A production process for austenitic stainless steel strip

Abstract

The present invention provides a production process for austenitic stainless steel strips. It prepares nickel-free stainless steel by increasing the nitrogen content; improves the hot working performance in austenitic stainless steel by adding boron; prepares an injection green body by introducing an electromagnetic vibration force field during the metal powder injection molding process and controls the introduced boron content. By defining the process parameters of subsequent degreasing, nitriding, and solution treatment, the precipitation of nitrides and borides is reduced. In the present invention, rare earth yttrium is added to the stainless steel for modification treatment. By controlling the introduced yttrium content, the effect of refining grains is achieved, and the precipitation of borides is synergistically reduced; anodic oxidation and sealing treatment are carried out on the surface of the austenitic stainless steel strip; and the modified molybdenum disulfide introduced into the sealing solution is a molybdenum-based metal framework obtained by encapsulating molybdenum disulfide spherical nanoflowers and zeolitic imidazolate frameworks together, which can effectively enhance the bonding force with the stainless steel surface.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel, and specifically to a production process of austenitic stainless steel strip. Background Art

[0002] Stainless steel has good properties such as corrosion resistance, high strength, high temperature resistance, and high recyclability, and is widely used in various fields such as construction, transportation, and energy. Stainless steel with a single-phase austenitic structure at room temperature is called austenitic stainless steel. In some austenitic stainless steels, the content of chromium and molybdenum is high, resulting in serious segregation of molybdenum elements during the solidification process. During the hot working process, the second phase is easily precipitated, which has an adverse effect on the pitting corrosion resistance and intergranular corrosion resistance of the material.

[0003] Nickel is the main austenitizing element in traditional austenitic stainless steel, which makes austenitic stainless steel have good strength, toughness, and plasticity. However, due to the scarcity of nickel in the earth's crust, it determines the high cost of nickel-containing stainless steel. Nitrogen is also an element that promotes austenite formation, which is beneficial to reducing the cost of stainless steel, improving mechanical properties and corrosion resistance. However, when preparing nitrided austenitic steel by the casting method, nitrogen is easily enriched at the front end of the solidification phase, and part of the nitrogen will escape during cooling, and the casting temperature is high, which is easy to burn manganese. Therefore, how to improve its thermal conductivity, corrosion resistance, and cutting performance while ensuring the excellent mechanical properties of austenitic stainless steel, and at the same time reduce its nickel content, is a hot issue in current research. Summary of the Invention

[0004] The purpose of the present invention is to provide a production process of austenitic stainless steel strip to solve the problems in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A production process of austenitic stainless steel strip includes the following steps:

[0007] S1: Under nitrogen protection, mix manganese powder, carbon powder, chromium powder, chromium nitride powder, molybdenum powder, chromium boride powder, yttrium powder, and iron powder for ball milling, screen to 9 - 12 µm, and add a polyaldehyde-based binder to continue ball milling for 15 - 20 min;

[0008] S2: Dynamically inject the ball-milled mixed powder through an electromagnetic vibration injection machine to obtain a pre-treated stainless steel strip;

[0009] S3: Catalytically degrease and thermally degrease the pre-treated stainless steel strip, and then perform nitriding sintering;

[0010] S4: Solution-treat the sintered stainless steel strip;

[0011] S5: After polishing the solution-treated stainless steel strip to a mirror finish, ultrasonically clean it in acetone and alcohol for 5 - 10 min successively. After drying, use the solution-treated stainless steel strip as the anode and graphite as the cathode, and place them in an electrolyte prepared from perchloric acid and ethylene glycol for anodic oxidation. Then, ultrasonically clean it in distilled water and alcohol for 5 - 10 min, and obtain the oxidized stainless steel strip after drying;

[0012] S6: Immerse the oxidized stainless steel strip in a pre-sealing solution for pre-sealing, then transfer it to a sealing solution for impregnation treatment for 5 - 10 min, and then wash it with acetone 3 - 5 times, and obtain the stainless steel strip with sealing treatment after drying;

[0013] S7: Perform chemical vapor deposition on the stainless steel strip with sealing treatment using polydimethylsiloxane to obtain an austenitic stainless steel strip.

[0014] Further, in terms of mass percentage, the elemental composition of the austenitic stainless steel strip is: manganese 10 - 12%, carbon 0.01 - 0.02%, chromium 17.5 - 18.5%, nitrogen 0.9 - 1.1%, molybdenum 3 - 3.2%, boron 0.02 - 0.03%, yttrium 0.01 - 0.015%, and the balance is iron; the mass percentage ratio of boron to yttrium in the austenitic stainless steel strip is 2.

[0015] Further, the working conditions for dynamic injection molding are: the injection temperature segments are 185 °C, 165 °C, 165 °C, and 155 °C in sequence, the mold temperature is 130 °C, the injection pressure during the injection process is 7×10 6 Pa, the holding pressure time is 25 s, and the working conditions for electromagnetic vibration are: the amplitude is 25 μm, and the vibration frequency is 2 Hz.

