High-manganese non-magnetic stainless steel and preparation process thereof

Abstract

The steel comprises the following chemical components in percentage by weight: 0.07 percent to 0.25 percent of C, 0.20 percent to 0.6 percent of Si, 11.5 percent to 22 percent of Mn, 10 percent to 17 percent of Cr, 0.95 percent to 6 percent of Ni, 0.25 percent to 0.9 percent of Cu, 0.15 percent to 0.26 percent of N, less than or equal to 0.05 percent of P, less than or equal to 0.005 percent of S, 0.05 percent to 1.0 percent of Mo, 0.01 percent to 0.1 percent of Al, less than or equal to 0.5 percent of Nb, less than 0.0002 percent of Pb, less than or equal to 0.001 percent of Cd and the balance of Fe and inevitable impurities. According to the non-magnetic stainless steel, the tensile strength is larger than or equal to 515 MPa, the yield strength is larger than or equal to 205 MPa, the ductility is larger than or equal to 35%, the HRB is smaller than or equal to 99, or the HV is smaller than or equal to 249, the non-magnetic stainless steel is mainly used for reprocessing and producing buttons, zippers, clothing accessories, mechanical hardware, deep stretching products and the like, and the magnetic permeability after reprocessing is smaller than or equal to 1.01 * 10 <-6 > H / m.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical process, and in particular relates to a high-manganese non-magnetic stainless steel and a preparation process thereof. Background Art

[0002] Austenitic stainless steel refers to stainless steel with austenite structure at room temperature. Austenitic stainless steel has non-magnetic properties, good elongation, good formability, good corrosion resistance and weldability, so it has been widely used.

[0003] However, ordinary austenitic stainless steel still has weak magnetism, especially after deep drawing and other mechanical processing, its weak magnetic characteristics are more obvious, and the magnetic permeability is usually greater than 1.01×10 -6 H / m, it is difficult to use in buttons, zippers, clothing accessories, mechanical hardware and deep-drawn products that require absolute non-magnetic application scenarios. Summary of the invention

[0004] In order to solve the above technical problems existing in the prior art, the purpose of the present invention is to provide a high manganese non-magnetic stainless steel and its preparation process. The non-magnetic stainless steel of the present invention has a tensile strength of ≥515MPa, a yield strength of ≥205MPa, an elongation of ≥35%, HRB≤99 or HV≤249. The non-magnetic stainless steel is mainly used for reprocessing and producing buttons, zippers, clothing accessories, mechanical hardware and deep drawing products, etc. The magnetic permeability after reprocessing is ≤1.01×10 -6 H / m.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A high manganese non-magnetic stainless steel, characterized in that the chemical components in the steel include, by weight percentage, C: 0.07%-0.25%, Si: 0.20%-0.6%, Mn: 11.5%-22%, Cr: 10%-17%, Ni: 0.95%-6%, Cu: 0.25%-0.9%, N: 0.15%-0.26%, P≤0.05%, S≤0.005%, Mo: 0.05%-1.0%, Al: 0.01%-0.1%, Nb≤0.5%, Pb<0.002%, Cd≤0.001%, and the rest are Fe and unavoidable impurities.

[0007] At the same time, it is necessary to meet P+S≤0.05%, and the martensite temperature Md30=551-462 * (C%+N%)-92 * (Si%) -8.1 * (Mn%)-29 * (Ni%+Cu%)-13.7 *(Cr%) -18.5 * (Mo%)≤100.

[0008] The tensile strength of the stainless steel is ≥515MPa, the yield strength is ≥205MPa, the elongation is ≥35%, HRB ≤99 or HV ≤249, and the magnetic permeability after further processing is ≤1.01×10 -6 H / m.

[0009] The stainless steel is used for producing buttons, zippers, clothing accessories, mechanical hardware and deep-drawn products.

[0010] A production process of high manganese non-magnetic stainless steel, specifically comprising:

[0011] 1) Chemical composition control: In addition to conventional chemical composition control, in order to ensure that the magnetic permeability of the finished product is ≤1.01×10 - 6 H / m, reduce the martensitic phase transformation during the cold working process of the product, which leads to an increase in material magnetism and needs to be controlled

[0012] Md30=551-462 * (C%+N%)-92 * (Si%) -8.1 * (Mn%)-29 * (Ni%+Cu%)-13.7 * (Cr%) -18.5 * (Mo%) ≤ 100; In order to ensure the yield rate of the material after cold working, the Al content needs to be controlled in the range of 0.01% to 0.1% to improve the purity of the material.

[0013] 2) Continuous casting process: The superheat of the continuous casting molten steel is controlled at 10-30°C, the continuous casting pulling speed is 0.8-1.2m / s, the continuous casting electromagnetic stirring current is controlled at 1000-1600A, the continuous casting secondary cooling zone adopts weak cooling mode, and the specific water volume is ≤1.0L / kg.

