A method for heat treatment of a co-based alloy diaphragm after stamping, the diaphragm and applications thereof

Abstract

The application belongs to the technical field of alloy heat treatment, and particularly discloses a heat treatment method for a stamping-formed cobalt-based alloy diaphragm, the diaphragm and application thereof, which comprises the following steps: placing the stamping-formed cobalt-based alloy diaphragm in ultrapure water for ultrasonic cleaning for 15-30 min, and then performing gas purging and air cooling drying; placing the obtained cobalt-based alloy diaphragm in a protective furnace, heating to 480-520 DEG C, and keeping warm for 30-60 min; after the keeping warm, continuously heating to 620-680 DEG C, and keeping warm for 60-180 min; after the keeping warm, cooling the protective furnace to 400-450 DEG C, and performing isothermal aging treatment at the temperature, keeping warm for 120-300 min; after the keeping warm, cooling the protective furnace to room temperature, and taking out the cobalt-based alloy diaphragm; and performing secondary tempering on the obtained cobalt-based alloy diaphragm: keeping warm at 520-560 DEG C for 4-8 h, and obtaining the diaphragm.

Description

Technical Field

[0001] This invention relates to the field of alloy heat treatment technology, and in particular to a heat treatment method for a cobalt-based alloy film after stamping, the film itself, and its applications. Background Technology

[0002] Elgiloy alloy is a cobalt-based alloy with excellent elasticity, corrosion resistance and fatigue resistance. It is widely used in elastic elements in precision instruments, aerospace and medical equipment, especially in diaphragms, which are key components in metal diaphragm valves, ALD valves and mass flow meters.

[0003] In metal diaphragm valves, ALD valves, and mass flow meters, the diaphragm opens and closes the valve through reciprocating motion. The diaphragm is typically made of sheet-like cobalt-based alloy, stamped into an arched structure with a specific curvature. However, the stamping process introduces significant residual stress into the diaphragm. If this residual stress is not effectively eliminated, the diaphragm's curvature will uncontrollably decrease during long-term opening and closing of the diaphragm valve, leading to reduced sealing performance, decreased flow accuracy, and even diaphragm fatigue fracture.

[0004] Existing technologies mostly focus on heat treatment of Elgiloy alloys using methods such as solution treatment and age hardening, but there is a lack of corresponding treatment methods for cobalt-based alloy films after stamping. Summary of the Invention

[0005] In order to overcome the problem that the curvature of cobalt-based alloy films after stamping will be uncontrollably reduced due to residual stress in the existing technology, the present invention provides a heat treatment method for cobalt-based alloy films after stamping, the film and its application.

[0006] The technical solution adopted by this invention to solve its technical problem is: A heat treatment method for a cobalt-based alloy film after stamping includes the following steps: S1. The stamped cobalt-based alloy film is placed in ultrapure water for ultrasonic cleaning for 15-30 minutes, then purged with gas and dried by air cooling. S2, place the cobalt-based alloy film obtained in S1 in a protective furnace, heat it to 480-520℃, and hold it for 30-60 minutes; After the heat preservation in S3 and S2 is completed, continue to raise the temperature to 620-680℃ and keep it for 60-180 minutes. After the heat preservation in S4 and S3 is completed, the protective furnace is cooled to 400-450℃ and isothermal aging treatment is carried out at this temperature for 120-300 minutes. After the heat preservation in S5 and S4 is completed, the protective furnace is cooled to room temperature and the cobalt-based alloy film is removed. S6. The cobalt-based alloy film obtained in S5 is subjected to secondary tempering: held at 520-560℃ for 4-8 hours to obtain the film.

[0007] Specifically, in S1, ultrasonic pretreatment cleaning removes oil and impurities from the surface of the cobalt-based alloy film, ensuring cleanliness; in S2, the cobalt-based alloy film undergoes preliminary preheating and homogenization in a protective furnace, resulting in uniform temperature across the entire film; in S3, the temperature range is higher than the recrystallization initiation temperature of the Elgiloy alloy but lower than the grain coarsening temperature, eliminating lattice distortion and microscopic residual stress introduced by stamping through a recovery process, achieving stress-relief annealing; in S4, this step involves... Arc-induced varistor regulation of alloy diaphragms: By controlling the morphology and distribution of precipitated phases (such as Ni3Mo, Co3Mo, etc.) in the alloy, a weak "compression arc-induced varistor regulation" trend is introduced in advance, so that when the diaphragm valve is subjected to opening and closing forces, the curvature of the diaphragm gradually and uniformly changes as the diaphragm height decreases, rather than collapsing suddenly; In S6, the treated cobalt-based alloy diaphragm is subjected to secondary tempering to further stabilize the alloy structure and improve the dimensional and curvature stability of the diaphragm at subsequent operating temperatures (~50℃ to +150℃).

