High-temperature-resistant seamless steel tube and preparation process thereof

Abstract

The invention provides a high-temperature-resistant seamless steel pipe and a preparation process thereof, and belongs to the technical field of alloy steel pipes. The steel comprises the following components in percentage by mass: 0.62%-0.68% of C, 0.18%-0.23% of Si, 0.40%-0.47% of Mn, 0.027%-0.038% of Al, 0.045%-0.055% of Cr, less than or equal to 0.016% of P, less than or equal to 0.014% of S and the balance of Fe and inevitable impurities. S2, preparing a high-temperature-resistant treatment agent; the composite material comprises the following components in parts by weight: 24 parts of polyvinylidene fluoride, 5-7 parts of 4-acryloyl benzophenone hydroxybenzoate, 0.5-1 part of benzoyl peroxide, 4-6 parts of modified glass powder, 6-8 parts of epoxy resin, 4-6 parts of ethyl cyanoacrylate and 5-7 parts of a solvent. And S3, preheating the high-temperature-resistant treatment agent to 70-80 DEG C, uniformly coating the seamless steel tube body with the high-temperature-resistant treatment agent, baking, curing, and cooling to room temperature to obtain the high-temperature-resistant seamless steel tube. The reduction amplitude of the yield strength at high temperature is effectively weakened, and the high-temperature resistance of the seamless steel pipe is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy steel pipes, and in particular relates to a high-temperature resistant seamless steel pipe and a preparation process thereof. Background Art

[0002] High carbon steel, also known as tool steel, is a type of steel with a high carbon content, ranging from 0.60% to 1.70%. This material is often used to make various tools and mechanical parts due to its excellent hardness and strength. Under high temperature conditions, high carbon steel is more prone to decarburization, that is, carbon atoms on the surface diffuse into the interior of the steel during oxidation, resulting in a decrease in surface hardness and an increase in roughness. In addition, under high temperature conditions, the internal metallographic structure of the steel may undergo transformation, such as the transformation from austenite to martensite. This transformation is accompanied by volume changes and can also lead to an increase in surface roughness.

[0003] In order to improve the high temperature resistance of seamless steel pipes made of high carbon steel, in the prior art, a treatment agent is applied to the surface of the seamless steel pipe to form a coating to achieve a heat insulation effect. However, the effects of high temperature environment are not completely offset by the coating. When the surface roughness of the seamless steel pipe increases, the uniformity and adhesion of the coating applied to the surface of the seamless steel pipe will be affected, thereby reducing its protective effect and accelerating the thermal softening of the seamless steel pipe. It may also cause surface defects such as microcracks and bubbles, which may become the starting point for crack expansion when subjected to stress, resulting in a decrease in the yield strength of the material. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a high-temperature resistant seamless steel pipe and its preparation process, and adopts a high-temperature resistant treatment agent to form a coating on the surface of the seamless steel pipe, thereby forming heat insulation and oxygen isolation protection, and can effectively maintain good uniformity and adhesion at high temperatures, effectively weaken the decrease in yield strength at high temperatures, and thus improve the high-temperature resistance of the seamless steel pipe.

[0005] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a preparation process of a high temperature resistant seamless steel pipe, comprising the following steps:

[0006] S1. Prepare seamless steel pipe body;

[0007] The composition of the seamless steel pipe body includes, by mass percentage, C: 0.62-0.68%, Si: 0.18-0.23%, Mn: 0.40-0.47%, Al: 0.027-0.038%, Cr: 0.045-0.055%, P≤0.016%, S≤0.014%, and the rest is Fe and unavoidable impurities;

[0008] S2, preparing high temperature resistant treatment agent;

[0009] The components of the high temperature resistant treatment agent include 24 parts of polyvinylidene fluoride, 5-7 parts of 4-acryloylhydroxybenzoic acid benzophenone, 0.5-1 parts of benzoyl peroxide, 4-6 parts of modified glass powder, 6-8 parts of epoxy resin, 4-6 parts of ethyl cyanoacrylate and 5-7 parts of solvent by weight;

[0010] S3, preparing high temperature resistant seamless steel pipe;

[0011] The high temperature resistant treatment agent prepared by S2 is preheated to 70-80°C, evenly coated on the seamless steel pipe body prepared by S1, and then baked, cured, and cooled to room temperature to form a coating to obtain a high temperature resistant seamless steel pipe.

