Hastelloy precision foil for superconducting tape and production method thereof

Abstract

The present invention provides a production method of Hastelloy precision foil, including an intermediate rolling process, a finished product rolling process, a cleaning step, a straightening step, a polishing step, and a longitudinal slitting step, wherein the intermediate rolling process includes at least two rolling processes, the rolling deformation of each rolling process is 35% to 55%, and the rolling deformation of the latter rolling process is not greater than the rolling deformation of the previous rolling process. The present invention also provides a Hastelloy precision foil. The present invention realizes the continuous and stable mass production of Hastelloy C276 precision foil, and the produced Hastelloy precision foil has excellent dimensional accuracy, surface roughness, and mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of precision foil production and manufacturing, and in particular to a Hastelloy precision foil for superconducting tape and a production method thereof. Background Art

[0002] Hastelloy C276 is a nickel-based corrosion-resistant alloy whose main components are nickel-chromium-molybdenum alloy. As Hastelloy has good corrosion resistance and thermal stability, it can be used as a metal base tape to prepare the second-generation high-temperature superconducting tape.

[0003] After long-term research and development, my country's second-generation high-temperature superconductors have achieved large-scale and industrialized production, with independent intellectual property rights and international competitive advantages in components and equipment. However, Hastelloy C276, as the metal base of the second-generation high-temperature superconducting strips, has been greatly restricted in the localization process of the second-generation high-temperature superconducting strips due to the current limitations of rolling level and its large surface roughness.

[0004] Therefore, there is an urgent need to provide a method for producing a Hastelloy precision foil for superconducting tape. Summary of the invention

[0005] The object of the present invention is to provide a Hastelloy precision foil for superconducting tape and a production method thereof in view of the defects of the prior art.

[0006] Specifically, the present invention is achieved through the following technical solutions:

[0007] A production method for Hastelloy alloy precision foil includes an intermediate rolling process, a finished product rolling process, a cleaning step, a straightening step, a polishing step and a longitudinal slitting step, wherein the intermediate rolling process includes at least two rolling processes, the rolling deformation amount of each rolling process is 35% to 55%, and the rolling deformation amount of the latter rolling process is not greater than the rolling deformation amount of the previous rolling process.

[0008] Optionally, in the intermediate rolling step, annealing treatment is performed after each rolling process; the annealing treatment is performed under full hydrogen protective gas conditions, the annealing temperature is 1100-1150° C., and the annealing speed is 20-35 m / min.

[0009] Optionally, in the intermediate rolling step, each rolling process includes at least two passes, the rolling deformation of each pass does not exceed 32.5%, and the rolling deformation of each pass decreases successively.

[0010] Optionally, the rolling deformation amount of the rolling step of the finished rolling process is 35%.

[0011] Optionally, in the cleaning step, an alkaline degreasing agent with a concentration of 3% to 5% is used for cleaning.

[0012] Optionally, in the stretching and leveling step, the elongation is 0.8% to 1.3%.

[0013] Optionally, Hastelloy C276 with a thickness of 0.3 to 0.6 mm and a width of 500 to 650 mm is used as the raw material.

[0014] A Hastelloy precision foil is prepared by adopting the above production method.

[0015] Optionally, the thickness of the Hastelloy precision foil does not exceed 0.05 mm, and the surface roughness Ra is less than 0.05 μm.

[0016] Optionally, the mechanical properties of the Hastelloy precision foil are RP 0.2 >780MPa, Rm is 1100~1300MPa.

[0017] It can be seen from the above technical solutions that the Hastelloy precision foil for superconducting tape and the production method thereof of the present invention have at least the following advantages:

[0018] The Hastelloy alloy precision foil for superconducting tape and the production method thereof of the present invention can realize the continuous and stable mass production of Hastelloy alloy C276 precision foil through systematic research of the whole process. The developed Hastelloy alloy C276 precision foil has excellent dimensional accuracy, surface roughness and mechanical properties. The produced Hastelloy alloy C276 precision foil can meet the requirements of the superconducting tape industry. DETAILED DESCRIPTION

[0019] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments. Except for the following contents, the process method of the present invention adopts conventional methods or devices in the art. Unless otherwise specified, the terms involved in the present invention have the meanings commonly understood by those skilled in the art.