[0016] Further, the working conditions for catalytic debinding are: carried out in a catalytic debinding furnace, the catalytic medium is concentrated nitric acid and nitrogen, the acid feeding rate is 0.02 mL / min, and the nitrogen rate is 80 mL / min; the working conditions for thermal debinding are: heat and debind under a vacuum of 10 -3 Pa, heat up at a heating rate of 5 °C / min to 400 °C, hold for 1 h, and heat up to 600 °C at a heating rate of 4 °C / min, and hold for 2 h.

[0017] Further, the working conditions for nitriding sintering are: the temperature is 1250 - 1260 °C, the nitriding pressure is 80 - 110 KPa, and the time is 4 - 8 h.

[0018] Further, the working conditions for solution treatment are: hold at 1075 °C for 4 h and cool with water.

[0019] Further, the composition of the electrolyte is as follows: ethylene glycol is used as the solvent, and the volume fraction of perchloric acid is 1.5% - 3%; the working conditions for anodic oxidation are: the anodic voltage is 20 - 30 V, the oxidation time is 5 - 10 min, the oxidation temperature is 2 - 4 °C, and the current density is 2 A / dm 2 .

[0020] Further, the composition of the pre-sealing solution is: deionized water is used as the solvent, and the concentration of hydrogen peroxide is 2 - 6 mL / L and the concentration of ammonium cerium nitrate is 4 - 6 g / L; the temperature is 25 - 60 °C and the sealing time is 5 - 10 min.

[0021] Further, the preparation of the sealing solution includes the following steps:

[0022] 1) Disperse molybdenum acetylacetonate and glycerol in a mixed solution of isopropanol and deionized water, perform ultrasonic treatment for 10 - 15 min, transfer to a high-pressure autoclave with a polytetrafluoroethylene liner, keep warm at 190 °C for 3 h, cool, centrifuge, wash, add ethanol, and obtain the MoG solution;

[0023] 2) Mix the MoG solution, thiourea, ethanol, and deionized water, keep at 195 - 200 °C for 5 - 6 h, centrifuge, wash, dry, introduce argon gas, heat up to 695 - 700 °C and calcine for 1 - 2 h to obtain molybdenum disulfide spherical nanoflowers;

[0024] 3) Mix molybdenum disulfide spherical nanoflowers, zinc acetate dihydrate, 4,5 - dichloroimidazole, and methanol and stir for 20 - 30 min to obtain modified molybdenum disulfide;

[0025] 4) Mix trimesic acid and N,N - dimethylformamide and stir, add polyvinylpyrrolidone, deionized water, and modified molybdenum disulfide to obtain the sealing solution.

[0026] Further, the mass molar ratio of molybdenum disulfide spherical nanoflowers, zinc acetate dihydrate, and 4,5 - dichloroimidazole is 0.02 g : 0.05 mmol : 0.01 mmol; the mass ratio of trimesic acid, polyvinylpyrrolidone, and modified molybdenum disulfide is 10 : 100 : 1.

[0027] The beneficial effects of the present invention:

[0028] The present invention provides a production process for austenitic stainless steel strips. Through process optimization and composition regulation, austenitic stainless steel strips with strong corrosion resistance, good wear resistance, and good hydrophobicity are prepared.

[0029] In the present invention, nickel-free stainless steel is prepared by increasing the nitrogen content. Due to the solution strengthening effect of nitrogen atoms and the formation of high-hardness alloy nitrides with the matrix, during the nitriding process, some carbon and manganese form dispersed alloy carbides, improving the strength and hardness. Boron is added to improve the hot working performance of austenitic stainless steel. By virtue of the special segregation behavior of boron at grain boundaries, the harmful effect of sulfur is inhibited, improving the hot working performance of the material. In addition, the present invention has a relatively high content of molybdenum. Molybdenum can act together with boron to increase the hardenability of stainless steel, thereby improving its hot plasticity, wear resistance, and high-temperature creep resistance;

[0030] However, the solubility of boron in ordinary austenitic stainless steel is very low, generally less than 0.026%, and the atomic radius of boron differs greatly from other atoms in the matrix. The elastic binding energy with defects such as dislocations, grain boundaries, and vacancies is relatively large. If the added content is too high, borides will precipitate at positions such as grain boundaries, deteriorating the mechanical properties and ductility of stainless steel;

[0031] Therefore, in the present invention, an electromagnetic vibration force field is introduced during the metal powder injection molding process to prepare injection green compacts, and the introduced boron content is controlled. By limiting the process parameters of subsequent debinding, nitriding, and solution treatment, the precipitation of nitrides and borides is reduced, solving the segregation problem that may be caused by adding a high content of molybdenum. Moreover, in the present invention, rare earth yttrium modification treatment is carried out in stainless steel. By controlling the introduced yttrium content, the effect of refining grains is achieved, synergistically reducing the precipitation of borides, thereby improving the elongation and corrosion resistance of austenitic stainless steel.