[0012] Furthermore, the specific operation steps of S2 are as follows:

[0013] S21, mixing polyvinylidene fluoride and 4-acryloylhydroxybenzoic acid benzophenone, adding benzoyl peroxide and modified glass powder, heating to 70-80° C., stirring for reaction for 1-2 hours, then adding epoxy resin, keeping the temperature and continuing stirring for 50-60 minutes to obtain a composite resin;

[0014] S22, stirring ethyl cyanoacrylate and solvent at a uniform speed for 15-25 minutes under sealed conditions to obtain a diluted curing solution;

[0015] S23, mixing the composite resin obtained in S21 with the diluted solidifying liquid obtained in S22, and stirring for 25-35 minutes to obtain a high temperature resistant treatment agent.

[0016] Furthermore, the preparation method of the modified glass powder is as follows:

[0017] A1. Immerse the glass powder in an aqueous solution of 5-6% hydrofluoric acid by mass, stir at 50-60r / min for 3-5 minutes at room temperature, filter, and wash with water until neutral to obtain roughened glass powder;

[0018] A2. Immerse the roughened glass powder obtained in A1 in a 10-12% by mass silane coupling agent n-butanol solution, heat to 75-85°C, stir at 50-60r / min for 4-5h, filter and dry to obtain the modified glass powder.

[0019] Furthermore, the glass powder has a softening temperature of 350-560° C., a thermal expansion coefficient of 65-125, and a fineness of 2-8 μm.

[0020] Furthermore, the silane coupling agent is KH550.

[0021] Furthermore, the solvent includes any one of acetone, butanone or dichloromethane.

[0022] Further, in S3, coating is performed 2-3 times, and the coating thickness is 0.3-0.5 mm.

[0023] Further, in S3, baking is performed at a temperature of 165-175° C. for 40-60 min.

[0024] A high temperature resistant seamless steel pipe is produced by adopting the above-mentioned preparation process.

[0025] This application has the following beneficial effects:

[0026] 1. The polyvinylidene fluoride and 4-acryloylhydroxybenzoic acid benzophenone of the present invention are copolymerized under the initiation conditions of benzoyl peroxide, and a benzophenone group is introduced, which has good light stability and weather resistance, and can effectively protect the coating surface from damage by factors such as oxidation, so as to obtain a copolymer with good heat resistance and oxygen resistance. Then a cross-linked network is formed with epoxy resin. On the one hand, the cross-linked network can improve the thermal stability (high temperature resistance) and self-repairing ability of the coating. On the other hand, epoxy resin has good bonding properties, which can make the coating and the surface of the substrate (seamless steel pipe) closely combined, which is more conducive to forming a stable protective layer; the heat insulation and oxygen isolation effect is better, and the yield strength of the substrate under high temperature environment is effectively avoided.

[0027] At the same time, modified glass powder is introduced into the cross-linked network to form uniform cross-linking points, and due to its low thermal conductivity and good chemical resistance, the heat insulation and oxygen isolation properties of the coating can be further enhanced; the glass powder can soften and fill the rough points on the surface of the high-carbon steel substrate that are more easily formed due to high temperature in a high temperature environment, thereby avoiding a decrease in coating uniformity and adhesion, effectively weakening the negative impact, weakening the decrease in the yield strength of the substrate in a high temperature environment, and improving high temperature resistance.

[0028] The solvent of the invention can effectively control the viscosity of ethyl cyanoacrylate, and at the same time avoid introducing too much water, thereby preventing the curing speed from being too fast and affecting the application effect.

[0029] 2. In the preparation of modified glass powder, the glass powder is roughened by treating it with hydrofluoric acid solution, which removes dirt and some inorganic matter on the surface of the glass powder, makes the surface of the glass powder rough, increases the contact area between the subsequent modifier (silane coupling agent) and the glass powder, and improves the modification effect; the silane coupling agent forms a chemical bond on the surface of the glass powder, thereby improving its compatibility and interfacial bonding strength with other materials such as resins, and also enhances the filling capacity, that is, improves the dispersibility of the glass powder in the resin, reduces agglomeration, and ensures that the glass powder is smoothly and evenly introduced into the cross-linked network. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 , a comparative trend chart of yield strength test data of products obtained in Examples 1-9 of the present invention and Comparative Examples 1-12 at room temperature and 400°C;

[0031] Figure 2 , a comparative trend chart of the loss rate of the yield strength test data of the products obtained in Examples 1-9 of the present invention and Comparative Examples 1-12 at 400°C compared with the yield strength test data at room temperature. DETAILED DESCRIPTION

[0032] The present application is further described in detail below with reference to the embodiments.