[0020] In the present invention, "Hastelloy C276", "nickel-based C276 alloy" and "C276 alloy" all have the same meaning and can be used interchangeably.

[0021] Hastelloy C276 belongs to the nickel-molybdenum-chromium-iron-tungsten nickel-based alloy, which is the most corrosion-resistant one among modern metal materials. Precision foil of Hastelloy C276 is used as metal base strip in high-temperature superconducting strip. However, the mechanical properties of nickel-based C276 alloy are very outstanding. It has the characteristics of high strength and high toughness, so it is difficult to produce and process. Moreover, its strain hardening tendency is very strong. When the deformation rate reaches 15%, it is about twice that of 18-8 stainless steel (304 stainless steel). Therefore, compared with the production method of ordinary stainless steel foil, its rolling process deformation design is different from the rolling method of ordinary stainless steel foil. At the same time, nickel-based C276 alloy is a high-temperature alloy with a molybdenum content of 15.0% to 17.0% and a tungsten content of 3.0% to 4.5%. Its precipitated phase carbide has a high melting point and high stability, and needs to be dissolved above 950°C, which is higher than the dissolution temperature of chromium carbide of stainless steel, 850°C. Due to the inherent characteristics of Hastelloy C276 and the requirements for process parameters such as rolling deformation and solution temperature, the existing stainless steel precision foil production method is not applicable to Hastelloy C276.

[0022] In order to obtain Hastelloy C276 precision foil with excellent dimensional accuracy, surface roughness and mechanical properties to meet the use requirements of the second-generation high-temperature superconducting tape, the inventors of the present invention conducted in-depth research on the production method in combination with the properties of Hastelloy C276, and creatively proposed a production method for Hastelloy precision foil.

[0023] In the production method of the present invention, according to the composition, performance and specification requirements of the final product, a Hastelloy C276 coil with a thickness of 0.3 mm to 0.6 mm and a width of 500 mm to 650 mm is selected as the raw material.

[0024] The production method of the Hastelloy alloy precision foil of the present invention comprises: intermediate rolling, finished product rolling, cleaning, straightening, polishing and longitudinal slitting. The details are as follows:

[0025] (1) The raw steel coil is subjected to intermediate rolling.

[0026] The intermediate rolling process adopts multi-pass rolling with small deformation.

[0027] The intermediate rolling process includes multiple rolling processes, such as two rolling processes, three rolling processes, four rolling processes, etc. The rolling deformation of each rolling process is 35% to 55%, and the rolling deformation of the latter rolling process is not greater than the rolling deformation of the previous rolling process.

[0028] In each rolling process, multiple rolling passes are used, and the deformation amount of each rolling pass is large at first and then small.

[0029] After each rolling process, annealing treatment (solution treatment) is carried out first, and then the next rolling process is carried out. The annealing treatment is carried out in a vertical bright continuous annealing furnace. The muffle furnace cover of the vertical bright annealing furnace is a high-purity (99.999%) full hydrogen protective gas to prevent the surface oxidation of the steel strip. The annealing temperature is 1100-1150℃, with a setting fluctuation of ±5℃, and the annealing speed is 20-35m / min.

[0030] In a preferred embodiment, the intermediate rolling process includes, in sequence: a first rolling process, a first annealing treatment, a second rolling process, a second annealing treatment, a third rolling process and a third annealing treatment.

[0031] The rolling deformation of the first rolling process is 52% to 54%, which includes three passes, and the rolling deformation of each pass is 30% to 32%, 19% to 20%, and 15% to 16% respectively.

[0032] The rolling deformation of the second rolling process is 52% to 54%, which includes three passes, and the rolling deformation of each pass is 30% to 32%, 19% to 20%, and 15% to 16% respectively.

