Nb55Ti plate for radio frequency superconducting cavity and preparation method of Nb55Ti plate

Abstract

The invention discloses an Nb55Ti plate for a radio frequency superconducting cavity and a preparation method of the Nb55Ti plate, and belongs to the field of superconducting acceleration cavities, and the preparation method comprises the steps of forging, plate blank surface treatment, rolling, plate surface treatment, plate heat treatment and finished product processing. According to the method, the original structure of the Nb55Ti blank is effectively crushed and refined through reasonable design of machining procedures and limitation of technological parameters in combination with vacuum heat treatment and surface treatment, the grain size uniformity and the uniformity of transverse and longitudinal structures and performance of the Nb55Ti plate product are remarkably improved, the hardness of the Nb55Ti plate is improved, and the Nb55Ti plate is suitable for a radio frequency superconducting cavity and has a good application prospect. And meanwhile, the machining yield of the Nb55Ti plate is increased, the raw material cost is reduced, and batch stable production can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of superconducting accelerating cavities, and in particular to a Nb55Ti plate for a radio frequency superconducting cavity and a preparation method thereof. Background Art

[0002] Superconducting radio frequency accelerator is a type of radio frequency field accelerator, that is, a device that uses the radio frequency electromagnetic field in the accelerating cavity to accelerate charged particles. The 1.3GHz9cell radio frequency accelerating cavity is mainly composed of a high-purity niobium cavity and a titanium jacket. The Nb55Ti plate is a transition connector between the two parts, which is assembled and welded with the niobium cavity and the titanium jacket respectively, and plays the role of positioning the cavity in the accelerator.

[0003] Nb55Ti alloy has the characteristics of high strength, low elastic modulus, good thermal conductivity, excellent plasticity, good cold formability, good corrosion resistance, etc. It has excellent comprehensive performance in the fields of aviation, aerospace, chemical industry and superconductivity. As a superconducting material, the alloy is used in nuclear magnetic resonance imaging (MRI), high-energy physics accelerators in the field of strong electromagnetic fields, plasma magnetic confinement devices, and superconducting energy storage devices. Since Nb55Ti alloy has good welding performance with titanium and niobium, it has also been used in connectors of titanium and niobium alloy materials in recent years.

[0004] In recent years, with the rapid development of radio frequency superconducting technology, the design of superconducting accelerating cavity structure has become increasingly complex, which has put forward new requirements for the strength of the cavity structure. It has high requirements on the mechanical properties and microstructure of Nb55Ti alloy disk. However, existing domestic research has not paid attention to the mechanical properties and microstructure of Nb55Ti. For the current new superconducting cavity structure, the key to the processing of Nb55Ti plate is to control the uniformity of material properties and microstructure. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a Nb55Ti plate for a radio frequency superconducting cavity and a preparation method thereof.

[0006] In order to realize the above technical solution, the present invention provides a method for preparing a Nb55Ti plate for a radio frequency superconducting cavity, comprising the steps of:

[0007] S1: Forging, heating a niobium-titanium alloy ingot with a size of Φ×L, a Nb mass fraction of 44-46%, and a Ti mass fraction of 54-56% to 850°C-900°C, and keeping the temperature for (0.5-0.6×Φ)min; then performing open forging to obtain a slab blank with a size of H1×B1×L1;

[0008] S2: slab surface treatment, using a CNC milling machine to machine the slab blank obtained in step S1 to remove surface defects;

[0009] S3: rolling, rolling the slab blank machined in step S2 to obtain a plate blank with a size of H2×B2×L2; during the rolling process, the rolling heating temperature is 800° C. to 850° C., and the heating and holding time is (0.8 to 1×H1) min;

[0010] S4: plate surface treatment, using a sanding machine to sand the plate blank obtained in step S3, and then placing it in an acid solution for pickling for 3min to 5min, and then rinsing it with clean water and drying it naturally, to ensure that the surface roughness of the plate blank after the treatment is Ra≤1.6μm;

[0011] S5: heat treatment of the plate, wiping the surface of the blank after the surface treatment in step S4 with an ethanol solution, and then placing it in a vacuum heat treatment furnace for vacuum heat treatment;

[0012] S6: Finished product processing, using a CNC machining center to machine the blank after heat treatment in step S5 to obtain a Nb55Ti plate product with a Nb mass fraction of 44-46%, a Ti mass fraction of 54-56%, Hv≥150, and a recrystallization rate of 100%.

