Invar foil and method for producing the same

Abstract

The application provides an inconel alloy foil and a preparation method thereof, and comprises the following steps: according to a preset alloy component ratio, feeding refined materials of each component of the alloy into a vacuum melting furnace to perform vacuum melting, and preparing a molten metal obtained by the vacuum melting into an inconel alloy cast strip with a target thickness through a plane flow casting process; cooling the plane flow cast inconel alloy extremely thin strip of the inconel alloy cast strip to room temperature under a protective atmosphere to obtain a room temperature cast strip; performing one rolling pass of cold finish rolling on the extremely thin strip of the room temperature cast strip through a rolling mill to obtain a semi-finished foil; and performing heat treatment on the semi-finished foil. The application can solve the problems in the prior art, such as a long and complicated process flow, a low yield, a waste of a large amount of resources and energy, poor uniformity of a prepared finished product, and poor mechanical properties.

Description

Technical Field

[0001] This invention relates to the fields of metallurgical engineering and materials science and technology, and more specifically, to an Invar alloy foil and its preparation method. Background Technology

[0002] Materials are the foundation and precursor of economic construction, social progress, and national security. Advanced materials possess strong fundamental, supporting, technical and economic, and urgent strategic needs. Invar alloy foil is a typical representative of nickel-based precision alloys. Due to its high magnetic saturation strength, low coercivity, and good corrosion resistance, it can be used as a magnetic shielding material and has been widely applied in the electronics, aerospace, and medical fields. my country's demand for shape memory alloys in the medical field has reached 5 billion yuan. Meanwhile, the demand for shape memory alloys in emerging industries such as aerospace, automobiles, and robotics is also showing a rapid growth trend. Furthermore, with the commercialization and promotion of 5G in the future, a new generation of "replacement waves" is imminent, and OLED display panels may usher in a new peak in demand. The metal photomask industry has significant future development potential. Moreover, the G6 generation line has a capacity exceeding 400k / month, with an annual total output value exceeding 10 billion yuan.

[0003] Currently, metal masks are a core raw material or component in the OLED industry. The future development of Invar alloy foil for metal masks has a huge market demand in China, playing a significant guiding role in driving national economic development. Domestic and foreign companies mainly use traditional vacuum induction melting, hot forging, hot rolling, pickling, cold rolling, and annealing processes to prepare Invar alloys. This production process is extremely lengthy, and the yield of Invar alloys prepared using traditional methods from ingots to cold-rolled strips is only about 50%, resulting in significant waste of resources and energy. Although there is considerable research on methods for preparing Invar alloy foils, some shortcomings and limitations still exist, such as:

[0004] Chinese invention patent CN201911151714.1 describes a method for manufacturing Invar alloy foil. It involves smelting molten metal in a medium-frequency vacuum induction furnace, producing Invar alloy strips through a thin-strip continuous casting device, and finally manufacturing Invar alloy foil through cold rolling and annealing. However, the thin-strip continuous casting method used in this invention produces thicker strips, requiring multiple rolling processes and intermediate annealing to achieve the target thickness. Furthermore, the strips must undergo surface oxide removal and pickling before cold rolling, significantly increasing the manufacturing process and pollutant emissions, and substantially raising production costs. Therefore, a redesign of the Invar alloy foil manufacturing system is needed to meet current and future requirements.

[0005] Chinese invention patent CN202211230570.0 describes a method for preparing ultra-thin Invar strips using a strip-spinning method. The method involves preparing Invar alloy blocks using a casting or powder metallurgy method, cutting the alloy blocks into substrates suitable for a strip-spinning machine, removing the surface oxide layer, and placing the substrates into a strip-spinning melting tube with an opening at the bottom. Under a protective atmosphere, the substrates are strip-spinned in the strip-spinning machine to obtain the Invar alloy strip. While this patent describes an excellent method for preparing ultra-thin Invar strips, it also suffers from the same problems as patent CN201911151714.1 mentioned above. The preparation process is lengthy and cumbersome, requiring the removal of the oxide layer from the substrate surface. Although the strip-spinning method can directly produce Invar strips with a thickness of 20μm or even thinner, the key issue is the inability to guarantee the dimensional accuracy and flatness of the material. The width and length of the strip are limited by the parameters and performance of the strip-spinning machine, and the width of the finished ultra-thin Invar strip does not exceed 200mm.

