Manufacturing method of high-manganese austenitic stainless steel for deep drawing

Abstract

The invention provides a manufacturing method of high-manganese austenitic stainless steel for deep drawing. The high-manganese austenitic stainless steel for deep drawing comprises the following components in percentage by mass: less than or equal to 0.17% of C, less than or equal to 0.75% of Si, 12.50-24.00% of Mn, less than or equal to 0.050% of P, less than or equal to 0.015% of S, 12.00-15.00% of Cr, more than or equal to 1.00% of Ni, less than or equal to 0.25% of N and the balance of Fe and inevitable impurity elements. The manufacturing method further comprises the steps of low-nickel molten iron primary smelting, AOD smelting hot continuous rolling and solid solution annealing acid pickling. The product provided by the invention has high strength, good cold deep drawing processing performance and good comprehensive performance, and has great market application prospects and cost competitiveness.

Description

Technical Field

[0001] This invention relates to the field of stainless steel production, and specifically to a method for manufacturing high-manganese austenitic stainless steel for deep drawing. Background Technology

[0002] Low-nickel austenitic stainless steel, by replacing some of the Ni element in Cr-Ni stainless steel with elements such as Mn and N, has lower costs and excellent comprehensive properties, and is widely used in the domestic decoration and welded pipe industries. However, the addition of Mn and N makes cold working of low-nickel austenitic stainless steel more difficult, resulting in higher strength and a higher work hardening index, which restricts the development and application of this steel grade.

[0003] Nickel expands the austenite phase region, and austenitic steels used at low temperatures generally have a high nickel content. Nickel is a precious metal, and its limited reserves coupled with increasing usage exacerbate its rising price. Manganese and nitrogen also expand the austenite phase region, and nitrogen has a strengthening effect when dissolved in steel. Replacing nickel with manganese and nitrogen can save precious metal resources. Therefore, research on low-nickel austenitic stainless steel, through advancements in manganese alloy smelting technology, aims to increase the Mn content in the steel, expand the austenite phase region, improve hot working performance and surface quality, improve the quality of raw materials for cold rolling, reduce cold working accidents and quality losses, and enhance market competitiveness.

[0004] The research results show that increasing the nitrogen content in steel significantly improves the mechanical properties and corrosion resistance of steel. However, when the nitrogen content in steel exceeds 0.8%, while the mechanical properties are improved, the corrosion resistance of steel is reduced, brittleness is increased, and the ductile-brittle transition temperature is also significantly increased.

[0005] In austenitic stainless steel, nickel is the main austenitizing element, its primary role being to form and stabilize austenite, giving the stainless steel its excellent strength, plasticity, and toughness. However, nickel is a precious and rare metal, and the production of austenitic stainless steel consumes a large amount of nickel, resulting in high product prices and hindering the development of resource-efficient materials.

[0006] In summary, the existing technology has the following problems: austenitic stainless steel is expensive and wastes resources. Summary of the Invention

[0007] This invention provides a method for manufacturing high-manganese austenitic stainless steel for deep drawing, which helps to reduce costs and save expensive strategic resources.

[0008] Therefore, the present invention proposes a method for manufacturing high-manganese austenitic stainless steel for deep drawing, comprising:

[0009] The high-manganese austenitic stainless steel for deep drawing uses the following composition and its mass percentage: C: 0.10%~0.17%, Si: ≤0.75%, Mn: 12.50~24.00%, P: ≤0.050%, S: ≤0.015%, Cr: 12.00~15.00%, Ni≥1.00%, N: ≤0.25%, with the remainder being Fe and unavoidable impurity elements;

[0010] The manufacturing method also includes: primary refining of low-nickel molten iron, hot continuous rolling with AOD smelting, solution annealing, and pickling. The primary refining of low-nickel molten iron involves sintering and blast furnace smelting of low-nickel laterite nickel ore to obtain low-nickel molten iron with a Ni content of 1.15%-1.5%, a Cr content of 2.0%-4.0%, a Mn content of 0.6%-2.5%, a Si content of 0.3%-3.5%, a P content of 0.02%-0.03%, and a S content of 0.025%-0.30%.

