Nickel-saving high-strength non-magnetic stainless steel and manufacturing method thereof

Abstract

The invention discloses nickel-saving type high-strength non-magnetic stainless steel and a preparation method thereof, and the nickel-saving type high-strength non-magnetic stainless steel comprises the following components in parts by mass: 0.10-0.20 of C; si is equal to 0.30 to 1.00; mn is equal to 18 to 22; p is less than or equal to 0.045; s is less than or equal to 0.010; cr is equal to 11.0 to 12.0; ni is equal to 1.0 to 2.0; cu is equal to 0.50 to 1.00; n is equal to 0.15 to 0.25; and the balance of inevitable impurities and the balance of Fe. The nickel-saving type high-strength non-magnetic stainless steel and the preparation method thereof are suitable for manufacturing high-strength building steel and engineering equipment which are high in non-magnetic requirement and have a certain anti-rust requirement.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel material preparation, and in particular to a nickel-saving high-strength non-magnetic stainless steel and a manufacturing method thereof. Background Art

[0002] Stainless steel has excellent corrosion resistance, formability, environmental compatibility, as well as high strength and toughness over a wide temperature range. It is widely used in military industry, heavy industry, light industry, electrical industry, aerospace, shipbuilding and other industries, as well as daily necessities industry and construction industry.

[0003] Non-magnetic stainless steel is a type of paramagnetic stainless steel. They are not magnetized with an external magnetic field and have a weak response to the magnetic field. They are used in many places, such as sleeves in solenoid valves, non-magnetic components in magnetic detection equipment, etc. Even if these components have weak magnetism, they will have an adverse effect on the performance of the equipment. Stainless steel with complete austenite has good non-magnetic properties, but sometimes there is a certain amount of residual ferrite in austenitic stainless steel, and austenitic stainless steel will show weak ferromagnetism after cold working. It can be seen that ensuring the stability of the full austenitic structure and deformation process is the core concern of non-magnetic stainless steel. In general, the higher the nickel content, the more stable the austenite phase, and the smaller the magnetic response from cold working. For example, after the same cold working, the magnetism of 316L with a higher nickel content is lower than that of 304 stainless steel with a lower nickel content. However, nickel is a precious metal, and adding nickel to austenitic steel will increase costs.

[0004] Among the relevant patents retrieved, Taigang Stainless Steel Patent CN202410772193.6 proposed a high-chromium, high-nickel non-magnetic stainless steel that can maintain non-magnetic properties in the cold-worked state. Changshu Institute of Technology Patent CN202311573183.1 proposed a wearable high-strength, high-toughness, corrosion-resistant non-magnetic stainless steel. Ningbo Qiyi Patent CN116497272A proposed a new type of ultra-thin non-magnetic stainless steel for hardened high-strength electronic devices. Posco Stainless Steel Patent CN202010106423.7 proposed a high-nickel, high-purity non-magnetic stainless steel. Baosteel Desheng's patent CN201911335675.0 proposed a high-nitrogen non-magnetic stainless steel with good comprehensive performance. The patent CN201910545405.6 of the Central Iron and Steel Research Institute proposed a high-strength, high-toughness, nitrogen-added non-magnetic stainless steel. The non-magnetic stainless steels proposed in the above patents have certain applications in different fields.

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a nickel-saving high-strength non-magnetic stainless steel and a manufacturing method thereof: the nickel-saving high-strength non-magnetic stainless steel has a yield strength Rp0.2 value ≥400MPa, an elongation A50 ≥30%, a relative magnetic permeability μr≤1.003, and a relative magnetic permeability μr≤1.005 when bent at 90°, and also has a certain rust resistance. The above-mentioned properties make the nickel-saving high-strength non-magnetic stainless steel suitable for manufacturing non-magnetic equipment, non-magnetic facilities, non-magnetic ships, etc. with a certain corrosion resistance. Summary of the invention

[0006] The object of the present invention is to provide a nickel-saving high-strength non-magnetic stainless steel and a manufacturing method thereof.