[0033] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0034] Embodiment 1: A process for preparing a high temperature resistant seamless steel pipe, comprising the following steps:

[0035] S1. Prepare seamless steel pipe body;

[0036] The composition of the seamless steel pipe body includes, by mass percentage, C: 0.65%, Si: 0.21%, Mn: 0.44%, Al: 0.033%, Cr: 0.047%, P: 0.012%, S: 0.008%, and the rest is Fe and unavoidable impurities.

[0037] The specific preparation steps are as follows:

[0038] S11, pre-treat the molten iron, smelt it in a converter, add alloy components, add refining agent and perform refining outside the furnace, and fill argon gas during the refining process. Then perform vacuum degassing, the vacuum degree is ≤0.1Kpa, and the degassing time is 20min. Then perform round billet continuous casting, cooling and annealing.

[0039] S12, preheat the round billet at 900℃ for 10h, then heat it at 980℃ in the first stage; heat it at 1110℃ in the second stage; heat it at 1180℃ in the third stage; heat it at 1220℃ in the fourth stage; and heat it at 1220℃. The time for the first stage, the second stage, the third stage, the fourth stage and the heat treatment is 1.5h. When perforating, the rotation speed of the perforator guide plate is controlled to be 2.5m / s, the rolling speed is 2.1m / s, the temperature of the tube is 1100℃, and the sizing temperature is 930℃. The heated round billet is subjected to the above-mentioned perforation, tube rolling and sizing to obtain a rolled steel pipe.

[0040] S13, the rolled steel pipe is subjected to quenching and tempering heat treatment, and then hot straightening is performed after heat treatment. The quenching temperature is 920℃, and the quenching holding time is 30min. The tempering temperature is 650℃, the heating time in the tempering furnace is 50min, and the straightening temperature is 550℃.

[0041] S2, prepare high temperature resistant treatment agent; the specific preparation steps are as follows:

[0042] S21. Mix 24 parts of polyvinylidene fluoride and 6 parts of 4-acryloylhydroxybenzoic acid benzophenone by weight, add 0.8 parts of benzoyl peroxide and 5 parts of modified glass powder, raise the temperature to 75°C, stir and react at 120 r / min for 1.5 hours, then add 7 parts of epoxy resin, keep warm and continue stirring for 55 minutes to obtain a composite resin.

[0043] S22. According to the same standard weight parts, 5 parts of ethyl cyanoacrylate and 6 parts of dichloromethane were stirred at a constant speed of 80 r / min for 20 minutes under sealed conditions to obtain a diluted solidifying liquid.

[0044] S23, mixing the composite resin obtained in S21 with the diluted solidifying liquid obtained in S22, and stirring at a constant speed of 90 r / min for 30 min to obtain a high temperature resistant treatment agent.

[0045] Polyvinylidene fluoride (USA Solvay PVDF5130) was purchased from Dongguan Zhanyang Polymer Materials Co., Ltd. 4-Acryloylhydroxybenzoic acid benzophenone (98%) was purchased from Hubei Hongxin Ruiyu Fine Chemical Co., Ltd. Benzoyl peroxide was purchased from Shandong Lierming Trading Co., Ltd. E-44 epoxy resin (A-grade Jinhong brand) was purchased from Hangzhou Wuhuigang Adhesive Co., Ltd. Ethyl cyanoacrylate (E1051) was purchased from Dongguan Qianqianhe Adhesive Technology Co., Ltd. Dichloromethane (99.9%) was purchased from Jinan Qichen Chemical Co., Ltd.

[0046] The preparation method of modified glass powder is as follows:

[0047] A1. Immerse the glass powder in an aqueous solution of 5.5% hydrofluoric acid by mass, stir at 55r / min for 4 minutes at room temperature, filter, and wash with water until neutral to obtain roughened glass powder.

[0048] A2. Immerse the roughened glass powder obtained in A1 in a n-butanol solution containing 11% by mass of silane coupling agent KH550, heat to 80°C, stir at 55 r / min for 4.5 hours, filter, and dry at 45°C for 2 hours to obtain modified glass powder.

[0049] Glass powder (industrial grade), softening temperature 350-560°C, thermal expansion coefficient 65-125, fineness 2-8μm, purchased from Foshan Jinggu Material Technology Co., Ltd. Hydrofluoric acid, purchased from Shandong Tengyun Chemical Technology Co., Ltd. Silane coupling agent KH550 (97%), purchased from Shandong Yousuo Chemical Technology Co., Ltd. n-Butanol (99.9%), purchased from Shandong Sanju Chemical Technology Co., Ltd.

