Stainless steel bar for new energy battery and preparation method of stainless steel bar

Abstract

The invention provides a stainless steel bar for a new energy battery and a preparation method of the stainless steel bar, and belongs to the technical field of stainless steel materials, the stainless steel bar provided by the invention comprises the following chemical elements in percentage by weight: less than or equal to 0.10% of C, less than or equal to 1.00% of Si, more than or equal to 4.0% and less than or equal to 8.0% of Mn, less than or equal to 0.05% of P, less than or equal to 0.005% of S, more than or equal to 18.0% and less than or equal to 20.0% of Cr, more than or equal to 2.00% and less than or equal to 3.50% of Ni, less than or equal to 0.60% of Mo, more than or equal to 1.50% and less than or equal to 3.50% of Cu, more than or equal to 0.20% and less than or equal to 0.30% the addition form of the element N is selected from any one or more of chromium nitride, nitrided ferromanganese and high-nitrogen ferrochromium. The stainless steel bar prepared by the preparation method provided by the invention has the advantages of high hardness, excellent corrosion resistance and impact resistance, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel materials, and in particular to a stainless steel bar for new energy batteries and a preparation method thereof. Background Art

[0002] Stainless steel for new energy batteries is a special new type of stainless steel, which is high-nitrogen stainless steel. Due to the addition of nitrogen, stainless steel for new energy batteries has the characteristics of high strength, high corrosion resistance and high toughness compared with traditional stainless steel. However, the addition of nitrogen has two sides. If the amount of nitrogen added is too high, nitrides are easily formed in the stainless steel, which will lead to reduced corrosion resistance, toughness and impact resistance of the final product. At the same time, in the prior art, due to the need to add a large amount of nitrogen, the preparation steps of stainless steel for new energy batteries are relatively cumbersome, and its cost is much higher than that of traditional austenitic stainless steel. Summary of the invention

[0003] The object of the present invention is to provide a stainless steel for new energy batteries which has low cost, simple preparation steps and excellent corrosion resistance, toughness and impact resistance.

[0004] To achieve the above object, the first aspect of the present invention provides a method for preparing a stainless steel bar for a new energy battery, which specifically comprises the following steps:

[0005] S1: preparing a stainless steel bar by smelting and performing peeling and shot peening on the same, wherein the stainless steel bar is composed of the following chemical elements in weight percentage: C≤0.10%, Si≤1.00%, 4.0%≤Mn≤8.0%, P≤0.05%, S≤0.005%, 18.0%≤Cr≤20.0%, 2.00%≤Ni≤3.50%, Mo≤0.60%, 1.50%≤Cu≤3.50%, 0.20%≤N≤0.30%, the remainder being Fe and unavoidable impurities, the addition form of the N element being selected from any one or more of chromium nitride, ferromanganese nitride, and high nitrogen ferrochrome, peeling and shot peening are used to remove impurities such as oxide scale and rust on the surface of the stainless steel substrate, so that the surface of the stainless steel is restored to a smooth and flat state;

[0006] S2: first drawing process;

[0007] S3: bright annealing treatment;

[0008] S4: shot peening;

[0009] S5: second drawing process;

[0010] S6: straightening treatment;

[0011] S7: The saw cuts the stainless steel bars into suitable lengths to produce the finished products.

[0012] The nitrogen content of existing stainless steel for new energy batteries is more than 1%, which will lead to the decline of toughness, corrosion resistance and impact resistance of the final stainless steel product. The nitrogen content of the stainless steel bar for new energy batteries provided by the present invention is 0.2-0.3%, which has good toughness and impact resistance. In addition, the present invention prepares the original stainless steel bar by smelting, which can ensure the correctness and uniformity of the material composition in the proportion.

[0013] Preferably, in step S1, the diameter of the stainless steel rod is 25 mm.

[0014] Preferably, in step S2, the first drawing process has a drawing reduction ratio of 20 to 25%.

[0015] Preferably, in step S3, the annealing temperature of bright annealing is 900-1000° C., and the holding time per millimeter of effective diameter is 130-140 seconds.

[0016] Preferably, in step S3, bright annealing is performed in a protective gas atmosphere, and the protective gas atmosphere is a nitrogen-hydrogen mixed gas with a volume ratio of 1:3.

[0017] Preferably, the flow rate of the protective gas atmosphere is (10±2)*2m / h.

