0060] Figure 1 The room temperature and high temperature yield strength comparison of the alloy of Example 1 and common corrosion-resistant nickel-based alloys shows that the alloy of Example 1 has higher room temperature and high temperature strength than common corrosion-resistant nickel-based alloys. Table 1 shows the mechanical properties and hardness data, which shows that Example 1 has very excellent comprehensive mechanical properties and hardness levels. Figure 2 The high temperature corrosion performance of Example 1 is compared with that of typical corrosion-resistant alloys 80A and 625 alloys. It can be seen that the alloy of Example 1 has less mass loss after corrosion and has excellent corrosion resistance. Figure 3 This is a metallographic structure photograph of Example 1 after solution treatment (1080°C). It can be seen that many spherical αCr phases with a size of <5μm are dispersed in this state. Figure 4 It can be seen that the grain size of Example 1 is very fine, with a grain size of 13 μm and ASTM grade 9.

[0061] Figure 5The metallographic and scanning electron microscope images of the alloy of Example 1 after solution aging treatment show that the microstructure of Example 1 is a composite precipitation of spherical α-Cr phases and lamellar structures. The lamellar structures are distributed in colonies between the spherical α-Cr phases, and the orientations of the colonies are similar. The average interlayer spacing in the lamellar structure is 170 nm. Figure 6 This is a transmission electron micrograph of the lamellar structure of the alloy of Example 1 after solution aging treatment. It can be seen that the lamellar structure comprises a lamellar structure composed of α-Cr phase lamellars, γ phase lamellars, and γ' phase with an average interlayer spacing of 170 nm. The α-Cr phase is slightly thinner than the γ phase, with an average layer thickness of 44 nm for the α-Cr phase, an average layer thickness of 130 nm for the γ phase, and an average size of 40 nm for the γ' phase. Figure 7 The ebsd grain analysis and precipitate phase analysis results of the alloy after solution aging treatment in Example 1 are shown in Figure 1. Figure 7 From (a) and (b), it can be seen that the lamellar structure with the same orientation is clustered in the area between the spherical a-Cr phases. The average size of the lamellar structure colonies is 2μm, ASTM grade 15.9, and the size and distribution are uniform. The average size of the spherical a-Cr phase is only 1μm, and the phase ratio is 13.5%. The characteristics of the solid solution aging structure give the alloy material excellent comprehensive mechanical properties, with high strength, high hardness and good toughness.

[0062] Example 2

[0063] The TA800 alloy in this embodiment is a nickel-based alloy with a high Cr content. Specifically, the high-temperature alloy composition, in mass percentage, includes: Cr: 37.8%, Al: 4.8%, Co: 3%, C: 0.02%, B: 0.004%, Zr: 0.03%, and the balance is Ni. The preparation process of this embodiment includes the following steps:

[0064] The first step is TA800 alloy smelting:

[0065] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0066] The second step is homogenization treatment of TA800 alloy:

[0067] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 4°C / min to 1180°C, keep at this temperature for 16 hours, then take it out and air cool it.

[0068] Step 3: TA800 alloy forging:

[0069] Forging process: The billet was fed into the furnace at 700°C, held for 5 hours, then heated at a rate of 4°C / min to 1150°C, held for 8 hours, and then removed from the furnace for open forging. Open forging was performed using an air hammer open forging method with axial drawing. The final forging temperature was no less than 900°C, with each reheat cycle held at 1150°C for 45 minutes. Following this process, the billet was forged three times, achieving a forging ratio of 6, producing TA800 alloy forged bars with a diameter of 30 mm and a length of 1200 mm.

[0070] TA800 alloy forging bars were prepared through the above preparation process, and then different solution and aging heat treatments were performed to evaluate their hardness. The sample block size was 12 mm. 12mm 10mm, the solution heat treatment temperature was 1050 ° C, 1100 ° C, 1140 ° C, the solution time was 1 h, and then water cooling was used. Then, each solution sample was subjected to aging heat treatment at different temperatures, and the aging temperature was 550 ° C, 600 ° C, 650 ° C, 700 ° C, 750 ° C, 800 ° C, 850 ° C, and the aging time was 16 h. After that, it was air-cooled to room temperature; the surface of the sample block was polished with 2000 mesh sandpaper and then the hardness test was carried out. The results are as follows Figure 8 As shown, it can be seen that the hardness of the alloy increases with the increase of the solution temperature and increases with the decrease of the aging temperature, with the hardness range being 400-750HV. The following table shows the mechanical properties of the alloy obtained by solution treatment at 1100°C for 1 hour, followed by water cooling, and then aging heat treatment at 830°C and 700°C for 16 hours for each solution sample, followed by air cooling and room temperature stretching of the sample. Vickers hardness was also measured for both samples. It can be found that the aging temperature significantly affects the mechanical properties of the alloy. The higher the aging temperature, the lower the strength and hardness of the alloy, but at the same time, its ductility will be significantly improved.