[0011] The present invention also provides a high-manganese austenitic stainless steel for deep drawing, wherein the high-manganese austenitic stainless steel for deep drawing adopts the following composition and its mass percentage: C: ≤0.17% (e.g., 0.10% to 0.17%), Si: ≤0.75%, Mn: 12.50 to 24.00%, P: ≤0.050%, S: ≤0.015%, Cr: 12.00 to 15.00%, Ni ≥1.00%, N: ≤0.25%, and the remainder is Fe and unavoidable impurity elements.

[0012] Furthermore, the high-manganese austenitic stainless steel for deep drawing adopts the following composition and its mass percentage: C: 0.12%, Si: 0.52%, Mn: 18.08%, P: 0.048%, S: 0.006%, Cr: 12.10%, Ni: 1.00%, N: 0.17%, with the remainder being Fe and unavoidable impurity elements; the cold-rolled bright annealed cold-rolled coil of high-manganese austenitic stainless steel for deep drawing has a thickness of 0.12 mm, a yield strength of 492 MPa, a tensile strength of 890 MPa, an elongation of 52.7%, and a Vickers hardness (HV0.5) value of 230 HV.

[0013] Furthermore, the high-manganese austenitic stainless steel for deep drawing adopts the following composition and its mass percentage: C: 0.14%, Si: 0.47%, Mn: 12.55%, P: 0.048%, S: 0.004%, Cr: 12.70%, Ni: 1.02%, N: 0.16%, with the remainder being Fe and unavoidable impurity elements; the thickness of the hot-rolled white sheet coil is 2.0 mm, the yield strength is 460 MPa, the tensile strength is 870 MPa, the elongation is 50.2%, and the Rockwell hardness is 97.7 HRB.

[0014] This invention expands the application of low-nickel austenitic stainless steel in deep-drawing products by increasing the Mn content and the comprehensive proportion of other elements in the steel composition, and through optimized manufacturing processes. The product exhibits excellent surface quality and processing performance, fully meeting market requirements. After bright annealing, the strip has a yield strength Rp0.2 ≥ 460 MPa, tensile strength Rm ≥ 820 MPa, elongation at break A ≥ 50%, and Vickers hardness HV ≤ 245. Compared with existing technologies, the high-manganese austenitic stainless steel for deep drawing of this invention is not only lower in cost and saves on expensive Ni elements, but also does not contain Cu. The product has high strength and good cold deep-drawing processing performance, exhibiting superior overall performance and possessing significant market application prospects and cost competitiveness. Detailed Implementation

[0015] To provide a clearer understanding of the technical features, objectives, and effects of this invention, the invention is now described.

[0016] 1) This invention provides a high-manganese austenitic stainless steel for deep drawing and its manufacturing method, comprising the following components and their mass percentages: C: ≤0.17%, Si: ≤0.75%, Mn: 12.50~24.00%, P: ≤0.050%, S: ≤0.015%, Cr: 12.00~15.00%, Ni≥1.00%, N: ≤0.25%, with the remainder being Fe and unavoidable impurity elements; the manufacturing method includes: low-nickel molten iron → AOD → LF refining → continuous casting → hot continuous rolling → solution annealing and pickling → white skin → 20-roll single-stand reversible rolling mill → bright annealing → quality inspection → finished product.

[0017] 2) Primary refining process

[0018] Low-nickel (0.8-1.0%) laterite nickel ore is sintered and smelted in a blast furnace to obtain low-nickel molten iron. The molten iron contains 1.15%-1.5% Ni, 2.0%-4.0% Cr, 0.6%-2.5% Mn, 0.3%-3.5% Si, 0.02%-0.03% P, and 0.025%-0.30% S.

[0019] 3) Smelting process

[0020] Molten iron and scrap steel are added to a 65t AOD furnace for smelting. The requirements are that the phosphorus content of the molten iron is ≤0.03%, and the scrap steel is mainly low-nickel iron with a phosphorus content of ≤0.032%. The smelting technology mainly relies on the low-cost, high-phosphorus, and high-carbon ferromanganese alloy system. The more high-carbon ferromanganese is added, the longer the AOD smelting cycle is, and the higher the phosphorus content of the molten steel. According to the technical and production organization requirements, the manganese content of the molten steel is increased by adding all or the maximum limit of high-carbon ferromanganese. The composition of the molten steel is monitored during the smelting process. Combined with the limit control of phosphorus content in the steel, when phosphorus or smelting cycle cannot meet the technical and production organization requirements, a small amount of electrolytic manganese is added to fine-tune the manganese content. This ensures that the manganese content, harmful elements, and smelting cycle in the steel meet the technical and production organization requirements, and maximizes the smelting technology and cost advantages of the high-carbon ferromanganese + electrolytic manganese alloy system.