[0018] Preferably, in step S5, the drawing reduction ratio of the second drawing process is 13-18%.

[0019] A second aspect of the present invention provides a stainless steel bar for new energy batteries, and the stainless steel bar for new energy batteries is prepared by the preparation method described in the first aspect.

[0020] The present invention has the beneficial effects: the stainless steel bar for new energy batteries provided by the present invention adopts a smelting process to prepare a base material, wherein the Mo element is added, which can greatly improve the corrosion resistance of the final product, and the added form of the N element is selected from any one or more of chromium nitride, manganese iron nitride, and high nitrogen chromium iron, and the preparation process is simple. The stainless steel for new energy batteries provided by the present invention strictly controls the element content, thereby ensuring that the final product has high corrosion resistance, high hardness, high toughness and high impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the first drawing and second drawing dies of the present invention;

[0022] Figure 2 It is a schematic diagram of the finished product of the present invention. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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, the terms with conventionally understood meanings are defined herein for the purpose of illustrating or facilitating 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 reagents and instruments is carried out in accordance with the schemes and parameters given by the manufacturer.

[0026] The specific embodiment of the present invention aims to provide a stainless steel for new energy batteries which has a simple preparation method, high toughness and high impact resistance.

[0027] Based on this, the method for preparing stainless steel bars for new energy batteries provided by the present invention comprises the following steps:

[0028] S1: preparing a stainless steel bar by smelting and performing peeling and shot peening on the same, wherein the stainless steel bar is composed of the following chemical elements in weight percentage: C≤0.10%, Si≤1.00%, 4.0%≤Mn≤8.0%, P≤0.05%, S≤0.005%, 18.0%≤Cr≤20.0%, 2.00%≤Ni≤3.50%, Mo≤0.60%, 1.50%≤Cu≤3.50%, 0.20%≤N≤0.30%, the remainder being Fe and unavoidable impurities, the addition form of the N element being selected from any one or more of chromium nitride, ferromanganese nitride, and high nitrogen ferrochrome, peeling and shot peening are used to remove impurities such as oxide scale and rust on the surface of the stainless steel substrate, so that the surface of the stainless steel is restored to a smooth and flat state;

[0029] S2: first drawing process;

[0030] S3: bright annealing treatment;

[0031] S4: shot peening;

[0032] S5: second drawing process;

[0033] S6: straightening treatment;

[0034] S7: The saw cuts the stainless steel bars into suitable lengths to produce the finished products.

[0035] In the above embodiment, the stainless steel bar for new energy batteries is finally prepared by smelting and two drawing processes. The preparation steps are greatly simplified compared with the prior art. At the same time, smelting can ensure the correctness and uniformity of the material composition in the proportion, and the preparation method is simple.

[0036] The technical solution of the present invention is further described below through specific embodiments.

[0037] Example 1

[0038] Preparation of stainless steel bars for new energy batteries

[0039] S1: A stainless steel rod is prepared by smelting and subjected to peeling and shot peening treatment, wherein the diameter of the stainless steel rod is 25.00 mm, and the diameter after peeling is 23.00 mm, and the stainless steel rod is composed of the following chemical elements in the following weight percentages:

[0040] C0.061%, Si0.35%, P0.045%, S0.002%, Mn6.7%, Cr18.22%, Ni3.04%, Cu1.82%, N0.248%, Mo0.07%, the balance is Fe and inevitable impurities, N element is added in the form of ferromanganese nitride, peeling and shot peening to remove the oxide scale, rust and other impurities on the surface of the stainless steel substrate, so that the stainless steel surface can be restored to a smooth and flat state;

[0041] S2: The first drawing process, wherein the first drawing process has a drawing reduction ratio of 23.9%. The die schematic diagram of the first drawing process is as follows: Figure 1 As shown, the size of the stainless steel square bar after drawing is 18.00*18.00mm;

[0042] S3: bright annealing, wherein the bright annealing is carried out in a protective gas atmosphere, wherein the protective gas atmosphere is a nitrogen-hydrogen mixture with a volume ratio of 1:3, a flow rate of (10±2)*2m / h, an annealing temperature of 950°C, and a holding time of 133 seconds per millimeter of effective diameter;

[0043] S4: shot peening;

[0044] S5: Second drawing, wherein the second drawing process has a drawing reduction ratio of 14.5%, and the size of the stainless steel square bar after drawing is 16.55*16.55mm. The die schematic diagram of the second drawing is as follows Figure 1 As shown;

[0045] S6: straightening treatment;

[0046] S7: The sawing machine cuts the stainless steel bar of appropriate length to obtain the finished stainless steel bar for new energy batteries. The finished product diagram is as follows Figure 2 shown.