[0032] In order to extend the service life of austenitic stainless steel strips and improve the corrosion resistance and hydrophobicity of the surface of austenitic stainless steel strips; in the present invention, anodic oxidation and sealing treatment are carried out on the surface of austenitic stainless steel strips. While improving the surface corrosion resistance of austenitic stainless steel strips, the contact between hydrogen and austenitic stainless steel strips is isolated.

[0033] The anodic oxidation used in the present invention does not change the crystal phase of austenitic stainless steel strips and does not generate new phases, but shows better corrosion resistance. The micro / nano pores generated are beneficial to improving the surface property uniformity of austenitic stainless steel strips after sealing;

[0034] In the present invention, ammonium cerium nitrate and hydrogen peroxide are used to prepare a pre-sealing solution. The decomposition of hydrogen peroxide can provide the required oxygen, promoting the generation of hydroxide ions. Cerium ions combine with hydroxide ions to form cerium hydroxide, which can be deposited in the pores of the anodic oxidation film to achieve a sealing effect; effectively delaying the erosion of corrosive media;

[0035] Then, through the combination of trimesic acid in the subsequent sealing solution with cerium hydroxide on the surface of stainless steel, a cerium-based metal framework is in-situ generated, and then through chemical vapor deposition, a superhydrophobic micro-nano structure is constructed on the surface of stainless steel, effectively improving the self-cleaning property of stainless steel;

[0036] The introduced modified molybdenum disulfide can effectively improve the wear resistance of the stainless steel surface, and the modified molybdenum disulfide introduced in the sealing liquid is a molybdenum-based metal framework obtained by encapsulating molybdenum disulfide spherical nanoflowers and zeolitic imidazolate frameworks together, which can effectively enhance the binding force with the stainless steel surface, thereby synergistically improving the hydrophobicity, wear resistance, oxidation and corrosion resistance of the stainless steel surface. Specific embodiments

[0037] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] It should be noted that if there are directional indications such as up, down, left, right, front, back... in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0039] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0040] Example 1

[0041] A production process of an austenitic stainless steel strip includes the following steps:

[0042] S1: Under nitrogen protection, manganese powder, carbon powder, chromium powder, chromium nitride powder, molybdenum powder, chromium boride powder, yttrium powder, and iron powder are mixed and ball-milled, screened to 9 µm, and polyaldehyde-based binder is added and ball-milled for another 15 min;

[0043] In terms of mass percentage, the elemental composition of the austenitic stainless steel strip is: manganese 10%, carbon 0.01%, chromium 17.5%, nitrogen 0.9%, molybdenum 3%, boron 0.02%, yttrium 0.01%, and the balance is iron;

[0044] S2: The ball-milled mixed powder is dynamically injection-molded through an electromagnetic vibration injection machine to obtain a pretreated stainless steel strip;

[0045] The working conditions for dynamic injection molding are as follows: the injection temperature sections are 185°C, 165°C, 165°C, and 155°C in sequence, the mold temperature is 130°C, the injection process pressure is 7×10 6 Pa, the holding pressure time is 25 s, and the working conditions for electromagnetic vibration are: the amplitude is 25 μm and the vibration frequency is 2 Hz;

[0046] S3: Catalytic degreasing and thermal degreasing treatments are carried out on the pretreated stainless steel strip, and then nitriding sintering is performed;

[0047] The working conditions for catalytic degreasing are: carried out in a catalytic degreasing furnace, the catalytic medium is concentrated nitric acid and nitrogen, the acid feeding rate is 0.02 mL / min, and the nitrogen rate is 80 mL / min; the working conditions for thermal degreasing are: heating and degreasing under a vacuum of 10 -3 Pa, heating at a heating rate of 5°C / min to 400°C, holding for 1 h, and heating to 600°C at a heating rate of 4°C / min and holding for 2 h;

[0048] The working conditions for nitriding sintering are: the temperature is 1250°C, the nitriding pressure is 80 KPa, and the time is 8 h;

[0049] S4: Solution treatment is carried out on the sintered stainless steel strip: holding at 1075°C for 4 h and cooling with water;

[0050] S5: After polishing the solution-treated stainless steel strip to a mirror state, ultrasonic cleaning is carried out in acetone and alcohol for 5 min in sequence. After drying, the solution-treated stainless steel strip is used as the anode and graphite as the cathode, and anodic oxidation is carried out in an electrolyte solution prepared from perchloric acid and ethylene glycol. Then, ultrasonic cleaning is carried out in distilled water and alcohol for 5 min, and after drying, the oxidized stainless steel strip is obtained;