[0021] Among them, the P content of the main materials is controlled as follows: P ≤ 0.03% for molten iron, P ≤ 0.032% for low-nickel iron, and P ≤ 0.090% for high-carbon ferromanganese. The P content of the main materials is strictly controlled to ensure that the P content of molten steel is ≤ 0.050%. Measures to overcome the long smelting cycle are: high-carbon ferromanganese is added in 3 batches during the oxidation period. When the blowing temperature is 1680-1720℃, the first batch of 4 tons of high-carbon ferromanganese is added to the 65t AOD furnace, with an oxygen-nitrogen ratio of 1 / 5 to 1 / 2, and a cumulative gas separation time of 8-10 minutes. When the temperature rises again to 1680-1720℃, the second batch of 4 tons of high-carbon ferromanganese is added, with an oxygen-nitrogen ratio of 1 / 5 to 1 / 2, and a gas separation time of 7-10 minutes. Temperature is measured midway to shorten the smelting cycle and control the temperature and decarburization efficiency, with a cumulative gas separation time of 15-20 minutes. When the temperature rises again to 1640-1680℃, the third batch of 2-4 tons of high-carbon ferromanganese is added, with an oxygen-nitrogen ratio of 1 / 5 to 1 / 2, and a cumulative gas separation time of 10-15 minutes. The entire smelting cycle is controlled within 125 minutes, achieving continuous casting with two strands.

[0022] The above method overcomes the difficulty of increasing Mn content through high-manganese alloys, which leads to a longer AOD smelting cycle, shortens the smelting cycle, and controls the content of harmful element P.

[0023] Ni extraction primarily utilizes 304 stainless steel scrap and high-nickel iron. The main production steps are: AOD furnace oxygen supply and heating → alloy melting → oxidation and decarburization → reduction → alloying → composition fine-tuning → qualified molten steel; steelmaking temperature ≥1490℃; during oxidation, alloy fine-tuning is performed according to the steelmaking composition, with temperature controlled at 1640-1680℃; top lance is used whenever possible; lime addition is 65-75 kg / t, added in small amounts multiple times; reduction basicity is controlled at 1.8-2.4; AOD tapping temperature is controlled at 1540-1560℃; LF refining slag formation includes lime addition ≤0.6 kg / t, fluorite addition ≤1.0 kg / t, and ferrosilicon powder ≤0.5 kg / t; samples are taken for composition analysis, and calcium treatment is performed according to the total aluminum content in the steel, followed by alloying for composition adjustment; medium-intensity argon blowing ≥3 minutes, with a bright surface achieved during the soft blowing process. The diameter is approximately 200mm, the diameter of the medium-strength blown bright surface is approximately 400mm, the soft blowing time is ≥10min, and the settling time is ≥15min; the LF outlet temperature is controlled at 147-1480℃, and the continuous casting start-up furnace temperature is increased by 40℃ on this basis; the continuous casting adopts a twin-strand slab continuous casting machine with cross-sectional dimensions of 150-180mm×620-850mm×9900mm, superheat of 25~40℃, and nozzle insertion depth of 90-100mm; the water flow rate of the narrow face of the primary cooling crystallizer is controlled at 280-300L / min, and the water flow rate of the wide face is controlled at 1650~1700L / min; the secondary cooling adopts a weak cooling regime, and the casting speed is controlled at 0.8-1.0m / min; after the billet is cut, it is put into a deburring machine to clean the end cutting slag.

[0024] 4) Hot rolling process

[0025] Hot rolling employs a 4-stand roughing mill and a 9-stand finishing mill in a fully continuous process. Heating temperature is controlled in three stages: preheating stage temperature 600-700℃, heating stage temperature 1260-1290℃, and finishing stage temperature 1250-1280℃, with a heating time ≥140 minutes, ensuring uniform billet heating and meeting mill temperature requirements. Roughing billet dimensions are 34-38mm thick × 600-800mm wide, with an initial roughing temperature of 1130-1150℃. 170℃; finishing rolling start temperature 1030-1100℃, finishing rolling finish temperature 1000-1060℃; coiling temperature 750-900℃; billet descaling before roughing rolling at 26.5-28MPa, descaling pressure after roughing R2 stand at 11.5-13MPa, and air blowing descaling before finishing F1 stand with compressed air pressure ≥0.5Mpa to ensure the surface quality of the strip after rolling and avoid the indentation of iron oxide scale.