[0006] Chinese invention patent CN201810770797.1 describes a process for preparing Invar alloy foil by electrodeposition. The process involves cutting and welding a large metal plate, removing surface contaminants, and then electrodepositing the treated iron and nickel anode material in an electrolytic cell to form Invar alloy foil. While this method produces foil with nanometer-level thickness, preparing thin film materials with ideal and complex compositions using electrodeposition is challenging. Controlling the generation and growth rate of crystal nuclei on the substrate surface is difficult, and the deposited catalyst particles are large, uneven in size and distribution, and prone to agglomeration. Therefore, the Invar alloy foil prepared by this process has low performance.

[0007] Therefore, in summary, current methods for preparing Invar alloy foil generally suffer from problems such as lengthy and cumbersome processes, low yields resulting in significant waste of resources and energy, and poor uniformity and mechanical properties of the finished products. Summary of the Invention

[0008] In view of the above problems, the purpose of this invention is to provide an Invar alloy foil and its preparation method, so as to solve the problems of the existing technology in the preparation of Invar alloy foil, which generally has a long and complicated process, low yield, resulting in a large waste of resources and energy, as well as poor uniformity and poor mechanical properties of the prepared product.

[0009] This invention provides a method for preparing Invar alloy foil, comprising the following steps:

[0010] S1. According to the preset alloy composition ratio, the refined materials of each component of the alloy are fed into a vacuum melting furnace for vacuum melting, and the molten metal obtained by vacuum melting is prepared into an Invar alloy strip of the target thickness by planar flow casting process.

[0011] S2. Under a protective atmosphere, the planar flow cast Invar alloy ultrathin strip of the Invar alloy strip is cooled to room temperature to obtain a room temperature cast strip.

[0012] S3. The extremely thin strip of the room temperature cast strip is cold-rolled for one pass using a rolling mill to obtain a semi-finished foil.

[0013] S4. The semi-finished foil is heat-treated by annealing under full argon protection to obtain Invar alloy foil.

[0014] Furthermore, a preferred embodiment is that the process of preparing the molten metal obtained from vacuum melting into an Invar alloy strip of the target thickness using a planar flow casting process includes:

[0015] The molten metal obtained from vacuum melting is prepared into an Invar alloy strip of the target thickness using a three-roll planar flow casting device with a stripping roller.

[0016] Furthermore, a preferred embodiment is that the three-roll planar flow casting apparatus with a stripping roller is used to prepare the molten metal obtained from vacuum melting into an Invar alloy strip of the target thickness, comprising:

[0017] The molten metal obtained from the vacuum melting is flowed into the electroslag remelting bottom casting furnace, and the electroslag remelting bottom casting furnace is moved above the nozzle.

[0018] The molten alloy obtained after refining in the electroslag remelting bottom casting furnace is injected into a nozzle package through a water nozzle, and sprayed onto the high-speed rotating main crystallizing roller surface through the nozzle package nozzle. After the molten alloy on the main crystallizing roller surface solidifies instantly, the solidified alloy is prepared into an Invar alloy strip of the target thickness using the three-roll planar flow casting device with a stripping roller.

[0019] Furthermore, a preferred embodiment is that the solidification time of the alloy liquid on the main crystallization roller surface is 1 / 1000 second.

[0020] Furthermore, a preferred embodiment is that, during the process of cooling the planar flow-cast Invar alloy ultrathin strip to room temperature under a protective atmosphere to obtain a room-temperature cast strip,

[0021] The protective atmosphere is nitrogen; and / or,

[0022] The cooling rate of the planar flow-cast Invar alloy ultrathin strip is 15–80 °C / s.