[0051] The composition of the electrolyte solution is: using ethylene glycol as the solvent, and the volume fraction of perchloric acid is 1.5%; the working conditions for anodic oxidation are: the anode voltage is 20 V, the oxidation time is 10 min, the oxidation temperature is 2°C, and the current density is 2 A / dm 2 ;

[0052] S6: The oxidized stainless steel strip is immersed in a pre-sealing solution for pre-sealing, then transferred to a sealing solution for impregnation treatment for 5 min, and then washed with acetone 3 times. After drying, the sealed stainless steel strip is obtained;

[0053] The composition of the pre-sealing solution: using deionized water as the solvent, with a hydrogen peroxide concentration of 2 mL / L and an ammonium cerium nitrate concentration of 4 g / L; temperature 25°C, sealing time 10 min;

[0054] The preparation of the sealing solution includes the following steps:

[0055] 1) Disperse 120 mg of molybdenum acetylacetonate and 8 mL of glycerol in 40 mL of a mixed solution of isopropanol and deionized water with a volume ratio of 3:1, ultrasonically treat for 10 min, transfer to a high-pressure autoclave with a polytetrafluoroethylene liner, keep at 190 °C for 3 h, cool, centrifuge, wash, add 5 mL of ethanol to obtain the MoG solution;

[0056] 2) Mix 1 mL of the MoG solution, 50 mg of thiourea, and 20 mL of a mixed solution of ethanol and deionized water with a volume ratio of 5:3, keep at 195 °C for 6 h, centrifuge, wash, dry, introduce argon gas, heat up to 695 °C and calcine for 2 h to obtain molybdenum disulfide spherical nanoflowers;

[0057] 3) Mix 0.02 g of molybdenum disulfide spherical nanoflowers, 0.05 mmol of zinc acetate dihydrate, 0.01 mmol of 4,5-dichloroimidazole, and 0.6 mL of methanol and stir for 20 min to obtain modified molybdenum disulfide;

[0058] 4) Mix 5 mg of trimesic acid and 2 mL of N,N-dimethylformamide and stir, add 50 mg of polyvinylpyrrolidone, 1.5 mL of deionized water, and 0.5 mg of modified molybdenum disulfide to obtain a sealing solution;

[0059] S7: At 230 °C, perform vapor deposition on the sealed stainless steel strip with polydimethylsiloxane for 6 h to obtain an austenitic stainless steel strip.

[0060] Example 2

[0061] A production process of an austenitic stainless steel strip includes the following steps:

[0062] S1: Under nitrogen protection, mix manganese powder, carbon powder, chromium powder, chromium nitride powder, molybdenum powder, chromium boride powder, yttrium powder, and iron powder and ball mill, screen to 11 µm, add a polyaldehyde binder and continue ball milling for 18 min;

[0063] By mass percentage, the elemental composition of the austenitic stainless steel strip is: manganese 11%, carbon 0.015%, chromium 18%, nitrogen 1%, molybdenum 3.1%, boron 0.025%, yttrium 0.0125%, and the balance is iron;

[0064] S2: Dynamically inject and mold the ball-milled mixed powder through an electromagnetic vibration injection machine to obtain a pretreated stainless steel strip;

[0065] The working conditions for dynamic injection molding are: the injection temperature segments are 185 °C, 165 °C, 165 °C, 155 °C in sequence, the mold temperature is 130 °C, the injection pressure during the injection process is 7×10 6 Pa, the holding pressure time is 25 s, and the working conditions for electromagnetic vibration are: the amplitude is 25 µm and the vibration frequency is 2 Hz;

[0066] S3: Catalytic degreasing and thermal degreasing treatments are carried out on the pretreated stainless steel strip, and then nitriding sintering is carried out.

[0067] The working conditions for catalytic degreasing are as follows: It is carried out in a catalytic degreasing furnace, the catalytic medium is concentrated nitric acid and nitrogen, the acid feeding rate is 0.02 mL / min, and the nitrogen rate is 80 mL / min. The working conditions for thermal degreasing are as follows: Heating and degreasing are carried out under a vacuum of 10 -3 Pa, heating up at a heating rate of 5 °C / min to 400 °C, holding for 1 h, and heating up to 600 °C at a heating rate of 4 °C / min and holding for 2 h.

[0068] The working conditions for nitriding sintering are as follows: The temperature is 1255 °C, the nitriding pressure is 100 KPa, and the time is 6 h.

[0069] S4: Solution treatment is carried out on the sintered stainless steel strip: Holding at 1075 °C for 4 h and cooling with water.

