Preparation method of high-precision bending-resistant tungsten strip

Abstract

The invention discloses a preparation method of a high-precision bending-resistant tungsten belt. The manufacturing method comprises the following steps: selecting a raw material phi 0.34-phi 0.36 mm tungsten filament, putting the tungsten filament into a rolling mill protected by an argon protection device for rolling, controlling the rolling temperature to be 700-1100 DEG C, controlling the rolling speed to be 0.5-3 m / min, and controlling the rolling width to be less than or equal to 0.38 mm. And the rolled semi-finished product is drawn, in the drawing step, the tungsten belt mold passing temperature ranges from 700 DEG C to 850 DEG C, the square mold frame temperature ranges from 400 DEG C to 500 DEG C, and the drawing speed ranges from 1 m / min to 5 m / min. And annealing treatment is conducted on the drawn semi-finished product, the annealing temperature ranges from 800 DEG C to 1200 DEG C, and the heat preservation time ranges from 1 H to 3 H. And the annealed semi-finished product is rolled again, drawn again and annealed again. And by taking the tungsten strip with the specification of 0.16 * 0.36 mm as an example, the tungsten strip with the tensile strength of more than 2000Mpa, continuous fifty points and the interval of 20-30mm of each point can be obtained, and the tungsten strip is not broken after being bent back and forth by 90 degrees.

Description

Technical Field

[0001] The invention relates to the field of preparation of doped tungsten belts, and in particular to a method for preparing a high-precision bending-resistant tungsten belt. Background Art

[0002] As an important basic material, tungsten strip is widely used. In the electronics industry, tungsten electrodes, space traveling wave tubes and other components rely on its excellent performance; in the aerospace field, it is suitable for components in high temperature and high stress environments. The existing tungsten strip preparation mainly relies on the rolling process, using tungsten wire as the raw material, and achieving thickness thinning and width expansion through multiple rolling processes. Conventional rolling uses a six-roll or twelve-roll mill for rolling. The surface finish of the roll is high. The working roll is often made of cemented carbide. The working roll must have no obvious pits under a 30x microscope, otherwise periodic convex points will appear on the surface of the narrow strip after rolling. The size of the convex points depends on the size of the pits on the roll surface, which seriously affects the surface quality of the tungsten strip; the service life of the roll is short, and pits of varying degrees will appear when the rolling length is about 1,000 meters. When rolled at high temperature in the air, the tungsten strip has a high degree of oxidation and is prone to brittle fracture of the material; in addition, the rolling process can also cause the strip to become brittle. Although the grains remain in a long strip or fibrous shape after rolling, the grain thickness direction is lamellar, and the material performance is poor in bending performance, which is easy to cause brittle fracture. Tungsten strips that are mainly deformed by rolling have a low tensile strength of 1800-2000MPa and poor bending performance. They can be bent back and forth at 90° and break more than 4 times in 10 times, resulting in frequent breakage of the winding spiral wire. If the surface quality of the raw material wire is not high, that is, if there are many grooves or other surface quality defects caused by wire drawing on the surface, they cannot be eliminated in the subsequent rolling process, which will cause the surface quality to expand into cracks and other quality defects, greatly affecting the product yield. Heating during the rolling process facilitates the deformation of the tungsten wire. However, the protection measures are not perfect, and the problem of oxide scale shedding still exists, affecting the surface quality. The existing technology mainly realizes the production of tungsten-molybdenum narrow strips through rolling deformation, hydrogen annealing, electrolytic polishing and other methods. The existing technology has the following problems: such as high requirements for rollers, brittle fracture of strips, rolling cracking, poor mechanical properties of narrow strips, low surface finish of narrow strips after rolling, and high requirements for the surface quality of raw material wires. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a high-precision bending-resistant tungsten belt.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A method for preparing a high-precision bending-resistant tungsten belt, the method comprising the following steps:

[0006] S1: Select raw tungsten wire;

[0007] S2: rough-processed tungsten belt;

[0008] S3: Semi-rough machined tungsten strip;

[0009] S4: Semi-finished machined tungsten strip;

[0010] S5: Finished machined tungsten strip;

[0011] S6: Finished product machined tungsten strip;

[0012] S7: Surface treatment.

