Corrosion-resistant low-carbon steel pipe and method for manufacturing the same

Abstract

The application relates to the field of low-carbon steel pipes, and particularly discloses a corrosion-resistant low-carbon steel pipe and a preparation method thereof; blank materials are taken, subjected to perforation, spheroidizing annealing, pickling, cold rolling, annealing, correction and head and tail cutting to obtain a low-carbon steel pipe; corrosion-resistant paint and hydrophobic paint are coated on the surface of the low-carbon steel pipe to obtain a corrosion-resistant low-carbon steel pipe; in the low-carbon steel pipe, the components include the following percentages: Mn: 1.20-1.30%; Cr: 0.30-0.50%; Ni: 0.30-0.40%; Si: 0.20-0.40%; Mo: 0.30-0.40%; C: 0.04-0.10%; V: 0.08-0.10%; Nb: 0.02-0.03%; P: <=0.015%; Cu: <=0.10%; Ti: <=0.01%; S: <=0.005%; B: <=0.0005%; and the rest is iron and inevitable impurities.

Description

Technical Field

[0001] This invention relates to the field of low-carbon steel pipes, and specifically discloses a corrosion-resistant low-carbon steel pipe and its preparation method. Background Technology

[0002] Steel pipes are widely used, and steel pipes used in different fields usually require different properties. Steel pipes used in chemical, marine engineering, and oil extraction fields have high requirements for corrosion resistance and often use low-carbon steel pipes. Due to their lower carbon content, low-carbon steel pipes have a certain degree of corrosion resistance, but this corrosion resistance is usually limited and needs to be further improved.

[0003] In existing technologies, commonly used anti-corrosion technologies mainly include electrochemical protection, coatings, and plating. Among these, coating technology is the most widely used due to its simple process and low energy consumption. However, single-component coatings have limited anti-corrosion effects, and two-component coatings suffer from poor coating uniformity, both of which lead to a reduction in the coating's corrosion resistance. Therefore, it is of great significance to study a corrosion-resistant low-carbon steel pipe with good anti-corrosion effect and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a corrosion-resistant low-carbon steel pipe and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing a corrosion-resistant low-carbon steel pipe includes the following steps: taking a billet, subjecting it to piercing, spheroidizing annealing, pickling, cold rolling, annealing, straightening, and trimming the ends to obtain a low-carbon steel pipe; coating the surface of the low-carbon steel pipe with a corrosion-resistant coating, subjecting it to a first ultraviolet irradiation, coating it with a hydrophobic coating, and subjecting it to a second ultraviolet irradiation to obtain the corrosion-resistant low-carbon steel pipe; wherein the composition of the low-carbon steel pipe includes, by percentage: Mn: 1.20-1.30%; Cr: 0.30-0.50%. %; Ni: 0.30-0.40%; Si: 0.20-0.40%; Mo: 0.30-0.40%; C: 0.04-0.10%; V: 0.08-0.10%; Nb: 0.02-0.03%; P: ≤0.015%; Cu: ≤0.10%; Ti: ≤0.01%; S: ≤0.005%; B: ≤0.0005%; the remainder is iron and unavoidable impurities.

[0007] Preferably, the low-carbon steel pipe comprises, by percentage: Mn: 1.30%; Cr: 0.4%; Ni: 0.3%; Si: 0.2%; Mo: 0.3%; C: 0.06%; V: 0.08%; Nb: 0.02%; P: 0.01%; Cu: 0.10%; Ti: 0.005%; S: 0.003%; B: 0.0003%; with the remainder being iron and unavoidable impurities.

[0008] Preferably, the spheroidizing annealing temperature is 790-800℃ and the time is 26-32h; during the spheroidizing annealing process, RX gas is added for carburizing protection; the composition of RX gas by volume percentage is: CO: 19-21%; H2: 18-22%; CO2: 0.25-0.45%, with the remainder being N2.

[0009] Preferably, the spheroidizing annealing temperature is 800℃ and the time is 30h; during the spheroidizing annealing process, RX gas is added for carburizing protection; the composition of RX gas by volume percentage is: CO: 21%; H2: 20%; CO2: 0.4%, with the remainder being N2.

[0010] Preferably, the preparation of the corrosion-resistant coating includes the following steps: S1: Take amino graphene, water, ethanol, and 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 60-70°C, stir for 2-4 hours, evaporate the solvent, and obtain modified graphene.

[0011] S2: Take isophorone diisocyanate, polytetrahydrofuran ether diol, tetrafluoroterephthalic acid diethanol and dibutyltin dilaurate, react at 85-90℃ for 3-4h, add 3-amino-1-propanol vinyl ether, react for 2-3h to obtain modified polyurethane.

[0012] S3: Take epoxy resin, photosensitive resin, (9CI)-2-(3-ethylene ethylene oxide)-pyridine, corrosion-resistant microcapsules, amino graphene, toluene, xylene, alicyclic amine curing agent, and photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0013] Preferably, the modified graphene comprises the following raw materials, by weight: 10 parts of aminated graphene, 10-20 parts of water, 80-100 parts of ethanol, and 4-6 parts of 8-hydroxyquinoline-2-carboxaldehyde; the modified polyurethane comprises the following raw materials, by weight: 8-15 parts of isophorone diisocyanate, 4-8 parts of polytetrahydrofuran ether diol, 0.2-0.5 parts of tetrafluoroterephthalic acid, 0.01-0.03 parts of dibutyltin dilaurate, and 1... ~2 parts of 3-amino-1-propanol vinyl ether; the corrosion-resistant coating comprises the following raw materials, by weight: 20-25 parts epoxy resin, 1-2 parts photosensitive resin, 1-2 parts (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 1-2 parts corrosion-resistant microcapsules, 0.2-0.5 parts aminographene, 15-20 parts toluene, 15-20 parts xylene, 4-6 parts alicyclic amine curing agent, and 0.02-0.03 parts photoinitiator.

