A corrosion-resistant bolt and a preparation method thereof

Abstract

The present invention relates to the field of bolt technology, specifically a corrosion-resistant bolt and a method for preparing the same. The corrosion-resistant bolt comprises the following elements in weight percentage: C: 0.25-0.35%, Si: 0.16-0.38%, Mn: 0.4-0.7%, Cr: 0.1-0.2%, Ni: 0.2-0.4%, Mo: 0.15-0.30%, Ti: 0.12-0.16%, Ru: 0.05-0.15%, Rh: 0.16-0.32%, Ir: 0.10-0.15%, with the remainder being iron and unavoidable impurities. The present invention manufactures the bolt through processes such as converter smelting, continuous rolling, and cold heading, and, combined with a double coating design, can provide excellent corrosion resistance and extend the service life of the bolt.

Description

Technical Field

[0001] The present invention relates to the technical field of bolts, in particular to a corrosion-resistant bolt and a preparation method thereof. Background Art

[0002] With the continuous advancement of industrialization, bolts, as a vital connection element, have been widely used in various fields. However, because bolts often operate in harsh environments, such as high temperatures, humidity, and acidic or alkaline environments, they are susceptible to corrosion, which shortens their service life and even causes connection failure. Corrosion can degrade the mechanical properties of bolts and even cause them to break, posing a safety hazard to equipment and structures.

[0003] Currently, conventional bolt corrosion protection methods primarily rely on surface coatings to improve their corrosion resistance. However, these methods have limitations. After prolonged use, the coatings can easily wear out or flake off, failing to provide long-term protection and shortening the bolt's service life.

[0004] Therefore, we propose a corrosion-resistant bolt and a preparation method thereof. Summary of the Invention

[0005] The object of the present invention is to provide a corrosion-resistant bolt and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing a corrosion-resistant bolt comprises the following steps:

[0008] Step S1: smelting the raw materials at 1500-1580°C to produce molten iron, which is then subjected to converter smelting and refining outside the converter to produce molten steel;

[0009] Step S2: continuously casting the molten steel into an ingot, and slowly cooling it; then heating and continuously rolling it to obtain a bar, and then slowly cooling it a second time; cold heading the slowly cooled bar to obtain a bolt blank; threading and heat treating the bolt blank to obtain a bolt;

[0010] Step S3: grinding, polishing, cleaning, degreasing and degreasing the bolts in sequence, and then placing them in an electroplating solution for electroplating to form an electroplating layer;

[0011] Step S4: In an ice bath, uniformly mix the corrosion inhibitor, aniline, and ethylbenzene to prepare solution A; uniformly mix 1-naphthol-4-sulfonic acid and deionized water, add sodium dodecylbenzenesulfonate, and stir uniformly to prepare solution B; dropwise add solution A to solution B over 30-40 minutes, and ultrasonically vibrate for 10-20 minutes; dropwise add a mixed solution of ammonium persulfate and deionized water over 30-60 minutes, react for 22-24 hours, filter, wash multiple times, and then vacuum dry at 50-60° C. for 24-48 hours to prepare a composite;

[0012] Step S5: uniformly mixing the epoxy resin, xylene, and n-butanol, adding the complex, a mixed solution of xylene and n-butanol, and then adding a defoamer and a curing agent, stirring at a speed of 800-1000 r / min for 30-50 minutes to prepare a modified epoxy resin coating;

[0013] Step S6: applying a modified epoxy resin coating on the surface of the electroplating layer to form an anti-corrosion coating, and curing the coating at 50-60° C. for 4-6 hours to obtain a corrosion-resistant bolt.

[0014] In the above technical solution, the raw materials are subjected to processes such as converter smelting, off-furnace refining, and continuous casting to produce steel ingots, which are then subjected to processes such as continuous rolling, cold heading, and heat treatment to produce bolts. After the bolts are surface treated, silicon dioxide and zinc are co-deposited on the bolt surface using electrodeposition technology to form an electroplating layer. Subsequently, solution A is prepared using ethylbenzene as an oil phase solvent and aniline and a corrosion inhibitor as raw materials. Solution B is prepared using 1-naphthol-4-sulfonic acid as a doping acid and sodium dodecylbenzenesulfonate as a surfactant. Solutions A and B are uniformly mixed and polymerized under the action of ammonium persulfate to form polyaniline hollow microspheres coated with a corrosion inhibitor, i.e., a composite. The composite is used as a filler and added to an epoxy resin system to produce a modified epoxy resin coating, which is applied to the surface of the electroplating layer to form an anti-corrosion coating, thereby producing corrosion-resistant bolts with a double coating.