[0071] Table 2, Room temperature mechanical properties and microhardness of Example 2

[0072]

[0073] Examples 3, 4, and 5

[0074] The alloy compositions of Examples 3, 4, and 5 are expressed in percentage by mass as shown in Table 3. Example 3 is a control experiment to explore the effects of the addition of rare earth elements La and Y.

[0075] Table 3, Alloy composition (wt%)

[0076]

[0077] The preparation process of this embodiment 3 comprises the following steps:

[0078] The first step is TA800 alloy smelting:

[0079] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0080] The second step is homogenization treatment of TA800 alloy:

[0081] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 2°C / min to 1100°C, keep at this temperature for 28h, then take out and air cool.

[0082] Step 3: TA800 alloy forging:

[0083] Forging process: The billet was fed into the furnace at 700°C, held for 3 hours, then heated at a rate of 2°C / min to 1100°C. After holding for 6 hours, the billet was removed from the furnace and forged. Open forging was performed using an air hammer open forging method with axial drawing. The final forging temperature was no less than 900°C. Each reheat was held at 1100°C for 40 minutes. The billet was forged three times using this process to produce TA800 alloy forging bars with a diameter of 30 mm and a length of 1200 mm.

[0084] The preparation process of this embodiment 4 comprises the following steps:

[0085] The first step is TA800 alloy smelting:

[0086] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0087] The second step is homogenization treatment of TA800 alloy:

[0088] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 2°C / min to 1100°C, keep at this temperature for 28h, then take out and air cool.

[0089] Step 3: TA800 alloy forging:

[0090] Forging process: The billet was fed into the furnace at 700°C, held for 3 hours, then heated at a rate of 2°C / min to 1100°C. After holding for 6 hours, the billet was removed from the furnace and forged. Open forging was performed using an air hammer open forging method with axial drawing. The final forging temperature was no less than 900°C. Each reheat was held at 1100°C for 40 minutes. The billet was forged three times using this process to produce TA800 alloy forging bars with a diameter of 30 mm and a length of 1200 mm.

[0091] The preparation process of this embodiment 5 comprises the following steps:

[0092] The first step is TA800 alloy smelting:

[0093] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0094] The second step is homogenization treatment of TA800 alloy:

[0095] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 2°C / min to 1100°C, keep at this temperature for 28h, then take out and air cool.

[0096] Step 3: TA800 alloy forging:

[0097] Forging process: The billet was fed into the furnace at 700°C, held for 3 hours, then heated at a rate of 2°C / min to 1100°C. After holding for 6 hours, the billet was removed from the furnace and forged. Open forging was performed using an air hammer open forging method with axial drawing. The final forging temperature was no less than 900°C. Each reheat was held at 1100°C for 40 minutes. The billet was forged three times using this process to produce TA800 alloy forging bars with a diameter of 30 mm and a length of 1200 mm.

[0098] Three ingots were produced by induction + electroslag melting with the same specifications. The homogenized microstructure was analyzed by ebsd. Figure 9 、 Figure 10 、 Figure 11 The EBSD grain analysis results of Examples 3, 4, and 5 respectively show that after adding Y and La elements, the grain size of Examples 4 and 5 becomes smaller than that of the alloy of Example 3, and the grains are significantly refined. The refined cast grain size is less than 50 μm, which can significantly reduce the difficulty of homogenization and forging and improve the alloy performance.

[0099] Examples 6, 7, and 8

[0100] The TA800 alloy in this embodiment is a nickel-based alloy with a high Cr content. Specifically, the composition of the high-temperature alloy is expressed in mass percentage. The compositions of the alloys of Comparative Example 1 and Examples 6, 7, and 8 are shown in Table 4.

[0101] Table 4 Alloy composition (wt%)

[0102]

[0103] The preparation process of this embodiment 6 comprises the following steps:

[0104] The first step is TA800 alloy smelting:

[0105] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0106] The second step is homogenization treatment of TA800 alloy:

[0107] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 3°C / min to 1140°C, keep at this temperature for 24 hours, then take it out and air cool it.