[0013] Furthermore, the rough machined tungsten strip, the semi-rough machined tungsten strip, the semi-finished machined tungsten strip, the finished machined tungsten strip and the finished product machined tungsten strip all include three steps of rolling, drawing and annealing.

[0014] Furthermore, the diameter range of the selected raw tungsten wire is φ0.34 - φ0.36mm.

[0015] Furthermore, the rolling temperature in the rolling step is controlled at 700°C - 1100°C, the rolling speed is 0.5 - 3m / min, and the rolling width ≤ 0.38mm.

[0016] Furthermore, the drawing step uses a square die for drawing. The temperature of the drawn tungsten wire passing through the die is 700 - 850°C, the temperature of the square die holder is 400 - 500°C, and the drawing speed is 1 - 5m / min.

[0017] Furthermore, an argon rolling protection device is used in the rolling step, and high-purity argon with a purity of 99.99% is introduced.

[0018] Furthermore, the annealing step can be carried out in one of three annealing environments: vacuum environment annealing, hydrogen environment annealing, and hydrogen-argon mixed gas environment annealing. The annealing temperature is 800 - 1200°C, and the holding time is 1 - 3H.

[0019] Furthermore, the material of the square die is specifically polycrystalline diamond material.

[0020] The beneficial effects of the present invention are as follows:

[0021] By using this method for production, the thickness and width of the tungsten strip can be precisely controlled, the shedding of oxide scale during the rolling process is reduced, the formation of pits on the surface of the roll and the tungsten strip due to the attachment of oxide scale is avoided, and the surface finish of the tungsten strip is greatly improved. At the same time, the bending performance of the material is improved, and the brittle fracture phenomenon is reduced. The toughness and ductility of the material are improved, and the application range of the tungsten strip is expanded. It can eliminate slight surface defects and ensure the surface quality. The optimized process flow and precise process control reduce defects and waste products during the production process, improve production efficiency and product yield, and reduce production costs. Description of the Drawings

[0022] Figure 1 is the process flow diagram of the present invention;

[0023] Figure 2 are the sectional dimension diagrams of five successively decreasing square die sizing zones in Example 1;

[0024] Figure 3 is the structure diagram of the argon protection device;

[0025] Figure 4 is the photo of the surface of the tungsten strip with scratches and pits after rolling without argon protection;

[0026] Figure 5 is the photo of the surface of the tungsten strip after rolling with argon protection;

[0027] Figure 6 is the photo of the tungsten strip with surface crack defects before drawing;

[0028] Figure 7 is the photo of the surface crack defects disappearing after drawing;

[0029] In the figure, 1 - nozzle, 2 - tee, 3 - quick connector, 4 - cylindrical screw, 5 - quartz tube, 6 - support rod, 7 - support. Specific Embodiments

[0030] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0031] Refer to Figures 1-7 , the present invention provides a technical solution:

[0032] A method for preparing a high-precision bend-resistant tungsten strip, the preparation method includes the following steps:

[0033] Select raw material tungsten wire;

[0034] Rough process the tungsten strip;

[0035] Semi-rough process the tungsten strip;

[0036] Semi-finish process the tungsten strip;

[0037] Finish process the tungsten strip;

[0038] Finish process the tungsten strip into a finished product;

[0039] Surface treatment.

[0040] The rough - processed tungsten strip, the semi - rough - processed tungsten strip, the semi - finish - processed tungsten strip, the finish - processed tungsten strip and the finished - product - processed tungsten strip all include three steps: rolling, drawing and annealing.

[0041] (1) Select tungsten wire as the raw material, and the diameter range of the tungsten wire is φ0.34 - φ0.36mm.

[0042] (2) For the rolling step of the rough - processed tungsten strip, the rolling temperature is controlled at 700℃ - 1100℃, the rolling speed is 0.5 - 3m / min, and the rolling width ≤ 0.38mm. An argon rolling protection device is used during rolling, and high - purity argon with a purity of 99.99% is introduced.