[0070] S5: After polishing the solution-treated stainless steel strip to a mirror state, ultrasonically cleaning it in acetone and alcohol for 8 min in sequence. After drying, taking the solution-treated stainless steel strip as the anode and graphite as the cathode, placing them in an electrolyte solution prepared from perchloric acid and ethylene glycol for anodic oxidation, and then ultrasonically cleaning it in distilled water and alcohol for 8 min. After drying, the anodized stainless steel strip is obtained.

[0071] The composition of the electrolyte solution is as follows: Using ethylene glycol as the solvent, and the volume fraction of perchloric acid is 2%. The working conditions for anodic oxidation are as follows: The anode voltage is 25 V, the oxidation time is 8 min, the oxidation temperature is 3 °C, and the current density is 2 A / dm 2 ;

[0072] S6: Immerse the anodized stainless steel strip in a pre-sealing solution for pre-sealing, then transfer it to a sealing solution for impregnation treatment for 8 min, and then wash it 4 times with acetone. After drying, the sealed stainless steel strip is obtained.

[0073] The composition of the pre-sealing solution: Using deionized water as the solvent, where the hydrogen peroxide concentration is 4 mL / L and the ammonium cerium nitrate concentration is 5 g / L; the temperature is 35 °C and the sealing time is 7 min.

[0074] The preparation of the sealing solution includes the following steps:

[0075] 1) Disperse 120 mg of molybdenum acetylacetonate and 8 mL of glycerol in 40 mL of a mixed solution of isopropanol and deionized water with a volume ratio of 3:1, ultrasonically treat for 12 min, transfer it to a high-pressure autoclave with a polytetrafluoroethylene inner liner, hold at 190 °C for 3 h, cool, centrifuge, wash, and add 5 mL of ethanol to obtain the MoG solution.

[0076] 2) Mix 1 mL of MoG solution, 50 mg of thiourea, 20 mL of an ethanol and deionized water mixed solution with a volume ratio of 5:3, keep it at 198 °C for 5.5 h, centrifuge, wash, and dry. Then introduce argon gas and heat up to 698 °C for calcination for 1.5 h to obtain molybdenum disulfide spherical nanoflowers;

[0077] 3) Mix 0.02 g of molybdenum disulfide spherical nanoflowers, 0.05 mmol of zinc acetate dihydrate, 0.01 mmol of 4,5-dichloroimidazole, and 0.6 mL of methanol and stir for 25 min to obtain modified molybdenum disulfide;

[0078] 4) Mix 5 mg of trimesic acid and 2 mL of N,N-dimethylformamide and stir, then add 50 mg of polyvinylpyrrolidone, 1.5 mL of deionized water, and 0.5 mg of modified molybdenum disulfide to obtain a sealing solution;

[0079] S7: At 232 °C, perform vapor deposition on the sealing-treated stainless steel strip with polydimethylsiloxane for 5.5 h to obtain an austenitic stainless steel strip.

[0080] Example 3

[0081] A production process of an austenitic stainless steel strip, comprising the following steps:

[0082] S1: Under nitrogen protection, mix manganese powder, carbon powder, chromium powder, chromium nitride powder, molybdenum powder, chromium boride powder, yttrium powder, and iron powder and perform ball milling, screen to 12 µm, and add a polyaldehyde binder and continue ball milling for 20 min;

[0083] By mass percentage, the elemental composition of the austenitic stainless steel strip is: manganese 12%, carbon 0.02%, chromium 18.5%, nitrogen 1.1%, molybdenum 3.2%, boron 0.03%, yttrium 0.015%, and the balance is iron; the mass percentage ratio of boron to yttrium in the austenitic stainless steel strip is 2;

[0084] S2: Perform dynamic injection molding on the ball-milled mixed powder through an electromagnetic vibration injection machine to obtain a pretreated stainless steel strip;

[0085] The working conditions of the dynamic injection molding are: the injection temperature sections are 185 °C, 165 °C, 165 °C, 155 °C in sequence, the mold temperature is 130 °C, the injection process pressure is 7×10 6 Pa, the holding pressure time is 25 s, and the working conditions of the electromagnetic vibration are: the amplitude is 25 µm and the vibration frequency is 2 Hz;

[0086] S3: Perform catalytic degreasing and thermal degreasing on the pretreated stainless steel strip, and then perform nitriding sintering;

[0087] The working conditions for catalytic debinding are as follows: It is carried out in a catalytic debinding furnace, the catalytic medium is concentrated nitric acid and nitrogen, the acid feeding rate is 0.02 mL / min, and the nitrogen rate is 80 mL / min; the working conditions for thermal debinding are as follows: Heating and debinding are carried out under a vacuum of 10 -3 Pa, heating at a heating rate of 5 °C / min to 400 °C, holding for 1 h, and heating to 600 °C at a heating rate of 4 °C / min and holding for 2 h;

[0088] The working conditions for nitriding sintering are as follows: The temperature is 1260 °C, the nitriding pressure is 110 KPa, and the time is 4 h;

