A method of producing an alloy sheet and an alloy sheet produced thereby

Abstract

The present application belongs to the field of metal materials, and particularly relates to a method for preparing an alloy plate, comprising: processing an alloy ingot into a blank; sequentially performing twice forging and three to four times rolling on the blank to obtain the alloy plate; and before each time of forging, the first time of rolling, the second time of rolling and the optional fourth time of rolling, the blank is subjected to heat treatment in a specific process in an environment with a vacuum degree of 4.0*10 ‑3 Pa. The present application also relates to the prepared alloy plate. The method of the present application improves the tensile strength, yield strength and elongation of the alloy plate, reduces the yield strength difference and tungsten segregation degree of the plate, and the grain size of the plate is small and uniform, the performance deviation of the plate in different directions is small, and the microstructure uniformity of the plate is good.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials, specifically relating to a method for preparing alloy plates, and also to the alloy plates obtained therefrom. Background Technology

[0002] Compared with other types of high-temperature alloys, high-temperature niobium alloys have advantages such as low density, high specific strength at high temperatures (600-1800℃), excellent cold and hot formability, and good weldability. They can be processed into sheet metal and complex-shaped parts, and are used to manufacture components such as thrust chamber extensions of attitude control / orbit control engines for rocket engines, satellites, spacecraft, and missiles. They are one of the important candidate materials for aerospace structural components.

[0003] However, current niobium alloy sheets exhibit poor tensile and yield strength, coarse grains, uneven microstructure, significant deviations in machinability in different directions, high axial properties, and low radial properties. Therefore, there is an urgent need to develop a niobium alloy sheet that overcomes these shortcomings. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing alloy plates, which improves the tensile strength, yield strength and elongation of the alloy plates, reduces the yield strength difference and tungsten segregation of the plates, and results in small and uniform grain size, small performance deviation in different directions and good microstructure uniformity of the plates.

[0005] To achieve the above objectives, the present invention provides a method for preparing alloy plates, comprising the following steps:

[0006] (1) Process the alloy ingot into billets;

[0007] (2) The billet is subjected to two forgings and three to four rollings in sequence to obtain an alloy sheet; and, before each forging, the first rolling, the second rolling, and optionally the fourth rolling, the billet is subjected to a vacuum degree ≤4.0×10 - 3 Pa (preferably vacuum degree ≤ 3.0 × 10⁻⁶) -3 Heat treatment is performed in an environment of Pa) according to the following process:

[0008] Raise the temperature to 400℃-600℃ (e.g., 400℃, 450℃, 500℃, 550℃, 600℃) within 20-40 minutes (e.g., 20, 25, 30, 35, 40 minutes), and hold at that temperature for 20-40 minutes (e.g., 20, 25, 30, 35, 40 minutes); then raise the temperature to 700℃-900℃ (e.g., 700℃, 750℃, 800℃, 850℃) within another 20-40 minutes (e.g., 20, 25, 30, 35, 40 minutes). Hold at 900℃ for 20-40 minutes (e.g., 20, 25, 30, 35, 40 minutes); then raise the temperature to 1350℃-1550℃ (e.g., 1350℃, 1400℃, 1450℃, 1500℃, 1550℃) within 55-75 minutes (e.g., 55, 60, 65, 70, 75 minutes), hold for 100-140 minutes (e.g., 100, 110, 120, 130, 140 minutes), and allow to cool naturally to ≤80℃.

[0009] In any embodiment, the heating process is carried out at a constant rate.

[0010] In any embodiment, in step (2), before each forging, the surface of the heat-treated billet is subjected to an anti-oxidation treatment, and then placed in a furnace at 1080℃-1250℃ (e.g., 1080℃, 1100℃, 1150℃, 1200℃, 1250℃) for 100-140 minutes (e.g., 100, 110, 120, 130, 140 min) and then removed from the furnace.

[0011] In any embodiment, in step (2), before the first rolling, the heat-treated billet is placed in a furnace at 380℃-580℃ (e.g., 380℃, 400℃, 420℃, 440℃, 450℃, 470℃, 480℃, 500℃, 520℃, 550℃, 560℃, 580℃) and held for 100-140 minutes (e.g., 100, 110, 120, 130, 140 min) and then removed from the furnace.

