A stainless steel bar for special-shaped transmission shaft and preparation method thereof

Abstract

The present invention provides a stainless steel bar for a special-shaped transmission shaft and a preparation method thereof, and relates to the technical field of stainless steel materials. The stainless steel for the special-shaped transmission shaft provided by the present invention comprises the following chemical components by mass: C≤0.08%, Si≤1.00%, Mn≤2.00%, P≤0.045%, S≤0.015%, 8.00%≤Ni≤10.50%, Cu≤0.70%, 18.00%≤Cr≤20.00%, and the remainder is Fe and inevitable impurities. The stainless steel and stainless steel bar for the special-shaped transmission shaft prepared by the preparation method provided by the present invention have a smooth surface without defects such as burrs, black and yellow skin, pull marks, cracks, folds, and warping, and its tensile strength is ≥780MPa. Different from conventional lathe processing, the present invention reduces raw material loss and saves costs through a drawing process, and has a wide range of applications.

Description

Technical Field

[0001] The invention relates to the field of stainless steel materials, and in particular to a stainless steel bar for a special-shaped transmission shaft and a preparation method thereof. Background Art

[0002] The drive shaft is a mechanical element used to transmit power. It is responsible for transmitting the rotational motion of the motor to different rotating shafts. Its compact structure, high transmission efficiency, and strong load-bearing capacity make the drive shaft a key component in various power transmission systems. Therefore, the tensile strength, wear resistance, and corrosion resistance of the drive shaft are crucial, which determine the service life of the drive shaft. Summary of the invention

[0003] The object of the present invention is to provide a stainless steel bar for a special-shaped transmission shaft and a preparation method thereof.

[0004] To achieve the above object, the present invention provides a stainless steel bar for a special-shaped transmission shaft in a first aspect, which comprises the following chemical components by weight:

[0005] C≤0.08%, Si≤1.00%, Mn≤2.00%, P≤0.045%, S≤0.015%, 8.00%≤Ni≤10.50%, Cu≤0.70%, 18.00%≤Cr≤20.00%, and the balance is Fe and unavoidable impurities.

[0006] In the present invention, the purpose of adding Cr is to improve the oxidation resistance and corrosion resistance of the steel and to form stable chromium carbide at high temperature.

[0007] Ni plays a role in suppressing the formation of ferrite.

[0008] A second aspect of the present invention provides a method for preparing a stainless steel bar for a special-shaped transmission shaft, comprising the following steps:

[0009] S1: preparing a stainless steel substrate that meets the standard of stainless steel bars for special-shaped transmission shafts according to the first aspect by smelting;

[0010] S2: Perform the first rough drawing and the first bright online annealing;

[0011] S3: Perform the first coating and drying process;

[0012] S4: Perform the second rough drawing and the second bright online annealing;

[0013] S5: Perform the second film coating and drying process;

[0014] S6: Perform the third rough drawing and the third bright online annealing;

[0015] S7: perform combined pulling;

[0016] Preferably, in step S1, the diameter of the stainless steel substrate obtained after smelting is 15 mm.

[0017] Preferably, in step S2, the first rough drawing has a surface reduction rate of 10-15%, the first online bright annealing temperature is 1000-1080°C, and the holding time per millimeter of effective diameter is 170-180s. Bright annealing is performed in a protective gas atmosphere, the protective gas atmosphere is a nitrogen-hydrogen mixed gas with a volume ratio of 1:3, and the flow rate of the protective gas atmosphere is 0.8±0.5m / h.

[0018] Preferably, in step S3, the temperature of the coating agent during the first coating treatment is 70-100°C, the coating treatment time is 15-45 minutes, and the stainless steel substrate after the coating treatment is dried at a temperature of 100-200°C for 20-70 minutes.

[0019] Preferably, in step S4, the second rough drawing has a surface reduction rate of 10-15%, the second online bright annealing temperature is 950-1000°C, and the holding time per millimeter of effective diameter is 70-80 seconds. Bright annealing is performed in a protective gas atmosphere, the protective gas atmosphere is a nitrogen-hydrogen mixed gas with a volume ratio of 1:3, and the flow rate of the protective gas atmosphere is 0.8±0.5m / h.

[0020] Preferably, in step S5, the temperature of the coating agent during the second coating treatment is 70-100°C, and the coating treatment time is 15-45 minutes; the stainless steel wire after the coating treatment is dried at a temperature of 100-200°C, and the drying time is 20-70 minutes.

[0021] Preferably, in step S6, the third rough drawing has a surface reduction rate of 10-15%, the third online bright annealing temperature is 950-1000°C, and the holding time per millimeter of effective diameter is 70-80 seconds. Bright annealing is performed in a protective gas atmosphere, the protective gas atmosphere is a nitrogen-hydrogen mixed gas with a volume ratio of 1:3, and the flow rate of the protective gas atmosphere is 0.8±0.5m / h.

[0022] Preferably, in step S7, the combined drawing reduction ratio is 10-15%.

[0023] The present invention has the beneficial effects that the special-shaped transmission shaft stainless steel bar prepared by the preparation method provided by the present invention has a smooth surface without defects such as burrs, black and yellow skin, pull marks, cracks, folds, and warping, and its tensile strength is ≥780MPa, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a schematic diagram of a rod obtained after the second rough drawing of the present invention;

[0025] Figure 2 This is a schematic diagram of a rod obtained after the third rough drawing of the present invention;

[0026] Figure 3 This is a schematic diagram of the finished rod obtained after combined drawing according to the present invention. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0028] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0029] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventionally understood meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available instruments is carried out in accordance with the protocols and parameters given by the manufacturer.