[0089] S4: Solution treatment of the sintered stainless steel strip: Holding at 1075 °C for 4 h and cooling with water;

[0090] S5: After polishing the solution-treated stainless steel strip to a mirror state, ultrasonically clean it in acetone and alcohol for 10 min in sequence. After drying, use the solution-treated stainless steel strip as the anode and graphite as the cathode, place it in an electrolyte prepared from perchloric acid and ethylene glycol for anodic oxidation, and then ultrasonically clean it with distilled water and alcohol for 5 - 10 min. After drying, the anodized stainless steel strip is obtained;

[0091] The composition of the electrolyte is as follows: Using ethylene glycol as the solvent, with the volume fraction of perchloric acid being 3%; the working conditions for anodic oxidation are as follows: The anode voltage is 30 V, the oxidation time is 5 min, the oxidation temperature is 4 °C, and the current density is 2 A / dm 2 ;

[0092] S6: Immerse the anodized stainless steel strip in a pre-sealing solution for pre-sealing, then transfer it to a sealing solution for impregnation treatment for 10 min, and then wash it with acetone 5 times. After drying, the sealed stainless steel strip is obtained;

[0093] The composition of the pre-sealing solution: Using deionized water as the solvent, with the hydrogen peroxide concentration being 6 mL / L and the ammonium cerium nitrate concentration being 6 g / L; the temperature is 60 °C and the sealing time is 5 min;

[0094] The preparation of the sealing solution includes the following steps:

[0095] 1) Disperse 120 mg of molybdenum acetylacetonate and 8 mL of glycerol in 40 mL of a mixed solution of isopropyl alcohol and deionized water with a volume ratio of 3:1, ultrasonically treat for 15 min, transfer it to a high-pressure autoclave with a polytetrafluoroethylene inner liner, hold at 190 °C for 3 h, cool, centrifuge, wash, and add 5 mL of ethanol to obtain the MoG solution;

[0096] 2) Mix 1 mL of MoG solution, 50 mg of thiourea, 20 mL of a mixed solution of ethanol and deionized water with a volume ratio of 5:3, keep it at 200 °C for 5 h, centrifuge, wash, and dry. Then, introduce argon and heat it to 700 °C for calcination for 1 h to obtain molybdenum disulfide spherical nanoflowers;

[0097] 3) Mix 0.02 g of molybdenum disulfide spherical nanoflowers, 0.05 mmol of zinc acetate dihydrate, 0.01 mmol of 4,5-dichloroimidazole, and 0.6 mL of methanol and stir for 30 min to obtain modified molybdenum disulfide;

[0098] 4) Mix 5 mg of trimesic acid and 2 mL of N,N-dimethylformamide and stir. Then, add 50 mg of polyvinylpyrrolidone, 1.5 mL of deionized water, and 0.5 mg of modified molybdenum disulfide to obtain a sealing solution;

[0099] S7: At 235 °C, perform vapor deposition on the stainless steel strip treated by sealing with polydimethylsiloxane for 5 h to obtain an austenitic stainless steel strip.

[0100] Comparative Example 1

[0101] Take Example 3 as the control group, without adding boron element, and other processes are normal.

[0102] Comparative Example 2

[0103] Take Example 3 as the control group, without adding yttrium element, and other processes are normal.

[0104] Comparative Example 3

[0105] Take Example 3 as the control group, the mass percentage of boron element and yttrium element is 1, and other processes are normal.

[0106] Comparative Example 4

[0107] Take Example 3 as the control group, without adding electromagnetic vibration, only use a vibration injection machine, and other processes are normal.

[0108] Comparative Example 5

[0109] Take Example 3 as the control group, the solution treatment temperature is 1100 °C, and other processes are normal.

[0110] Comparative Example 6

[0111] Take Example 3 as the control group, without performing anodic oxidation, and other processes are normal.

[0112] Comparative Example 7

[0113] Take Example 3 as the control group, without sealing treatment, and other processes are normal.

[0114] Comparative Example 8

[0115] Taking Example 3 as the control group, no vapor deposition was carried out, and other processes were normal.

[0116] Comparative Example 9

[0117] Taking Example 3 as the control group, modified molybdenum disulfide was not added during the sealing treatment, and other processes were normal.

[0118] Comparative Example 10

[0119] Taking Example 3 as the control group, molybdenum disulfide (molybdenum disulfide 234842: Merck reagent) was used to replace the modified molybdenum disulfide, and other processes were normal.