[0033] The rolling deformation of the third rolling process is 37% to 39%, which includes two passes, and the rolling deformation of each pass is 22% to 23.5% and 20% to 21% respectively.

[0034] The temperatures of the first annealing treatment, the second annealing treatment, and the third annealing treatment are preferably 1100 to 1140° C., and the temperatures of the first annealing treatment, the second annealing treatment, and the third annealing treatment are sequentially decreased.

[0035] Based on the strong strain hardening tendency of C276 alloy and the on-site rolling research conducted by the inventor, the deformation of each pass in a single rolling process is designed to be large first and small later, otherwise the deformation of the later pass will not be able to be pressed down normally. The method of reducing the deformation in multiple rolling processes is because the thickness of the strip gradually decreases with the rolling process, and thin materials with large deformation are prone to breaking strips. Therefore, in order to solve the problem of thin material breaking strips, the method of gradually reducing the deformation in multiple rolling processes is adopted. Hastelloy C276 belongs to the nickel-molybdenum-chromium-iron-tungsten nickel-based alloy, which is a high-temperature and corrosion-resistant alloy. Its high content of high-melting-point alloying elements such as molybdenum and tungsten makes its solid solution temperature different from that of austenitic stainless steel of the same specification. The inventor explored the heat treatment process and rolling test research, and found that the optimal annealing temperature of the intermediate rolling process is 1100-1150℃, and its annealing temperature decreases with the reduction of the thickness of the intermediate rolling process.

[0036] (2) Finished product rolling process

[0037] The steel strip obtained by the intermediate rolling process is rolled in the finished product rolling process, and the finished product rolling process adopts a fixed deformation amount. Preferably, the finished product rolling process adopts a 35% rolling deformation amount.

[0038] In a preferred embodiment, the final rolling process includes three passes, each of which uses a small deformation amount and decreases successively, for example, 10% to 15%.

[0039] The intermediate and finished rolling processes are rolled using a four-column twenty-high mill, which enables precise control of the thickness and shape of the finished product. For example, the raw steel coil is rolled into a finished product with a thickness of 0.05mm and a thickness tolerance of ±0.005mm using a four-column twenty-high mill. High-speed steel rolls are used as the working rolls for each rolling pass.

[0040] (3) Cleaning

[0041] The strip steel obtained from the finished rolling process is cleaned with a chemical spray liquid to degrease the surface of the strip steel. The chemical spray liquid uses an alkaline degreasing agent with a concentration of 3 to 5% (by weight). The alkaline degreasing agent can refer to the scheme in the prior art, and those skilled in the art can make a reasonable selection according to needs in the actual production process, and it is not limited here.

[0042] The water temperature of the pre-spraying, scrubbing machine and high-pressure spraying water tank used in the cleaning process is set at 60-80°C. After drying in the dryer, the surface is clean and free of rolling oil residue.

[0043] (4) Straightening

[0044] After degreasing and cleaning, the strip steel is straightened, for example, a 23-roller straightening machine is used for straightening. The straightening process adopts the elongation mode, and the tension control device and the plate shape control system of the straightening machine are used to perform an elongation of 0.8-1.3%. After straightening, the plate shape is straight and there is no obvious rolling wave.

[0045] Because the strip is a cold hard finished product, its mechanical properties RP 0.2 >780MPa, Rm is 1100~1300MPa, which is a high-strength material. Small elongation cannot effectively improve the quality of the plate. Therefore, the high tension and high elongation mode can effectively eliminate the defects such as edge waves and plate waves generated during strip rolling, and achieve a straight strip shape without obvious rolling waves.

[0046] (5) Polishing

[0047] The straightened strip is subjected to surface polishing treatment to make the surface roughness Ra of the strip less than 0.05 μm. For example, the surface polishing treatment can be carried out by using a cloth wheel polishing in a fully automatic precision mirror production line, with a polishing removal thickness of about 1 μm and a line speed of about 100 m / h.