[0012] In any implementation, step (1) specifically includes:

[0013] The alloy ingot is cut to obtain a rough billet;

[0014] The surface of the rough billet undergoes an anti-oxidation treatment, followed by sequentially raising the temperature to 750℃-850℃ (e.g., 750℃, 800℃, 850℃), 950℃-1050℃ (e.g., 950℃, 1000℃, 1050℃), and 1150℃-1200℃ (e.g., 1150℃, 1180℃, 1200℃) and holding for 1-5 minutes (e.g., 1, 2, 3, 4, 5 minutes), then raising the temperature to 1250℃-1300℃ (e.g., 1250℃, 1280℃, 1300℃) and holding for a total holding time of 25-40 minutes (e.g., 25, 28, 30, 33, 35, 37, 38, 40 minutes). After this, the surface of the rough billet undergoes a high-temperature resistant treatment to obtain a pretreated billet.

[0015] The pretreated billet is extruded, straightened, and sanded to obtain a billet material.

[0016] In any embodiment, the alloy ingot is obtained by melting and casting alloy raw materials; wherein, the alloy raw materials include the following elements:

[0017] Zirconium 1.5-3.5% by weight, preferably 2.1-2.7% by weight;

[0018] Tungsten 8-15% by weight, preferably 10-12% by weight;

[0019] Carbon 0.01-0.50% by weight, preferably 0.05-0.10% by weight.

[0020] Oxygen 0.005-0.05% by weight, preferably 0.008-0.012% by weight, for example 0.01% by weight;

[0021] Nitrogen is 0.005-0.05% by weight, preferably 0.008-0.012% by weight, for example 0.01% by weight;

[0022] Hydrogen 0.0005-0.005% by weight, preferably 0.0008-0.0012% by weight, for example 0.001% by weight;

[0023] The rest is niobium.

[0024] In any implementation, the two forging processes satisfy one or more of the following:

[0025] (A) The first forging is carried out by a precision forging machine, wherein the hammer of the precision forging machine strikes 400-600 times per minute (e.g., 420, 450, 480, 500, 530, 550, 570, 580, 600 times), and the outer diameter is reduced by 4-10 mm per pass (e.g., 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm). The forging is reheated in the furnace for 25-35 minutes (e.g., 25, 30, 35 minutes).

[0026] (B) The thickness of the billet after the first forging is 60-86 mm, preferably 70-76 mm;

[0027] (C) The second forging is carried out by a fast forging hydraulic press, wherein the reduction of each pass of the fast forging hydraulic press is 8-12mm (e.g. 8mm, 9mm, 10mm, 11mm, 12mm) and the edges are tucked up. The forging is then returned to the furnace for reheating for 25-35 minutes (e.g. 25, 30, 35 minutes).

[0028] (D) The thickness of the billet after the second forging is 20-43 mm (preferably 30-33 mm), and the width is 75-102 mm (preferably 85-92 mm);

[0029] (E) The temperature of the billet after each forging is ≥850℃, preferably ≥950℃.

[0030] In any embodiment, the three to four rolling processes satisfy one or more of the following:

[0031] (a) In the first rolling and / or the second rolling, the rolling pressure for the first 2 to 4 passes is controlled at 350-800 tons (preferably 400-800 tons), and then the pressure is controlled at 801-1350 tons (preferably 801-1300 tons). When the thickness differs from the required thickness by 0.3-0.4 mm, the pressure is controlled at 350-800 tons (preferably 400-800 tons).

[0032] (b) The first rolling is performed using a reversible two-roll mill;

[0033] (c) The thickness of the billet after the first rolling is 8-17 mm (preferably 10-12 mm) and the width is 180-230 mm (preferably 200-210 mm);

[0034] (d) The second rolling is carried out by a reversible large two-roll mill;

[0035] (e) The thickness of the billet after the second rolling is 4-7 mm (preferably 5-6 mm) and the width is 315-343 mm (preferably 335-340 mm);

[0036] (f) In the third and / or fourth rolling, the rolling pressure for the first 2 to 4 passes is controlled at 10-60 tons (preferably 20-60 tons), and then the pressure is controlled at 61-140 tons (preferably 61-130 tons). When the difference from the required thickness is 0.1-0.6 mm (preferably 0.2-0.5 mm), the pressure is controlled at 20-70 tons (preferably 30-60 tons).