[0008] It should be noted that the resistivity of the ultrapure water in S1 reaches 18 MΩ. cm (25℃), this is common knowledge, so I will not elaborate further. In S6, it is usually cooled with the furnace after the second tempering.

[0009] As a further embodiment, the cobalt-based alloy membrane comprises, by mass percentage: Co 38–42%, Cr 18–21%, Ni 14–16%, Mo 6–8%, Mn 1.5–2.5%, Si ≤1.2%, C ≤0.15%, P <0.1%, S <0.002%, Cu <0.1%, Ta <0.02%, V <0.05%, B <0.001%, Cb <0.05%, Pb <0.0001%, W <0.1%, Ag <0.0002%, Be <0.001%, with the balance being Fe.

[0010] As a further option, in S1, the gas is nitrogen with a purity of 99.999%.

[0011] Specifically, high-purity nitrogen is used to avoid oxidizing the surface of the cobalt-based alloy film.

[0012] As a further embodiment, in S2, the protective furnace is a vacuum protective furnace or a protective atmosphere furnace filled with inert gas. The vacuum degree of the vacuum protective furnace is less than or equal to 1 × 10⁻⁶. -³ Pa; or, the inert gas is argon or nitrogen with a purity of 99.999%.

[0013] As a further option, in S2, the heating rate is 5–10 °C / min; in S3, the heating rate is 3–8 °C / min.

[0014] As a further option, in S4, the cooling rate is 0.5 to 2 °C / min; in S5, the cooling rate is 10 to 15 °C / min, and a shaping fixture is used to constrain the outer edge of the cobalt-based alloy diaphragm during the cooling process.

[0015] Specifically, in S4, a uniformly distributed fine precipitate phase is obtained through extremely low cooling rate and aging treatment, which improves the overall elasticity and creep resistance of the membrane; in S5, a shaping fixture is used to constrain the outer edge of the cobalt-based alloy membrane during the cooling process, allowing the curvature of its center to be naturally fine-tuned during the cooling process, avoiding warping caused by thermal stress.

[0016] As a further embodiment, the thickness of the cobalt-based alloy diaphragm after stamping is 0.05 mm to 0.5 mm; the diameter of the diaphragm is 10 mm to 100 mm.

[0017] The present invention also discloses a diaphragm, which is obtained by heat treatment as described above.

[0018] The present invention also discloses the application of the above-mentioned diaphragm in a diaphragm valve.

[0019] This invention has at least one of the following beneficial effects: 1. Through multi-stage heat treatment processes, residual stress inside the diaphragm after stamping is greatly eliminated, reducing the risk of stress corrosion cracking. By introducing the "arc-induced curvature control" stage in S4, the diaphragm height decreases linearly or nearly linearly during the opening and closing of the diaphragm valve, thereby allowing the diaphragm curvature to change linearly or nearly linearly, effectively eliminating diaphragm curvature curvature and avoiding the problem of sudden diaphragm curvature collapse.

[0020] 2. The diaphragm treated by this heat treatment method can achieve 10 million cycles without leakage in the simulated diaphragm valve opening and closing cycle test, which greatly improves the service life of the diaphragm. Attached Figure Description

[0021] Figure 1 The image shown is a physical representation of an embodiment of the present invention. Figure 2 This is a photograph of the blank control group. Figure 3 This is a schematic cross-sectional view of the blank control group. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] It is worth noting that: when specific experimental steps or conditions are not specified in the examples, the procedures or conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0024] The composition of the cobalt-based alloy membrane used in the examples is as follows: Fe 1.5%, Co 40%, Cr 20%, Ni 15%, Mo 7%, Mn 2.0%, Si 1.2%, C 0.15%, P 0.08%, S 0.0015%, Cu 0.08%, Ta 0.015%, V 0.04%, B 0.0008%, Cb 0.04%, Pb 0.00008%, W 0.08%, Ag 0.00015%, Be 0.0009%.

[0025] The cobalt-based alloy diaphragm, after being stamped, has a thickness of 0.127 mm, a diameter of 22 mm, an arc radius of R = 64.5 mm, and a height of 0.8 ± 0.05 mm.