[0007] A nickel-saving high-strength non-magnetic stainless steel comprising the following components in parts by mass:

[0008] C=0.10~0.20

[0009] Si=0.30~1.00

[0010] Mn=18~22

[0011] P≤0.045

[0012] S≤0.010

[0013] Cr=11.0~12.0

[0014] Ni=1.0~2.0

[0015] Cu=0.50~1.00

[0016] N=0.15~0.25

[0017] Others are inevitable impurities and the balance is Fe.

[0018] A nickel-saving high-strength non-magnetic stainless steel comprises the following preparation steps:

[0019] S1 Preparation of steel billets or continuous casting billets

[0020] Selecting the nickel-saving high-strength non-magnetic stainless steel chemical composition to prepare steel billets or continuous casting billets;

[0021] S2 Heat Treatment

[0022] The steel billet or continuous casting billet is heat treated to obtain nickel-saving high-strength non-magnetic stainless steel.

[0023] As a further improvement of the present solution, the specific processing steps of the S2 heat treatment are: heating the steel billet or continuous casting billet, completing final rolling, and then performing solution heat treatment.

[0024] As a further improvement of the present solution, the steel billet or continuous casting billet is heated within a temperature range of 1100 to 1250°C.

[0025] The steel billet or continuous casting billet is heated within the temperature range of 1100-1250°C to make the structure uniform austenite, ensuring that the steel billet or continuous casting billet has reduced high temperature strength and higher high temperature plasticity.

[0026] As a further improvement of this solution, final rolling is completed at above 900°C.

[0027] Finish hot rolling is completed at above 900℃. The higher finishing temperature will partially eliminate the work hardening.

[0028] As a further improvement of this scheme, solution heat treatment is carried out in a temperature range of 950 to 1100°C.

[0029] Solution heat treatment is carried out in the high temperature range of 950-1100℃, so that the carbon and nitrogen after hot rolling are completely dissolved, and the structure is a softened full austenite structure. If cold working is performed later, intermediate annealing is allowed, and the temperature of intermediate annealing and final annealing is 950-1100℃.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The nickel-type high-strength non-magnetic stainless steel and the manufacturing method thereof of the present invention have the following beneficial effects compared with the prior art:

[0032] 1) In the present invention, the functions of the chemical components are as follows:

[0033] Carbon: 0.10-0.20. Carbon is an important austenitizing stabilizing element. Adding a higher carbon element can make the stainless steel structure fully austenitic, while reducing the deformation-induced martensite phase during cold working and keeping the stainless steel non-magnetic. Carbon is also an important strengthening element, but the higher the carbon content, the greater the amount of chromium carbides formed. The formation of chromium carbides will form chromium-poor areas in the steel, greatly reducing the corrosion resistance of the steel.

[0034] Silicon: 0.30-1.00. Silicon is added to steel mainly as a deoxidizer, and it also plays a role in solid solution strengthening. However, the higher the silicon content in steel, the poorer the ductility. In order to improve the machinability of stainless steel, its content should not exceed 1%.

[0035] Manganese: 18-22. Manganese is both a deoxidizing element and an important austenite stabilizing element. At the same time, manganese solid solution strengthening can significantly improve the strength of steel. A manganese content of 18-22% is an important basis for ensuring a stable full austenite structure.

[0036] Phosphorus: Phosphorus is a harmful element, so it should be reduced as much as possible according to production control levels.

[0037] Sulfur: Sulfur is also a harmful element. Not only will sulfides cause hot brittleness but they will also reduce corrosion resistance. Therefore, it should be reduced as much as possible according to the production control level.

[0038] Chromium: 11.0-12.0. In order to ensure the corrosion resistance of stainless steel, the chromium content is controlled above 11%. Chromium is an important ferrite element. When the chromium content is high, the ferrite phase will appear in the stainless steel and the austenite phase will be unstable during the deformation process. Therefore, the chromium content is kept below 12%.

[0039] Nickel: 1.0-2.0. Nickel is an important austenite stabilizing element and a precious metal. It is indispensable, but using more will increase the cost.