[0037] (g) The third and / or fourth rolling processes are performed using a reversible four-high mill;

[0038] (h) The thickness of the billet after the third rolling is 1.8-3.5 mm (preferably 2.8-3.0 mm) and the width is 345-360 mm (preferably 345-350 mm);

[0039] (i) The thickness of the billet after the fourth rolling is 0.5-1.0 mm (preferably 0.7-0.8 mm) and the width is 345-370 mm (preferably 345-350 mm).

[0040] In any implementation, the method further includes:

[0041] After the final rolling, the billet is sequentially pickled, heat-treated, leveled, polished, and inspected to obtain alloy sheet; wherein the heat treatment is carried out in accordance with the heat treatment process described above.

[0042] In any implementation, one or more of the following are included:

[0043] 1) In step (1), the thickness of the alloy ingot is 195-215mm (e.g., 195mm, 200mm, 205mm, 210mm, 215mm) and the width is 1460-1570mm (preferably 1480-1550mm);

[0044] 2) In step (1), the thickness of the cut blank is 195-215mm (e.g., 195mm, 197mm, 198mm, 200mm, 202mm, 205mm, 207mm, 210mm, 212mm, 215mm) and the width is 473-536mm (preferably 493-516mm);

[0045] 3) In step (1) and / or step (2), the antioxidant treatment is to apply an antioxidant coating; the antioxidant coating is a commonly used antioxidant coating in the art;

[0046] 4) In step (1), the high-temperature resistant treatment is to coat with high-temperature glass powder; optionally, the high-temperature glass powder can be purchased from the market.

[0047] 5) In step (1), the extrusion pressure is 40-45MN (e.g., 40MN, 42MN, 42.8MN, 43MN, 44MN, 45MN), and before extrusion, a glass pad is filled between the surface of the pretreated billet and the extrusion equipment.

[0048] 6) In step (1), the straightening is to hold the extruded pretreated billet at 900℃-1000℃ (e.g., 900℃, 950℃, 980℃, 1000℃) for 100-140 min (e.g., 100 min, 110 min, 120 min, 130 min, 140 min) and then straighten it through a high-speed forging machine;

[0049] 7) In step (2), before each heat treatment, the billet is pickled until a metallic luster is observed and there are no blemishes; optionally, the acid solution used for pickling includes HCl, HF and water in a volume ratio of 5:2:3.

[0050] 8) In step (2), before the first rolling, the surface and internal defects of the heat-treated billet are removed;

[0051] 9) In step (2), before the second rolling and / or the third rolling, the surface defects of the heat-treated billet are removed.

[0052] In any implementation, after the final rolling, the polishing includes sequential rough polishing and fine polishing.

[0053] In another aspect, the present invention provides an alloy sheet obtained by the method described in the preceding aspect.

[0054] The present invention has achieved at least one of the following beneficial effects:

[0055] 1. The alloy sheet prepared by the method of the present invention has high tensile strength and yield strength, low yield strength difference, high elongation, and is not easy to crack.

[0056] 2. The alloy plates prepared by the method of the present invention have low tungsten segregation, small and uniform grain size, small performance deviation in different directions, and uniform microstructure. Detailed Implementation

[0057] The embodiments of the present invention will now be clearly and completely described in conjunction with examples. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0058] Example

[0059] The preparation method of niobium-tungsten alloy plate includes:

[0060] 1) Melting and casting: Niobium-tungsten alloy (containing 0.05-0.10% carbon, 0.01% oxygen, 0.01% nitrogen, 0.0010% hydrogen, 2.1-2.7% zirconium, 10-12% tungsten, with the remainder being niobium) is melted in an EB furnace and cast into ingots with a thickness of 205mm and a width of 1480-1550mm.