[0026] The following are relevant examples: Example 1 This embodiment provides a heat treatment method for a cobalt-based alloy film after stamping, including the following steps: S1. The stamped cobalt-based alloy diaphragm was placed in ultrapure water for ultrasonic cleaning for 15 minutes, then purged with 99.999% pure nitrogen and air-cooled to dry. S2, the cobalt-based alloy film obtained in S1 is placed in a vacuum with a degree of 1×10 - In a vacuum furnace with a pressure of 3 Pa, the temperature is increased to 480°C at a heating rate of 5°C / min and held for 60 min. After the heat preservation in S3 and S2 is completed, the temperature is continued to rise to 620℃ at a heating rate of 3℃ / min, and then held for 180min. After the heat preservation in S4 and S3 is completed, the protective furnace is cooled to 400℃ at a cooling rate of 0.5℃ / min, and isothermal aging treatment is performed at this temperature for 300min. After the heat preservation in S5 and S4 is completed, the protective furnace is cooled to room temperature at a cooling rate of 10℃ / min. During the cooling process, a shaping fixture is used to constrain the outer edge of the cobalt-based alloy film, and then the cobalt-based alloy film is removed.

[0027] S6. The cobalt-based alloy film obtained in S5 is subjected to secondary tempering: held at 520℃ for 8 hours to obtain the film.

[0028] Example 2

[0029] This embodiment provides a heat treatment method for a cobalt-based alloy film after stamping, including the following steps: S1, the stamped cobalt-based alloy diaphragm is placed in ultrapure water for ultrasonic cleaning for 20 minutes, then purged with 99.999% pure nitrogen and air-cooled to dry. S2, the cobalt-based alloy film obtained in S1 is placed in a protective atmosphere furnace with 99.999% pure argon gas, and heated to 500℃ at a heating rate of 7℃ / min, and held at that temperature for 50min. After the heat preservation in S3 and S2 is completed, continue to heat up to 650℃ at a heating rate of 5℃ / min and hold for 100min. After the heat preservation in S4 and S3 is completed, the protective furnace is cooled to 430℃ at a cooling rate of 1℃ / min, and isothermal aging treatment is performed at this temperature for 200min. After the heat preservation in S5 and S4 is completed, the protective furnace is cooled to room temperature at a cooling rate of 12℃ / min. During the cooling process, a shaping fixture is used to constrain the outer edge of the cobalt-based alloy film, and then the cobalt-based alloy film is removed.

[0030] S6. The cobalt-based alloy film obtained in S5 is subjected to secondary tempering: held at 540℃ for 6 hours to obtain the film.

[0031] Example 3

[0032] This embodiment provides a heat treatment method for a cobalt-based alloy film after stamping, including the following steps: S1. The stamped cobalt-based alloy diaphragm was placed in ultrapure water for ultrasonic cleaning for 30 minutes, then purged with 99.999% pure nitrogen and air-cooled to dry. S2, the cobalt-based alloy film obtained in S1 is placed in a protective atmosphere furnace with nitrogen gas of 99.999% purity, and heated to 520℃ at a heating rate of 10℃ / min, and held at that temperature for 30min. After the heat preservation in S3 and S2 is completed, continue to heat up to 680℃ at a heating rate of 8℃ / min and hold for 60min. After the heat preservation in S4 and S3 is completed, the protective furnace is cooled to 450℃ at a cooling rate of 2℃ / min, and isothermal aging treatment is performed at this temperature for 120min. After the heat preservation in S5 and S4 is completed, the protective furnace is cooled to room temperature at a cooling rate of 15℃ / min. During the cooling process, a shaping fixture is used to constrain the outer edge of the cobalt-based alloy film, and then the cobalt-based alloy film is removed.

[0033] S6. The cobalt-based alloy film obtained in S5 is subjected to secondary tempering: held at 560℃ for 4 hours to obtain the film.

[0034] The membrane obtained in Example 2 is shown in the attached figure. Figure 1 As shown.

[0035] Blank control group

[0036] As attached Figure 2-3 As shown, the cobalt-based alloy film after stamping and without this heat treatment method has a film thickness of 0.127 mm, an arc radius R=64.5 mm, a diameter of 22 mm, and a height of 0.8±0.05 mm.

[0037] Performance testing

[0038] Multiple samples were prepared from the blank control group and the diaphragm obtained in Example 2, and applied to simulated diaphragm valve opening and closing cycle tests. The results are shown in Tables 1 and 2 below: Table 1:

[0039] Table 2:

[0040] As shown in Table 1, the height of the diaphragm after stamping was 0.84 mm. After being installed in the diaphragm valve and opened and closed 10 times, the diaphragm was removed and its height was measured again. At this time, the height ranged from 0.77 mm (minimum) to 0.84 mm (maximum), with a maximum error of 0.07 mm, which is relatively large. This proves that the diaphragm has an "arc-shaped partial morphology" after stamping, and this morphology is not uniform. The diaphragm was then reinstalled in the diaphragm valve and subjected to 100,000, 500,000, 1,000,000, 2,000,000, and 5,000,000 cycles of opening and closing. After disassembly, the diaphragm height was measured again. The diaphragm height of each sample not only decreased significantly but also showed irregular and inconsistent variations. Furthermore, the flow rate attenuation rate after valve circulation was inconsistent with the initial flow rate, with severe flow rate attenuation (the highest flow rate attenuation rate reached 16%), and even diaphragm rupture leading to gas leakage.