[0014] Preferably, the preparation of the corrosion-resistant microcapsules includes the following steps: taking modified graphene, ethanol, and water, sonicating until uniformly dispersed, adding acrylamide, methacrylic acid, and modified polyurethane, stirring, adding potassium persulfate and methylenebisacrylamide under nitrogen protection, refluxing for 8-9 hours, filtering and drying to obtain corrosion-resistant microcapsules.

[0015] Preferably, the corrosion-resistant microcapsules comprise the following raw materials, by mass parts: 0.3-0.5 parts modified graphene, 120-150 parts ethanol, 50-80 parts water, 0.1-0.2 parts acrylamide, 0.1-0.2 parts methacrylic acid, 0.1-0.2 parts modified polyurethane, 1.5-2 parts potassium persulfate, and 0.5-0.8 parts methylenebisacrylamide.

[0016] Preferably, the preparation of the hydrophobic coating includes the following steps: S1: Sodium silicate nonahydrate and water are taken, stirred evenly, and the pH is adjusted to 2-3 to obtain acidic silica sol; hexadecyltrimethylammonium bromide, polyoxyethylene octylphenol ether-10, and water are taken, stirred evenly to obtain a composite emulsifier; photosensitive resin and polydimethylsiloxane are taken, stirred, the composite emulsifier is added dropwise, stirred, acidic silica sol is added dropwise, heated and stirred, vinyltriethoxysilane is added, stirred, filtered and dried to obtain silica microcapsules;

[0017] S2: Take polydimethylsiloxane, vinyl-terminated poly(dimethylsiloxane), methyltriethoxysilane, vinyltriethoxysilane, and tetrahydrofuran, stir for 1 hour to obtain a dispersion; take the dispersion, add silica microcapsules and photoinitiator, ultrasonically disperse, stir to obtain a hydrophobic coating.

[0018] Preferably, the silica microcapsules comprise the following raw materials, by weight: 1-2 parts hexadecyltrimethylammonium bromide, 1-2 parts polyoxyethylene octylphenol ether-10, 200 parts water, 3-5 parts photosensitive resin, 5-10 parts polydimethylsiloxane, 10-15 parts sodium silicate nonahydrate, and 0.1-0.2 parts vinyltriethoxysilane; the dispersion comprises the following raw materials, by weight: 1-2 parts polydimethylsiloxane, 0.5-1 part vinyl-terminated poly(dimethylsiloxane), 0.05-0.1 parts methyltriethoxysilane, 0.1-0.15 parts vinyltriethoxysilane, and 100-150 parts tetrahydrofuran; the hydrophobic coating comprises the following raw materials, by weight: 10-15 parts dispersion, 0.1-0.2 parts silica microcapsules, and 0.01 parts photoinitiator.

[0019] Preferably, the specific process for preparing corrosion-resistant low-carbon steel pipes includes the following steps: coating the surface of the low-carbon steel pipe with a corrosion-resistant coating, and uniformly irradiating it with ultraviolet light at a distance of 10 cm for 8–12 minutes, with an ultraviolet light intensity of 50–55 mw / cm. 2 A corrosion-resistant coating of 50–70 μm is obtained; then a hydrophobic coating is applied, and the mixture is uniformly irradiated with ultraviolet light at a distance of 10 cm for 20–25 minutes at an ultraviolet light intensity of 50–55 mw / cm². 2 A 2-4 μm hydrophobic coating is obtained, resulting in a corrosion-resistant low-carbon steel pipe.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) RX gas spheroidizing annealing is used to reduce the carbon content;

[0021] (2) A corrosion-resistant coating and a hydrophobic coating are sequentially coated on the surface of the steel pipe. The corrosion-resistant coating includes epoxy resin, photosensitive resin, (9CI)-2-(3-ethylene ethylene oxide)-pyridine, corrosion-resistant microcapsules, amino graphene, and photoinitiator. Epoxy resin has excellent corrosion resistance. (9CI)-2-(3-ethylene ethylene oxide)-pyridine contains a pyridine structure and has coordination ability, which helps to improve the bonding force between the coating and the surface of the steel pipe. It also contains epoxy groups, which have good compatibility with epoxy resin. The double bonds can also participate in the photocuring process in the subsequent process.

[0022] The corrosion-resistant microcapsules are obtained by coating modified graphene with acrylamide, methacrylic acid, and modified polyurethane through potassium sulfate catalysis. They have good compatibility with epoxy resin, and the complexing ability of the surface carboxyl groups helps to improve the bonding force with the steel pipe surface. The introduction of modified polyurethane increases corrosion resistance and wear resistance. The modified graphene is prepared from aminated graphene and 8-hydroxyquinoline-2-carboxaldehyde and has a good corrosion inhibition effect.