[0030] The purpose of the specific implementation of the present invention is to provide a stainless steel for a special-shaped transmission shaft, which comprises the following chemical components by weight:

[0031] C0.025%, Si0.42%, Mn0.84%, P0.038%, S0.002%, Ni8.03%, Cr18.43%, Cu0.32%, the balance is Fe and unavoidable impurities

[0032] In the above embodiment, the important alloying elements are C and Cr, and changes in their contents will significantly affect the ultimate tensile strength of the stainless steel.

[0033] In the above embodiment, C and Cr are very likely to segregate, which may result in residual gas or ferrite inside the stainless steel containing these elements. Based on this, the specific embodiment of the present invention uses a smelting method to prepare the stainless steel for the transmission shaft. The austenitic stainless steel for the transmission shaft prepared by this method can ensure that the residual porosity and ferrite are negligible. For specific steps, please refer to the specific embodiment.

[0034] Example 1

[0035] Preparation of stainless steel bars for special-shaped transmission shafts

[0036] S1: preparing a stainless steel substrate of 15 mm stainless steel standard for a transmission shaft by melting;

[0037] S2: Perform the first rough drawing and the first online bright annealing, wherein the first rough drawing obtains a 14.00 mm stainless steel round bar with a surface reduction rate of 12.88%, the first online bright annealing temperature is 1050°C, and the holding time per millimeter of effective diameter is 177 seconds;

[0038] S3: performing a first film treatment, wherein the temperature of the film agent during the first film treatment is 100° C., the film treatment time is 30 minutes, and the stainless steel substrate after the film treatment is dried at a temperature of 200° C.;

[0039] S4: Perform the second rough drawing and the second bright online annealing. The second rough drawing obtains a 13.60*12.50mm special-shaped stainless steel bar. The schematic diagram of the bar obtained after the second rough drawing is as follows: Figure 1 As shown, the area reduction rate is 13.79%, the second online bright annealing temperature is 980°C, and the holding time per millimeter of effective diameter is 74 seconds;

[0040] S5: performing a second film treatment, wherein the temperature of the film agent during the second film treatment is 100° C., and the film treatment time is 45 minutes; drying the stainless steel wire after the film treatment at a temperature of 100° C., and the drying time is 30 minutes;

[0041] S6: The third rough drawing and the third bright online annealing are performed. The third rough drawing obtains a 13.10*11.50mm special-shaped stainless steel bar. The schematic diagram of the bar obtained after the third rough drawing is as follows: Figure 2 As shown, the area reduction rate is 12.26%, the third online bright annealing temperature is 980°C, and the holding time per millimeter of effective diameter is 77 seconds;

[0042] S7: Combined drawing is performed to obtain a 12.60*10.65mm special-shaped stainless steel product. The schematic diagram of the bar product obtained after combined drawing is as follows Figure 3 As shown, the combined drawing reduction ratio is 12.45%.

[0043] Example 2

[0044] Tensile strength test

[0045] The tensile strength of the stainless steel bar for the special-shaped transmission shaft prepared in Example 1 was measured using a universal testing machine, and the final tensile strength was 788 MPa.

[0046] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A stainless steel bar for a special-shaped transmission shaft, characterized in that: By mass, it includes the following chemical components: C≤0.08%, Si≤1.00%, Mn≤2.00%, P≤0.045%, S≤0.015%, 8.00%≤Ni≤10.50%, Cu≤0.70%, 18.00%≤Cr≤20.00%, and the balance is Fe and unavoidable impurities.

2. A method for preparing a stainless steel bar for a special-shaped transmission shaft, characterized in that: The following steps are involved: S1: preparing a stainless steel substrate that meets the standard of the stainless steel bar for the special-shaped transmission shaft according to claim 1 by smelting; S2: Perform the first rough drawing and the first bright online annealing; S3: Perform the first coating and drying process; S4: Perform the second rough drawing and the second bright online annealing; S5: Perform the second film coating and drying process; S6: Perform the third rough drawing and the third bright online annealing; S7: Perform combined pulling.

3. The preparation method according to claim 2, characterized in that: In the step S1, the diameter of the stainless steel substrate obtained by smelting is 15 mm.

4. The preparation method according to claim 2, characterized in that: In the steps S2, S4 and S6, bright annealing is performed in a protective gas atmosphere, wherein the protective gas atmosphere is a nitrogen-hydrogen mixed gas with a volume ratio of 1:3, and the flow rate of the protective gas atmosphere is 0.8±0.5 m / h.

5. The preparation method according to claim 2, characterized in that: In the step S2, the first rough drawing has a surface reduction rate of 10-15%, the first online bright annealing temperature is 1000-1080° C., and the heat preservation time per millimeter of effective diameter is 170-180 seconds.

6. The preparation method according to claim 2, characterized in that: In the step S3, the temperature of the coating agent during the first coating treatment is 70-100°C, the coating treatment time is 15-45 minutes, and the stainless steel substrate after the coating treatment is dried at a temperature of 100-200°C for 20-70 minutes.

7. The preparation method according to claim 2, characterized in that: In the step S4, the second rough drawing has a surface reduction rate of 10-15%, the second online bright annealing temperature is 950-1000° C., and the heat preservation time is 70-80 seconds per millimeter of effective diameter.

8. The preparation method according to claim 2, characterized in that: In the step S5, the temperature of the coating agent during the second coating treatment is 70-100°C, and the coating treatment time is 15-45 minutes; the stainless steel wire after the coating treatment is dried at a temperature of 100-200°C, and the drying time is 20-70 minutes.

9. The preparation method according to claim 2, characterized in that: In the step S6, the third rough drawing has a surface reduction rate of 10-15%, the third online bright annealing temperature is 950-1000° C., and the heat preservation time is 70-80 seconds per millimeter of effective diameter.

10. The preparation method according to claim 2, characterized in that: In the step S7, the combined drawing reduction ratio is 10-15%.

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