[0015] Furthermore, the raw materials in step S1 include the following elements in weight percentage: C: 0.25-0.35%, Si: 0.16-0.38%, Mn: 0.4-0.7%, Cr: 0.1-0.2%, Ni: 0.2-0.4%, Mo: 0.15-0.30%, Ti: 0.12-0.16%, Ru: 0.05-0.15%, Rh: 0.16-0.32%, Ir: 0.10-0.15%, and the balance is iron and unavoidable impurities.

[0016] Furthermore, in step S1, argon is blown bottom and stirred throughout the converter smelting process, the converter endpoint P is controlled to be ≤ 0.02%, and the tapping temperature is controlled to be 1600-1700°C.

[0017] Furthermore, the refining outside the furnace in step S1 includes deoxidation, degassing, and soft blowing processes: 2-4% of the mass of the molten iron is added with silicon barium wire for deoxidation, and the degassing is a vacuum degassing treatment at a vacuum degree of 20-65 Pa for 10-20 minutes, and after the vacuum treatment, argon is soft blown for 20-30 minutes.

[0018] Furthermore, the continuous casting process conditions in step S2 are: superheat of 15-30° C., electromagnetic stirring of the crystallizer, electromagnetic stirring current of 200-300 A, and electromagnetic stirring frequency of 5-10 Hz.

[0019] Furthermore, the slow cooling process conditions in step S2 are: pit entry temperature 655-680°C, slow cooling time 78-84h, and pit exit temperature 160-185°C.

[0020] Furthermore, the heating and continuous rolling process conditions in step S2 are: heating temperature 1100-1250°C, starting rolling temperature 920-990°C, and finishing rolling temperature 950-1050°C.

[0021] Furthermore, the size of the rod in step S2 is Ø8-20 mm.

[0022] Furthermore, the secondary slow cooling process conditions in step S2 are: pit entry temperature 420-560° C., and slow cooling time 48-58 hours.

[0023] Furthermore, in step S2, the thread is processed by using a thread rolling machine.

[0024] Furthermore, the heat treatment process conditions in step S2 are: quenching temperature 850-870°C, holding time 1-2h, water cooling, cooling rate 10-15°C / s; tempering temperature 450-500°C, holding time 1-3h, air cooling, cooling rate 20-30°C / min.

[0025] Furthermore, the degreasing process conditions in step S3 are as follows: the degreasing agent is a mixed solution of acetone and ethanol, the mass ratio of which is 1:(1-2), and the ultrasonic degreasing is performed for 5-10 minutes.

[0026] Furthermore, the degreasing process conditions in step S3 are as follows: the formula of the degreasing liquid includes: 18-20 g / L sodium hydroxide, 7-9 g / L sodium carbonate, 7-9 g / L sodium pyrophosphate, 1-2 g / L alkylphenol polyoxyethylene ether; the degreasing temperature is 60-70° C., and the degreasing time is 5-10 min.

[0027] Furthermore, the formula of the electroplating solution in step S3 includes: 220-250 g / L zinc sulfate heptahydrate, 5-8 g / L silicon dioxide, 30-40 g / L boric acid, and 1-2 g / L sodium dodecylbenzenesulfonate.

[0028] Furthermore, the electroplating process conditions in step S3 are as follows: the pH of the electroplating solution is 2-3, the temperature is 40-50°C, the electrodeposition is carried out under direct current for 10-15 minutes, the titanium-based iridium dioxide coated electrode is used as the anode, the treated bolt is used as the cathode, the distance between the anode and cathode plates is 2-3 cm, and the current density is 0.15-0.20 A / cm 2 .

[0029] Furthermore, the thickness of the electroplating layer in step S3 is 10-15 μm.

[0030] Furthermore, in step S4, the corrosion inhibitor is prepared by compounding 2-mercaptobenzothiazole, sodium molybdate and potassium iodide in a mass ratio of 1:(1-2):(1-2).

[0031] Furthermore, in step S4, the mass ratio of the corrosion inhibitor, aniline, and ethylbenzene is 1:(4-5):(1-1.5).

[0032] Furthermore, in step S4, the mass of 1-naphthol-4-sulfonic acid is 22-25% of the mass of aniline; the mass ratio of 1-naphthol-4-sulfonic acid to deionized water is 1:(18-20).

[0033] Furthermore, the mass of sodium dodecylbenzenesulfonate in step S4 is 50-60% of the mass of 1-naphthol-4-sulfonic acid.

[0034] Furthermore, in step S4, the mass ratio of ammonium persulfate to deionized water is 1:(2-3), and the mass of ammonium persulfate is 27-30% of the mass of aniline.