[0061] 2) Sawing: Sawing the ingot into billets with a thickness of 205mm and a width of 493-516mm;

[0062] 3) Pretreatment: At 80℃, apply a special anti-oxidation coating to the surface of the billet, and then heat it to 800℃, 1000℃ and 1200℃ in sequence and keep it at each temperature for 2-3 minutes. Finally, heat it to 1250℃ and keep it at the temperature for a total of 28 minutes. Then, apply high-temperature glass powder to the surface of the billet to obtain the pretreated billet.

[0063] 4) Extrusion: The pretreated billet is extruded using a SMS 45MN extrusion press with an extrusion pressure of 42.8MN; before extrusion, a glass pad is used to fill the space between the billet surface and the equipment surface.

[0064] 5) Straightening: The extruded billet is loaded into a box-type resistance furnace, heated to 950℃ and held for 120 minutes, and then straightened using a 16MN hydraulic high-speed forging machine;

[0065] 6) Grinding: Use a grinding wheel to grind the surface of the straightened billet to remove residual glass powder and extrusion defects;

[0066] 7) First pickling: The surface of the blank after polishing is cleaned with an acid solution until a metallic luster is visible to the naked eye and there are no blemishes, in order to remove surface impurities and oil stains. The volume ratio of HCl, HF and H2O in the acid solution is 5:2:3.

[0067] 8) First heat treatment: The pickled billet is heat-treated in an environment with a vacuum degree ≤3.0×10-3Pa according to the following heating procedure:

[0068] First, raise the temperature to 500℃ at a constant rate for 30 minutes, hold at 500℃ for 30 minutes, then raise the temperature to 800℃ at a constant rate for 30 minutes, hold at 800℃ for 30 minutes, then raise the temperature to 1450℃ at a constant rate for 65 minutes, hold at 1450℃ for 120 minutes, and finally allow it to cool naturally (without argon gas) to ≤80℃ before removing it from the furnace.

[0069] 9) First forging: Coat the surface of the heat-treated billet with an anti-oxidation protective material, preheat the box-type resistance furnace to 1150℃, put the billet into the box-type resistance furnace and hold it for 120 minutes, then take it out of the furnace; use the four hammers of the precision forging machine to strike the billet at a high frequency, 500 times per minute, reduce the outer diameter by 8-5mm per pass, forging to a thickness of 70-76mm, return to the furnace for reheating for 30 minutes during the forging process, and the temperature of the billet after forging is ≥950℃;

[0070] 10) Second pickling: Clean the surface of the forged billet with an acid solution until a metallic luster is visible to the naked eye and there are no blemishes. The acid solution is the same as in step 7).

[0071] 11) Second heat treatment: Same as step 8);

[0072] 12) Second forging: Coat the surface of the heat-treated billet with an anti-oxidation protective material, preheat the box-type resistance furnace to 1150℃, put the billet into the box-type resistance furnace and hold it for 120 minutes, then take it out of the furnace; use a fast forging hydraulic press (composed of a forging machine and an operating machine) to forge the billet, with a reduction of 10mm per pass and the edges being trimmed, forging to a thickness of 30-33mm and a width of 85-92mm, returning to the furnace for reheating for 30 minutes during the forging process, and the temperature of the billet after forging is ≥950℃;

[0073] 13) Third pickling: Same as step 10);

[0074] 14) Third heat treatment: Same as step 8);

[0075] 15) Machining: After heat treatment, the surface defects of the billet are removed by turning tool and the side defects are removed by milling cutter to obtain a billet with a thickness of 24-26mm and a width of 80-88mm;

[0076] 16) Flaw detection: Ultrasonic testing is used to identify and remove any defects that may exist inside the billet.

[0077] 17) First rolling: Preheat the box-type resistance furnace to 480℃, load the billet into the furnace, hold for 120 minutes, and then remove it from the furnace; use a reversible two-roll mill to roll the billet to a thickness of 10-12mm and a width of 200-210mm; rolling parameters: control the rolling pressure at 400-800 tons for the first 2 to 4 passes to adjust the thickness difference of the incoming material; control the pressure at 801-1300 tons for the intermediate passes to reduce the rolling time; when the required thickness of 0.3-0.4mm is approached, control the pressure within 400-800 tons to ensure the thickness difference and plate shape of the product;

[0078] 18) Fourth pickling: Clean the surface of the rolled billet with an acid solution until a metallic luster is visible to the naked eye and there are no blemishes. The acid solution is the same as in step 7).