[0120] Sources of raw materials used in the above examples and comparative examples:

[0121] Molybdenum acetylacetonate 227749, ammonium cerium nitrate 229547 (99.9%), thiourea T8656, N,N-dimethylformamide PHR1553, polyvinylpyrrolidone PVP40, polydimethylsiloxane 1546300: Merck reagent; chromium boride powder: Shanghai Gelin Technology Co., Ltd.; polyaldehyde binder: BASF Germany; electromagnetic vibration injection molding machine UP88S: Guangzhou Yida Injection Molding Machinery Co., Ltd.; perchloric acid, ethylene glycol, acetone, hydrogen peroxide, methanol, trimellitic acid, zinc acetate dihydrate: Sinopharm Chemical Reagent Co., Ltd.; glycerol; concentrated nitric acid, isopropyl alcohol, analytical pure: Beijing Chemical Plant; 4,5-dichloroimidazole (98%): Shanghai Macklin Biochemical Technology Co., Ltd.

[0122] Performance testing:

[0123] The properties of the austenitic stainless steel strips prepared in Examples 1-3 and Comparative Examples 1-10 were measured;

[0124] Rockwell hardness: Nine positions were measured in sequence from the edge to the center. After removing unreasonable values, the remaining values were averaged;

[0125] Tensile test: The tensile strength was measured at 20 °C and 200 °C using an American Instron 8801 universal testing machine;

[0126] The salt spray resistance was tested with reference to GB / T1771-1991; the contact angle of the sample was measured: 5 µL water droplets; the results are shown in Table 1;

[0127]

[0128] Table 1

[0129] The present invention provides a production process of an austenitic stainless steel strip. Through process optimization and composition regulation, an austenitic stainless steel strip with strong corrosion resistance and good wear resistance is prepared.

[0130] Comparing Example 3 with Comparative Example 1 shows that the absence of boron element will deteriorate the mechanical properties of the stainless steel strip; comparing Example 3 with Comparative Examples 2 and 3 shows that adding rare earth yttrium modification treatment to stainless steel can achieve the effect of grain refinement by controlling the introduced yttrium content, synergistically reducing the precipitation of borides, thereby improving the tensile strength of austenitic stainless steel at room temperature and high temperature; comparing Example 3 with Comparative Example 4 shows that introducing an electromagnetic vibration force field during the metal powder injection molding process can effectively enhance the combination of various elements in the stainless steel strip, thereby improving its high-temperature creep resistance; comparing Example 3 with Comparative Example 5 shows that too high a solution temperature is not conducive to the improvement of the properties of the austenitic stainless steel strip.

[0131] By using the electromagnetic vibration force field introduced during the metal powder injection molding process to prepare the injection green body, controlling the introduced boron content, and limiting the process parameters of subsequent degreasing, nitriding, and solution treatment, the precipitation of nitrides and borides is reduced. And in the present invention, adding rare earth yttrium modification treatment to stainless steel can achieve the effect of grain refinement by controlling the introduced yttrium content, synergistically reducing the precipitation of borides, thereby improving the properties of the austenitic stainless steel strip.

[0132] Comparing Example 3 with Comparative Example 6 shows that anodic oxidation does not change the crystal phase of the sample and does not generate new phases, showing better corrosion resistance; comparing Example 3 with Comparative Examples 7 and 8 shows that in the present invention, ammonium cerium nitrate and hydrogen peroxide are used to prepare the pre-sealing solution, and the decomposition of hydrogen peroxide can provide the required oxygen to promote the generation of hydroxide ions. The cerium ions combine with the hydroxide ions to form cerium hydroxide, which can be deposited in the pores of the anodic oxidation film to achieve a sealing effect; effectively delaying the erosion of corrosive media; then through the combination of trimesic acid in the subsequent sealing solution with cerium hydroxide on the stainless steel surface, a cerium-based metal framework is in-situ generated, and then through chemical vapor deposition, a superhydrophobic micro-nano structure is constructed on the stainless steel surface, effectively improving the self-cleaning property of the stainless steel.

[0133] Comparing Example 3 with Comparative Examples 9 and 10 shows that the introduced modified molybdenum disulfide can effectively improve the wear resistance of the stainless steel surface, and the modified molybdenum disulfide introduced in the sealing solution is a molybdenum-based metal framework obtained by encapsulating molybdenum disulfide spherical nanoflowers and zeolitic imidazolate frameworks together, which can effectively enhance the binding force with the stainless steel surface, thereby synergistically improving the hydrophobicity, wear resistance, oxidation and corrosion resistance of the stainless steel surface.