[0048] Usually, in the process of preparing precision foil, the surface roughness of the product strip is controlled by using work rolls with specific diameter, material, roughness and surface hardness. In the present invention, the desired surface roughness is obtained by adding a polishing step, which not only reduces the requirements for the work rolls and makes the rolling process go smoothly, but also solves the problem of surface defects such as scratches caused by roller slippage during rolling, cleaning and straightening due to low strip surface roughness, and can effectively improve the surface quality of the strip.

[0049] (6) Slitting

[0050] The steel strip after tensioning and straightening is produced in strips in the longitudinal cutting unit. The finished product width is 10mm, the steel strip width tolerance is controlled between -0.1 and 0.1mm, and the burr height is controlled within 5%.

[0051] The Hastelloy C276 precision foil produced by the above production method has excellent dimensional accuracy, surface roughness and mechanical properties. Its thickness does not exceed 0.05mm, the thickness tolerance meets ±0.005mm, the surface roughness Ra<0.05μm, and the mechanical properties are RP 0.2 >780MPa, Rm is 1100~1300MPa.

[0052] Example

[0053] The sources of various substances used in the examples are described below. If not otherwise specified, the raw materials and instruments used are all commercially available and are conventionally used instruments and raw materials in the art, as long as they can meet the experimental requirements.

[0054] Example 1

[0055] The target finished product thickness of this embodiment is 0.05 mm, and the steel grade is Hastelloy C276.

[0056] In this embodiment, C276 cold-rolled stainless steel coil with a thickness of 0.6 mm and a width of 600 mm is selected as the raw material. After four-pass cold rolling, the thickness of the finished steel strip is 0.05 mm.

[0057] This embodiment includes:

[0058] (1) Intermediate rolling

[0059] The intermediate rolling process includes: a first rolling process, a first annealing treatment, a second rolling process, a second annealing treatment, a third rolling process and a third annealing treatment.

[0060] The first rolling process: the Hastelloy C276 raw material with a thickness of 0.6mm is rolled on a four-column twenty-high rolling mill, and is rolled to 0.28mm in three passes. The rolling thickness is 0.6mm→0.41mm→0.33mm→0.28mm in sequence, and the working rolls of each rolling pass are high-speed steel rolls.

[0061] The first annealing treatment: a vertical continuous bright annealing furnace is used for solution treatment at a speed of 23m / min and a temperature of 1140°C±5°C, and a high-purity (99.999%) full hydrogen protective gas is used, and the fan cooling speed is 2200-2400r / min.

[0062] Second rolling process: A four-column twenty-high rolling mill is used for the second rolling process. The thickness of the steel strip is rolled from 0.28mm to 0.13mm through three rolling passes. The rolling thickness is 0.28mm→0.19mm→0.153mm→0.13mm in sequence. High-speed steel rolls are used for the working rolls in each rolling pass.

[0063] Second annealing treatment: a vertical continuous bright annealing furnace is used for solution treatment at a speed of 33 m / min and a temperature of 1130°C ± 5°C, and a high-purity (99.999%) full hydrogen protective gas is used, and the fan cooling speed is 2000 r / min.

[0064] The third rolling process: A four-column twenty-high rolling mill is used for the third rolling process. The thickness of the steel strip is rolled from 0.13mm to 0.08mm through two rolling passes. The rolling thickness is 0.13mm→0.10mm→0.08mm in sequence. High-speed steel rolls are used for the working rolls of each rolling pass.

[0065] The third annealing treatment: a vertical continuous bright annealing furnace is used for solution treatment at a speed of 33m / min and a temperature of 1100°C±5°C, and a high-purity (99.999%) full hydrogen protective gas is used, and the fan cooling speed is 1000r / min.

[0066] (2) Finished product rolling process

[0067] A four-column twenty-high rolling mill is used for the finished product rolling process. The steel strip thickness is rolled from 0.08mm to 0.05mm through three rolling passes. The rolling thickness is 0.08mm→0.068mm→0.058mm→0.05mm. High-speed steel rolls are used for the working rolls in each rolling pass.