[0026] 5) Solution annealing and pickling process

[0027] The hot-rolled black strip steel was solution annealed in a 950mm double-belt continuous annealing furnace at a temperature of 1010–1100℃. Zone 10 with burners was 1010℃, with temperatures gradually increasing to 1100℃ from zones 10 to 15. The soaking zone temperature was controlled at ≥1080℃, and the annealing speed was 11.5–22.8 m / min. The hardness of the steel strip after annealing was controlled at ≤99 HRB. Pickling was performed in three sections, with pickling tank lengths of 35m, 25m, and 25m respectively. Sections one and two used a mixture of H2SO4, HF, and HNO3. Acid pickling is performed using acid solutions with concentrations of HF: 0–60 g / L, H2SO4: 180–300 g / L, and HNO3: 90–150 g / L, at a temperature of 70–85°C. The third stage uses pure HNO3 pickling at a temperature of 35–55°C and a pickling speed ≤60 m / min. The pH value of the alkaline solution in the neutralization tank is controlled at 12–13. The rinsing water temperature is 70–80°C. After the strip passes through the extrusion rollers, no visible water should remain on the surface. The drying temperature is ≥80°C to ensure the steel strip surface is dry and to prevent rust.

[0028] 6) Cold rolling and annealing process

[0029] White steel coils after solution annealing and pickling are used as raw materials for a cold-rolling 20-roll single-machine reversible mill. The raw material properties include a yield strength Rp0.2 ≥ 400 MPa, tensile strength Rm ≥ 750 MPa, elongation at break A50 ≥ 50%, a good 180° cold bending test (D = 2a), and Rockwell hardness HRB ≤ 98. Depending on the required thickness, cold rolling can be performed in one, two, or three passes. The thinner the finished product, the more rolling passes are required. Each pass has a total reduction of 30%-60%, with 3-6 rolling passes: 6 passes in the first pass, 4-5 passes in the second pass, and 3 passes in the third pass. The first pass process is cold rolling - bright annealing - finished product; the second pass process is cold rolling - bright annealing - cold rolling - bright annealing - finished product; and the third pass process is cold rolling - bright annealing - cold rolling - bright annealing - cold rolling - bright annealing - finished product. Bright annealing temperature 1080℃, TV value 4-5.

[0030] 7) Finished product performance

[0031] After bright annealing, the strip has a yield strength Rp0.2≥460MPa, tensile strength Rm≥820MPa, elongation after fracture A≥50%, and Vickers hardness HV≤245.

[0032] Results: By employing a low-cost, high-carbon ferromanganese smelting technology, the Mn content in the steel is increased during the AOD smelting process. After hot rolling and pickling, the average Rockwell hardness of the product decreases by 3 HRB, and the average elongation increases by 8.6%, significantly improving the rolling and deep-drawing performance of the product. This replaces the technical bottleneck of traditional low-nickel austenitic stainless steel, which relies on adding Cu to improve deep-drawing performance. Conventional low-nickel austenitic stainless steel for stamping requires the addition of more than 0.5% Cu. Since Cu is a scarce strategic resource with high prices, adding 0.1% Cu to steel increases the cost per ton of steel by approximately 80 RMB / ton. This invention, by removing Cu and increasing Mn content, fully meets the deep-drawing performance requirements, saving approximately 400 RMB / ton in cost for scarce and expensive strategic Cu. Simultaneously, by increasing the Mn content, the stability of hot-rolled austenitic steel is improved, the heating temperature and rolling mill force are reduced, and the cost per ton of steel decreases by 3 HRB. 3 Electricity consumption per ton of steel decreased by 10 kWh, resulting in energy cost savings of approximately 70 yuan per ton of steel. In summary, by adopting low-cost, high-carbon ferromanganese smelting technology, increasing the Mn content in steel, and removing Cu by removing Mn, the scarce and expensive strategic metal Cu is saved. Simultaneously, the product possesses the properties of deep-drawing austenitic stainless steel, saving approximately 400 yuan per ton of expensive metal and reducing energy costs by approximately 70 yuan per ton. After Mn removal, the added value per ton of steel increases by 950 yuan, and the profit-generating capacity is more than 250 yuan per ton higher than conventional low-nickel austenitic stainless steel. The product performance and surface quality fully meet the requirements of the deep-drawing process.