[0023] Hydrophobic coatings include polydimethylsiloxane, vinyl-terminated poly(dimethylsiloxane), methyltriethoxysilane, vinyltriethoxysilane, silica microcapsules, and photoinitiators. They have good hydrophobicity, effectively reducing the corrosive effect of water containing corrosive substances on steel pipes. They can also crosslink with corrosion-resistant coatings through photoinitiator catalysis, thereby improving adhesion.

[0024] Silica microcapsules are made by encapsulating photosensitive resin and polydimethylsiloxane with silica, which gives the coating excellent self-healing ability and improves corrosion resistance;

[0025] (3) First, apply a corrosion-resistant coating with strong adhesion to the steel pipe and irradiate with ultraviolet light for 8 to 12 minutes. Then, apply a hydrophobic coating and irradiate with ultraviolet light for 20 to 25 minutes. The resulting coatings have strong adhesion and further improve corrosion resistance and hydrophobicity. Detailed Implementation

[0026] The following are preferred embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. For those skilled in the art, all other embodiments obtained by those skilled in the art without creative effort without departing from the principles of the embodiments of the present invention are within the scope of protection of the present invention.

[0027] Unless otherwise specified, all the following quantities are parts by weight.

[0028] The billet is pierced, spheroidizing annealed, pickled, cold rolled, annealed, straightened, and the ends are trimmed to obtain a low-carbon steel pipe. A corrosion-resistant coating is then applied to the surface of the low-carbon steel pipe, and it is uniformly irradiated with ultraviolet light at a distance of 10 cm for 10 minutes, with an ultraviolet light intensity of 55 mw / cm². 2 A 60μm corrosion-resistant coating was obtained; then a hydrophobic coating was applied, and the mixture was uniformly irradiated with ultraviolet light at a distance of 10cm for 25 minutes, with an ultraviolet light intensity of 55mw / cm. 2 A 3μm hydrophobic coating is obtained, resulting in a corrosion-resistant low-carbon steel pipe.

[0029] Example 1: The preparation of the corrosion-resistant coating and hydrophobic coating includes the following steps: S1: Take 10 parts of amino graphene, 15 parts of water, 90 parts of ethanol, and 5 parts of 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 70°C, stir for 4 hours, evaporate the solvent, and obtain modified graphene.

[0030] S2: Take 15 parts of isophorone diisocyanate, 6 parts of polytetrahydrofuran ether diol, 0.4 parts of tetrafluoroterephthalic acid diethanol, and 0.02 parts of dibutyltin dilaurate, react at 90℃ for 3 hours, add 1.5 parts of 3-amino-1-propanol vinyl ether, and react for 2 hours to obtain modified polyurethane.

[0031] S3: Take 0.5 parts modified graphene, 120 parts ethanol, and 50 parts water, sonicate until uniformly dispersed, add 0.1 parts acrylamide, 0.2 parts methacrylic acid, and 0.2 parts modified polyurethane, stir at 300 r / min for 15 min, add 1.5 parts potassium persulfate and 0.8 parts methylenebisacrylamide under nitrogen protection, reflux for 9 h, filter and dry to obtain corrosion-resistant microcapsules;

[0032] S4: Take 25 parts epoxy resin, 1.5 parts photosensitive resin, 1 part (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 2 parts corrosion-resistant microcapsules, 0.3 parts amino graphene, 15 parts toluene, 20 parts xylene, 5 parts alicyclic amine curing agent, and 0.02 parts photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0033] S5: Take 15 parts of sodium silicate nonahydrate and 100 parts of water, stir evenly, add 6 mol / L hydrochloric acid to adjust pH to 3, and obtain acidic silica sol; take 2 parts of hexadecyltrimethylammonium bromide, 1 part of polyoxyethylene octylphenol ether-10, and 100 parts of water, stir evenly, and obtain composite emulsifier; take 4 parts of photosensitive resin and 8 parts of polydimethylsiloxane, stir at 300 r / min, add composite emulsifier dropwise, stir at 2000 r / min for 50 min, add acidic silica sol dropwise at 0.5 mL / min, stir at 300 r / min for 3 h at 70 °C, add 0.2 parts of vinyltriethoxysilane, stir for 2 h, filter and dry to obtain silica microcapsules;

[0034] S6: Take 2 parts of polydimethylsiloxane, 0.8 parts of vinyl-terminated poly(dimethylsiloxane), 0.05 parts of methyltriethoxysilane, 0.15 parts of vinyltriethoxysilane, and 150 parts of tetrahydrofuran, stir for 1 hour to obtain a dispersion; take 12 parts of the dispersion, add 0.15 parts of silica microcapsules and 0.01 parts of photoinitiator, ultrasonically disperse for 30 minutes, stir for 1 hour to obtain a hydrophobic coating.

[0035] Example 2: The preparation of the corrosion-resistant coating and hydrophobic coating includes the following steps: S1: Take 10 parts of aminated graphene, 15 parts of water, 90 parts of ethanol, and 4 parts of 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 70°C, stir for 4 hours, evaporate the solvent, and obtain modified graphene.