[0023] Furthermore, a preferred embodiment is that, during the process of cooling the planar flow-cast Invar alloy ultrathin strip to room temperature under a protective atmosphere to obtain a room-temperature cast strip,

[0024] The planar flow-cast Invar alloy ultrathin strip was cooled to room temperature using a combination of water and air cooling to obtain a room-temperature cast strip.

[0025] Furthermore, a preferred embodiment is that during the process of cold finishing the extremely thin strip of the room-temperature cast strip through a rolling mill for one pass to obtain the semi-finished foil,

[0026] The deformation of the extremely thin strip cast at room temperature after one cold finishing rolling pass is 23%–98%, the pass rate is 3–14%, the rolling speed is 20–60 m / min, the rolling force is 1210 KN–1510 KN, and the front and rear tensions are 110 KN–180 KN; and / or,

[0027] The final thickness of the semi-finished foil is 0.02mm to 0.15mm, the width is 200mm to 650mm, and the thickness tolerance is ±5μm.

[0028] Furthermore, a preferred embodiment is that during the heat treatment of the semi-finished foil, the semi-finished foil is annealed under argon protection throughout the process to obtain Invar alloy foil.

[0029] Argon gas purity ≥ 99.999%;

[0030] The annealing temperature is 600℃~650℃;

[0031] After annealing, the material is kept at a temperature of 1.5 to 4 hours to obtain Invar alloy foil.

[0032] This invention provides an Invar alloy foil, which is prepared by the Invar alloy foil preparation method described above.

[0033] Furthermore, a preferred embodiment is that the Invar alloy foil comprises the following chemical composition by weight percentage: Ni: 35.01–37%, C: 0.017–0.05%, Si: 0.098–0.2%, Mn: 0.30–0.425%, P: 0.011–0.02%, S: 0.006–0.01%, with the balance being Fe and unavoidable impurities.

[0034] As can be seen from the above technical solution, the Invar alloy foil and its preparation method provided by the present invention utilize planar flow casting technology combined with fire-formed materials to prepare heat-free rolled Invar alloy cold-rolled base material. By utilizing the rapid / sub-rapid solidification of ultra-thin strips and the rapid secondary cooling characteristics after casting, the grain boundary segregation of impurity elements in the Invar alloy cast-rolled base material is suppressed, the high solid solution advantage of elements is improved, and the oxidation problems within and at grain boundaries of the base material are alleviated. The conventional production processes such as hot rolling, forging, and pickling to remove the oxide surface layer are eliminated, and cold finishing rolling can be directly connected, significantly reducing production costs, simplifying the process, producing products with uniform composition, little or no segregation, and high efficiency, enabling mass production. Using planar flow casting technology, the required thickness of the original base material can be calculated based on the thickness of the final foil product, flexibly preparing the required thickness of the cold-rolled base material. The final product can be produced by rolling and leveling through a rolling mill in just one cold rolling pass. Compared with the existing technology, the production process is reduced by more than 80%, significantly improving the dimensional accuracy, flatness, production efficiency, and yield of Invar alloy foil, and greatly reducing its production costs.

[0035] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0036] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings. In the drawings:

[0037] Figure 1 This is a flowchart of a method for preparing Invar alloy foil according to an embodiment of the present invention.

[0038] In all the accompanying drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed Implementation

[0039] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details.

[0040] In view of the problems that the existing methods for preparing Invar alloy foil generally have, such as lengthy and cumbersome process flow, low yield, resulting in a large waste of resources and energy, and poor uniformity and mechanical properties of the prepared product, an Invar alloy foil and its preparation method are proposed.

[0041] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0042] To illustrate the Invar alloy foil and device provided by the present invention Figure 1 The flowchart of the method for preparing Invar alloy foil according to an embodiment of the present invention is shown.