[0108] Step 3: TA800 alloy forging:

[0109] Forging process: The billet is fed into the furnace at 700°C, held for 3 hours, then heated at a rate of 3°C / min to 1140°C. After holding for 4 hours, the billet is removed from the furnace and forged. Open forging is performed using an air hammer forging method with axial drawing. The final forging temperature is no less than 900°C. Each reheat is held at 1140°C for 40 minutes. The billet is forged three times using this process, resulting in a forged bar with a diameter of 25 mm and a length of 1000 mm.

[0110] The preparation process of this embodiment 7 comprises the following steps:

[0111] The first step is TA800 alloy smelting:

[0112] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0113] The second step is homogenization treatment of TA800 alloy:

[0114] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 3°C / min to 1140°C, keep at this temperature for 24 hours, then take it out and air cool it.

[0115] Step 3: TA800 alloy forging:

[0116] Forging process: The billet is fed into the furnace at 700°C, held for 3 hours, then heated at a rate of 3°C / min to 1140°C. After holding for 4 hours, the billet is removed from the furnace and forged. Open forging is performed using an air hammer forging method with axial drawing. The final forging temperature is no less than 900°C. Each reheat is held at 1140°C for 40 minutes. The billet is forged three times using this process, resulting in a forged bar with a diameter of 25 mm and a length of 1000 mm.

[0117] The preparation process of this embodiment 8 comprises the following steps:

[0118] The first step is TA800 alloy smelting:

[0119] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0120] The second step is homogenization treatment of TA800 alloy:

[0121] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 3°C / min to 1140°C, keep at this temperature for 24 hours, then take it out and air cool it.

[0122] Step 3: TA800 alloy forging:

[0123] Forging process: The billet is fed into the furnace at 700°C, held for 3 hours, then heated at a rate of 3°C / min to 1140°C. After holding for 4 hours, the billet is removed from the furnace and forged. Open forging is performed using an air hammer forging method with axial drawing. The final forging temperature is no less than 900°C. Each reheat is held at 1140°C for 40 minutes. The billet is forged three times using this process, resulting in a forged bar with a diameter of 25 mm and a length of 1000 mm.

[0124] The preparation process of this comparative example 1 comprises the following steps:

[0125] The first step is TA800 alloy smelting:

[0126] High-purity component raw materials were used to prepare the ingredients according to mass percentage (wt. %), and the ingredients were processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots with a diameter of 80 mm.

[0127] The second step is homogenization treatment of TA800 alloy:

[0128] Homogenization heat treatment process: feed the material into the furnace at 700°C, heat up at a rate of 3°C / min to 1140°C, keep at this temperature for 24 hours, then take it out and air cool it.

[0129] Step 3: TA800 alloy forging:

[0130] Forging process: The billet is fed into the furnace at 700°C, held for 3 hours, then heated at a rate of 3°C / min to 1140°C. After holding for 4 hours, the billet is removed from the furnace and forged. Open forging is performed using an air hammer forging method with axial drawing. The final forging temperature is no less than 900°C. Each reheat is held at 1140°C for 40 minutes. The billet is forged three times using this process, resulting in a forged bar with a diameter of 25 mm and a length of 1000 mm.

[0131] The alloy compositions of Comparative Example 1, Example 6, Example 7, and Example 8 are shown in Table 4. The main difference between the four groups of comparative experiments is the amount of Co added. Ingots were prepared by induction + electroslag smelting, and the as-cast structure was first evaluated. Figure 12 、 Figure 13 、 Figure 14 The metallographic photos of the as-cast structures of Examples 6, 7, and 8 are shown. It can be seen that the as-cast structures are good, no obvious harmful phases are formed, and only some carbides are distributed along the grain boundaries. Afterwards, the same homogenization heat treatment was performed on Comparative Example 1, Example 6, and Example 7, and the metallographic tests were performed on the homogenized samples. The results are shown in FIG. Figure 15 、 Figure 16 、 Figure 17 As shown, from the metallographic photographs of the homogenized structures of Comparative Example 1 and Examples 6 and 7, it can be seen that the alloy without Co element addition still has relatively serious segregation after homogenization heat treatment and is not completely eliminated, while the alloys with 2% Co element and 6% Co element addition have basically eliminated segregation after homogenization heat treatment, which is in sharp contrast to the alloy without Co element addition. Therefore, the addition of Co content helps to alleviate alloy segregation and reduce the difficulty of homogenization heat treatment.

[0132] The above-described embodiments merely express the implementation methods of the present invention, but should not be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A corrosion-resistant nickel-based high-temperature alloy, characterized in that: The components of the corrosion-resistant nickel-based high-temperature alloy include, by mass percentage, Cr: 34% to 38%, Al: 3.5% to 5%, Co: 0.5-10%, C: 0.01-0.05%, B: 0.001-0.006%, Zr: 0.02-0.05%, Y: less than 0.08%, La: less than 0.08%, and the balance is Ni.