[0036] S2: Take 8 parts of isophorone diisocyanate, 4 parts of polytetrahydrofuran ether diol, 0.2 parts of tetrafluoroterephthalic acid diethanol, and 0.02 parts of di-n-butyltin dilaurate, react at 90℃ for 3 hours, add 1 part of 3-amino-1-propanol vinyl ether, and react for 2 hours to obtain modified polyurethane.

[0037] S3: Take 0.3 parts modified graphene, 120 parts ethanol, and 50 parts water, sonicate until uniformly dispersed, add 0.1 parts acrylamide, 0.1 parts methacrylic acid, and 0.1 parts modified polyurethane, stir at 300 r / min for 15 min, add 1.5 parts potassium persulfate and 0.8 parts methylenebisacrylamide under nitrogen protection, reflux for 9 h, filter and dry to obtain corrosion-resistant microcapsules;

[0038] S4: Take 20 parts epoxy resin, 1 part photosensitive resin, 1 part (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 1 part corrosion-resistant microcapsule, 0.2 parts amino graphene, 15 parts toluene, 20 parts xylene, 4-6 parts alicyclic amine curing agent, and 0.02 parts photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0039] S5: Take 15 parts of sodium silicate nonahydrate and 100 parts of water, stir evenly, add 6 mol / L hydrochloric acid to adjust the pH to 3, and obtain acidic silica sol; take 2 parts of hexadecyltrimethylammonium bromide, 1 part of polyoxyethylene octylphenol ether-10, and 100 parts of water, stir evenly, and obtain composite emulsifier; take 3 parts of photosensitive resin and 5 parts of polydimethylsiloxane, stir at 300 r / min, add the composite emulsifier dropwise, stir at 2000 r / min for 50 min, add acidic silica sol dropwise at 0.5 mL / min, stir at 70℃ and 300 r / min for 3 h, add 0.2 parts of vinyltriethoxysilane, stir for 2 h, filter and dry to obtain silica microcapsules;

[0040] S6: Take 1 part polydimethylsiloxane, 1 part vinyl-terminated poly(dimethylsiloxane), 0.05 part methyltriethoxysilane, 0.1 part vinyltriethoxysilane, and 150 parts tetrahydrofuran, stir for 1 hour to obtain a dispersion; take 10 parts of the dispersion, add 0.1 part silica microcapsules and 0.01 part photoinitiator, sonicate for 30 minutes, stir for 1 hour to obtain a hydrophobic coating.

[0041] Example 3: The preparation of the corrosion-resistant coating and hydrophobic coating includes the following steps: S1: Take 10 parts of amino graphene, 15 parts of water, 90 parts of ethanol, and 6 parts of 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 70°C, stir for 4 hours, evaporate the solvent, and obtain modified graphene.

[0042] S2: Take 15 parts of isophorone diisocyanate, 8 parts of polytetrahydrofuran ether diol, 0.5 parts of tetrafluoroterephthalic acid diethanol, and 0.02 parts of di-n-butyltin dilaurate, react at 90℃ for 3 hours, add 2 parts of 3-amino-1-propanol vinyl ether, and react for 2 hours to obtain modified polyurethane.

[0043] S3: Take 0.5 parts modified graphene, 120 parts ethanol, and 50 parts water, sonicate until uniformly dispersed, add 0.2 parts acrylamide, 0.2 parts methacrylic acid, and 0.2 parts modified polyurethane, stir at 300 r / min for 15 min, add 1.5 parts potassium persulfate and 0.8 parts methylenebisacrylamide under nitrogen protection, reflux for 9 h, filter and dry to obtain corrosion-resistant microcapsules;

[0044] S4: Take 25 parts epoxy resin, 2 parts photosensitive resin, 2 parts (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 2 parts corrosion-resistant microcapsules, 0.5 parts amino graphene, 15 parts toluene, 20 parts xylene, 4-6 parts alicyclic amine curing agent, and 0.02 parts photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0045] S5: Take 15 parts of sodium silicate nonahydrate and 100 parts of water, stir evenly, add 6 mol / L hydrochloric acid to adjust the pH to 3, and obtain acidic silica sol; take 2 parts of hexadecyltrimethylammonium bromide, 1 part of polyoxyethylene octylphenol ether-10, and 100 parts of water, stir evenly, and obtain composite emulsifier; take 5 parts of photosensitive resin and 10 parts of polydimethylsiloxane, stir at 300 r / min, add the composite emulsifier dropwise, stir at 2000 r / min for 50 min, add acidic silica sol dropwise at 0.5 mL / min, stir at 300 r / min for 3 h at 70 °C, add 0.2 parts of vinyltriethoxysilane, stir for 2 h, filter and dry to obtain silica microcapsules;

[0046] S6: Take 2 parts of polydimethylsiloxane, 0.5 parts of vinyl-terminated poly(dimethylsiloxane), 0.1 parts of methyltriethoxysilane, 0.15 parts of vinyltriethoxysilane, and 150 parts of tetrahydrofuran, stir for 1 hour to obtain a dispersion; take 15 parts of the dispersion, add 0.2 parts of silica microcapsules and 0.01 parts of photoinitiator, ultrasonically disperse for 30 minutes, stir for 1 hour to obtain a hydrophobic coating.

[0047] Comparative Example 1 (a mixed coating was prepared by mixing a corrosion-resistant coating and a hydrophobic coating, and then applied once. The remaining steps were the same as in Example 1): S1: Take 10 parts of amino graphene, 15 parts of water, 90 parts of ethanol, and 5 parts of 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 70°C, stir for 4 hours, and evaporate the solvent to obtain modified graphene.