[0043] (3) For the drawing step of the rough - processed tungsten strip, square - die drawing is adopted. The temperature of the tungsten wire passing through the die during drawing is 700 - 850℃, the temperature of the square - die holder is 400 - 500℃, and the drawing speed is 1 - 5m / min.

[0044] (4) For the annealing step of the rough - processed tungsten strip, the annealing environment can be vacuum annealing, hydrogen - environment annealing, or hydrogen - and - argon - mixed - gas - environment annealing. One of the three annealing environments is selected. The annealing temperature is 800 - 1200℃, and the holding time is 1 - 3H.

[0045] (5) For the rolling step of the semi - rough - processed tungsten strip, the rolling temperature is controlled at 700℃ - 1100℃, the rolling speed is 0.5 - 3m / min, and the rolling width ≤ 0.38mm. An argon rolling protection device is used during rolling, and high - purity argon with a purity of 99.99% is introduced.

[0046] (6) For the drawing step of the semi - rough - processed tungsten strip, square - die drawing is adopted. The temperature of the tungsten wire passing through the die during drawing is 700 - 850℃, the temperature of the square - die holder is 400 - 500℃, and the drawing speed is 1 - 5m / min.

[0047] (7) For the annealing step of the semi - rough - processed tungsten strip, the annealing environment can be vacuum annealing, hydrogen - environment annealing, or hydrogen - and - argon - mixed - gas - environment annealing. One of the three annealing environments is selected. The annealing temperature is 800 - 1200℃, and the holding time is 1 - 3H.

[0048] (8) For the rolling step of the semi - finish - processed tungsten strip, the rolling temperature is controlled at 700℃ - 1100℃, the rolling speed is 0.5 - 3m / min, and the rolling width ≤ 0.38mm. An argon rolling protection device is used during rolling, and high - purity argon with a purity of 99.99% is introduced.

[0049] (9) For the drawing step of the semi - finish - processed tungsten strip, square - die drawing is adopted. The temperature of the tungsten wire passing through the die during drawing is 700 - 850℃, the temperature of the square - die holder is 400 - 500℃, and the drawing speed is 1 - 5m / min.

[0050] (10) Annealing step of semi-finished tungsten strip. The annealing environment can be vacuum annealing, hydrogen annealing, or annealing in a mixed gas environment of hydrogen and argon. One of the three annealing environments is selected. The annealing temperature is 800 - 1200 °C, and the holding time is 1 - 3 hours.

[0051] (11) Rolling step of finished tungsten strip. The rolling temperature is controlled at 700 °C - 1100 °C, the rolling speed is 0.5 - 3 m / min, and the rolling width ≤ 0.38 mm. An argon rolling protection device is used during rolling, and high-purity argon with a purity of 99.99% is introduced.

[0052] (12) Drawing step of finished tungsten strip. Square die drawing is adopted. The temperature of the tungsten wire passing through the die is 700 - 850 °C, the temperature of the square die holder is 400 - 500 °C, and the drawing speed is 1 - 5 m / min.

[0053] (13) Annealing step of finished tungsten strip. The annealing environment can be vacuum annealing, hydrogen annealing, or annealing in a mixed gas environment of hydrogen and argon. One of the three annealing environments is selected. The annealing temperature is 800 - 1200 °C, and the holding time is 1 - 3 hours.

[0054] (14) Rolling step of the tungsten strip for finished product processing. The rolling temperature is controlled at 700 °C - 1100 °C, the rolling speed is 0.5 - 3 m / min, and the rolling width ≤ 0.38 mm. An argon rolling protection device is used during rolling, and high-purity argon with a purity of 99.99% is introduced.

[0055] (15) Drawing step of the tungsten strip for finished product processing. Square die drawing is adopted. The temperature of the tungsten wire passing through the die is 700 - 850 °C, the temperature of the square die holder is 400 - 500 °C, and the drawing speed is 1 - 5 m / min.