[0013] Furthermore, in step S1, the forging method is axial upsetting, two upsettings, two drawing, and forming, and the upsetting deformation amount is (0.6-0.7×L)min; the thickness H1 of the slab blank is (0.25-0.35×Φ)min.

[0014] Further, in step S3, the rolling method is: first rolling along the slab width B1 direction to a thickness H2, and then switching 90 degrees to rolling along the slab length direction to a thickness H3.

[0015] Furthermore, H2 is (0.3~0.4×H1)min, and H3 is the upper limit of the product thickness tolerance (+0.2~0.25)mm.

[0016] Furthermore, in step S4, the acid solution is formed by uniformly mixing a hydrofluoric acid solution with a mass concentration of 30%, a nitric acid solution with a mass concentration of 70%, and water in a volume ratio of 3:1:1.

[0017] Further, in step S5, the vacuum heat treatment method comprises the steps of: when the vacuum degree in the furnace is 3×10 -3 Pa~2.5×10 -3 The temperature is raised when Pa is reached; the temperature raising process includes: raising the temperature to 500°C±10°C within 60 minutes and keeping the temperature for 30 minutes; after the temperature is kept, raising the temperature to 770°C~800°C±5°C within 30 minutes and keeping the temperature for 90 minutes; after the temperature is kept, cooling with the furnace until the furnace temperature is less than 100°C and then taking out of the furnace.

[0018] Furthermore, in step S6, before machining, the heat-treated blank is coated for protection.

[0019] Furthermore, a Nb55Ti plate for a radio frequency superconducting cavity is prepared by the method for preparing the Nb55Ti plate for a radio frequency superconducting cavity as claimed in any one of claims 1 to 7.

[0020] In summary, the present invention has the following beneficial effects compared with the prior art:

[0021] 1. The present invention sequentially forges and rolls the Nb55Ti alloy billet, effectively crushes and refines the original structure of the Nb55Ti alloy billet, and significantly improves the uniformity of the transverse and longitudinal structure and performance of the Nb55Ti alloy plate product by controlling the total deformation degree and processing direction in each processing process. Combined with the vacuum heat treatment of the finished product, the recrystallization degree, grain size and transverse and longitudinal grain difference of the Nb55Ti alloy plate are effectively controlled, the uniformity of the grain size in the Nb55Ti alloy plate is improved, and the content of C, H, O, and N gas elements in the plate is effectively controlled, so that it is suitable for use in radio frequency superconducting cavities.

[0022] 2. The present invention effectively removes surface pollutants introduced into the Nb55Ti alloy plate during the processing by performing surface treatment on the blank after each forging and rolling process, so that the surface of the Nb55Ti alloy plate is uniform and the surface roughness satisfies the roughness average value Ra≤1.6μm.

[0023] 3. The mechanical property difference and hardness difference between the vertical rolling direction and the rolling direction of the Nb55Ti alloy plate prepared by the present invention are both less than 5%, the recrystallization rate of the plate is 100%, and the grain size difference between the vertical rolling direction and the rolling direction is ≤ASTM grade 0.5 (ASTM E112-13), ensuring that the gas element content, mechanical properties, hardness, grain size and recrystallization rate of the plate meet the use requirements of the 1.3GHz9cell radio frequency superconducting cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 This is a transverse (vertical to the rolling direction) microstructure metallographic diagram of the δ3mm Nb55Ti alloy plate prepared in Example 1 of the present invention;

[0026] Figure 2 This is a longitudinal (rolling direction) microstructure metallographic diagram of a δ3 mm Nb55Ti alloy plate prepared in Example 1 of the present invention;

[0027] Figure 3 This is a transverse (vertical to the rolling direction) microstructure metallographic diagram of the δ6mm Nb55Ti alloy plate prepared in Example 2 of the present invention;

[0028] Figure 4 This is a longitudinal (rolling direction) microstructure metallographic diagram of the δ6mm Nb55Ti alloy plate prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form can also include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0032] The present invention provides a method for preparing a Nb55Ti plate for a radio frequency superconducting cavity, comprising the steps of:

[0033] S1: Forging, heating the niobium-titanium alloy ingot with a size of Φ×L, a Nb mass fraction of 44-46%, and a Ti mass fraction of 54-56% to 850°C-900°C, and keeping it warm for (0.5-0.6×Φ)min; then forging to obtain a slab blank with a size of H1×B1×L1. Among them, Φ is the diameter (mm); L is the plate length (mm); B1 is the slab width (mm); H1 is the thickness of the slab blank (mm); L1 is the slab thickness (mm).