[0050] S3, preparing high temperature resistant seamless steel pipe;

[0051] The high temperature resistant treatment agent prepared by S2 is preheated to 75°C, and evenly coated on the seamless steel pipe body prepared by S1, coated 3 times, and then baked at 170°C for 50 minutes, solidified, and naturally cooled to room temperature to form a coating with a coating thickness of 0.45mm, thereby obtaining a high temperature resistant seamless steel pipe.

[0052] Example 2: The difference between this example and Example 1 is: S1, preparing a seamless steel pipe body; the composition of the seamless steel pipe body includes, by mass percentage, C: 0.62%, Si: 0.18%, Mn: 0.40%, Al: 0.027%, Cr: 0.045%, P: 0.012%, S: 0.01%, and the rest is Fe and unavoidable impurities.

[0053] Example 3: The difference between this example and Example 1 is that: S1, preparing a seamless steel pipe body; the composition of the seamless steel pipe body includes, by mass percentage, C: 0.68%, Si: 0.23%, Mn: 0.47%, Al: 0.038%, Cr: 0.055%, P: 0.016%, S: 0.014%, and the rest is Fe and unavoidable impurities.

[0054] Example 4: The difference between this example and Example 1 is that: S2, preparing a high temperature resistant treatment agent; the specific preparation steps are as follows:

[0055] S21. Mix 24 parts of polyvinylidene fluoride and 5 parts of 4-acryloylhydroxybenzoic acid benzophenone by weight, add 0.5 parts of benzoyl peroxide and 4 parts of modified glass powder, raise the temperature to 70°C, stir and react for 1 hour, then add 6 parts of epoxy resin, keep warm and continue stirring for 50 minutes to obtain a composite resin.

[0056] S22. According to the same standard weight parts, 4 parts of ethyl cyanoacrylate and 5 parts of dichloromethane were stirred at a constant speed for 15 minutes under sealed conditions to obtain a diluted solidifying liquid.

[0057] S23, mixing the composite resin obtained in S21 with the diluted solidifying liquid obtained in S22, and stirring for 25 minutes to obtain a high temperature resistant treatment agent.

[0058] Example 5: The difference between this example and Example 1 is that: S2, preparing a high temperature resistant treatment agent; the specific preparation steps are as follows:

[0059] S21. Mix 24 parts of polyvinylidene fluoride and 7 parts of 4-acryloylhydroxybenzoic acid benzophenone by weight, add 1 part of benzoyl peroxide and 6 parts of modified glass powder, raise the temperature to 80°C, stir and react for 2 hours, then add 8 parts of epoxy resin, keep warm and continue stirring for 60 minutes to obtain a composite resin.

[0060] S22. According to the same standard weight parts, 6 parts of ethyl cyanoacrylate and 7 parts of dichloromethane were stirred at a constant speed for 25 minutes under sealed conditions to obtain a diluted solidifying liquid.

[0061] S23, mixing the composite resin obtained in S21 with the diluted solidifying liquid obtained in S22, and stirring for 35 minutes to obtain a high temperature resistant treatment agent.

[0062] Example 6: The difference between this example and Example 1 is that the preparation method of the modified glass powder is as follows:

[0063] A1. Immerse the glass powder in an aqueous solution of 5% hydrofluoric acid by mass, stir at 50r / min for 3 minutes at room temperature, filter, and wash with water until neutral to obtain roughened glass powder.

[0064] A2. Immerse the roughened glass powder obtained in A1 in a 10% by mass silane coupling agent KH550 n-butanol solution, heat to 75°C, stir at 50 r / min for 4 hours, filter, and dry to obtain the modified glass powder.

[0065] Embodiment 7: The difference between this embodiment and embodiment 1 is that the preparation method of the modified glass powder is as follows:

[0066] A1. Immerse the glass powder in an aqueous solution of 6% hydrofluoric acid by mass, stir at 60r / min at room temperature for 5 minutes, filter, and wash with water until neutral to obtain roughened glass powder.

[0067] A2. Immerse the roughened glass powder obtained in A1 in a 12% by mass silane coupling agent KH550 n-butanol solution, heat to 85°C, stir at 60 r / min for 5 hours, filter, and dry to obtain the modified glass powder.

[0068] Embodiment 8: The difference between this embodiment and embodiment 1 is that: S3, preparing a high temperature resistant seamless steel pipe;

[0069] The high temperature resistant treatment agent prepared by S2 is preheated to 70°C, and evenly coated on the seamless steel pipe body prepared by S1, coated twice, and then baked at 165°C for 40 minutes, cured, and cooled to room temperature to form a coating with a coating thickness of 0.33mm, thereby obtaining a high temperature resistant seamless steel pipe.