[0056] (16) Annealing step of the tungsten strip for finished product processing. The annealing environment can be vacuum annealing, hydrogen annealing, or annealing in a mixed gas environment of hydrogen and argon. One of the three annealing environments is selected. The annealing temperature is 800 - 1200 °C, and the holding time is 1 - 3 hours.

[0057] (17) Surface treatment. Multi-stage polishing process is carried out successively using abrasive pastes of 2 μm, 1 μm, and 0.5 μm. The abrasive paste is applied using non-woven fabric. After clamping the strip, one end winds the wire and the other end unwinds the wire, and polishing is carried out quickly. The wire running speed < 1 m / min.

[0058] Example 1:

[0059] Taking a tungsten strip with a specification of 0.16×0.36mm as an example, a potassium-doped tungsten wire with a diameter of φ0.35mm is selected, and its surface is smooth without obvious defects such as grooves. The rolling temperature is 900°C, the rolling speed is <3m / min, the single-pass deformation is <15%, and the cumulative deformation is <30%. The tungsten wire is gradually deformed into a tungsten strip with the required thickness, and the required thickness is controlled by increasing 10-20 microns according to the die hole thickness of each square die. An argon protection device is used during the rolling process. The support rod 6 is fixed to the support 7 with screws, the tee 2 is welded to the support rod 6, the quartz tube 5 is fixed to the tee 2 with cylindrical screws 4, the nozzle 1 is screwed into the tee 2 through the thread on the outer surface, the argon pipe is connected to the quick connector 3, and high-purity argon with a purity ≥99.999% is introduced, with a flow rate <5ml / min. The argon fills the quartz tube 5, and the material passes through the nozzle 1 and comes out from the right end of the quartz tube 5 to the working rolls of the rolling mill. The effective application of the argon protection device reduces the shedding of oxide scales during the rolling process, avoids the formation of pits on the surface of the rolling rolls and the tungsten strip due to the attachment of oxide scales, and greatly improves the surface finish of the tungsten strip. After fine polishing, the surface roughness can reach the nanometer level, meeting the strict requirements for surface quality in high-end application fields. A square die made of polycrystalline diamond material is used for drawing deformation. The sizes of the square die are 0.3×0.36mm, 0.24×0.36mm, 0.21×0.36mm, 0.18×0.36mm, 0.16×0.36, etc. in 5 die sequences. The holes of the polycrystalline square die are cut by slow wire cutting. Limited by the wire diameter of the wire cutting wire, the minimum radius of the die hole fillet size is 0.05mm; the die hole width is set according to the width of the finished tungsten strip, and the die hole thickness = the thickness before passing through the die - 10μm. The temperature of the tungsten strip passing through the die is 750°C, the temperature of the die holder of the square die is 450°C, the drawing speed is <3m / min, and the surface is coated with graphite emulsion. The surface quality is inspected after each pass of drawing to ensure no cracks and surface defects. By alternately performing rolling and square die drawing, the thickness and width of the tungsten strip can be precisely controlled. In traditional rolling deformation, there is natural extension in the width direction without restraint, making it difficult to control the dimensions. The width tolerance can only be controlled within ±5μm. By using square die drawing deformation, since the width dimension of the square die is fixed, the thickness and width accuracy of the drawn strip is relatively high, up to ±2μm, which greatly meets the requirements of traveling wave tubes for strip accuracy. After drawing, hydrogen or a hydrogen-argon mixture annealing is carried out. The annealing equipment uses an intermediate frequency annealing furnace, the annealing temperature is 850°C, the holding time is 1.5H, and it is cooled naturally. The electrolytic polishing method is used to remove the surface graphite emulsion and other dirt. The polishing voltage is 3V, and the wire running speed is 8m / min. A multi-stage polishing process is carried out successively using polishing pastes of 2μm, 1μm, and 0.5μm. The polishing paste is applied with non-woven fabric. After clamping the strip, one end winds the wire and the other end unwinds the wire, and polishing is carried out quickly, with a wire running speed <1m / min. The finished product 1 is tested, with a tensile strength of 2338MPa, an elongation of 2.87%, and it does not break after 50 bends. As Figure 6 andFigure 7 As shown, surface rolling cracks appear on the tungsten strip when its size is 0.24×0.36mm. After passing through a die with a size of 0.16×0.36mm subsequently, the surface cracks are eliminated, indicating that drawing at a certain temperature can eliminate slight surface defects and ensure surface quality.