[0033] Example 1

[0034] It has been applied in the development of 0.12mm thick TGM high-manganese austenitic stainless steel cold-rolled coils. The main steps are as follows:

[0035] 1) Chemical composition control of TGM high manganese austenitic stainless steel cold-rolled coil: C: 0.12%, Si: 0.52%, Mn: 18.08%, P: 0.048%, S: 0.006%, Cr: 12.10%, Ni: 1.00%, N: 0.17%.

[0036] 2) The preheating section temperature of the heating furnace is 650℃, the heating section temperature is 1280℃, the homogenization temperature is 1260℃, and the heating time is 145min; the roughing rolling start temperature is 1140℃; the intermediate billet thickness is 36mm; the finishing rolling start temperature is 1060℃, the finishing rolling finish temperature is 1002℃; and the coiling temperature is 890℃.

[0037] 3) Solution annealing temperature 1090℃, annealing rate 22m / min, pickling rate 60m / min.

[0038] 4) The yield strength of the solution-treated and acid-washed white leather roll is 400 MPa, the tensile strength is 753 MPa, the elongation is 60.5%, and the Rockwell hardness is 95.9 HRB.

[0039] 5) The 20-roll cold rolling mill adopts a three-pass production process: cold rolling - bright annealing - cold rolling - bright annealing - cold rolling - bright annealing - finished product. 6) The finished cold-rolled and bright-annealed 0.12mm thick cold-rolled coil has a yield strength of 492MPa, a tensile strength of 890MPa, an elongation of 52.7%, a Vickers hardness (HV0.5) of 230HV, and an austenitic microstructure with a grain size of 8.47.

[0040] Example 2

[0041] It has been applied in the development of 0.19mm thick TGM high-manganese austenitic stainless steel cold-rolled coils. The main steps are as follows:

[0042] 1) Chemical composition control of TGM high manganese austenitic stainless steel cold-rolled coil: C: 0.13%, Si: 0.42%, Mn: 18.15%, P: 0.047%, S: 0.005%, Cr: 12.15%, Ni: 1.05%, N: 0.18%.

[0043] 2) The preheating section temperature of the heating furnace is 650℃, the heating section temperature is 1280℃, the soaking section temperature is 1260℃, and the heating time is 145min; the roughing rolling start temperature is 1130℃; the intermediate billet thickness is 35mm; the finishing rolling start temperature is 1050℃, the finishing rolling finish temperature is 998℃; and the coiling temperature is 830℃.

[0044] 3) Solution annealing temperature 1085℃, annealing rate 21.8m / min, pickling rate 60m / min.

[0045] 4) The yield strength of the solution-treated and acid-washed white leather roll is 458 MPa, the tensile strength is 785 MPa, the elongation is 61%, and the Rockwell hardness is 96.8 HRB.

[0046] 5) The cold rolling 20-roll mill adopts a two-pass rolling process: cold rolling - bright annealing - cold rolling - bright annealing - finished product.

[0047] 6) Cold-rolled bright annealed 0.19mm thick cold-rolled coil has a yield strength of 465MPa, a tensile strength of 830MPa, an elongation of 61%, a Vickers hardness (HV1.0) value of 232HV, and a metallographic structure of austenite with a grain size of 8.52.

[0048] Example 3

[0049] It has been applied in the development of 2.0mm thick D2 high-manganese austenitic stainless steel hot-rolled white sheet coils. The main steps are as follows:

[0050] 1) Chemical composition control of D2 high manganese austenitic stainless steel cold-rolled coil: C: 0.14%, Si: 0.47%, Mn: 12.55%, P: 0.048%, S: 0.004%, Cr: 12.70%, Ni: 1.02%, N: 0.16%.

[0051] 2) The preheating section temperature of the heating furnace is 665℃, the heating section temperature is 1275℃, the soaking temperature is 1260℃, and the heating time is 150min; the roughing rolling start temperature is 1160℃; the intermediate billet thickness is 34mm; the finishing rolling start temperature is 1065℃, the finishing rolling finish temperature is 920℃; and the coiling temperature is 826℃.