[0035] Furthermore, in step S5, the mass ratio of epoxy resin to xylene and n-butanol is 5:(2-3):(0.6-0.8).

[0036] Furthermore, in step S5, the mass of the composite is 1.0-1.5% of the mass of the epoxy resin, and the mass ratio of the composite to xylene and n-butanol is 1:(16-28):(6-12).

[0037] Furthermore, the mass of the defoaming agent in step S5 is 0.1-0.2% of the mass of the epoxy resin.

[0038] Furthermore, in step S5, the curing agent is polyamide 650, and its mass is 60-80% of the mass of the epoxy resin.

[0039] Furthermore, the coating process conditions in step S6 are: air spraying process, spraying pressure 0.4-0.8 MPa, spraying distance 15-20 cm, spraying speed 20-30 cm / s, and spraying direction perpendicular to the sprayed object.

[0040] Furthermore, the thickness of the anti-corrosion coating in step S6 is 60-100 μm.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The present invention discloses a corrosion-resistant bolt and a method for producing the same. The raw materials are selected from materials containing carbon, silicon, manganese, chromium, nickel, molybdenum, titanium, ruthenium, rhodium, iridium, and iron. These elements synergistically exert their respective advantages during the production process to improve the bolt's performance. Carbon provides strength and hardness, silicon enhances corrosion resistance, manganese increases toughness, chromium improves high-temperature resistance, nickel improves corrosion resistance and wear resistance, molybdenum enhances strength and hardness, titanium improves corrosion resistance and strength, ruthenium, rhodium, and iridium improve corrosion resistance and high-temperature resistance, and iron, as the primary component, provides the bolt's basic performance. The raw materials are subjected to smelting, converter smelting, refining outside the furnace, and continuous casting to produce steel ingots. These ingots are then subjected to continuous rolling, cold heading, and heat treatment to produce the bolts. By selecting appropriate raw materials and processes, the present invention produces bolts with excellent performance.

[0043] 2. A corrosion-resistant bolt and its preparation method of the present invention, after the bolt is surface treated, silicon dioxide and zinc are co-deposited on the bolt surface using electrodeposition technology to form an electroplated layer, which can provide good corrosion resistance and protect the bolt from erosion by corrosive media; solution A is prepared by using ethylbenzene as the oil phase solvent, aniline and corrosion inhibitor as raw materials; solution B is prepared by using 1-naphthol-4-sulfonic acid as the doping acid and sodium dodecylbenzenesulfonate as the surfactant, solution A and solution B are evenly mixed, and under the action of ammonium persulfate, a polymerization reaction occurs to form polyaniline hollow microspheres coated with a corrosion inhibitor, that is, a composite. The corrosion inhibitor can form a protective film to prevent contact between the corrosive medium and the bolt surface, delaying the occurrence of corrosion; the composite is added as a filler to an epoxy resin system to prepare a modified epoxy resin coating, which is applied to the surface of the electroplated layer to form an anti-corrosion coating, further enhancing the corrosion resistance of the bolt. The double coating design can provide excellent corrosion resistance, extend the service life of the bolt, and is suitable for application in various corrosive environments. DETAILED DESCRIPTION

[0044] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0045] In this embodiment, carbon: graphite, fixed carbon 99.99%, item number 42, sourced from Taizhou Hongnaide Carbon Products Co., Ltd.; silicon: silicon block, silicon content ≥99.9%, sourced from Qinghe County Chuangying Metal Materials Co., Ltd.; manganese: electrolytic manganese flake, manganese content ≥99.9%, sourced from Suzhou Rongqian Rare Metal Products Co., Ltd.; chromium: chromium block, chromium content ≥99.9%, sourced from Beijing Xingrongyuan Technology Co., Ltd.; nickel: nickel beads, nickel content ≥99.9%, sourced from Beijing Xingrongyuan Technology Co., Ltd.; molybdenum: molybdenum granules, molybdenum content ≥99.95%, sourced from Beijing Xingrongyuan Technology Co., Ltd.; titanium: TA1 pure titanium plate, titanium content ≥99.9%, sourced from Xinghua Juyun Metal Products Factory; ruthenium: ruthenium rod, Content ≥99.95%, sourced from Changsha Xinkang New Materials Co., Ltd.; Rhodium: rhodium block, content ≥99.95%, sourced from Beijing Yi Jin New Materials Technology Co., Ltd.; Iridium: iridium tube, content ≥99.95%, sourced from Zhongrui Metal Technology (Wuxi) Co., Ltd.; Iron: iron mineral, iron content ≥60%, sourced from Henan Denuo Metallurgical Materials Co., Ltd.; Epoxy resin: bisphenol A type epoxy resin E-51, item number CYD-128, epoxy equivalent 184-194g / eq, sourced from Guangzhou Fufei Chemical Co., Ltd.; Defoamer: item number F-8504, sourced from Guangdong Tianfeng Defoamer Co., Ltd.; Polyamide 650: molecular weight 600-1100, sourced from Henan Shuizhihuan Industrial Co., Ltd.