[0134] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. All equivalent structural transformations made using the description of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A production process of austenitic stainless steel strip, characterized in that, it comprises the following steps: S1: Under nitrogen protection, mix manganese powder, carbon powder, chromium powder, chromium nitride powder, molybdenum powder, chromium boride powder, yttrium powder, and iron powder and ball mill them, screen to 9 - 12 µm, add polyaldehyde binder and continue ball milling for 15 - 20 min; S2: Dynamically inject the ball - milled mixed powder through an electromagnetic vibration injector to obtain a pretreated stainless steel strip; S3: Perform catalytic degreasing and thermal degreasing on the pretreated stainless steel strip, and then carry out nitriding sintering; S4: Perform solution treatment on the sintered stainless steel strip; S5: After polishing the solution - treated stainless steel strip to a mirror state, ultrasonically clean it in acetone and alcohol for 5 - 10 min in sequence. After drying, use the solution - treated stainless steel strip as the anode and graphite as the cathode, place them in an electrolyte prepared from perchloric acid and ethylene glycol for anodic oxidation, and then ultrasonically clean it with distilled water and alcohol for 5 - 10 min. After drying, obtain the oxidized stainless steel strip; S6: Immerse the oxidized stainless steel strip in a pre - sealing solution for pre - sealing, then transfer it to a sealing solution for impregnation treatment for 5 - 10 min, and then wash it with acetone 3 - 5 times. After drying, obtain the stainless steel strip with sealing treatment; S7: At 230 - 235 °C, perform vapor deposition on the stainless steel strip with sealing treatment using polydimethylsiloxane for 5 - 6 h to obtain an austenitic stainless steel strip; By mass percentage, the elemental composition of the austenitic stainless steel strip is: manganese 10 - 12%, carbon 0.01 - 0.02%, chromium 17.5 - 18.5%, nitrogen 0.9 - 1.1%, molybdenum 3 - 3.2%, boron 0.02 - 0.03%, yttrium 0.01 - 0.015%, and the balance is iron; in the austenitic stainless steel strip, the mass percentage ratio of boron to yttrium is 2:1; The working conditions for dynamic injection molding are as follows: the injection temperature segments are 185°C, 165°C, 165°C, and 155°C in sequence, the mold temperature is 130°C, the pressure during the injection process is 7×10 6 Pa, and the holding pressure time is 25 s; the working conditions for electromagnetic vibration are: the amplitude is 25 μm and the vibration frequency is 2 Hz; The working conditions for catalytic debinding are as follows: it is carried out in a catalytic debinding furnace, the catalytic medium is concentrated nitric acid and nitrogen, the acid feeding rate is 0.02 mL / min, and the nitrogen rate is 80 mL / min; the working conditions for thermal debinding are as follows: heating and debinding are carried out under a vacuum of 10 -3 Pa, heating at a heating rate of 5 °C / min to 400 °C, holding for 1 h, and heating to 600 °C at a heating rate of 4 °C / min and holding for 2 h; The working conditions of nitriding sintering are: temperature is 1250 - 1260 °C, nitriding pressure is 80 - 110 KPa, and time is 4 - 8 h; The working conditions of solution treatment are: keep at 1075 °C for 4 h and cool with water; The composition of the electrolyte is as follows: ethylene glycol is used as the solvent, and the volume fraction of perchloric acid is 1.5% - 3%; the working conditions for anodic oxidation are: the anodic voltage is 20 - 30 V, the oxidation time is 5 - 10 min, the oxidation temperature is 2 - 4 °C, and the current density is 2 A / dm 2 ; Composition of the pre - sealing solution: Using deionized water as the solvent, where the hydrogen peroxide concentration is 2 - 6 mL / L and the ammonium cerium nitrate concentration is 4 - 6 g / L; sealing temperature is 25 - 60 °C, and sealing time is 5 - 10 min.

2. According to the production process of an austenitic stainless steel strip described in claim 1, characterized in that, the preparation of the sealing solution comprises the following steps: 1) Disperse molybdenum acetylacetonate and glycerol in a mixed solution of isopropanol and deionized water, ultrasonically treat for 10 - 15 min, transfer to a high - pressure autoclave with a polytetrafluoroethylene inner lining, keep at 190 °C for 3 h, cool, centrifuge, wash, add ethanol to obtain MoG solution; 2) Mix the MoG solution, thiourea, ethanol, and deionized water, keep at 195 - 200 °C for 5 - 6 h, centrifuge, wash, dry, introduce argon gas, heat up to 695 - 700 °C and calcine for 1 - 2 h to obtain molybdenum disulfide spherical nanoflowers; 3) Mix molybdenum disulfide spherical nanoflowers, zinc acetate dihydrate, 4,5 - dichloroimidazole, and methanol and stir for 20 - 30 min to obtain modified molybdenum disulfide; 4) Mix trimellitic acid and N,N-dimethylformamide and stir. Then add polyvinylpyrrolidone, deionized water, and modified molybdenum disulfide to obtain a sealing solution.

3. The production process of an austenitic stainless steel strip according to claim 2, characterized in that, the mass molar ratio of molybdenum disulfide spherical nanoflowers, zinc acetate dihydrate, and 4,5-dichloroimidazole is 0.02 g: 0.05 mmol: 0.01 mmol; the mass ratio of trimellitic acid, polyvinylpyrrolidone, and modified molybdenum disulfide is 10: 100: 1.

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