[0079] 19) Fourth heat treatment: Same as step 8);

[0080] 20) First finishing: Use a grinding wheel to grind the surface of the blank to remove residual defects and fine cracks on the edges, and to make the four sides neat;

[0081] 21) Second rolling: At room temperature, a reversible large two-roll mill is used to roll the trimmed billet to a thickness of 6-5 mm and a width of 335-340 mm. Rolling parameters: The rolling pressure for the first 2 to 4 passes is controlled at 400-800 tons to adjust the thickness difference of the incoming material; the intermediate passes are controlled at 801-1300 tons to reduce the rolling time; when the required thickness of 0.3-0.4 mm is approached, the pressure is controlled within 400-800 tons to ensure the thickness difference and plate shape of the product.

[0082] 22) Fifth pickling: Same as step 18);

[0083] 23) Second trimming: Same as step 20);

[0084] 24) Third rolling: At room temperature, the trimmed billet is rolled to a thickness of 2.8-3.0 mm and a width of 345-350 mm using a reversible four-high rolling mill; rolling parameters: the rolling pressure for the first 2 to 4 passes is controlled at 20-60 tons, the intermediate passes are controlled at 61-130 tons, and when the thickness differs from the required thickness by 0.5 mm, the pressure is controlled at 30-60 tons to ensure the product thickness and plate shape;

[0085] 25) Sixth pickling: Same as step 18);

[0086] 26) Fifth heat treatment: Same as step 8);

[0087] 27) Fourth rolling: At room temperature, the heat-treated billet is rolled to a thickness of 0.7-0.8 mm and a width of 345-350 mm using a reversible four-roll mill; rolling parameters: the rolling pressure for the first 2 to 4 passes is controlled at 20-60 tons, the intermediate passes are controlled at 61-130 tons, and when the thickness differs from the required thickness by 0.2 mm, the pressure is controlled at 30-60 tons to ensure the product thickness and plate shape;

[0088] 28) Seventh pickling: Same as step 18);

[0089] 29) Sixth heat treatment: Same as step 8);

[0090] 30) Leveling: Use a multi-roller leveling machine to level the billet, with a flatness of ≤0.6mm; use a shearing machine to scribing and rough cutting.

[0091] 31) Surface treatment: Use a water bath belt sander to grind and polish the surface of the rough material;

[0092] 32) Cutting: Use a shearing machine to precisely cut the material by marking lines;

[0093] 33) Fine polishing: Use a water bath belt sander to grind and polish the surface of the material;

[0094] 34) The product leaves the factory after passing inspection.

[0095] Comparative Example 1

[0096] In step 3), the coated blank is heated to 800℃ and 1000℃ in sequence and held for 2-3 minutes each, and finally heated to 1200℃ and held for a total holding time of 25 minutes. The rest is the same as in the example.

[0097] The results showed that during subsequent extrusion, the pretreated billet was not fully extruded, and the pretreated billet was prone to "stuck" phenomenon, that is, the pretreated billet could not be removed from the extrusion cylinder; while the above phenomenon did not occur in the example.

[0098] Comparative Example 2

[0099] The heat treatment heating procedure in steps 8), 11), 14), 19), 26), and 29) is as follows: heat up to 1200℃ in 60 minutes, hold for 60 minutes, and finally cool naturally (without argon gas) to ≤80℃ before removing from the furnace; the rest is the same as in the example.

[0100] Comparative Example 3

[0101] In step 9), before the first forging, the box-type resistance furnace is preheated to 1050°C, the billet is placed in the box-type resistance furnace and kept at that temperature for 120 minutes, and then removed from the furnace; the rest is the same as in the example.

[0102] The results showed that the end of the billet cracked during the forging process, making it impossible to continue the forging process; however, the above phenomenon did not occur during the forging process of the embodiment.