[0043] like Figure 1 As shown, the method for preparing Invar alloy foil provided by the present invention includes the following steps:

[0044] S1. According to the preset alloy composition ratio, the refined materials of each component of the alloy are sent into a vacuum melting furnace for vacuum melting, and the molten metal obtained by vacuum melting is prepared into an Invar alloy strip of the target thickness through a planar flow casting process.

[0045] Planar flow casting technology (i.e., planar flow casting method) is a cutting-edge technology that integrates sub-rapid solidification and rolling deformation, directly producing ultra-thin strips from liquid metal. It features sub-rapid solidification and an ultra-short process, allowing for the flexible manufacture of cold-rolled substrates using planar rheology technology based on product thickness specifications. In this invention, it is applied to the preparation process of Invar alloy foil, eliminating the traditional hot forging, hot rolling, and pickling processes, aligning with the national "dual-carbon" development strategy. Based on a scientifically sound alloy system design, this invention flexibly prepares Invar alloy foil with controllable strip thickness, good uniformity, no surface oxidation, and high yield through planar flow casting technology combined with a short-process rolling mill.

[0046] The alloy composition ratio can be set according to the actual product performance requirements. For example, Invar alloy foil includes the following chemical composition by weight percentage: Ni: 35.01-37%, C: 0.017-0.05%, Si: 0.098-0.2%, Mn: 0.30-0.425%, P: 0.011-0.02%, S: 0.006-0.01%, with the balance being Fe and unavoidable impurities.

[0047] As a preferred embodiment of the present invention, the preparation of Invar alloy strips of the target thickness from vacuum-melted molten metal using a planar flow casting process includes:

[0048] A three-roll planar flow casting apparatus with a stripping roller is used to prepare Invar alloy strips of the target thickness from vacuum melting molten metal. The planar flow casting apparatus can be any existing one, but a three-roll planar flow casting apparatus with a stripping roller produces better results for Invar alloy strips of the target thickness.

[0049] As a preferred embodiment of the present invention, the preparation of Invar alloy strip of target thickness from vacuum-melted molten metal into a three-roll planar flow casting apparatus with a stripping roller includes:

[0050] The molten metal obtained from vacuum melting flows into the electroslag remelting bottom casting furnace, and the electroslag remelting bottom casting furnace is moved above the nozzle.

[0051] The molten alloy obtained after refining in an electroslag remelting bottom casting furnace is injected into a nozzle package through a sprue. The molten alloy is then sprayed onto the surface of a high-speed rotating main crystallizing roller through the nozzle of the nozzle package. After the molten alloy on the surface of the main crystallizing roller solidifies instantly, the solidified alloy is prepared into an Invar alloy strip of the target thickness using a three-roll planar flow casting device with a stripping roller.

[0052] The refined raw materials of the alloy are vacuum melted in a vacuum melting furnace to obtain molten metal with many impurities. Therefore, the molten metal is fed into an electroslag remelting bottom casting furnace, where it is refined to obtain alloy liquid. The alloy liquid is then injected into a nozzle package through a sprue and sprayed onto the high-speed rotating main crystallizing roller surface through the nozzle of the nozzle package. The alloy liquid on the main crystallizing roller surface solidifies instantly, and then a three-roll planar flow casting device is used to flexibly prepare Invar alloy casting strips of the target thickness.

[0053] In a preferred embodiment of the present invention, the solidification time of the alloy liquid on the main crystallizing roller surface is 1 / 1000 second.

[0054] S2. Under a protective atmosphere, the planar flow-cast Invar alloy ultrathin strip is cooled to room temperature to obtain a room temperature cast strip.

[0055] By utilizing the rapid / sub-rapid solidification of ultra-thin strips and the rapid secondary cooling characteristics after casting, the grain boundary segregation of impurity elements in the Invar alloy cast-rolled matrix is ​​suppressed, the high solid solution advantage of the elements is enhanced, and the oxidation problems within and at the grain boundaries of the matrix are improved.