[0046] Example 1: A method for preparing a corrosion-resistant bolt, comprising the following steps:

[0047] Step S1: Smelting the raw materials at 1500°C to produce molten iron, which is then subjected to converter smelting (with argon blowing and stirring throughout the process, controlling the converter endpoint P ≤ 0.02%, and controlling the tapping temperature at 1600°C), and refining outside the furnace (deoxidation is performed by adding 2% of the molten iron's mass of silicon barium wire, and degassing is performed by vacuum degassing at a vacuum degree of 20 Pa for 10 minutes, followed by soft argon blowing for 20 minutes) to produce molten steel;

[0048] Step S2: Continuously casting the molten steel into an ingot (superheat of 15°C, using electromagnetic stirring in the crystallizer, electromagnetic stirring current of 200A, and electromagnetic stirring frequency of 5Hz), and performing slow cooling (entry temperature of 655°C, slow cooling time of 78h, and exit temperature of 160°C); then heating and continuous rolling treatment (heating temperature of 1100°C, start rolling temperature of 920°C, and final rolling temperature of 950°C) are performed to obtain a bar, which is then subjected to secondary slow cooling (entry temperature of 420°C, slow cooling time of 48h); cold heading processing is performed on the slowly cooled bar to obtain a bolt blank; the bolt blank is threaded (threaded using a thread rolling machine) and heat treated (quenching temperature of 850°C, holding time of 1h, water cooling, cooling rate of 10°C / s; tempering temperature of 450°C, holding time of 1h, air cooling, cooling rate of 20°C / min) to obtain a bolt;

[0049] Step S3: The bolts were sequentially ground, polished, cleaned, degreased (the degreasing agent was a mixed solution of acetone and ethanol, with a mass ratio of 1:1, and ultrasonic degreasing was performed for 5 minutes) and degreased (the formula of the degreasing solution included: 18 g / L sodium hydroxide, 7 g / L sodium carbonate, 7 g / L sodium pyrophosphate, 1 g / L alkylphenol polyoxyethylene ether; the degreasing temperature was 60°C, and the degreasing time was 5 minutes). After that, they were placed in an electroplating solution (220 g / L zinc sulfate heptahydrate, 5 g / L silicon dioxide, 30 g / L boric acid, and 1 g / L sodium dodecylbenzene sulfonate) and electroplated (the pH of the electroplating solution was 2, the temperature was 40°C, and the electrodeposition was carried out under direct current for 10 minutes, with a titanium-based iridium dioxide coated electrode as the anode and the treated bolt as the cathode. The distance between the anode and cathode plates was 2 cm, and the current density was 0.15 A / cm 2 ), forming an electroplating layer;

[0050] Step S4: In an ice bath, 1 g of 2-mercaptobenzothiazole, 1 g of sodium molybdate, 1 g of potassium iodide, and 12 g of aniline and 3 g of ethylbenzene were mixed to obtain a solution A; 2.64 g of 1-naphthol-4-sulfonic acid and 47.52 g of deionized water were mixed to obtain a solution B; 1.32 g of sodium dodecylbenzenesulfonate was added dropwise to the solution B over a period of 30 minutes, and ultrasonically vibrated for 10 minutes; a mixed solution of 3.24 g of ammonium persulfate and 6.48 g of deionized water was added dropwise over a period of 30 minutes, and the mixture was reacted for 22 hours. After filtration and multiple washings, the mixture was vacuum dried at 50° C. for 24 hours to obtain a composite.

[0051] Step S5: 10 g of epoxy resin, 4 g of xylene, and 1.2 g of n-butanol were uniformly mixed, 0.1 g of the complex, 1.6 g of xylene, and 0.6 g of n-butanol were added, 0.01 g of a defoamer and 6 g of polyamide 650 were added, and the mixture was stirred at a speed of 800 r / min for 50 min to prepare a modified epoxy resin coating;

[0052] Step S6: applying a modified epoxy resin coating to the surface of the electroplating layer (using an air spraying process with a spraying pressure of 0.4 MPa, a spraying distance of 15 cm, a spraying speed of 20 cm / s, and a spraying direction perpendicular to the sprayed object) to form an anti-corrosion coating, and curing the coating at 50° C. for 6 h to obtain a corrosion-resistant bolt;

[0053] The raw materials include the following elements in weight percentage: C: 0.25%, Si: 0.16%, Mn: 0.4%, Cr: 0.1%, Ni: 0.2%, Mo: 0.15%, Ti: 0.12%, Ru: 0.05%, Rh: 0.16%, Ir: 0.1%, and the balance is iron and inevitable impurities.