[0034] S2: slab surface treatment, using a CNC milling machine to machine the slab blank obtained in step S1 to remove surface defects; after machining, it is necessary to ensure that the surface of the slab blank is smooth and uniform, without traces of grinding, and without defects such as pits, cracks, fissures, inclusions, etc. visible to the naked eye.

[0035] S3: rolling, rolling the slab billet after machining in step S2 to obtain a plate billet with a size of H2×B2×L2. During the rolling process, the rolling heating temperature must be 800℃~850℃, and the heating and insulation time must be (0.8~1×H1)min. Among them, H2 is the thickness of the plate after rolling (mm); B2 is the width of the plate after rolling (mm); L2 is the length of the plate after rolling (mm).

[0036] S4: Plate surface treatment, using a sanding machine to sand the plate blank obtained in step S3 to within the product thickness tolerance range, then placing it in an acid solution for pickling for 3min to 5min, then rinsing it with clean water and drying it naturally; after this step, it is necessary to ensure that the surface of the plate blank after sanding is smooth and uniform, without traces of grinding, and without defects such as pits, cracks, fissures, inclusions, etc. visible to the naked eye, that is, it is necessary to ensure that the surface roughness of the plate blank Ra≤1.6μm.

[0037] S5: heat treatment of the plate, wiping the surface of the blank after the surface treatment in step S4 with an ethanol solution, and then placing it in a vacuum heat treatment furnace for vacuum heat treatment.

[0038] S6: Finished product processing, using a CNC machining center to machine the blank after heat treatment in step S5 to within the product length and width tolerance range, to obtain a Nb55Ti plate product with a Nb mass fraction of 44-46%, a Ti mass fraction of 54-56%, Hv≥150, and a recrystallization rate of 100%.

[0039] The method effectively crushes and refines the original structure of the Nb55Ti billet through reasonable design of the processing procedures and limitation of the process parameters, combined with vacuum heat treatment and surface treatment, and significantly improves the uniformity of the grain size and the uniformity of the transverse and longitudinal structure and performance of the Nb55Ti plate product, improves the hardness of the Nb55Ti plate, making it suitable for radio frequency superconducting cavities, and also improves the processing yield of the Nb55Ti plate, reduces the cost of raw materials, and can be stably produced in batches.

[0040] As a preferred method, in step S1, in order to make the forging process faster, the forging method is axial upsetting, two upsettings, two drawing + forming blanking, and the upsetting deformation is (0.6-0.7×L) mm. After forming blanking, the thickness H1 of the slab blank is (0.25-0.35×Φ) mm to facilitate subsequent processing. In this preferred method, only the thickness H1 needs to be considered during forging, and B1 and L1 are processed through subsequent steps. This method can significantly improve the preparation speed of Nb55Ti plates.

[0041] As a preferred method, in step S3, the rolling method is: first rolling to a thickness of H2 along the slab width B1 direction, and then changing 90° to rolling to a thickness of H3 along the slab length direction. Wherein H2 is (0.3-0.4×H1) mm, and H3 is the upper limit of the product thickness tolerance (+0.2-0.25) mm. The method of gradually meeting the size requirements of the slab billet by rolling to a thickness of H2 along the slab width B1 direction, and then changing 90° to rolling to a thickness of H3 along the slab length direction can make the internal structure of the plate uniform and the mechanical properties isotropic, so that the difference in mechanical properties and hardness in the transverse and longitudinal directions does not exceed 5%, and the difference in grain size in the transverse and longitudinal directions is ≤ASTM 0.5 grade.

[0042] As a preferred embodiment, in step S4, the acid solution used is a mixture of a hydrofluoric acid solution with a mass concentration of 30%, a nitric acid solution with a mass concentration of 70% and water in a volume ratio of 3:1:1. It has been found in actual use that the acid solution mixed with this ratio can ensure that after pickling of the sheet blank, the surface of the blank is smooth, has a metallic color and is uniform and free of traces of acid solution.