[0048] S2: Take 15 parts of isophorone diisocyanate, 6 parts of polytetrahydrofuran ether diol, 0.4 parts of tetrafluoroterephthalic acid diethanol, and 0.02 parts of dibutyltin dilaurate, react at 90℃ for 3 hours, add 1.5 parts of 3-amino-1-propanol vinyl ether, and react for 2 hours to obtain modified polyurethane.

[0049] S3: Take 0.5 parts modified graphene, 120 parts ethanol, and 50 parts water, sonicate until uniformly dispersed, add 0.1 parts acrylamide, 0.2 parts methacrylic acid, and 0.2 parts modified polyurethane, stir at 300 r / min for 15 min, add 1.5 parts potassium persulfate and 0.8 parts methylenebisacrylamide under nitrogen protection, reflux for 9 h, filter and dry to obtain corrosion-resistant microcapsules;

[0050] S4: Take 25 parts epoxy resin, 1.5 parts photosensitive resin, 1 part (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 2 parts corrosion-resistant microcapsules, 0.3 parts amino graphene, 15 parts toluene, 20 parts xylene, 5 parts alicyclic amine curing agent, and 0.02 parts photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0051] S5: Take 15 parts of sodium silicate nonahydrate and 100 parts of water, stir evenly, add 6 mol / L hydrochloric acid to adjust pH to 3, and obtain acidic silica sol; take 2 parts of hexadecyltrimethylammonium bromide, 1 part of polyoxyethylene octylphenol ether-10, and 100 parts of water, stir evenly, and obtain composite emulsifier; take 4 parts of photosensitive resin and 8 parts of polydimethylsiloxane, stir at 300 r / min, add composite emulsifier dropwise, stir at 2000 r / min for 50 min, add acidic silica sol dropwise at 0.5 mL / min, stir at 300 r / min for 3 h at 70 °C, add 0.2 parts of vinyltriethoxysilane, stir for 2 h, filter and dry to obtain silica microcapsules;

[0052] S6: Take 2 parts of polydimethylsiloxane, 0.8 parts of vinyl-terminated poly(dimethylsiloxane), 0.05 parts of methyltriethoxysilane, 0.15 parts of vinyltriethoxysilane, and 150 parts of tetrahydrofuran, stir for 1 hour to obtain a dispersion; take 12 parts of the dispersion, add 0.15 parts of silica microcapsules and 0.01 parts of photoinitiator, ultrasonically disperse for 30 minutes, stir for 1 hour to obtain a hydrophobic coating; mix the hydrophobic coating and the corrosion-resistant coating at a mass ratio of 1:1 to obtain a mixed coating; take the billet, and pass it through piercing, spheroidizing annealing, pickling, cold rolling, annealing, straightening, and head and tail trimming to obtain a low-carbon steel pipe; coat the surface of the low-carbon steel pipe with the mixed coating, and irradiate it uniformly with ultraviolet light at 10 cm for 30 minutes with an ultraviolet light intensity of 55 mw / cm. 2 A 63μm mixed coating was obtained, resulting in a corrosion-resistant low-carbon steel pipe.

[0053] Comparative Example 2 (without introducing modified polyurethane, the remaining methods and steps are the same as in Example 1): The preparation of the corrosion-resistant coating and the hydrophobic coating includes the following steps: S1: Take 10 parts of aminated graphene, 15 parts of water, 90 parts of ethanol, and 5 parts of 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 70°C, stir for 4 hours, evaporate the solvent, and obtain modified graphene.

[0054] S2: Take 0.5 parts modified graphene, 120 parts ethanol, and 50 parts water, sonicate until uniformly dispersed, add 0.1 parts acrylamide and 0.2 parts methacrylic acid, stir at 300 r / min for 15 min, add 1.5 parts potassium persulfate and 0.8 parts methylenebisacrylamide under nitrogen protection, reflux for 9 h, filter and dry to obtain corrosion-resistant microcapsules;

[0055] S3: Take 25 parts epoxy resin, 1.5 parts photosensitive resin, 1 part (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 2 parts corrosion-resistant microcapsules, 0.3 parts amino graphene, 15 parts toluene, 20 parts xylene, 5 parts alicyclic amine curing agent, and 0.02 parts photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0056] S4: Take 15 parts of sodium silicate nonahydrate and 100 parts of water, stir evenly, add 6 mol / L hydrochloric acid to adjust the pH to 3, and obtain acidic silica sol; take 2 parts of hexadecyltrimethylammonium bromide, 1 part of polyoxyethylene octylphenol ether-10, and 100 parts of water, stir evenly, and obtain composite emulsifier; take 4 parts of photosensitive resin and 8 parts of polydimethylsiloxane, stir at 300 r / min, add the composite emulsifier dropwise, stir at 2000 r / min for 50 min, add acidic silica sol dropwise at 0.5 mL / min, stir at 300 r / min for 3 h at 70 °C, add 0.2 parts of vinyltriethoxysilane, stir for 2 h, filter and dry to obtain silica microcapsules;

[0057] S5: Take 2 parts of polydimethylsiloxane, 0.8 parts of vinyl-terminated poly(dimethylsiloxane), 0.05 parts of methyltriethoxysilane, 0.15 parts of vinyltriethoxysilane, and 150 parts of tetrahydrofuran, stir for 1 hour to obtain a dispersion; take 12 parts of the dispersion, add 0.15 parts of silica microcapsules and 0.01 parts of photoinitiator, ultrasonically disperse for 30 minutes, stir for 1 hour to obtain a hydrophobic coating.