[0056] In a preferred embodiment of the present invention, during the process of cooling the planar flow-cast Invar alloy ultrathin strip to room temperature under a protective atmosphere to obtain a room-temperature cast strip,

[0057] The protective atmosphere is nitrogen; and / or,

[0058] The cooling rate of planar flow-cast Invar alloy ultrathin strips is 15–80 °C / s.

[0059] The protective atmosphere can be a nitrogen atmosphere or an inert gas atmosphere, such as helium and argon, without any particular limitation.

[0060] In a preferred embodiment of the present invention, during the process of cooling the planar flow-cast Invar alloy ultrathin strip to room temperature under a protective atmosphere to obtain a room-temperature cast strip,

[0061] The planar flow-cast Invar alloy ultrathin strip is cooled to room temperature using a combination of water and air cooling to obtain a room-temperature cast strip. Alternatively, water cooling alone or air cooling alone can be used, and combining the two methods allows for flexible adjustment of the cooling rate.

[0062] S3. The extremely thin strip of room-temperature cast strip is cold-rolled in one pass using a rolling mill to obtain semi-finished foil. The final product can be produced through only one cold rolling pass, reducing the production steps by more than 80% compared to the traditional process. This significantly improves the dimensional accuracy, flatness, production efficiency, and yield of Invar alloy foil, and greatly reduces its production cost.

[0063] In a preferred embodiment of the present invention, during the process of cold finishing the extremely thin strip of room-temperature cast strip through a rolling mill for one rolling pass to obtain semi-finished foil,

[0064] The deformation of ultra-thin strips cast at room temperature after one cold finishing rolling pass is 23%–98%, the pass rate is 3–14%, the rolling speed is 20–60 m / min, the rolling force is 1210 KN–1510 KN, and the front and rear tensions are 110 KN–180 KN; and / or,

[0065] The final thickness of the semi-finished foil is 0.02mm to 0.15mm, the width is 200mm to 650mm, and the thickness tolerance is ±5μm.

[0066] S4. Heat-treat the semi-finished foil material by annealing it under argon protection throughout the process to obtain Invar alloy foil material.

[0067] In a preferred embodiment of the present invention, during the heat treatment of the semi-finished foil material, annealing the semi-finished foil material under argon protection throughout the process to obtain Invar alloy foil material,

[0068] Argon gas purity ≥ 99.999%;

[0069] The annealing temperature is 600℃~650℃;

[0070] After annealing, the material is kept at a temperature of 1.5 to 4 hours to obtain Invar alloy foil.

[0071] The present invention provides an Invar alloy foil, which is prepared by any of the Invar alloy foil preparation methods described above.

[0072] As a preferred embodiment of the present invention, the Invar alloy foil comprises the following chemical composition by weight percentage: Ni: 35.01-37%, C: 0.017-0.05%, Si: 0.098-0.2%, Mn: 0.30-0.425%, P: 0.011-0.02%, S: 0.006-0.01%, with the balance being Fe and unavoidable impurities.

[0073] By employing planar flow casting technology combined with fire-formed materials to prepare heat-free rolled Invar alloy cold-rolled base material, the rapid / sub-rapid solidification of ultra-thin strips and the rapid secondary cooling characteristics after casting are utilized to suppress the grain boundary segregation of impurity elements in the Invar alloy cast-rolled base material, enhance the high solid solution advantage of elements, and improve the oxidation problems within and at grain boundaries of the base material. This eliminates conventional production processes such as hot rolling, forging, and pickling to remove the oxide surface layer, allowing direct connection to cold finishing rolling. This significantly reduces production costs, simplifies the process, produces products with uniform composition, little or no segregation, and high efficiency, enabling mass production. Using planar flow casting technology, the required thickness of the original base material can be calculated based on the thickness of the final foil product, flexibly preparing the required thickness of the cold-rolled base material. Rolling and leveling are performed using a rolling mill, and the final product can be produced in just one cold rolling pass. Compared to existing technologies, this reduces production steps by more than 80%, significantly improving the dimensional accuracy, flatness, production efficiency, and yield of Invar alloy foil, and greatly reducing production costs.