[0054] Example 2: A method for preparing a corrosion-resistant bolt, comprising the following steps:

[0055] Step S1: Smelting the raw materials at 1550°C to produce molten iron, which is then subjected to converter smelting (with argon blowing and stirring throughout the process, controlling the converter endpoint P≤0.02%, and controlling the tapping temperature at 1650°C), and refining outside the furnace (deoxidation, degassing, and soft blowing processes: adding 3% of the molten iron's mass of barium silicon wire for deoxidation, vacuum degassing at a vacuum of 40 Pa for 15 minutes, and soft blowing argon for 25 minutes after the vacuum treatment) to produce molten steel;

[0056] Step S2: Continuously casting the molten steel into an ingot (superheat of 20°C, using electromagnetic stirring in the crystallizer, electromagnetic stirring current of 250A, and electromagnetic stirring frequency of 8Hz), and performing slow cooling (entry temperature of 670°C, slow cooling time of 80h, and exit temperature of 170°C); then heating and continuous rolling treatment (heating temperature of 1200°C, start rolling temperature of 950°C, and final rolling temperature of 990°C) are performed to obtain a bar, which is then subjected to secondary slow cooling (entry temperature of 540°C, slow cooling time of 52h); cold heading processing is performed on the slowly cooled bar to obtain a bolt blank; the bolt blank is threaded (threaded using a thread rolling machine) and heat treated (quenching temperature of 860°C, holding time of 1.5h, water cooling, cooling rate of 14°C / s; tempering temperature of 480°C, holding time of 2h, air cooling, cooling rate of 25°C / min) to obtain a bolt;

[0057] Step S3: The bolts are sequentially ground, polished, cleaned, degreased (the degreasing agent is a mixed solution of acetone and ethanol, the mass ratio of which is 1:1.5, and ultrasonic degreasing is performed for 8 minutes) and degreased (the formula of the degreasing solution includes: 19 g / L sodium hydroxide, 8 g / L sodium carbonate, 8 g / L sodium pyrophosphate, 1.5 g / L alkylphenol polyoxyethylene ether; the degreasing temperature is 65°C, and the degreasing time is 8 minutes). After treatment, they are placed in an electroplating solution (230 g / L zinc sulfate heptahydrate, 6 g / L silicon dioxide, 35 g / L boric acid, 1.5 g / L sodium dodecylbenzene sulfonate) and electroplated (the pH of the electroplating solution is 2.5, the temperature is 45°C, and the electrodeposition is carried out under direct current for 13 minutes, with a titanium-based iridium dioxide coated electrode as the anode and the treated bolt as the cathode. The distance between the anode and cathode plates is 2.5 cm, and the current density is 0.18 A / cm 2 ), forming an electroplating layer;

[0058] Step S4: In an ice bath, 1 g of 2-mercaptobenzothiazole, 1.5 g of sodium molybdate, 1.5 g of potassium iodide, 18 g of aniline, and 4.8 g of ethylbenzene were mixed to obtain a solution A; 4.3 g of 1-naphthol-4-sulfonic acid and 82 g of deionized water were mixed to obtain a solution B; 2.4 g of sodium dodecylbenzenesulfonate was added dropwise to the solution B over a period of 35 minutes, and ultrasonically vibrated for 15 minutes; a mixed solution of 5 g of ammonium persulfate and 12.5 g of deionized water was added dropwise over a period of 50 minutes, and the mixture was reacted for 23 hours. After filtration and multiple washings, the mixture was vacuum dried at 55° C. for 36 hours to obtain a composite.

[0059] Step S5: 10 g of epoxy resin, 5 g of xylene, and 1.4 g of n-butanol were uniformly mixed, 0.12 g of the complex, 3 g of xylene, and 1.2 g of n-butanol were added, 0.015 g of a defoamer and 7 g of polyamide 650 were added, and the mixture was stirred at a speed of 900 r / min for 40 min to prepare a modified epoxy resin coating;

[0060] Step S6: applying a modified epoxy resin coating to the surface of the electroplating layer (using an air spraying process with a spraying pressure of 0.6 MPa, a spraying distance of 18 cm, a spraying speed of 25 cm / s, and a spraying direction perpendicular to the sprayed object) to form an anti-corrosion coating, which was cured at 55° C. for 5 h to obtain a corrosion-resistant bolt;

[0061] The raw materials include the following elements in weight percentage: C: 0.3%, Si: 0.25%, Mn: 0.6%, Cr: 0.15%, Ni: 0.3%, Mo: 0.2%, Ti: 0.14%, Ru: 0.1%, Rh: 0.22%, Ir: 0.12%, and the balance is iron and inevitable impurities.