2. The corrosion-resistant nickel-based high-temperature alloy according to claim 1, characterized in that: The microstructure of the corrosion-resistant nickel-based high-temperature alloy includes equiaxed austenite alloy grains, dispersed spherical a-Cr phases, and lamellar structures distributed in a colony-like manner in areas between the spherical a-Cr phases.

3. The corrosion-resistant nickel-based high-temperature alloy according to claim 2, characterized in that: The grain size of the equiaxed austenitic alloy grains reaches level 7 or above; the average size of the dispersed spherical a-Cr phase is less than 5 μm, and the phase ratio of the spherical a-Cr phase is less than 16%.

4. The corrosion-resistant nickel-based high-temperature alloy according to claim 2, characterized in that: The lamellar structure has the following characteristics: the structure of the lamellar structure is composed of α-Cr phase lamellars, γ phase lamellars and γ' phase; the average spacing between adjacent a-Cr phase lamellar layers in the lamellar structure is less than 300 nm; the α-Cr phase layer thickness is less than that of the γ phase, the α-Cr phase layer thickness is less than 75 nm, the average γ phase layer thickness is less than 150 nm, and the average size of the γ' phase is less than 75 nm; the lamellar structure is distributed in a colony-like manner in the area between the spherical a-Cr phases, with the same orientation; and the size of the lamellar structure colonies is less than 10 μm.

5. The corrosion-resistant nickel-based high-temperature alloy according to claim 1, characterized in that: The corrosion-resistant nickel-based high-temperature alloy has the following properties: solution hardness ranges from 150 to 350 HV, aging hardness ranges from 380 to 750 HV; tensile strength ranges from 1200 to 2100 MPa, yield strength ranges from 800 to 1800 MPa, elongation ranges from 2 to 30%, and cross-sectional shrinkage ranges from 5 to 60%.

6. A method for preparing the corrosion-resistant nickel-based high-temperature alloy according to any one of claims 1 to 5, characterized in that: The following steps are involved: The first step is TA800 alloy smelting: High-purity component raw materials are used to prepare the ingredients according to the mass percentage, and the ingredients are processed by a double melting method of induction melting and electroslag remelting to obtain TA800 alloy ingots; The second step is homogenization treatment of TA800 alloy: Homogenization heat treatment process: feed the material into the furnace at 700°C, heat it to 1100-1180°C, keep it at this temperature for 16-28 hours, then take it out and air cool it; Step 3: TA800 alloy forging: Forging process: feed the material into the furnace at 700°C, keep it warm for 3-7 hours, then heat it up to 1100-1150°C and keep it warm for 4-8 hours before taking it out of the furnace and starting the blank forging to obtain forged bars.

7. The method for preparing a corrosion-resistant nickel-based high-temperature alloy according to claim 6, characterized in that: In the second step, the heating rate is 2-4°C / min; and the heating rate of the third step forging process is 2-4°C / min.

8. The method for preparing a corrosion-resistant nickel-based high-temperature alloy according to claim 6, characterized in that: In the third step, the blank forging method is air hammer free forging, axial stretching, and the final forging temperature is not less than 900°C, wherein the heat preservation temperature of each fire is 1100-1150°C, and the heat preservation time is not less than 40min. According to the above process, the blank is forged several times to obtain a forged bar.

9. The method for preparing a corrosion-resistant nickel-based high-temperature alloy according to claim 6, characterized in that: In the third step, the TA800 alloy is rolled to obtain a rod blank: for forging bars with a diameter of ≥50 mm and a length of ≥2000 mm, the TA800 alloy needs to be hot-rolled and stretched after blanking and forging. The specific process includes: putting the bar into the furnace at 700°C, heating it to 1130°C, keeping it warm for 3 hours, and then rolling it out of the furnace. The rolling is carried out in two fires, the first fire has 9-12 passes, and the feed amount for each pass is 5 mm. The second fire has 5-8 passes, and the feed amount for each pass is 2 mm. The diameter allowance of the rolled bar is 3-4 mm on one side, and finally a black forged bar is obtained.

10. Use of the corrosion-resistant nickel-based high-temperature alloy according to any one of claims 1 to 5, characterized in that: The corrosion-resistant nickel-based high-temperature alloy is a high-performance nickel-based high-temperature alloy that can meet the needs of hot-end components serving in complex environments. It is used in combustion chamber nozzles and fuel control system-related components of gas turbines, key components of combustion chambers of marine low-speed engines, or other hot-end components requiring high strength, corrosion resistance, and wear resistance.

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