[0068] (3) Cleaning

[0069] After rolling, the finished product is cleaned with chemical spray liquid to degrease the strip surface. The chemical spray liquid is an alkaline degreasing agent with a concentration of 5%. The water temperature of the pre-spraying, scrubbing machine, and high-pressure spraying water tank is set at 60-80℃. After drying in the dryer, the surface is clean and free of rolling oil residue.

[0070] (4) Straightening

[0071] After degreasing and cleaning, the plate is straightened by a 23-roller straightening machine. The elongation mode is adopted. The straightening machine has a unique process tension control device and plate shape control system, and the elongation is 1.0%. After straightening, the plate shape is straight and there is no obvious rolling wave.

[0072] (5) Polishing

[0073] The straightened strip is surface polished to make the surface roughness Ra less than 0.05 μm.

[0074] (6) Striping

[0075] The polished steel strip is produced in strips in the longitudinal cutting unit. The finished product width is 10mm, the steel strip width tolerance is controlled between -0.1 and 0.1mm, and the burr height is controlled within 5%.

[0076] The performance of the product was tested and the results are as follows:

[0077] 1) Thickness deviation: 0.05mm, i.e. (-0.005, 0.005)mm;

[0078] 2) Mechanical properties: RP 0.2 is 1150MPa, Rm is 1270MPa;

[0079] 3) Surface roughness: Ra is 0.035 μm.

[0080] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other substitutions, modifications, combinations, changes, simplifications, etc. made without departing from the spirit and principles of the present invention shall be equivalent replacement modes and shall be included in the protection scope of the present invention.

Claims

1. A method for producing Hastelloy precision foil for superconducting strip, comprising an intermediate rolling process, a finished product rolling process, a cleaning process, a straightening process, a polishing process and a longitudinal slitting process. Features: The intermediate rolling process includes a first rolling process, a first annealing treatment, a second rolling process, a second annealing treatment, a third rolling process and a third annealing treatment, and the rolling deformation of the latter rolling process is not greater than the rolling deformation of the previous rolling process; the temperatures of the first annealing treatment, the second annealing treatment and the third annealing treatment are successively reduced; Among them, the rolling deformation of the first rolling process is 52% to 54%, including three passes, and the rolling deformation of each pass is: 30% to 32%, 19% to 20%, and 15% to 16%; the rolling deformation of the second rolling process is 52% to 54%, including three passes, and the rolling deformation of each pass is: 30% to 32%, 19% to 20%, and 15% to 16%; the rolling deformation of the third rolling process is 37% to 39%, including two passes, and the rolling deformation of each pass is: 22% to 23.5%, 20% to 21%; The temperatures of the first annealing treatment, the second annealing treatment and the third annealing treatment are 1100-1140° C., and the annealing speed is 20-35 m / min.

2. The method for producing Hastelloy precision foil according to claim 1, It is characterized in that The rolling deformation amount of the rolling step of the finished rolling process is 35%.

3. The method for producing Hastelloy precision foil according to claim 1, It is characterized in that In the cleaning step, an alkaline degreasing agent with a concentration of 3% to 5% is used for cleaning.

4. The method for producing Hastelloy precision foil according to claim 1, It is characterized in that In the stretching and leveling step, the elongation is 0.8% to 1.3%.

5. The method for producing Hastelloy precision foil according to claim 1, It is characterized in that Hastelloy C276 with a thickness of 0.3 to 0.6 mm and a width of 500 to 650 mm is used as the raw material.

6. A Hastelloy precision foil for superconducting tape, It is characterized in that The product is prepared by the production method according to any one of claims 1 to 5.

7. The Hastelloy precision foil according to claim 6, It is characterized in that The thickness of the Hastelloy precision foil does not exceed 0.05 mm, and the surface roughness Ra is less than 0.05 μm.

8. The Hastelloy precision foil according to claim 6, It is characterized in that The mechanical properties of the Hastelloy precision foil are RP 0.2 >780MPa, Rm is 1100~1300MPa.