[0062] Example 3: A method for preparing a corrosion-resistant bolt, comprising the following steps:

[0063] Step S1: Smelting the raw materials at 1580°C to produce molten iron, which is then subjected to converter smelting (with argon blowing and stirring throughout the entire process, controlling the converter endpoint P≤0.02%, and controlling the tapping temperature at 1700°C), and refining outside the furnace (deoxidation, degassing, and soft blowing steps: adding 4% of the molten iron's mass of barium silicon wire for deoxidation, vacuum degassing at a vacuum of 65 Pa for 20 minutes, and soft blowing argon for 30 minutes after the vacuum treatment) to produce molten steel;

[0064] Step S2: Continuously casting the molten steel into an ingot (superheat of 30°C, using electromagnetic stirring in the crystallizer, electromagnetic stirring current of 300A, and electromagnetic stirring frequency of 10Hz), and performing slow cooling (entry temperature of 680°C, slow cooling time of 84h, and exit temperature of 185°C); then heating and continuous rolling treatment (heating temperature of 1250°C, start rolling temperature of 990°C, and final rolling temperature of 1050°C) are performed to obtain a bar, which is then subjected to secondary slow cooling (entry temperature of 560°C, slow cooling time of 58h); cold heading processing is performed on the slowly cooled bar to obtain a bolt blank; the bolt blank is threaded (threaded using a thread rolling machine) and heat treated (quenching temperature of 870°C, holding time of 2h, water cooling, cooling rate of 15°C / s; tempering temperature of 500°C, holding time of 3h, air cooling, cooling rate of 30°C / min) to obtain a bolt;

[0065] Step S3: The bolts were sequentially ground, polished, cleaned, degreased (the degreasing agent was a mixed solution of acetone and ethanol, with a mass ratio of 1:2, and ultrasonic degreasing for 10 minutes) and degreased (the formula of the degreasing solution included: 20 g / L sodium hydroxide, 9 g / L sodium carbonate, 9 g / L sodium pyrophosphate, 2 g / L alkylphenol polyoxyethylene ether; the degreasing temperature was 70°C, and the degreasing time was 10 minutes). After that, they were placed in an electroplating solution (250 g / L zinc sulfate heptahydrate, 8 g / L silicon dioxide, 40 g / L boric acid, and 2 g / L sodium dodecylbenzene sulfonate) and electroplated (the pH of the electroplating solution was 3, the temperature was 50°C, and the electrodeposition was carried out under direct current for 15 minutes, with a titanium-based iridium dioxide coated electrode as the anode and the treated bolt as the cathode. The distance between the anode and cathode plates was 3 cm, and the current density was 0.20 A / cm 2 ), forming an electroplating layer;

[0066] Step S4: In an ice bath, 1 g of 2-mercaptobenzothiazole, 2 g of sodium molybdate, 2 g of potassium iodide, 25 g of aniline, and 7.5 g of ethylbenzene were mixed uniformly to prepare solution A; 6.25 g of 1-naphthol-4-sulfonic acid and 125 g of deionized water were mixed uniformly, 3.75 g of sodium dodecylbenzenesulfonate was added, and the mixture was stirred uniformly to prepare solution B; solution A was added dropwise to solution B over 40 minutes, and ultrasonically shaken for 20 minutes; a mixed solution of 7.5 g of ammonium persulfate and 22.5 g of deionized water was added dropwise over 60 minutes, and the mixture was reacted for 24 hours. After suction filtration and multiple washings, the mixture was vacuum dried at 60°C for 48 hours to prepare a composite;

[0067] Step S5: 10 g of epoxy resin, 6 g of xylene, and 1.6 g of n-butanol were uniformly mixed, 0.15 g of the complex, 4.2 g of xylene, and 1.8 g of n-butanol were added, 0.02 g of a defoamer, and 8 g of polyamide 650 were added, and the mixture was stirred at a speed of 1000 r / min for 30 min to prepare a modified epoxy resin coating;

[0068] Step S6: applying a modified epoxy resin coating to the surface of the electroplating layer (using an air spraying process with a spraying pressure of 0.8 MPa, a spraying distance of 20 cm, a spraying speed of 30 cm / s, and a spraying direction perpendicular to the sprayed object) to form an anti-corrosion coating, and curing the coating at 60° C. for 4 h to obtain a corrosion-resistant bolt;

[0069] The raw materials include the following elements in weight percentage: C: 0.35%, Si: 0.38%, Mn: 0.7%, Cr: 0.2%, Ni: 0.4%, Mo: 0.30%, Ti: 0.16%, Ru: 0.15%, Rh: 0.32%, Ir: 0.15%, and the balance is iron and inevitable impurities.