[0058] Comparative Example 3 (silica replaces silica microcapsules, and the remaining methods and steps are the same as in Example 1): The preparation of the corrosion-resistant coating and hydrophobic coating includes the following steps: S1: Take 10 parts of aminated graphene, 15 parts of water, 90 parts of ethanol, and 5 parts of 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 70°C, stir for 4 hours, evaporate the solvent, and obtain modified graphene.

[0059] S2: Take 15 parts of isophorone diisocyanate, 6 parts of polytetrahydrofuran ether diol, 0.4 parts of tetrafluoroterephthalic acid diethanol, and 0.02 parts of dibutyltin dilaurate, react at 90℃ for 3 hours, add 1.5 parts of 3-amino-1-propanol vinyl ether, and react for 2 hours to obtain modified polyurethane.

[0060] S3: Take 0.5 parts modified graphene, 120 parts ethanol, and 50 parts water, sonicate until uniformly dispersed, add 0.1 parts acrylamide, 0.2 parts methacrylic acid, and 0.2 parts modified polyurethane, stir at 300 r / min for 15 min, add 1.5 parts potassium persulfate and 0.8 parts methylenebisacrylamide under nitrogen protection, reflux for 9 h, filter and dry to obtain corrosion-resistant microcapsules;

[0061] S4: Take 25 parts epoxy resin, 1.5 parts photosensitive resin, 1 part (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 2 parts corrosion-resistant microcapsules, 0.3 parts amino graphene, 15 parts toluene, 20 parts xylene, 5 parts alicyclic amine curing agent, and 0.02 parts photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0062] S5: Take 2 parts of polydimethylsiloxane, 0.8 parts of vinyl-terminated poly(dimethylsiloxane), 0.05 parts of methyltriethoxysilane, 0.15 parts of vinyltriethoxysilane, and 150 parts of tetrahydrofuran, stir for 1 hour to obtain a dispersion; take 12 parts of the dispersion, add 0.15 parts of silica and 0.01 parts of photoinitiator, ultrasonically disperse for 30 minutes, stir for 1 hour to obtain a hydrophobic coating.

[0063] Comparative Example 4 (without adding photosensitive resin and (9CI)-2-(3-ethylene ethylene oxide)-pyridine, and the remaining methods and steps are the same as in Example 1): The preparation of the corrosion-resistant coating and hydrophobic coating includes the following steps: S1: Take 10 parts of amino graphene, 15 parts of water, 90 parts of ethanol, and 5 parts of 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 70°C, stir for 4 hours, evaporate the solvent, and obtain modified graphene;

[0064] S2: Take 15 parts of isophorone diisocyanate, 6 parts of polytetrahydrofuran ether diol, 0.4 parts of tetrafluoroterephthalic acid diethanol, and 0.02 parts of dibutyltin dilaurate, react at 90℃ for 3 hours, add 1.5 parts of 3-amino-1-propanol vinyl ether, and react for 2 hours to obtain modified polyurethane.

[0065] S3: Take 0.5 parts modified graphene, 120 parts ethanol, and 50 parts water, sonicate until uniformly dispersed, add 0.1 parts acrylamide, 0.2 parts methacrylic acid, and 0.2 parts modified polyurethane, stir at 300 r / min for 15 min, add 1.5 parts potassium persulfate and 0.8 parts methylenebisacrylamide under nitrogen protection, reflux for 9 h, filter and dry to obtain corrosion-resistant microcapsules;

[0066] S4: Take 27.5 parts epoxy resin, 2 parts corrosion-resistant microcapsules, 0.3 parts aminated graphene, 15 parts toluene, 20 parts xylene, 5 parts alicyclic amine curing agent, and 0.02 parts photoinitiator, mix them evenly to obtain a corrosion-resistant coating.

[0067] S5: Take 15 parts of sodium silicate nonahydrate and 100 parts of water, stir evenly, add 6 mol / L hydrochloric acid to adjust pH to 3 to obtain acidic silica sol; take 2 parts of hexadecyltrimethylammonium bromide, 1 part of polyoxyethylene octylphenol ether-10, and 100 parts of water, stir evenly to obtain composite emulsifier; take 12 parts of polydimethylsiloxane, stir at 300 r / min, add the composite emulsifier dropwise, stir at 2000 r / min for 50 min, add acidic silica sol dropwise at 0.5 mL / min, stir at 70℃ and 300 r / min for 3 h, add 0.2 parts of vinyltriethoxysilane, stir for 2 h, filter and dry to obtain silica microcapsules;

[0068] S6: Take 2 parts of polydimethylsiloxane, 0.8 parts of vinyl-terminated poly(dimethylsiloxane), 0.05 parts of methyltriethoxysilane, 0.15 parts of vinyltriethoxysilane, and 150 parts of tetrahydrofuran, stir for 1 hour to obtain a dispersion; take 12 parts of the dispersion, add 0.15 parts of silica microcapsules and 0.01 parts of photoinitiator, ultrasonically disperse for 30 minutes, stir for 1 hour to obtain a hydrophobic coating.