[0052] 3) Solution annealing temperature 1080℃, annealing rate 21m / min, pickling rate 58m / min.

[0053] 4) Solution-treated and pickled hot-rolled white steel coils have a yield strength of 460 MPa, a tensile strength of 870 MPa, an elongation of 50.2%, and a Rockwell hardness of 97.7 HRB. The microstructure is austenitic with a grain size of 8.48.

[0054] Example 4

[0055] It has been applied in the development of 2.4mm thick D2 high-manganese austenitic stainless steel hot-rolled white sheet coils. The main steps are as follows:

[0056] 1) Chemical composition control of D2 high manganese austenitic stainless steel cold-rolled coil: C: 0.15%, Si: 0.52%, Mn: 12.72%, P: 0.045%, S: 0.005%, Cr: 12.65%, Ni: 1.12%, N: 0.17%.

[0057] 2) The preheating section temperature of the heating furnace is 665℃, the heating section temperature is 1275℃, the soaking section temperature is 1260℃, and the heating time is 150min; the roughing rolling start temperature is 1140℃; the intermediate billet thickness is 35mm; the finishing rolling start temperature is 1065℃, the finishing rolling finish temperature is 950℃; and the coiling temperature is 826℃.

[0058] 3) Solution annealing temperature 1080℃, annealing rate 18m / min, pickling rate 50m / min.

[0059] 4) The solution-treated and pickled hot-rolled white steel coil has a yield strength of 460 MPa, a tensile strength of 870 MPa, an elongation of 50.2%, a Rockwell hardness of 97.7 HRB, and an austenitic microstructure with a grain size of 7.49.

[0060] Example 5

[0061] It was applied in the development of 2.0mm thick TGM high-manganese austenitic stainless steel hot-rolled white sheet coils. The main steps are: 1) Chemical composition control of TGM high-manganese austenitic stainless steel cold-rolled coils: C: 0.16%, Si: 0.55%, Mn: 18.15%, P: 0.046%, S: 0.005%, Cr: 12.15%, Ni: 1.12%, N: 0.18%.

[0062] 2) The preheating section temperature of the heating furnace is 650℃, the heating section temperature is 1270℃, the soaking section temperature is 1260℃, and the heating time is 150min; the roughing rolling start temperature is 1150℃; the intermediate billet thickness is 34mm; the finishing rolling start temperature is 1075℃, the finishing rolling finish temperature is 960℃; and the coiling temperature is 820℃.

[0063] 3) Solution annealing temperature 1095℃, annealing rate 22m / min, pickling rate 60m / min.

[0064] 4) Solution-treated and pickled hot-rolled white steel coils have a yield strength of 402 MPa, a tensile strength of 753 MPa, an elongation of 60.5%, a Rockwell hardness of 95.9 HRB, and a metallographic structure of austenite with a grain size of 7.25.

[0065] Example 6

[0066] It was applied in the development of 4.2mm thick TGM high-manganese austenitic stainless steel hot-rolled white sheet coils. The main steps are: 1) Chemical composition control of TGM high-manganese austenitic stainless steel cold-rolled coils: C: 0.12%, Si: 0.52%, Mn: 18.25%, P: 0.048%, S: 0.005%, Cr: 12.15%, Ni: 1.05%, N: 0.17%.

[0067] 2) The preheating section temperature of the heating furnace is 650℃, the heating section temperature is 1265℃, the soaking section temperature is 1260℃, and the heating time is 145min; the roughing rolling start temperature is 1130℃; the intermediate billet thickness is 38mm; the finishing rolling start temperature is 1060℃, the finishing rolling finish temperature is 945℃; and the coiling temperature is 800℃.

[0068] 3) Solution annealing temperature 1086℃, annealing rate 11.5m / min, pickling rate 45m / min.

[0069] 4) The solution-treated and pickled hot-rolled white steel coil has a yield strength of 467 MPa, a tensile strength of 785 MPa, an elongation of 60.7%, a Rockwell hardness of 98.3 HRB, and a metallographic structure of austenite with a grain size of 7.75.