[0014] 3) Hot rolling production process: The steel billet enters the heating furnace and is heated to a temperature of 1250-1300°C. It is heated for 180-280 minutes and then taken out of the furnace. It undergoes high-pressure dephosphorization before entering the rough rolling process. The steel billet is rolled back and forth for 3-5 passes until the thickness is 30-50 mm. It then enters the 5-7 continuous rolling process to form a black steel coil with a thickness of 6.0-2.0 mm and a width of 900-1600 mm.

[0015] 4) After the black steel coils are stored in the warehouse and cooled naturally for 3 to 5 days, 1 to 2 coils are randomly inspected to check whether there is peeling, cracks, etc., and then qualified ones enter the next production process.

[0016] 5) Solution pickling production process: The black steel coil undergoes high temperature annealing heat treatment at 1100-1200℃ and then enters the pickling process. The acid composition ratio is 150-300 g / L of sulfuric acid, 100-200 g / L of nitric acid, and 5-15 g / L of hydrofluoric acid. The TV value speed of the entire solution pickling line is 80-150 m / min. After that, the silver-white hot-rolled high-manganese stainless steel coil is obtained by coiling; the coil specification is 6.0-2.0 mm and the width is 900-1600 mm.

[0017] 6) Cold rolling production process: The silvery white high manganese stainless steel coil is cut into different widths and sent to a large four-roller rolling mill. After 6 to 15 reciprocating rolling passes, a semi-finished product is formed. The semi-finished product with a thickness of 0.4 to 1.5 mm enters the annealing furnace for a high-temperature heat treatment of 1080 to 1200 ° C. The steel coil runs at a speed of 5 to 20 m / min. It is then trimmed and re-rolled, and enters the finishing mill. After 3 to 7 passes of finishing rolling, the finished product is formed and subjected to a high-temperature heat treatment of 1080 to 1200 ° C again, finally forming a bright silvery white stainless steel finished strip with a thickness of 0.07 to 0.7 mm. The finished stainless steel strip is packaged and stored and delivered to customers.

[0018] The invention undergoes two high-temperature heat treatments at 1080-1200°C during the rolling process, thereby ensuring the non-magnetic cold processing performance of the austenitic stainless steel and improving the forming performance of the steel material, with an elongation of ≥35%.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention effectively avoids the formation of martensite magnetism after hot rolling and cold rolling by regulating the chemical composition and coordinating the heat treatment process, and at the same time achieves the softness, strong tensile strength and ductility of the steel. The tensile strength of the non-magnetic stainless steel of the present invention is ≥515MPa, the yield strength is ≥205MPa, the elongation is ≥35%, HRB ≤99 or HV ≤249, and the magnetic permeability after further processing is ≤1.01×10 -6 H / m, this non-magnetic stainless steel is mainly used for reprocessing and producing buttons, zippers, clothing accessories, mechanical hardware and deep drawing products, etc. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the specific implementation methods of the present invention are further described below in conjunction with embodiments. The following embodiments are used to specifically illustrate the contents of the present invention. These embodiments are only general descriptions of the contents of the present invention and do not limit the contents of the present invention.

[0022] The chemical composition of the embodiment of the present invention is shown in Table 1; the production process parameters of the embodiment are shown in Table 2; the pickling composition of the embodiment is shown in Table 3; and the properties of the steel plate of the embodiment are shown in Table 4.

[0023] Table 1 Chemical composition of Examples 1-10 (wt%)

[0024] Example C Si Mn Cr Ni Cu N P S Mo Al Nb Pb Cd P+S Md30 212W 0.13 0.25 11.8 13.3 1.0 0.41 0.17 0.046 0.0015 0.05 0.012 0.5 0.0018 0.001 0.0475 90.5 213W 0.17 0.2 15.5 13.2 1.0 0.48 0.22 0.045 0.0010 0.05 0.016 0.5 0.0008 0.001 0.090 18.75 216W 0.1 0.45 16.5 13.1 1.1 0.51 0.22 0.041 0.0021 0.05 0.23 0.05 0.0005 0.001 0.0431 38.29 217W 0.14 0.35 18.1 12.6 0.95 0.45 0.21 0.045 0.0007 0.055 0.013 0.5 0.0004 0.001 0.0457 25.23 226W 0.09 0.115 18 12.1 1.0 0.35 0.2 0.045 0.0005 0.05 0.057 0.5 0.0008 0.001 0.0455 64.32 XW214 0.12 0.33 14 17 4.2 0.50 0.21 0.035 0.0004 0.05 0.078 0.5 0.0007 0.001 0.0354 -88.02 XW216 0.09 0.31 15 16.5 5.0 0.8 0.16 0.028 0.0031 0.05 0.0.85 0.5 0.0005 0.001 0.0311 -98.43