[0103] Comparative Example 4

[0104] In step 17), before the first rolling, the box-type resistance furnace is preheated to 480°C, the billet is loaded into the furnace, kept at the temperature for 60 minutes, and then removed from the furnace; the rest is the same as in the example.

[0105] The results showed that the billet cracked severely during the rolling process, while no cracking occurred in the billet during the rolling process of the example.

[0106] Test methods and results

[0107] 1. Test of tungsten segregation of the plate: Samples are taken from different locations on the plate, and the tungsten content is tested according to the national standard GB / T15076. The tungsten segregation of the plate is calculated according to the following formula.

[0108] Tungsten segregation of the plate = 100% × (maximum value - minimum value) / minimum value

[0109] 2. Grain size test: Samples were taken from different locations on the board and the grain size was tested using an Olympus GX51f metallographic instrument. The grain size was classified according to the national standard GB / T6394-2017.

[0110] 3. Testing of tensile strength, yield strength, elongation, and yield strength difference: A sheet metal specimen measuring 103.32 mm in length and 12 mm in width was used. Following national standard GB / T228.1-2021, a universal testing machine (INSTRON 4505, Inström) was employed to test the tensile strength, yield strength, and elongation of the specimen. The initial load was less than 100 N. An extensometer was applied, and when the material strain reached 1%, the extensometer was removed. Before removal, a load was applied at a displacement of 2 mm / min; after removal, the load was continued at 4 mm / min until the specimen fractured. The yield strength difference was obtained by subtracting the yield strength from the tensile strength. Before testing, a 30 mm gauge length was taken at the midpoint of the specimen's length. After testing, the elongation was calculated using the following formula.

[0111] Elongation = 100% × (Gazelle length after test - Gazelle length before test) / Gazelle length before test

[0112] The plate 1 obtained in step 24) of the above embodiment, the plate 2 obtained in step 34) and the final plate product of comparative example 2 were tested using the above method. The results are shown in Table 1. The tensile strength, yield strength and elongation of the plates 1-2 in the embodiment were tested twice.

[0113] Table 1. Test results of the examples and comparative examples.

[0114]

[0115]

[0116] "-" indicates that it was not measured.

[0117] The results in the table show that, compared with Comparative Example 2, the tensile strength and yield strength of plates 1-2 in this embodiment of the invention are significantly higher, and the yield strength difference is significantly lower. Plate 2 in this embodiment of the invention has higher tensile strength and yield strength, and a lower yield strength difference than plate 1.

[0118] Therefore, the alloy plates prepared by the method of the present invention have high tensile strength and yield strength, low yield strength difference, high elongation, low tungsten segregation, small grain size, small performance deviation in different directions, good microstructure uniformity, and are not prone to cracking.

[0119] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing alloy plates, comprising the following steps: (1) Cut the alloy ingot to obtain a rough billet with a thickness of 195-215 mm and a width of 473-536 mm; perform anti-oxidation treatment on the surface of the rough billet, and then heat it to 750 ℃-850 ℃, 950 ℃-1050 ℃, and 1150 ℃-1200 ℃ respectively and hold for 1-5 minutes, and then heat it to 1250 ℃-1300 ℃ and hold for a total holding time of 25-40 minutes. After that, perform high temperature resistance treatment on the surface of the rough billet to obtain a pretreated billet; extrude the pretreated billet, straighten it, and grind it to obtain a billet material. (2) The billet is forged twice and rolled three to four times in sequence. After the last rolling, the billet is pickled, heat-treated, leveled, polished, and inspected in sequence to obtain alloy sheet. Furthermore, before each forging, the first rolling, the second rolling, and optionally the fourth rolling, the billet is heat-treated. Each heat treatment is performed independently at a vacuum degree ≤ 4.0 × 10⁻⁶. -3 In the environment of Pa, the following procedure shall be followed: Increase the temperature to 400℃-600℃ within 20-40 minutes and hold for 20-40 minutes; then increase the temperature to 700℃-900℃ within 20-40 minutes and hold for 20-40 minutes; then increase the temperature to 1350℃-1550℃ within 55-75 minutes and hold for 100-140 minutes, then allow to cool naturally to ≤80℃. Before each forging, the surface of the heat-treated billet is subjected to an anti-oxidation treatment, and then placed in a furnace at 1080 ℃ - 1250 ℃ for 100-140 minutes before being removed from the furnace; Before the first rolling, the heat-treated billet is placed in a furnace at 380 ℃ - 580 ℃ and held for 100-140 minutes before being removed from the furnace; in, The alloy ingot is obtained by melting and casting alloy raw materials; The alloy raw material includes the following elements: Zirconium 1.5 – 3.5% by weight; Tungsten 8-15% by weight; Carbon 0.01 - 0.50% by weight; Oxygen 0.005 - 0.05% by weight; Nitrogen 0.005 - 0.05% by weight; Hydrogen 0.0005 - 0.005% by weight; The rest is niobium.