[0069] Unless otherwise specified, the experimental methods used in the above embodiments are conventional methods; the raw materials used are commercially available unless otherwise specified, and the sources of the raw materials are as follows: aminographene (catalog number: 180117145026, Kramar); ethanol (CAS: 64-17-5); 8-hydroxyquinoline-2-carboxaldehyde (CAS: 14510-06-6); isophorone diisocyanate (CAS: 4098-71-9); polytetrahydrofuran ether diol (PTMEG650, Shandong Suihua Biotechnology Co., Ltd.); tetrafluoroterephthalic acid (CAS: 92339-07-6); dibutyltin dilaurate (CAS: 77-58-7); 3-amino-1-propanol vinyl ether (CAS: 66415-5) 5-2); Acrylamide (CAS: 79-06-1); Methacrylic acid (CAS: 79-41-4); Potassium persulfate (CAS: 7727-21-1); Nymethylene bisacrylamide (S14002, Shanghai Yuanye Biotechnology Co., Ltd.); Epoxy resin (E51, Jinan Chuangshi Chemical Co., Ltd.); Photosensitive resin (polymer of 4'-(1-methylethylene)diphenol and (chloromethyl)ethylene oxide 2-acrylate, CH0269, Hubei Chenghai Chemical Co., Ltd.); (9CI)-2-(3-ethylene ethylene oxide)-pyridine (CAS: 132356-15-1); Toluene (CAS: 108-88-3); Xylene (CAS: 1330-20-7); Alicyclic amine curing agent (EPIKURE) 3370, Hansen); Photoinitiator (CAS: 7473-98-5, Photoinitiator 1173); Sodium silicate nonahydrate (CAS: 13517-24-3); Hexadecyltrimethylammonium bromide (CAS: 57-09-0); Polyoxyethylene octylphenol ether-10 (OP-10, Jinan Xinyuda Trading Co., Ltd.); Polydimethylsiloxane (S26896, Shanghai Yuanye); Vinyltriethoxysilane (CAS: 78-08-0); Vinyl-terminated poly(dimethylsiloxane): (average Mw~25000, Sigma-Aldrich (Shanghai) Trading Co., Ltd.); Methyltriethoxysilane (CAS: 2031-67-6); Tetrahydrofuran (CAS: 109-99-9).

[0070] Experiment: Corrosion-resistant low-carbon steel pipes prepared with coatings obtained in Examples 1-3 and Comparative Examples 1-4 were used; (1) The pipes were kept at 35°C and sprayed with a 5% sodium chloride aqueous solution in the test chamber to simulate accelerated corrosion in the environment and test the time it took to remain rust-free in order to determine its corrosion resistance; (2) The water contact angle was measured; the specific data are shown in the table below.

[0071] Time / h Water contact angle / ° Example 1 1269 146 Example 2 1265 145 Example 3 1268 146 Comparative Example 1 1103 124 Comparative Example 2 1134 140 Comparative Example 3 1110 126 Comparative Example 4 1150 128

[0072] Conclusions: Comparative Example 1, which mixed corrosion-resistant and hydrophobic coatings and applied them in a single coat, exhibited poor coating uniformity and insufficient adhesion, leading to a decline in performance; Comparative Example 2, which did not introduce modified polyurethane, showed a decrease in corrosion resistance; Comparative Example 3, which replaced silica microcapsules with silica, experienced a decrease in corrosion resistance due to reduced self-healing ability; Comparative Example 4, which did not add photosensitive resin or (9CI)-2-(3-ethylene ethylene oxide)-pyridine, had performance inferior to the examples; In summary, the corrosion-resistant low-carbon steel pipe prepared by this invention exhibits good corrosion resistance.