[0047] Example 2

[0048] Corrosion resistance test

[0049] A neutral salt spray test was conducted using a 5% mass fraction NaCl solution to determine the corrosion resistance of the stainless steel bar for new energy batteries prepared in Example 1, wherein the pH of the salt solution was controlled as follows: when atomized at 35°C, the pH of the collected solution was 6.5-7.2. The sample placement angle was 15°, the exposure time was 1000h, and the corrosion degree of the stainless steel bar was recorded at 2, 6, 24, 48, 72, 96, 144, 240, 480, 720, and 1000h after the start of the salt spray test, wherein the corrosion degree was divided into 11 levels, and the level determination criteria are shown in Table 1.

[0050] Table 1

[0051] Corrosion degree Defect area A(%) Corrosion degree Defect area A(%) 10 No defects 4 2.5～5 9 0～0.1 3 5～10 8 0.1～0.25 2 10～25 7 0.25～0.5 1 25～50 6 0.5～1 0 ≥50 5 1～2.5

[0052] The neutral salt spray resistance test results of the stainless steel bar for new energy batteries prepared in Example 1 are shown in Table 2.

[0053] Table 2

[0054] Test duration (h) 0 2 6 24 48 72 96 Rating 10 10 10 10 10 10 10 Test duration (h) 144 240 480 720 1000 Rating 10 9 9 9 8

[0055] From the results in Table 2, it can be seen that the stainless steel bar prepared in Example 1 can maintain excellent corrosion resistance within 720 hours.

[0056] Example 3

[0057] Mechanical properties testing

[0058] The mechanical properties of the stainless steel bar for new energy batteries prepared in Example 1 were measured using a universal testing machine, and the final tensile strength was measured to be 912 MPa and the yield strength was 881 MPa.

[0059] 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 method for preparing stainless steel bars for new energy batteries, characterized in that: The following steps are involved: S1: A stainless steel rod substrate is prepared by smelting and the stainless steel rod substrate is peeled and shot peened, wherein the stainless steel rod is composed of the following chemical elements in weight percentage: C≤0.10%, Si≤1.00%, 4.0%≤Mn≤8.0%, P≤0.05%, S≤0.005%, 18.0%≤Cr≤20.0%, 2.00%≤Ni≤3.50%, Mo≤0.60%, 1.50% ≤Cu≤3.50%, 0.20%≤N≤0.30%, the balance is Fe and inevitable impurities, the addition form of N element is selected from any one or more of chromium nitride, ferromanganese nitride, high nitrogen ferrochrome, peeling and shot peening to remove the oxide scale, rust and other impurities on the surface of the stainless steel substrate, so that the stainless steel surface is restored to a smooth and flat state; S2: first drawing process; S3: bright annealing treatment; S4: shot peening; S5: second drawing process; S6: straightening treatment; S7: The saw cuts the stainless steel bars into suitable lengths to produce the finished products.

2. The preparation method according to claim 1, characterized in that In the step S1, the diameter of the stainless steel rod substrate is 25 mm.

3. The preparation method according to claim 1, characterized in that: In the step S2, the first drawing process has a drawing reduction ratio of 20 to 25%.

4. The preparation method according to claim 1, characterized in that: In step S3, the annealing temperature of bright annealing is 900-1000° C., and the holding time per millimeter of effective diameter is 130-140 seconds.

5. The preparation method according to claim 1, characterized in that: In the step S3, bright annealing is performed in a protective gas atmosphere, and the protective gas atmosphere is a nitrogen-hydrogen mixed gas with a volume ratio of 1:

3.

6. The preparation method according to claim 5, characterized in that: The flow rate of the protective gas atmosphere is (10±2)*2m / h.

7. The preparation method according to claim 1, characterized in that: In the step S5, the second drawing process has a drawing reduction ratio of 13-18%.

8. A stainless steel bar for new energy batteries, characterized in that: The stainless steel bar for new energy batteries is prepared by any preparation method described in claims 1 to 7.

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