2. The method according to claim 1, wherein, The two forging processes described herein satisfy one or more of the following conditions: (A) The first forging is carried out by a precision forging machine, the hammer of which strikes 400-600 times per minute, and the outer diameter is reduced by 4-10 mm per pass. The forging is then reheated in the furnace for 25-35 minutes. (B) The thickness of the billet after the first forging is 60-86 mm; (C) The second forging is carried out by a fast forging hydraulic press, wherein the reduction of each pass of the fast forging hydraulic press is 8-12 mm and the edges are tucked up. The forging is then returned to the furnace for reheating for 25-35 minutes. (D) The thickness of the billet after the second forging is 20-43 mm and the width is 75-102 mm; (E) The temperature of the billet after each forging is ≥850℃.

3. The method according to claim 1, wherein, The three to four rolling processes satisfy one or more of the following: (a) In the first rolling and / or the second rolling, the rolling pressure for the first 2 to 4 passes is controlled at 350-800 tons, and then the pressure is controlled at 801-1350 tons. When the difference from the required thickness is 0.3-0.4 mm, the pressure is controlled at 350-800 tons. (b) The first rolling is performed using a reversible two-roll mill; (c) The thickness of the billet after the first rolling is 8-17 mm and the width is 180-230 mm; (d) The second rolling is carried out using a reversible large two-roll mill; (e) The thickness of the billet after the second rolling is 4-7 mm and the width is 315-343 mm; (f) In the third and / or fourth rolling, the rolling pressure for the first 2 to 4 passes is controlled at 10-60 tons, and then the pressure is controlled at 61-140 tons. When the difference from the required thickness is 0.1-0.6 mm, the pressure is controlled at 20-70 tons. (g) The third and / or fourth rolling processes are performed using a reversible four-high mill; (h) The thickness of the billet after the third rolling is 1.8 - 3.5 mm and the width is 345 - 360 mm; (i) The thickness of the billet after the fourth rolling is 0.5 - 1.0 mm and the width is 345 - 370 mm.

4. The method according to any one of claims 1 to 3, characterized in that... One or more of the following: 1) In step (1), the thickness of the alloy ingot is 195-215 mm and the width is 1460-1570 mm; 2) In step (1) and / or step (2), the antioxidant treatment is to apply an antioxidant coating; 3) In step (1), the high-temperature resistant treatment is to coat with high-temperature glass powder; 4) In step (1), the extrusion pressure is 40-45 MN, and before extrusion, a glass pad is filled between the surface of the pretreated billet and the extrusion equipment; 5) In step (1), the straightening is to keep the extruded pretreated billet at 900 ℃ - 1000 ℃ for 100-140 min and then straighten it through a high-speed forging machine; 6) In step (2), before each heat treatment, the billet is pickled until a metallic luster is observed and there are no blemishes; 7) In step (2), before the first rolling, the surface and internal defects of the heat-treated billet are removed; 8) In step (2), before the second rolling and / or the third rolling, the surface defects of the heat-treated billet are removed.

5. In the method according to claim 4, in item (6), the acid solution used in step (2) comprises HCl, HF and water in a volume ratio of 5:2:

3.

6. An alloy sheet, prepared by the method according to any one of claims 1 to 5.

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