[0070] Comparative Example 1: Compared with Example 2, the raw materials in step S1 of Comparative Example 1 include the following elements in weight percentage: C: 0.12%, Si: 0.12%, Mn: 0.2%, Cr: 0.05%, Ni: 0.1%, Mo: 0.05%, Ti: 0.05%, Ru: 0.01%, Rh: 0.05%, Ir: 0.05%, and the balance is iron and unavoidable impurities; Comparative Example 1 reduces the addition amount of each raw material element, and the other steps and processes are the same as Example 1.

[0071] Comparative Example 2: A method for preparing a corrosion-resistant bolt, comprising the following processes:

[0072] Compared with Example 1, Comparative Example 2 does not add 2-mercaptobenzothiazole, sodium molybdate, and potassium iodide, and other steps are the same as Example 1.

[0073] Comparative Example 3: A method for preparing a corrosion-resistant bolt, comprising the following processes:

[0074] Compared with Example 2, Comparative Example 3 does not include steps S4, S5, and S6, and the other steps are the same as those in Example 2.

[0075] Comparative Example 4: A method for preparing a corrosion-resistant bolt, comprising the following processes:

[0076] Compared with Example 2, in step S4 of Comparative Example 4, the mass of 1-naphthol-4-sulfonic acid is 5% of the mass of aniline, and the other steps are the same as those in Example 2.

[0077] experiment

[0078] The corrosion-resistant bolts obtained in Examples 1-3 and Comparative Examples 1-4 were used to prepare samples, and their properties were tested and the test results were recorded:

[0079] GB / T 228.1-2010 "Tension tests on metallic materials - Part 1: Test methods at room temperature" is used to determine tensile strength. The following experimental steps are used: The specimen has a diameter of 16 mm and a length of 50 mm. The specimen is clamped on a testing machine. The tensile testing machine is started and the tensile load is gradually increased at a loading rate of 1 mm / s until the bolt breaks. The data is then recorded.

[0080] Hardness was measured according to GB / T 230.1-2018, "Rockwell hardness test for metallic materials - Part 1: Test method." The test procedure was as follows: The specimen was 15 mm thick and its surface was flat and clean. A 10 mm carbide ball was pressed into the specimen surface under a test force of 3000 N. The force was maintained for 10 seconds before the test force was removed. The diameter of the indentation on the specimen surface was measured and the data was calculated.

[0081] Corrosion resistance test: The specimen is 90 mm long and 25 mm in diameter. After cleaning and drying the surface, the specimen is placed in a 0.01 mol / L sodium bisulfite solution with a pH of 4, a temperature of 45°C, and a humidity of 70% RH. The test period is 48 hours. After the test, the specimen is removed and dried. The original mass of the specimen before corrosion and the mass of the specimen after corrosion are measured. The corrosion weight loss rate is calculated as (original mass of the specimen before corrosion - mass of the specimen after corrosion) / (corroded area × test time).

[0082] Test results

[0083]

[0084] According to the data in the above table, we can clearly draw the following conclusions:

[0085] 1. Compared with implementations 1-3, the tensile strength and hardness of the product obtained in comparative example 1 are both reduced, indicating that the performance of the corrosion-resistant bolts prepared by the present invention is affected by the composition ratio thereof. By selecting the composition ratio within the above range, bolts with excellent performance can be prepared.

[0086] 2. Compared with Examples 1-3, the tensile strength and hardness of the products obtained in Examples 2 and 3 are both reduced, and the corrosion weight loss rate is increased. It can be seen that the addition of corrosion inhibitors in the present invention can slow down the corrosion rate; at the same time, the anti-corrosion coating prepared by the present invention has excellent corrosion resistance, achieving a corrosion-resistant effect.

[0087] 3. Compared with Examples 1-3, the tensile strength and hardness of the product obtained in Comparative Example 4 are slightly decreased, and the corrosion weight loss rate is also increased, indicating that the performance of the corrosion-resistant bolts prepared by the present invention is affected by the ratio of each reagent in the preparation process. When the reagent ratio is selected within the range, the performance of the prepared product is better.