[0060] Example 2:

[0061] The remaining steps are the same as those in Example 1, except that: pure drawing is adopted, and the number of die passes is increased to 10. The sizes of the square dies are 0.3×0.36mm, 0.28×0.36mm, 0.26×0.36mm, 0.24×0.36mm, 0.225×0.36mm, 0.21×0.36mm, 0.195×0.36mm, 0.18×0.36mm, 0.17×0.36mm, 0.16×0.36mm in sequence. The finished product 2 is tested, and its tensile strength is 2353MPa, elongation is 3.24%, and it does not break after being bent 80 times. It can be seen that the tungsten strip prepared by pure drawing with polycrystalline square dies has higher tensile strength and elongation, and better bending performance. This benefits from the fact that the pure drawing method makes the grains present a slender fibrous shape.

[0062] Example 3:

[0063] The remaining steps are the same as those in Example 2, and a tungsten strip with a finished product size of 0.12×0.40mm is made. The number of die passes is 8, and the sizes of the square dies are 0.35×0.4mm, 0.31×0.4mm, 0.27×0.4mm, 0.24×0.4mm, 0.225×0.4mm, 0.21×0.4mm, 0.195×0.4mm, 0.18×0.4mm in sequence. The finished product 3 is tested, and its tensile strength is 2402MPa, elongation is 3.33%, and it does not break after being bent back and forth 90° at 100 points with an interval of 20mm for each point.

[0064] The above is only the preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for preparing a high-precision bending-resistant tungsten belt, characterized in that: The preparation method comprises the following steps: S1: Select raw tungsten wire; S2: rough-processed tungsten belt; S3: semi-rough processed tungsten belt; S4: semi-finished tungsten belt; S5: Finished tungsten belt; S6: Finished product processing tungsten belt; S7: Surface treatment.

2. The method for preparing a high-precision bending-resistant tungsten belt according to claim 1, characterized in that: The rough-processed tungsten belt, the semi-rough-processed tungsten belt, the semi-finished tungsten belt, the fine-processed tungsten belt and the finished tungsten belt all include three steps of rolling, drawing and annealing.

3. The method for preparing a high-precision bending-resistant tungsten belt according to claim 1, characterized in that: The diameter of the selected raw material tungsten wire ranges from φ0.34 to φ0.36 mm.

4. The method for preparing a high-precision bending-resistant tungsten belt according to claim 2, characterized in that: The rolling temperature of the rolling step is controlled to be 700° C. to 1100° C., the rolling speed is 0.5 to 3 m / min, and the rolling width is ≤0.38 mm.

5. The method for preparing a high-precision bending-resistant tungsten belt according to claim 2, characterized in that: The drawing step adopts square die drawing, the over-die temperature of the drawn tungsten wire is 700-850° C., the temperature of the square die frame is 400-500° C., and the drawing speed is 1-5 m / min.

6. The method for preparing a high-precision bending-resistant tungsten belt according to claim 4, characterized in that: The rolling step uses an argon rolling protection device, and high-purity argon gas with a purity of 99.99% is introduced.

7. The method for preparing a high-precision bending-resistant tungsten belt according to claim 2, characterized in that: The annealing step can be performed in one of the three annealing environments: vacuum environment annealing, hydrogen environment annealing, and hydrogen and argon mixed gas environment annealing. The annealing temperature is 800-1200° C. and the holding time is 1-3 hours.

8. The method for preparing a high-precision bending-resistant tungsten belt according to claim 5, characterized in that: The material of the square mold is specifically diamond polycrystalline material.

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