[0070] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. The various components of the present invention can be combined with each other without conflict. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing high-manganese austenitic stainless steel for deep drawing, characterized in that, The manufacturing method of the high-manganese austenitic stainless steel for deep drawing includes: The high-manganese austenitic stainless steel for deep drawing uses the following composition and its mass percentage: C: 0.10%~0.17%, Si: ≤0.75%, Mn: 12.50~24.00%, P: ≤0.050%, S: ≤0.015%, Cr: 12.00~15.00%, Ni≥1.00%, N: ≤0.25%, with the remainder being Fe and unavoidable impurity elements; The manufacturing method also includes: primary refining of low-nickel molten iron, AOD smelting, hot continuous rolling, and solution annealing and pickling. The primary refining of low-nickel molten iron involves sintering and blast furnace smelting of low-nickel laterite nickel ore to obtain low-nickel molten iron with a Ni content of 1.15%-1.5%, a Cr content of 2.0%-4.0%, a Mn content of 0.6%-2.5%, a Si content of 0.3%-3.5%, a P content of 0.02%-0.03%, and a S content of 0.025%-0.30%.

2. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the AOD smelting process, high-carbon ferromanganese is added in three batches. When the blowing temperature is 1680-1720℃, the first batch consists of 4 tons of high-carbon ferromanganese, with an oxygen-nitrogen ratio of 1 / 5 to 1 / 2 and a cumulative gas separation time of 8-10 minutes. When the temperature rises again to 1680-1720℃, the second batch consists of 4 tons of high-carbon ferromanganese, with an oxygen-nitrogen ratio of 1 / 5 to 1 / 2 and a gas separation time of 7-10 minutes, for a cumulative gas separation time of 15-20 minutes. When the temperature rises again to 1640-1680℃, the third batch consists of 2-4 tons of high-carbon ferromanganese, with an oxygen-nitrogen ratio of 1 / 5 to 1 / 2 and a cumulative gas separation time of 10-15 minutes. The entire smelting cycle is controlled within 125 minutes.

3. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, The manufacturing method of the deep-drawing high-manganese austenitic stainless steel also includes: a cold rolling annealing process after solution annealing and pickling, wherein the white sheet after solution annealing and pickling is used as raw material for a cold rolling 20-roll single-machine reversible mill, and the raw material properties are: yield strength Rp0.2≥400MPa, tensile strength Rm≥750MPa, elongation after fracture A50≥50%, good 180° cold bending test, and Rockwell hardness HRB≤98.

4. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the hot continuous rolling process, the roughing rolling temperature is 1130-1170℃; the intermediate billet thickness is 34-38mm.

5. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the hot continuous rolling process, the initial rolling temperature of the finishing mill is 1030-1100℃, and the final rolling temperature of the finishing mill is 1000-1060℃.

6. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the hot continuous rolling process, the coiling temperature is 750-900℃.

7. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the hot continuous rolling process, the billet is descaled once before the roughing mill starts rolling at a pressure of 26.5-28 MPa. After the R2 stand of the roughing mill, the descaling pressure is 11.5-13 MPa. Before the F1 stand of the finishing mill, air blowing descaling is used with a compressed air pressure ≥0.5 MPa to ensure the surface quality of the strip after rolling and to prevent iron oxide scale from being pressed in.

8. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the solution annealing and pickling process, the hot-rolled black strip steel is solution annealed in a double-belt continuous annealing furnace with an annealing temperature of 1010–1100℃. In the annealing furnace, the temperature in zone 10 with burners is 1010℃, and the temperature in zones 10 to 15 gradually increases to 1100℃. The temperature in the soaking zone is controlled at ≥1080℃, and the annealing speed is 11.5–22.8 m / min. After annealing, the hardness of the steel strip is controlled at ≤99HRB.

9. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the solution annealing pickling process, the pickling is divided into three sections, with each section having a pickling tank length of 35m, 25m, and 25m respectively. The first and second sections of pickling use a mixed acid of H2SO4, HF, and HNO3, with acid concentrations of HF: 0-60g / L, H2SO4: 180-300g / L, and HNO3: 90-150g / L, respectively, and an acid temperature of 70-85℃. The third section of pickling uses pure HNO3, with a pickling temperature of 35-55℃ and a pickling speed ≤60m / min.

10. The method for manufacturing high-manganese austenitic stainless steel for deep drawing as described in claim 1, characterized in that, In the solution annealing pickling process, the pH value of the alkaline solution in the neutralization tank is controlled at 12-13; the temperature of the rinsing water is 70-80℃.