[0074] To better illustrate the technical effects of the Invar alloy foil and its preparation process provided by the present invention, the following specific embodiments are provided.

[0075] Example 1

[0076] The composition of Invar alloy foil is designed as follows: Ni: 35.01%, C: 0.017%, Si: 0.098%, Mn: 0.30%, P: 0.011%, S: 0.006%, with the balance being Fe and unavoidable impurities.

[0077] S1. According to the above alloy composition ratio, the refined materials of each component of the alloy are fed into a vacuum melting furnace for vacuum melting. The molten metal flows into the electroslag remelting bottom casting furnace. The bottom casting furnace is moved above the nozzle package. The alloy liquid is injected into the nozzle package through the water nozzle and then sprayed onto the surface of the high-speed rotating main crystallizing roller through the nozzle, so that it solidifies instantly (about 1 / 1000 second). The Invar alloy casting strip of the target thickness is flexibly prepared using a three-roll planar flow casting device with a peeling roller.

[0078] S2. Under a protective atmosphere, the planar flow-cast Invar alloy ultrathin strip is cooled to room temperature to obtain a room temperature cast strip; wherein, the protective atmosphere is nitrogen gas with a purity ≥99.999%; the planar flow-cast Invar alloy ultrathin strip is cooled to room temperature at a cooling rate of 15~80℃ / s by water cooling + air cooling to obtain a room temperature cast strip with a thickness of 0.030mm and a width of 650mm;

[0079] S3. The ultra-thin strip of room temperature cast strip is cold-rolled in one pass using an HL800 rolling mill to obtain a semi-finished foil. The deformation of the ultra-thin strip during the cold-rolling process is 33%, the reduction rate per pass is 3% to 5%, the rolling speed is 20 to 25 m / min, the rolling force is 1300 KN to 1450 KN, and the front and rear tensions are 60 KN to 120 KN. The final thickness of the Invar alloy finished foil is 0.02 mm, the width is 650 mm, and the thickness tolerance is ±5 μm. The rolling process parameters are shown in Table 1.

[0080] S4. Heat treatment is performed on the semi-finished foil material. The semi-finished foil material is annealed under argon protection throughout the process to obtain Invar alloy foil material. The annealing temperature is 610℃, the holding time is 1.5 hours, and the argon purity is ≥99.999%. Invar alloy foil material is prepared by annealing the finished product.

[0081]

[0082] Table 1

[0083] Example 2

[0084] The process is the same as in Example 1, except that:

[0085] The alloy composition of Invar alloy foil is designed as follows: Ni: 37%, C: 0.05%, Si: 0.2%, Mn: 0.425%, P: 0.02%, S: 0.01%, with the balance being Fe and unavoidable impurities;

[0086] The Invar alloy room temperature casting strip has a thickness of 0.15mm and a width of 650mm;

[0087] The cold finishing rolling process has a deformation of 67%, a reduction rate of 5% to 14% per pass, a rolling speed of 35 to 60 m / min, a rolling force of 800 KN to 1250 KN, and a front and rear tension of 60 KN to 150 KN.

[0088] The annealing temperature is 620℃ and the holding time is 2 hours. The final thickness of the Invar alloy foil prepared by the finished product annealing is 0.05mm and the width is 650mm.

[0089] Table 2 shows the rolling process parameters for Example 2.