[0043] As a preferred embodiment, in step S5, the vacuum heat treatment system is: when the vacuum degree in the furnace is 2.5×10 -3 Pa~3×10 -3 Pa, first heat it to 500℃±10℃ within 60min and keep it warm for 30min, then heat it to 770℃~800℃±5℃ within 30min and keep it warm for 90min, then cool it down to the furnace temperature less than 100℃ and take it out of the furnace.

[0044] As a preferred embodiment, the heat-treated blank is coated for protection before machining in step 6. The coated sheet blank has a thin and transparent plastic film on its surface, which can protect the blank from surface scratches and other defects during machining, and can also play a protective role in waterproofing, anti-fouling, wear resistance, and chemical corrosion resistance.

[0045] In addition, the present invention also provides a Nb55Ti plate for a radio frequency superconducting cavity, characterized in that it is prepared by the above method.

[0046] The example of using the above method to prepare Nb55Ti plate is as follows:

[0047] Example 1

[0048] This embodiment includes the following steps:

[0049] Step 1, forging: The Nb55Ti billet with a size (diameter × length) of Φ180 × 300 mm is heated at 850 ° C / 90 min, followed by two upsetting and two drawing of Φ180 × 300 → Φ284 × 120 → Φ142 × 300 → Φ284 × 120 → Φ142 × 300, and finally the billet is formed in the axial direction, i.e., 300 mm, to obtain a Nb55Ti slab billet with a size (thickness × width × length) of δ45 × 300 × 565 mm.

[0050] Step 2: Surface treatment of the slab: The Nb55Ti alloy slab blank of step 1 with dimensions (thickness × width × length) of δ45 × 300 × 565 mm is machined and planed along the 565 mm direction to obtain a slab with dimensions (thickness × width × length) of Nb55Ti alloy slab billet.

[0051] Step 3: Rolling: Change the dimensions (thickness × width × length) in step 2 to The Nb55Ti billet was heated at 800°C / 35min, then rolled to a thickness of δ12mm along the 295mm direction, and then the billet was rotated 90° and rolled to a thickness of The size (thickness × width × length) is of sheet metal blanks.

[0052] Step 4: Plate surface treatment: Use a sanding machine to sand the plate blank obtained in step 3 until the product thickness is within the tolerance range, and use a 400# sanding belt to sand both sides of the plate blank until the thickness is within the tolerance range. Then, the surface treated product was placed in an acid solution for pickling for 3 minutes, then rinsed with clean water and dried naturally. The size of the finished product (thickness × width × length) was

[0053] Step 5: Plate heat treatment: wipe the surface of the plate blank after surface treatment in step 4 with ethanol solution, and then place it in a vacuum heat treatment furnace for vacuum heat treatment; the vacuum heat treatment system is: when the vacuum degree in the furnace does not exceed 3×10 -3 The temperature starts to rise after Pa, first rising to 500℃±10℃ within 60min and keeping it warm for 30min, then rising to 770℃±5℃ within 30min and keeping it warm for 90min, and then taking out of the furnace after cooling down to the furnace temperature less than 100℃.

[0054] Step 6: Finished product processing: Use a CNC machining center to machine the heat-treated sheet blanks in step 5 to within the product length and width tolerance range. Before machining, clean the equipment of the CNC machining center and coat the heat-treated sheet blanks with a protective film to obtain 8 pieces with the dimensions (diameter × thickness) of The Nb55Ti plate product has a Nb mass fraction of 44-46%, a Ti mass fraction of 54-56%, Hv≥150, and a recrystallization rate of 100%.

[0055] The acid solution used in step 4 of this embodiment is formed by uniformly mixing a hydrofluoric acid solution with a mass concentration of 30%, a nitric acid solution with a mass concentration of 70% and water in a volume ratio of 3:1:1, and the surface of the blank after pickling in step 4 is smooth, metallic in color and uniform, without any traces of acid solution; the surface of the slab blank after grinding in step 2 and the plate blank after sanding in step 4 is smooth and uniform, without any traces of grinding, and without defects such as pits, cracks, fissures, inclusions, etc. visible to the naked eye.

[0056] Figure 1 This is the transverse (vertical to the rolling direction) microstructure metallographic diagram of the δ3 mm high purity niobium plate prepared in Example 1 of the present invention. Figure 1 It can be seen that all grains in the structure are 100% recrystallized, and the grains are equiaxed and uniform in size, and the main grain size is ASTM grade 8 (0.022 mm).