[0088] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include," "comprise," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0089] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a corrosion-resistant bolt, characterized in that: The steps include: Step S1: smelting raw materials at 1500-1580° C. to produce molten iron, and subjecting the molten iron to converter smelting and refining outside the furnace to produce molten steel; the raw materials in step S1 include the following elements in weight percentage: C: 0.25-0.35%, Si: 0.16-0.38%, Mn: 0.4-0.7%, Cr: 0.1-0.2%, Ni: 0.2-0.4%, Mo: 0.15-0.30%, Ti: 0.12-0.16%, Ru: 0.05-0.15%, Rh: 0.16-0.32%, Ir: 0.10-0.15%, and the balance is iron and unavoidable impurities; Step S2: continuously casting the molten steel into an ingot and slowly cooling it; then heating and continuously rolling it to obtain a bar, which is then slowly cooled for a second time; cold heading the slowly cooled bar to obtain a bolt blank; threading and heat treating the bolt blank to obtain a bolt; the heat treatment process conditions in step S2 are: quenching temperature 850-870°C, holding time 1-2 hours, water cooling, and a cooling rate of 10-15°C / s; tempering temperature 450-500°C, holding time 1-3 hours, air cooling, and a cooling rate of 20-30°C / min; Step S3: After grinding, polishing, cleaning, degreasing, and degreasing the bolts in sequence, the bolts are placed in an electroplating solution for electroplating to form an electroplated layer; the electroplating solution in step S3 comprises: 220-250 g / L zinc sulfate heptahydrate, 5-8 g / L silicon dioxide, 30-40 g / L boric acid, and 1-2 g / L sodium dodecylbenzene sulfonate; Step S4: in an ice bath, uniformly mixing a corrosion inhibitor, aniline, and ethylbenzene to prepare a solution A; uniformly mixing 1-naphthol-4-sulfonic acid and deionized water, adding sodium dodecylbenzenesulfonate, and stirring to prepare a solution B; dropwise adding solution A to solution B for 30-40 minutes, and ultrasonically shaking for 10-20 minutes; dropwise adding a mixed solution of ammonium persulfate and deionized water for 30-60 minutes, and reacting for 22-24 hours. After suction filtration and multiple washings, the mixture is vacuum-dried at 50-60° C. for 24-48 hours to prepare a composite. In the step S4, the corrosion inhibitor is prepared by compounding 2-mercaptobenzothiazole, sodium molybdate, and potassium iodide in a mass ratio of 1:(1-2):(1-2); Step S5: uniformly mixing the epoxy resin, xylene, and n-butanol, adding the complex, a mixed solution of xylene and n-butanol, and then adding a defoamer and a curing agent, stirring at a speed of 800-1000 r / min for 30-50 minutes to prepare a modified epoxy resin coating; Step S6: coating the surface of the electroplating layer with a modified epoxy resin coating to form an anti-corrosion layer, and curing the coating at 50-60° C. for 4-6 hours to obtain a corrosion-resistant bolt.

2. The method for preparing a corrosion-resistant bolt according to claim 1, wherein: The continuous casting process conditions in step S2 are: superheat of 15-30° C., electromagnetic stirring of the crystallizer, electromagnetic stirring current of 200-300 A, and electromagnetic stirring frequency of 5-10 Hz.

3. The method for preparing a corrosion-resistant bolt according to claim 1, wherein: The electroplating process conditions in step S3 are as follows: the pH of the electroplating solution is 2-3, the temperature is 40-50° C., the electrodeposition is carried out under direct current for 10-15 minutes, the titanium-based iridium dioxide coated electrode is used as the anode, the treated bolt is used as the cathode, the distance between the anode and cathode plates is 2-3 cm, and the current density is 0.15-0.20 A / cm 2 .

4. The method for preparing a corrosion-resistant bolt according to claim 1, wherein: In step S4, the mass of 1-naphthol-4-sulfonic acid is 22-25% of the mass of aniline; the mass ratio of 1-naphthol-4-sulfonic acid to deionized water is 1:(18-20).

5. The method for preparing a corrosion-resistant bolt according to claim 1, wherein: The mass of the composite in step S5 is 1.0-1.5% of the mass of the epoxy resin, and the mass ratio of the composite to xylene and n-butanol is 1:(16-28):(6-12).

6. The method for preparing a corrosion-resistant bolt according to claim 1, characterized in that: The coating process conditions in step S6 are: air spraying process, spraying pressure 0.4-0.8 MPa, spraying distance 15-20 cm, spraying speed 20-30 cm / s, and spraying direction perpendicular to the object to be sprayed.

7. A corrosion-resistant bolt prepared according to the preparation method according to any one of claims 1 to 6.

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