[0090] 1 0.150 0.130 13.33 850 60 150 130 2 0.130 0.114 12.31 900 55 150 130 3 0.114 0.101 11.40 1000 50 140 120 4 0.101 0.089 11.88 1050 46 130 120 5 0.089 0.078 12.35 1050 35 120 100 6 0.078 0.070 10.25 1100 35 110 90 7 0.070 0.063 10.00 1100 35 110 90 8 0.063 0.057 9.52 1200 35 100 70 9 0.057 0.053 7.01 1250 35 110 65 10 0.053 0.050 5.66 1250 35 100 65

[0091] Table 2

[0092] Example 3

[0093] The process is the same as in Example 2, except that:

[0094] The alloy composition of Invar alloy foil is designed as follows: Ni: 36%, C: 0.03%, Si: 0.1%, Mn: 0.37%, P: 0.016%, S: 0.008%, with the balance being Fe and unavoidable impurities;

[0095] Invar alloy room temperature casting strip with a thickness of 0.10 mm and a width of 650 mm;

[0096] The cold finishing rolling process has a deformation of 40%, a reduction rate of 6% to 12% per pass, a rolling speed of 50 to 60 m / min, a rolling force of 1050 KN to 1200 KN, and a front and rear tension of 80 KN to 120 KN.

[0097] The annealing temperature was 610℃ and the holding time was 3 hours. The final thickness of the Invar alloy foil prepared by the finished product annealing was 0.06mm and the width was 650mm.

[0098] Table 3 shows the rolling process parameters for Example 3.

[0099]

[0100] Table 3

[0101] The Invar alloy foils prepared by the processes described in Examples 1 to 3 above were subjected to mechanical property tests and appearance quality inspections, and the test results are shown in Tables 4 and 5 below.

[0102] Table 4 shows the appearance quality inspection of flexible Invar alloy foil in specific implementation cases 1-3.

[0103]

[0104] Table 4

[0105] Table 5 shows the heat treatment process and mechanical property test results of the Invar alloy foils flexibly prepared in the above implementation cases 1 to 3.

[0106]

[0107] Analysis of the data in Table 4 shows that the Invar alloy foils prepared in Examples 1-3 have excellent mechanical parameters, superior plate shape, and superior product appearance. The surface roughness Ra of the Invar alloy foil is ≤0.25μm, the maximum roughness Rz is ≤0.15μm, and the roughness skewness is above 0. Analysis of the data in Table 5 shows that by designing three different alloy compositions, cold finishing rolling process parameters, and heat treatment, the basic mechanical properties of the Invar alloy foil can be met. The surface hardness of the Invar alloy foil reaches 180HV; its tensile strength R... m ≥450MPa, yield strength R P0.2 ≥274MPa, elongation after fracture A 50 ≥35%.

[0108] Therefore, the preparation method of Invar alloy foil provided by the present invention can overcome the shortcomings and deficiencies of the prior art. Its preparation process is simple, the composition is uniform and the efficiency is high, which can greatly reduce its production cost and has significant advantages.

[0109] As can be seen from the above specific embodiments, the Invar alloy foil and its preparation method provided by the present invention adopt planar flow casting technology combined with fire-formed materials to prepare heat-free rolled Invar alloy cold-rolled base material. By utilizing the rapid / sub-rapid solidification of ultra-thin strips and the rapid secondary cooling characteristics after casting, the grain boundary segregation of impurity elements in the Invar alloy cast-rolled base material is suppressed, the high solid solution advantage of elements is improved, and the oxidation problems within the grains and grain boundaries of the base material are improved. The conventional production processes such as hot rolling, forging, pickling to remove the oxide surface layer are eliminated, and it can be directly connected to cold precision rolling, which significantly reduces its production cost, simplifies the process, produces products with uniform composition, little or no segregation, and high efficiency, and can realize mass production. By adopting planar flow casting technology, the required thickness of the original base material can be calculated according to the thickness of the final foil product, and the required thickness of the cold-rolled base material can be flexibly prepared. The final product can be produced by rolling and leveling through a rolling mill with only one cold rolling pass. Compared with the existing technology, the production process is reduced by more than 80%, which significantly improves the dimensional accuracy, flatness, production efficiency and yield of Invar alloy foil, and greatly reduces its production cost.