[0073] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the spirit and principles of the present invention and within the technical scope disclosed in this application should be included within the scope of protection of this application. Where there is no conflict, the embodiments and features described in the embodiments of this application can be combined with each other. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a corrosion-resistant low-carbon steel pipe, characterized in that: Includes the following steps: Step 1: Take the billet, and proceed with piercing, spheroidizing annealing, pickling, cold rolling, annealing, straightening, and cutting off the ends to obtain low carbon steel pipe; Step 2: Coat the surface of the low-carbon steel pipe with a corrosion-resistant coating, irradiate with ultraviolet light for the first time, then coat with a hydrophobic coating, and irradiate with ultraviolet light for the second time to obtain a corrosion-resistant low-carbon steel pipe. The preparation of the corrosion-resistant coating includes the following steps: S1: Take amino-based graphene, water, ethanol, and 8-hydroxyquinoline-2-carboxaldehyde, stir evenly, heat to 60-70℃, stir for 2-4 hours, evaporate the solvent to obtain modified graphene. S2: Take isophorone diisocyanate, polytetrahydrofuran ether diol, tetrafluoroterephthalic acid diethanol and dibutyltin dilaurate, react at 85-90℃ for 3-4h, add 3-amino-1-propanol vinyl ether, react for 2-3h to obtain modified polyurethane. S3: Take modified graphene, ethanol, and water, sonicate until uniformly dispersed, add acrylamide, methacrylic acid, and modified polyurethane, stir, add potassium persulfate and methylenebisacrylamide under nitrogen protection, reflux for 8-9 hours, filter and dry to obtain corrosion-resistant microcapsules; S4: Take epoxy resin, photosensitive resin, (9CI)-2-(3-ethylene ethylene oxide)-pyridine, corrosion-resistant microcapsules, amino graphene, toluene, xylene, alicyclic amine curing agent, and photoinitiator, mix them evenly to obtain a corrosion-resistant coating. The corrosion-resistant coating comprises the following raw materials, by weight: 20-25 parts epoxy resin, 1-2 parts photosensitive resin, 1-2 parts (9CI)-2-(3-ethylene ethylene oxide)-pyridine, 1-2 parts corrosion-resistant microcapsules, 0.2-0.5 parts aminographene, 15-20 parts toluene, 15-20 parts xylene, 4-6 parts alicyclic amine curing agent, and 0.02-0.03 parts photoinitiator; The preparation of the hydrophobic coating includes the following steps: S1: Take sodium silicate nonahydrate and water, stir evenly, adjust pH to 2-3 to obtain acidic silica sol; take hexadecyltrimethylammonium bromide, polyoxyethylene octylphenol ether-10, and water, stir evenly to obtain composite emulsifier; take photosensitive resin and polydimethylsiloxane, stir, add composite emulsifier dropwise, stir, add acidic silica sol dropwise, heat and stir, add vinyltriethoxysilane, stir, filter and dry to obtain silica microcapsules; S2: Take polydimethylsiloxane, vinyl-terminated poly(dimethylsiloxane), methyltriethoxysilane, vinyltriethoxysilane, and tetrahydrofuran, stir for 1 hour to obtain a dispersion; take the dispersion, add silica microcapsules and photoinitiator, ultrasonically disperse, stir to obtain a hydrophobic coating; The hydrophobic coating comprises the following raw materials, by mass: 10-15 parts dispersion, 0.1-0.2 parts silica microcapsules, and 0.01 parts photoinitiator.

2. The method for preparing a corrosion-resistant low-carbon steel pipe according to claim 1, characterized in that: The spheroidizing annealing temperature is 790–800℃, and the time is 26–32 h. During the spheroidizing annealing process, RX gas is added for carburizing protection. The composition of RX gas by volume percentage is: CO: 19–21%; H2: 18–22%; CO2: 0.25–0.45%, with the remainder being N2.

3. The method for preparing a corrosion-resistant low-carbon steel pipe according to claim 1, characterized in that: The modified graphene comprises the following raw materials, by mass parts: 10 parts of aminated graphene, 10-20 parts of water, 80-100 parts of ethanol, and 4-6 parts of 8-hydroxyquinoline-2-carboxaldehyde; the modified polyurethane comprises the following raw materials, by mass parts: 8-15 parts of isophorone diisocyanate, 4-8 parts of polytetrahydrofuran ether diol, 0.2-0.5 parts of tetrafluoroterephthalic acid, 0.01-0.03 parts of dibutyltin dilaurate, and 1-2 parts of 3-amino-1-propanol vinyl ether.

4. The method for preparing a corrosion-resistant low-carbon steel pipe according to claim 1, characterized in that: The corrosion-resistant microcapsules comprise the following raw materials, by weight: 0.3–0.5 parts modified graphene, 120–150 parts ethanol, 50–80 parts water, 0.1–0.2 parts acrylamide, 0.1–0.2 parts methacrylic acid, 0.1–0.2 parts modified polyurethane, 1.5–2 parts potassium persulfate, and 0.5–0.8 parts methylenebisacrylamide.

5. The method for preparing a corrosion-resistant low-carbon steel pipe according to claim 1, characterized in that: The silica microcapsules comprise the following raw materials, by weight: 1-2 parts hexadecyltrimethylammonium bromide, 1-2 parts polyoxyethylene octylphenol ether-10, 200 parts water, 3-5 parts photosensitive resin, 5-10 parts polydimethylsiloxane, 10-15 parts sodium silicate nonahydrate, and 0.1-0.2 parts vinyltriethoxysilane; the dispersion comprises the following raw materials, by weight: 1-2 parts polydimethylsiloxane, 0.05-0.1 parts methyltriethoxysilane, 0.5-1 parts vinyl-terminated poly(dimethylsiloxane), 0.1-0.15 parts vinyltriethoxysilane, and 100-150 parts tetrahydrofuran.

6. The method for preparing a corrosion-resistant low-carbon steel pipe according to claim 1, characterized in that: Specific process for preparing corrosion-resistant low-carbon steel pipes The process includes the following steps: coating the surface of a low-carbon steel pipe with a corrosion-resistant coating, and then uniformly irradiating it with ultraviolet light at a distance of 10cm for 8–12 minutes at an ultraviolet light intensity of 50–55 mw / cm. 2 A corrosion-resistant coating of 50–70 μm is obtained; then a hydrophobic coating is applied, and the mixture is uniformly irradiated with ultraviolet light at a distance of 10 cm for 20–25 minutes at an ultraviolet light intensity of 50–55 mw / cm². 2 A 2-4 μm hydrophobic coating is obtained, ultimately resulting in a corrosion-resistant low-carbon steel pipe.

7. The corrosion-resistant low-carbon steel pipe prepared by the method for preparing a corrosion-resistant low-carbon steel pipe according to any one of claims 1 to 6.