[0057] Figure 2 This is the longitudinal (rolling direction) microstructure metallographic diagram of the δ3 mm high purity niobium plate prepared in Example 1 of the present invention. Figure 2 It can be seen that all grains in the structure are 100% recrystallized, and the grains are equiaxed and uniform in size, and the main grain size is ASTM grade 8 (0.022 mm).

[0058] The performance and composition of the Nb55Ti plate product prepared in this embodiment were tested, and the test results are shown in Table 1 below.

[0059] Table 1 Composition of Nb55Ti plate obtained in Example 1

[0060]

[0061]

[0062] The surface of the Nb55Ti plate product prepared in this embodiment is uniform, and its gas element content, mechanical properties, hardness, grain size and recrystallization rate all meet the use requirements of the radio frequency superconducting cavity.

[0063] Example 2

[0064] This embodiment includes the following steps:

[0065] Step 1, forging: The Nb55Ti billet with a size (diameter × length) of Φ220 × 400mm is heated at 900℃ / 130min, followed by two upsetting and two drawing of Φ220×400→Φ400×120→Φ195×400→Φ400×120→Φ195×400, and finally the billet is formed in the axial direction, i.e., 400mm direction, to obtain a Nb55Ti slab billet with a size (thickness × width × length) of δ77×400×493mm.

[0066] Step 2: Surface treatment of the slab: The Nb55Ti alloy slab with the size (thickness × width × length) of δ77 × 400 × 493 mm in step 1 is machined and planed along the 493 mm direction to obtain a slab with the size (thickness × width × length) of Nb55Ti alloy slab billet.

[0067] Step 3: Rolling: Change the dimensions (thickness × width × length) in step 2 to The Nb55Ti billet was heated at 850°C for 70 min and then rolled to a thickness of δ31 mm along the 395 mm direction. The billet was then rotated 90° and rolled to a thickness of δ31 mm along the 485 mm direction. The size (thickness × width × length) is of sheet metal blanks.

[0068] Step 4: Plate surface treatment: Use a sanding machine to sand the plate blank obtained in step 3 until the product thickness is within the tolerance range, and use a 400# sanding belt to sand both sides of the plate blank until the thickness is within the tolerance range. Then, the surface treated product was placed in an acid solution for pickling for 5 minutes, then rinsed with clean water and dried naturally. The size of the finished product (thickness × width × length) after surface treatment was

[0069] Step 5: Plate heat treatment: wipe the surface of the plate blank after surface treatment in step 4 with ethanol solution, and then place it in a vacuum heat treatment furnace for vacuum heat treatment; the vacuum heat treatment system is: when the vacuum degree in the furnace does not exceed 3×10 -3 The temperature starts to rise after Pa, first to 500℃±10℃ within 60min and keep warm for 30min, then to 800℃±5℃ within 30min and keep warm for 90min, and then it is taken out of the furnace after cooling down to the furnace temperature less than 100℃.

[0070] Step 6: Finished product machining: Use a CNC machining center to machine the heat-treated sheet blanks in step 5 to within the product length and width tolerance range. Before machining, clean the equipment of the CNC machining center and coat the heat-treated sheet blanks with a protective film to obtain 10 pieces with the dimensions (diameter × thickness) of The Nb55Ti plate product has a Nb mass fraction of 44-46%, a Ti mass fraction of 54-56%, Hv≥150, and a recrystallization rate of 100%.

[0071] The acid solution used in step 4 of this embodiment is formed by uniformly mixing a hydrofluoric acid solution with a mass concentration of 30%, a nitric acid solution with a mass concentration of 70% and water in a volume ratio of 3:1:1, and the surface of the blank after pickling in step 4 is smooth, metallic in color and uniform, without any traces of acid solution; the surface of the slab blank after grinding in step 2 and the plate blank after sanding in step 4 is smooth and uniform, without any traces of grinding, and without defects such as pits, cracks, fissures, inclusions, etc. visible to the naked eye.

[0072] Figure 3 This is the transverse (vertical to the rolling direction) microstructure metallographic diagram of the δ6 mm high purity niobium plate prepared in Example 2 of the present invention. Figure 3 It can be seen that all grains in the structure are 100% recrystallized, and the grains are equiaxed and uniform in size, and the main grain size is ASTM grade 7 (0.032 mm).