[0025] Table 2 Production process parameters of Examples 1-10

[0026]

[0027]

[0028] Table 2 Production process parameters of Examples 1-10 (continued)

[0029]

[0030] Table 3 Acid washing ingredients of Examples 1-10

[0031] Example Sulfuric acid / g / L Nitric acid / g / L Hydrofluoric acid / g / L Pickling line TV value speed m / min 212w 300 200 15 85 213w 200 120 15 95 216w 200 120 8 100 217w 150 100 5 120 226w 150 100 5 130 Xw214 280 180 15 110 Xw216 280 180 15 110

[0032] Table 4 Performance of finished steel plates produced in Examples 1-10

[0033]

[0034]

Claims

1. A high manganese non-magnetic stainless steel, characterized in that: The chemical composition of steel by weight percentage includes: C: 0.07% ~ 0.25%, Si: 0.20% ~ 0.6%, Mn: 11.5% ~ 22%, Cr: 10% ~ 17%, Ni: 0.95% ~ 6%, Cu: 0.25% ~ 0.9%, N: 0.15% ~ 0.26%, P ≤ 0.05%, S ≤ 0.005%, Mo: 0.05% ~ 1.0%, Al: 0.01% ~ 0.1%, Nb ≤ 0.5%, Pb < 0.002%, Cd ≤ 0.001%, and the rest is Fe and unavoidable impurities.

2. The high manganese non-magnetic stainless steel according to claim 1, characterized in that: P+S≤0.05%, and martensite temperature Md30=551-462 * (C%+N%)-92 * (Si%) -8.1 * (Mn%)-29 * (Ni%+Cu%)-13.7 * (Cr%) -18.5 * (Mo%)≤100.

3. The high manganese non-magnetic stainless steel according to claim 1, characterized in that: The tensile strength of the stainless steel is ≥515MPa, the yield strength is ≥205MPa, the elongation is ≥35%, the hardness is ≤99HRB or HV is ≤249, and the magnetic permeability after further processing is ≤1.01×10 -6 H / m.

4. The high manganese non-magnetic stainless steel according to claim 1, characterized in that: The stainless steel is used for producing buttons, zippers, clothing accessories, mechanical hardware and deep-drawn products.

5. A production process of high manganese non-magnetic stainless steel according to any one of claims 1 to 4, characterized in that: Specifically include: 1) Hot rolling production process: The steel billet enters the heating furnace and is heated to 1250-1300°C for 180-280 minutes before being taken out of the furnace. After high pressure dephosphorization, it enters the rough rolling and continuous rolling to obtain black steel coils; 2) The black steel coil is cooled naturally after 3 to 5 days; 3) Solution pickling production process: After the black steel coil is annealed at 1100-1200℃, it enters the pickling process and then coiled to obtain the silvery white hot-rolled high manganese stainless steel coil; 4) Cold rolling production process: The semi-finished product is rolled by a four-roll rolling mill, and then enters the annealing furnace for high-temperature heat treatment at 1080-1200°C. The steel coil runs at a speed of 5-20m / min. It then enters the finishing mill, and the finished product is again subjected to high-temperature heat treatment at 1080-1200°C to finally form a bright silver-white stainless steel finished strip.

6. The production process of high manganese non-magnetic stainless steel according to claim 5, characterized in that: It also includes a continuous casting process, in which the superheat of the continuous casting molten steel is controlled at 10 to 30°C, and the continuous casting pulling speed is 0.8 to 1.2 m / s; the continuous casting electromagnetic stirring current is controlled at 1000 to 1600 A, and the continuous casting secondary cooling zone adopts a weak cooling mode, with a specific water volume of ≤1.0 L / kg.

7. The production process of high manganese non-magnetic stainless steel according to claim 5, characterized in that: The rough rolling is repeated 3 to 5 times to roll the steel billet to a thickness of 30 to 50 mm, and then the steel billet is rolled for 5 to 7 times in a row to obtain a black steel coil with a thickness of 6.0 to 2.0 mm and a width of 900 to 1600 mm.

8. The production process of high manganese non-magnetic stainless steel according to claim 5, characterized in that: The composition ratio of the acid in step 4) is: 150-300 g / L sulfuric acid, 100-200 g / L nitric acid, and 5-15 g / L hydrofluoric acid. The TV value speed of the entire solution pickling line is 80-150 m / min.

9. The production process of high manganese non-magnetic stainless steel according to claim 5, characterized in that: In the step 5), the four-roller rolling mill performs 6 to 15 reciprocating passes, and the finishing rolling is performed for 3 to 7 passes.

10. A production process for high manganese non-magnetic stainless steel according to claim 5 or 10, characterized in that: The thickness of the semi-finished product is 0.4-1.5 mm, and the thickness of the finished stainless steel strip is 0.07-0.7 mm.

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