Control method for shortening aging period of ultra-high-strength spring steel wire

Abstract

The invention discloses a control method for shortening the aging period of an ultrahigh-strength spring steel wire rod, which specifically comprises the following steps: S1, medium-temperature finish rolling is adopted during rolling production, and the reducing and sizing inlet temperature is 880 + / -20 DEG C; s2, medium-temperature spinning is adopted during rolling production, and the spinning temperature is 870 + / -20 DEG C; s3, the rolled wire enters a Stelmor air cooling line to be cooled; s4, after the coils are collected, the coils are hung on a C-shaped hook to be transported, the temperature during coil collection is 540-580 DEG C, when the temperature of the coils is 400 DEG C, a subsequent cooling fan is turned off, heat preservation is conducted for 30 minutes, and then packaging is conducted; the problem of self-breaking in a standing state after heat treatment by a user can be successfully solved, the use performance of the ultra-high-strength spring steel wire rod is improved, the aging period of the ultra-high-strength spring steel wire rod can be effectively shortened, and the storage and delivery pressure is further solved.

Description

Technical Field

[0001] The invention relates to a control method for shortening the aging period of an ultra-high strength spring steel wire. Background Art

[0002] Ultra-high strength spring steel wire refers to spring steel material with a tensile strength greater than 2000Mpa and a cross-sectional shrinkage greater than 40% after heat treatment. Under such high-strength conditions, the quality stability during spring processing is very sensitive to the aging time of the hot-rolled raw materials. At present, the aging period of raw materials needs to reach 15 days or more. Spring steel wire with a short aging period often breaks on its own in a static state after heat treatment at customers' locations. By analyzing the self-broken fracture, it is found that the surface structure of the fracture is finer and there is a quenching layer structure; by scanning and analyzing the fracture, there is a morphology of hydrogen-induced delayed fracture. In response to this phenomenon, the material must be shipped to users for use only when the aging period reaches more than 15 days, which brings great pressure to warehousing and delivery. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a control method for shortening the aging period of ultra-high strength spring steel wire in view of the shortcomings of the above-mentioned prior art, which can successfully solve the problem of self-breaking in a static state after heat treatment by users, improve the performance of ultra-high strength spring steel wire, effectively shorten the aging period of ultra-high strength spring steel wire, and further solve the pressure of warehousing and delivery.

[0004] The technical solution of the present invention to solve the above technical problems is: a control method for shortening the aging period of ultra-high strength spring steel wire, the method specifically comprising the following steps: S1 rolling production adopts medium temperature final rolling, and the sizing inlet temperature is 880±20℃; S2 rolling production uses medium temperature spinning, the spinning temperature is 870±20℃; After S3 wire is rolled, it enters the Stelmor air cooling line for cooling; After the S4 coil is collected, it is hung on a C-hook for transportation.

[0005] The present invention further defines the scheme: Preferably, the cooling process of the Stelmor air-cooling line in S3 is: 1# fan opening 70%, 2# fan opening 60%, 3# fan opening 50%, 4# fan opening 40%, 5# fan opening 30%, and 1-9 covers are opened.

[0006] Preferably, the cooling water tanks used for controlling the temperature before final rolling and spinning in S1 or S2 are two groups of water tanks, and the opening degrees of the two groups of water tanks are the same, both of which are 40%-60%.

[0007] Preferably, the coiling temperature in S4 is 540-580°C, and when the coil temperature drops to a certain temperature, the subsequent cooling fan is turned off for heat preservation before packaging. Preferably, when the coil temperature drops to 400°C, the subsequent cooling fan is turned off for heat preservation for 30 minutes before packaging.