[0073] Figure 4 This is the longitudinal (rolling direction) microstructure metallographic diagram of the δ6 mm high purity niobium plate prepared in Example 2 of the present invention. Figure 4 It can be seen that all grains in the structure are 100% recrystallized, and the grains are equiaxed and uniform in size, and the main grain size is ASTM grade 7 (0.032 mm).

[0074] The performance and composition of the high-purity niobium plate product prepared in this example were tested, and the test results are shown in Table 2 below.

[0075] Table 2 Composition of Nb55Ti plate obtained in Example 2

[0076]

[0077] The surface of the Nb55Ti plate product prepared in this embodiment is uniform, and its gas element content, mechanical properties, hardness, grain size and recrystallization rate all meet the use requirements of the radio frequency superconducting cavity.

[0078] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing Nb55Ti plates for radio frequency superconducting cavities, characterized in that: Includes steps: S1: Forging, heating a niobium-titanium alloy ingot with a size of Φ×L, a Nb mass fraction of 44-46%, and a Ti mass fraction of 54-56% to 850°C-900°C, and keeping the temperature for (0.5-0.6×Φ)min; then performing open forging to obtain a slab blank with a size of H1×B1×L1; S2: slab surface treatment, using a CNC milling machine to machine the slab blank obtained in step S1 to remove surface defects; S3: rolling, rolling the slab blank machined in step S2 to obtain a plate blank with a size of H2×B2×L2; during the rolling process, the rolling heating temperature is 800° C. to 850° C., and the heating and holding time is (0.8 to 1×H1) min; S4: plate surface treatment, using a sanding machine to sand the plate blank obtained in step S3, and then placing it in an acid solution for pickling for 3min to 5min, and then rinsing it with clean water and drying it naturally, to ensure that the surface roughness of the plate blank after the treatment is Ra≤1.6μm; S5: heat treatment of the plate, wiping the surface of the blank after the surface treatment in step S4 with an ethanol solution, and then placing it in a vacuum heat treatment furnace for vacuum heat treatment; S6: Finished product processing, using a CNC machining center to machine the blank after heat treatment in step S5 to obtain a Nb55Ti plate product with a Nb mass fraction of 44-46%, a Ti mass fraction of 54-56%, Hv≥150, and a recrystallization rate of 100%.

2. The method for preparing Nb55Ti sheet for radio frequency superconducting cavity according to claim 1, characterized in that: In step S1, the forging method is axial upsetting, two upsettings, two drawing, and forming, and the upsetting deformation amount is (0.6-0.7×L) mm; the thickness H1 of the slab blank is (0.25-0.35×Φ) mm.

3. The method for preparing Nb55Ti sheet for radio frequency superconducting cavity according to claim 1, characterized in that: In step S3, the rolling method is: first rolling along the slab width B1 direction to a thickness H2, and then switching 90 degrees to rolling along the slab length direction to a thickness H3.

4. The method for preparing Nb55Ti sheet for radio frequency superconducting cavity according to claim 3, characterized in that: H2 is (0.3~0.4×H1)mm, and H3 is the upper limit of product thickness tolerance (+0.2~0.25)mm.

5. The method for preparing Nb55Ti sheet for radio frequency superconducting cavity according to claim 1, characterized in that: In step S4, the acid solution is formed by uniformly mixing a hydrofluoric acid solution with a mass concentration of 30%, a nitric acid solution with a mass concentration of 70%, and water in a volume ratio of 3:1:

1.

6. The method for preparing Nb55Ti plate for radio frequency superconducting cavity according to claim 1, characterized in that: In step S5, the vacuum heat treatment method comprises the steps of: when the vacuum degree in the furnace is 3×10 -3 Pa~2.5×10 -3 The temperature is raised when Pa is reached; the temperature raising process includes: raising the temperature to 500°C±10°C within 60 minutes and keeping the temperature for 30 minutes; after the temperature is kept, raising the temperature to 770°C~800°C±5°C within 30 minutes and keeping the temperature for 90 minutes; after the temperature is kept, cooling with the furnace until the furnace temperature is less than 100°C and then taking out of the furnace.

7. The method for preparing Nb55Ti plate for radio frequency superconducting cavity according to claim 1, characterized in that: In step S6, before machining, the heat-treated blank is coated for protection.

8. A Nb55Ti plate for a radio frequency superconducting cavity, characterized in that: It is made by the preparation method of Nb55Ti plate for radio frequency superconducting cavity as claimed in any one of claims 1 to 7.

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