[0110] The Invar alloy foil and its preparation method according to the present invention have been described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various modifications can be made to the Invar alloy foil and its preparation method according to the present invention without departing from the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the contents of the appended claims.

Claims

1. A method for preparing Invar alloy foil, characterized in that, Includes the following steps: S1. According to the preset alloy composition ratio, the refined materials of each component of the alloy are fed into a vacuum melting furnace for vacuum melting. The molten metal obtained by vacuum melting is prepared into an Invar alloy strip of the target thickness using a three-roll planar flow casting device with a stripping roller. S2. Under a protective atmosphere, the Invar alloy casting strip is cooled to room temperature to obtain a room temperature casting strip; wherein, the cooling rate of the Invar alloy casting strip is 15-80℃ / s; S3. The room temperature cast strip is cold-rolled for one pass using a rolling mill to obtain a semi-finished foil. S4. The semi-finished foil is heat-treated by annealing under full argon protection to obtain Invar alloy foil.

2. The method for preparing Invar alloy foil according to claim 1, characterized in that, The method of using a three-roll planar flow casting device with a stripping roller to prepare the molten metal obtained from vacuum melting into an Invar alloy strip of the target thickness includes: The molten metal obtained from the vacuum melting is flowed into the electroslag remelting bottom casting furnace, and the electroslag remelting bottom casting furnace is moved above the nozzle. The molten alloy obtained after refining in the electroslag remelting bottom casting furnace is injected into a nozzle package through a water nozzle, and sprayed onto the high-speed rotating main crystallizing roller surface through the nozzle package nozzle. After the molten alloy on the main crystallizing roller surface solidifies instantly, the solidified alloy is prepared into an Invar alloy strip of the target thickness using the three-roll planar flow casting device with a stripping roller.

3. The method for preparing Invar alloy foil according to claim 2, characterized in that, The solidification time of the alloy liquid on the main crystallization roller surface is 1 / 1000 second.

4. The method for preparing Invar alloy foil according to claim 1, characterized in that, During the process of cooling the Invar alloy cast strip to room temperature under a protective atmosphere to obtain a room temperature cast strip, The protective atmosphere is nitrogen.

5. The method for preparing Invar alloy foil according to claim 1, characterized in that, During the process of cooling the Invar alloy cast strip to room temperature under a protective atmosphere to obtain a room temperature cast strip, The Invar alloy casting strip was cooled to room temperature using a combination of water and air cooling to obtain a room temperature casting strip.

6. The method for preparing Invar alloy foil according to claim 1, characterized in that, In the process of cold finishing the room-temperature cast strip through a rolling mill for one pass to obtain semi-finished foil, The deformation of the ambient temperature cast strip after one cold finishing rolling is 23% to 98%, the pass rate is 3 to 14%, the rolling speed is 20 to 60 m / min, the rolling force is 1210 KN to 1510 KN, and the front and rear tensions are 110 KN to 180 KN. The final thickness of the semi-finished foil is 0.02mm to 0.15mm, the width is 200mm to 650mm, and the thickness tolerance is ±5μm.

7. The method for preparing Invar alloy foil according to claim 1, characterized in that, In the process of heat-treating the semi-finished foil material and annealing it under argon protection throughout the process to obtain Invar alloy foil material, Argon gas purity ≥ 99.999%; The annealing temperature is 600℃~650℃; After heat preservation for 1.5 to 4 hours, Invar alloy foil is obtained.

8. An Invar alloy foil, characterized in that, Invar alloy foil prepared by the method for preparing Invar alloy foil as described in any one of claims 1-7.

9. The Invar alloy foil according to claim 8, characterized in that, The Invar alloy foil comprises the following chemical components by weight percentage: Ni: 35.01~37%, C: 0.017~0.05%, Si: 0.098~0.2%, Mn: 0.30~0.425%, P: 0.011~0.02%, S: 0.006~0.01%, balance Fe and unavoidable impurities.

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