[0008] The beneficial effects of the present invention are as follows: the present invention can successfully solve the problem of self-breaking in a static state after heat treatment by the user, improve the performance of ultra-high strength spring steel wire, effectively shorten the aging period of ultra-high strength spring steel wire from 15 days to 7 days, and further solve the pressure of warehousing and delivery, and the warehousing circulation turnover can be increased by 25%. DETAILED DESCRIPTION Example

[0009] This embodiment provides a control method for shortening the aging period of an ultra-high strength spring steel wire, which is applied to an ultra-high strength spring steel wire SAE9254. The method specifically includes the following steps: S1 rolling production adopts medium temperature final rolling, and the sizing inlet temperature is 880℃; S2 rolling production uses medium temperature spinning, the spinning temperature is 870℃; The cooling water tanks used for the temperature control before S3 final rolling and spinning are two groups of water tanks, and the opening degree of the two groups of water tanks is the same, both 50%; After rolling, the S4 wire rod enters the Stelmore air cooling line for cooling. Since the carbon content of ultra-high strength spring steel is 0.52%-0.58%, it belongs to hypoeutectoid steel. The ferrite and pearlite microstructures are transformed in the Stelmore air cooling line. In order to make the microstructures uniformly transformed, the ultra-high strength spring steel wire rod is properly opened when entering the Stelmore air cooling line after spinning. The opening of 1# fan is 70%, the opening of 2# fan is 60%, the opening of 3# fan is 50%, the opening of 4# fan is 40%, the opening of 5# fan is 30%, and 9 covers are opened. The spring steel wire rod is cooled to the phase change point of 720℃ in the Stelmore air cooling line and enters the insulation cover for microstructure transformation; After S4 coils are rolled up, they are hung on C-type hooks for transportation. The temperature during rolling is 560℃. Since the removal rate of hydrogen is highest at 300℃-400℃, the dissolution rate of hydrogen increases with the temperature above this temperature; the release rate of hydrogen decreases when the temperature is below this temperature. Therefore, when the coil temperature is 400℃, the subsequent cooling fan is turned off to keep warm for 30 minutes before packaging, so as to solve the problem of self-breaking of the material in a static state after heat treatment.

[0010] This batch of φ15mm SAE9254 was sent to the user after aging for 7 days to make 2000MPa grade ultra-high strength spring steel wire. It is in good condition and no self-breaking phenomenon after heat treatment occurs.

[0011] Table 1

[0012] Table 2

[0013] Table 1 shows the frequency of spontaneous breakage after heat treatment of materials with a short aging period of 7 days as reported by customers one year before the method of this embodiment was used. Table 2 shows the frequency of spontaneous breakage after heat treatment of materials with a short aging period of 7 days as reported by customers one year after the method of this embodiment was used. It can be seen that the present invention can successfully solve the problem of spontaneous breakage in a static state after heat treatment by users, and can effectively shorten the aging period of ultra-high strength spring steel wire.

[0014] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A control method for shortening the aging period of ultra-high strength spring steel wire, characterized in that: The method specifically comprises the following steps: S1 rolling production adopts medium temperature final rolling, and the sizing inlet temperature is 880±20℃; S2 rolling production uses medium temperature spinning, the spinning temperature is 870±20℃; After S3 wire is rolled, it enters the Stelmor air cooling line for cooling; After the S4 coil is collected, it is hung on a C-hook for transportation.

2. A control method for shortening the aging period of ultra-high strength spring steel wire according to claim 1, characterized in that: The cooling process of the Stelmor air cooling line in S3 is: 1# fan opening 70%, 2# fan opening 60%, 3# fan opening 50%, 4# fan opening 40%, 5# fan opening 30%, and 1-9 covers are opened.

3. A control method for shortening the aging period of ultra-high strength spring steel wire according to claim 1, characterized in that: The cooling water tanks used for controlling the temperature before final rolling and spinning in S1 or S2 are both two groups of water tanks, and the opening degrees of the two groups of water tanks are the same, both of which are 40%-60%.

4. A control method for shortening the aging period of ultra-high strength spring steel wire according to claim 1, characterized in that: The coiling temperature in S4 is 540-580°C. When the coiling temperature drops to a certain temperature, the subsequent cooling fan is turned off to keep the temperature, and then packaging is carried out.

5. A control method for shortening the aging period of ultra-high strength spring steel wire according to claim 4, characterized in that: When the coil temperature drops to 400° C., the cooling fan for subsequent packaging is turned off to keep the coil warm for 30 minutes before packaging.

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