[0040] Copper: 0.50-1.00. Copper plays many roles in austenitic stainless steel, including improving corrosion resistance, improving cold working performance, and reducing cold working hardening tendency. However, increasing copper content will significantly increase costs.

[0041] Nitrogen: N = 0.15 ~ 0.25. Nitrogen is a strong austenitizing element, and it works with carbon, manganese, nickel, and copper to make the structure a stable full austenite structure. Nitrogen is an interstitial atom with a solid solution strengthening effect, which can improve the strength of the material, but adding too much will increase the difficulty of production.

[0042] 2) The non-magnetic stainless steel and its manufacturing technology provided by the present invention have a reasonable chemical composition range and a simple and easy production process.

[0043] 3) The non-magnetic stainless steel prepared by the present invention can meet the following performance requirements:

[0044] Yield Strength Rp 0.2 Value ≥ 400MPa, elongation A 50 ≥30%, relative magnetic permeability μ r ≤1.003, relative magnetic permeability μ when bent 90° r ≤1.005, and also has certain rust resistance.

[0045] 4) The non-magnetic stainless steel proposed in the present invention has good performance and low cost. It is suitable for manufacturing high-strength construction steel and engineering equipment with high non-magnetic requirements and certain rust prevention requirements. It can also be used to manufacture non-magnetic equipment, non-magnetic facilities, non-magnetic ships, etc. with certain corrosion resistance. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described below in conjunction with embodiments:

[0047] A nickel-saving high-strength non-magnetic stainless steel comprising the following components in parts by mass:

[0048] C=0.10~0.20

[0049] Si=0.30~1.00

[0050] Mn=18~22

[0051] P≤0.045

[0052] S≤0.010

[0053] Cr=11.0~12.0

[0054] Ni=1.0~2.0

[0055] Cu=0.50~1.00

[0056] N=0.15~0.25

[0057] Others are inevitable impurities and the balance is Fe.

[0058] A nickel-saving high-strength non-magnetic stainless steel, specifically comprising the following preparation steps:

[0059] S1 Preparation of steel billets or continuous casting billets

[0060] Selecting the nickel-saving high-strength non-magnetic stainless steel chemical composition to prepare steel billets or continuous casting billets;

[0061] S2 Heat Treatment

[0062] The steel billet or continuous casting billet is heat treated to obtain nickel-saving high-strength non-magnetic stainless steel.

[0063] The steel billet or continuous casting billet is heated in the temperature range of 1100-1250°C, final rolling is completed at above 900°C, and solution heat treatment is performed in the temperature range of 950-1100°C.

[0064] The steel billet or continuous casting billet is heated in the temperature range of 1100-1250℃ to make the structure uniform austenite, ensuring that the steel billet or continuous casting billet has reduced high temperature strength and higher high temperature plasticity. The hot rolling final rolling is completed above 900℃, and the higher final rolling temperature will partially eliminate the work hardening. The solid solution heat treatment is carried out in the higher temperature range of 950-1100℃, so that the carbon and nitrogen after hot rolling are completely dissolved, and the structure is a softened full austenite structure. If cold working is performed later, intermediate annealing is allowed, and the temperature of intermediate annealing and final annealing is 950-1100℃.

[0065] Example

[0066] The ingredients of Examples A to E of the present invention and Comparative Examples F to H are shown in Table 1, and the performance test of the product prepared by the preparation method of the present invention is shown in Table 2

[0067] Table 1 Chemical composition of Examples A to E (wt, %)

[0068] Example C Si Mn P S Cr Ni Cu N other A 0.10 0.40 20.1 0.023 0.002 11.9 2.0 0.7 0.23 else B 0.13 0.36 18.2 0.014 0.003 11.6 1.6 1.0 0.17 else C 0.16 0.31 21.1 0.042 0.001 11.2 1.5 0.6 0.15 else D 0.20 0.97 22.0 0.011 0.005 12.0 1.4 0.5 0.25 else E 0.17 0.62 19.6 0.032 0.010 11.3 1.0 0.7 0.20 else Comparative Example F 0.08 0.21 18.4 0.018 0.003 11.7 1.2 0.6 0.12 else Comparative Example G 0.10 0.32 16.7 0.029 0.003 11.4 1.0 0.5 0.15 else Comparative Example H 0.11 0.27 18.2 0.018 0.001 12.4 1.1 0.6 0.12 else