[0041] As shown in Table 2 above, the height of the diaphragm after molding is 0.84 mm. After being treated by the heat treatment method of this invention, it is installed in the diaphragm valve. After 10 opening and closing cycles, the diaphragm is disassembled and the height is measured again. At this time, the height is between 0.79 mm (minimum) and 0.83 mm (maximum), with the error controlled within 0.04 mm. It is then installed in the diaphragm valve again and cycled for 100,000, 500,000, 1,000,000, 2,000,000, 5,000,000, and 10,000,000 cycles. After disassembly, the diaphragm height is measured. The diaphragm height is between 0.78 mm (minimum) and 0.82 mm (maximum). The error control is very stable, and the diaphragm height decreases linearly or nearly linearly, so that the diaphragm curvature changes linearly or nearly linearly, effectively eliminating the desensitization of the diaphragm curvature and avoiding the problem of sudden collapse of the diaphragm curvature.

[0042] The flow rate attenuation rate after valve circulation is controlled within 6% of the initial flow rate, indicating that the residual stress inside the diaphragm is greatly reduced, proving that this heat treatment method can greatly eliminate the residual stress inside the diaphragm after stamping.

[0043] Furthermore, diaphragms treated by this heat treatment method, when applied to diaphragm valves, can withstand 10 million cycles without leakage, greatly improving the service life of the diaphragms.

[0044] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A heat treatment method for a cobalt-based alloy film after stamping, characterized in that: Includes the following steps: S1. The stamped cobalt-based alloy film is placed in ultrapure water for ultrasonic cleaning for 15-30 minutes, then purged with gas and dried by air cooling. S2, place the cobalt-based alloy film obtained in S1 in a protective furnace, heat it to 480-520℃, and hold it for 30-60 minutes; After the heat preservation in S3 and S2 is completed, continue to raise the temperature to 620-680℃ and keep it for 60-180 minutes. After the heat preservation in S4 and S3 is completed, the protective furnace is cooled to 400-450℃ and isothermal aging treatment is carried out at this temperature for 120-300 minutes. After the heat preservation in S5 and S4 is completed, the protective furnace is cooled to room temperature and the cobalt-based alloy film is removed. S6. The cobalt-based alloy film obtained in S5 is subjected to secondary tempering: held at 520-560℃ for 4-8 hours to obtain the film.

2. The heat treatment method for a cobalt-based alloy film after stamping according to claim 1, characterized in that: The cobalt-based alloy membrane comprises, by mass percentage: Co 38–42%, Cr 18–21%, Ni 14–16%, Mo 6–8%, Mn 1.5–2.5%, Si ≤1.2%, C ≤0.15%, P <0.1%, S <0.002%, Cu <0.1%, Ta <0.02%, V <0.05%, B <0.001%, Cb <0.05%, Pb <0.0001%, W <0.1%, Ag <0.0002%, Be <0.001%, with the balance being Fe.

3. The heat treatment method for a cobalt-based alloy film after stamping according to claim 1, characterized in that: In S1, the gas is nitrogen with a purity of 99.999%.

4. The heat treatment method for a cobalt-based alloy film after stamping according to claim 1, characterized in that: In S2, the protective furnace is a vacuum protective furnace or a protective atmosphere furnace with an inert gas.

5. The heat treatment method for a cobalt-based alloy film after stamping according to claim 4, characterized in that: The vacuum degree of the vacuum protection furnace is less than or equal to 1×10⁻⁶. - ³ Pa; or, The inert gas is argon or nitrogen with a purity of 99.999%.

6. The heat treatment method for a cobalt-based alloy film after stamping according to claim 1, characterized in that: In S2, the heating rate is 5–10 °C / min; In S3, the heating rate is 3–8 °C / min.

7. The heat treatment method for a cobalt-based alloy film after stamping according to claim 1, characterized in that: In S4, the cooling rate is 0.5–2 °C / min; In S5, the cooling rate is 10-15℃ / min, and a shaping fixture is used to constrain the outer edge of the cobalt-based alloy diaphragm during the cooling process.

8. The heat treatment method for a cobalt-based alloy film after stamping according to claim 1, characterized in that: The thickness of the cobalt-based alloy film after stamping is 0.05 mm to 0.5 mm; The diaphragm diameter is 10mm to 100mm.

9. A diaphragm, characterized in that: It is obtained by heat treatment as described in any one of claims 1 to 8.

10. The application of the membrane according to claim 9, characterized in that: The diaphragm is used in diaphragm valves.

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