[0069] Table 2 Process and performance of Examples A to E

[0070]

[0071] Table 3 Comparison of chemical composition of non-magnetic stainless steel patents in the prior art and the present invention, wt%

[0072]

[0073] As shown in Tables 1, 2 and 3, the yield strength Rp of the finished steel bar (diameter 28 mm) is 0.2 Value ≥ 400MPa, elongation A 50 ≥30%, relative magnetic permeability μ r ≤1.003, relative magnetic permeability μ when bent 90° r ≤1.005. Contains more than 11% chromium and less than 2% nickel, has certain rust resistance and low cost.

[0074] When the carbon content and nitrogen content of Comparative Example F are lower than the design requirements, the yield strength of the material drops to below 400 MPa, thereby failing to meet the design performance requirements.

[0075] Similarly, when the carbon content and nitrogen content are at the lower limit of the designed chemical composition range, the addition of manganese is very critical. When the manganese content is lower than the designed lower limit, in Example G, the yield strength of the material drops to below 400 MPa, thereby failing to meet the designed performance requirements.

[0076] Furthermore, when the austenitizing elements such as carbon, nitrogen, nickel, copper, etc. are at the lower limit of the design chemical composition range, the chromium content is high, especially when it exceeds the upper limit of the design range, the relative magnetic permeability μ of the material in Example H is r The stability decreases to 1.003, and the relative magnetic permeability μ when bent 90° r It is 1.006, which exceeds the design performance requirements.

[0077] In summary, the non-magnetic stainless steel proposed in the present invention is particularly suitable for manufacturing high-strength construction steel and engineering equipment with high non-magnetic requirements and certain rust-proof requirements. It can be manufactured into steel plates, steel strips, rods and wires, and used to manufacture non-magnetic equipment, non-magnetic facilities, non-magnetic ships, etc. with certain corrosion resistance. The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent changes made using the present invention are within the patent protection scope of the present invention.

Claims

1. A nickel-saving high-strength non-magnetic stainless steel, characterized in that: Includes the following components in parts by mass: C＝0.10～0.20 Si=0.30~1.00 Mn=18~22 P≤0.045 S≤0.010 Cr＝11.0～12.0 Ni=1.0~2.0 Cu=0.50~1.00 N＝0.15～0.25 Others are inevitable impurities and the balance is Fe.

2. A method for preparing the nickel-saving high-strength non-magnetic stainless steel according to claim 1, characterized in that: The method comprises the following preparation steps: S1 Preparation of steel billets or continuous casting billets Selecting the nickel-saving high-strength non-magnetic stainless steel chemical composition to prepare steel billets or continuous casting billets; S2 Heat Treatment The steel billet or continuous casting billet is heat treated to obtain nickel-saving high-strength non-magnetic stainless steel.

3. According to the method for preparing nickel-saving high-strength non-magnetic stainless steel as described in claim 2, the specific processing steps of S2 heat treatment are: heating the steel billet or continuous casting billet, completing final rolling, and then performing solid solution heat treatment.

4. The method for preparing nickel-saving high-strength non-magnetic stainless steel according to claim 2, characterized in that: The steel billet or continuous casting billet is heated within the temperature range of 1100-1250°C.

5. The method for preparing nickel-saving high-strength non-magnetic stainless steel according to claim 2, characterized in that: Finish rolling is completed at above 900°C.

6. The method for preparing nickel-saving high-strength non-magnetic stainless steel according to any one of claims 2, 3 or 4, characterized in that: The solution heat treatment is carried out in the temperature range of 950-1100°C.

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