[0070] Embodiment 9: The difference between this embodiment and embodiment 1 is that: S3, preparing a high temperature resistant seamless steel pipe;

[0071] The high temperature resistant treatment agent prepared by S2 is preheated to 80°C, and evenly coated on the seamless steel pipe body prepared by S1, coated 3 times, and then baked at 175°C for 60 minutes, cured, and cooled to room temperature to form a coating with a coating thickness of 0.48mm, thereby obtaining a high temperature resistant seamless steel pipe.

[0072] Comparative Example 1: The difference between this comparative example and Example 1 is that in the preparation of the modified glass powder, the A2 modification step is deleted.

[0073] Comparative Example 2: The difference between this comparative example and Example 1 is that in the preparation of the modified glass powder, the A1 pickling step is deleted.

[0074] Comparative Example 3: The difference between this comparative example and Example 1 is that in the preparation of the high temperature resistant treatment agent, the modified glass powder is replaced by glass powder.

[0075] Comparative Example 4: The difference between this comparative example and Example 1 is that the modified glass powder is deleted in the preparation of the high temperature resistant treatment agent.

[0076] Comparative Example 5: The difference between this comparative example and Example 1 is that 4-acryloylhydroxybenzoic acid benzophenone is deleted in the preparation of the high temperature resistant treatment agent.

[0077] Comparative Example 6: The difference between this comparative example and Example 1 is that the epoxy resin is deleted in the preparation of the high temperature resistant treatment agent.

[0078] Comparative Example 7: The difference between this comparative example and Example 1 is that in the preparation of the high temperature resistant treatment agent, the modified glass powder and epoxy resin are deleted.

[0079] Comparative Example 8: The difference between this comparative example and Example 1 is that in the preparation of the high temperature resistant treatment agent, dichloromethane is replaced by ethanol.

[0080] Comparative Example 9: The difference between this comparative example and Example 1 is that the high temperature resistant treatment agent is deleted.

[0081] Comparative Example 10: The difference between this comparative example and Example 1 is that the composition of the seamless steel pipe body contains 0.32% C.

[0082] Comparative Example 11: The difference between this comparative example and Example 1 is that the composition of the seamless steel pipe body contains 0.32% C, and the modified glass powder is deleted in the preparation of the high temperature resistant treatment agent.

[0083] Comparative Example 12: The difference between this comparative example and Example 1 is that the composition of the seamless steel pipe body contains 0.32% C and the high temperature resistant treatment agent is deleted.

[0084] Test example: Test method: According to the contents specified in Examples 1-9 and Comparative Examples 1-12, (cut) a 50mm×25mm×3mm seamless steel pipe steel sample; at room temperature 25°C and 400°C, the yield strength of the steel sample was tested with a tensile testing machine, with a tensile speed of 15mm / min; and the loss rate was calculated, loss rate = (yield strength at room temperature - yield strength at 400°C) / yield strength at room temperature * 100%; the smaller the loss rate, the stronger the high temperature resistance.

[0085] Test results: See Table 1.

[0086] Table 1. Test example data

[0087]

[0088] Result analysis: Analyze Examples 1-9 and combine the data in Table 1 and Figure 1-2 It can be seen that the yield strength measured at 400°C has a loss rate as low as 17.9% compared with the yield strength measured at room temperature, indicating that the product prepared by the present invention has excellent high temperature resistance.

[0089] When the carbon content is high (C: 0.65%), comparative examples 3 and 4 are analyzed and combined with the data in Table 1 and Figure 1-2 It can be seen that in the preparation of the high temperature resistant treatment agent of the present invention, the addition of glass powder has no obvious effect on the yield strength of the obtained product at room temperature, but can obviously reduce the loss rate of the yield strength of the obtained product at 400°C, that is, weaken the decrease in the yield strength of the obtained product at 400°C; indicating that the addition of glass powder can improve the high temperature resistance of the obtained product.

[0090] Analyze Example 1 and Comparative Examples 1-3 and combine the data in Table 1 and Figure 1-2 It can also be seen that pickling treatment and silane coupling agent modification treatment of the glass powder can further improve the high temperature resistance of the obtained product. There is also a synergistic effect between the two treatments, which can synergistically improve the high temperature resistance of the obtained product.

[0091] Analyze Example 1 and Comparative Example 5 and combine the data in Table 1 and Figure 1-2 It can be seen that in the preparation of the high temperature resistant treatment agent of the present invention, the addition of 4-acryloylhydroxybenzoic acid benzophenone has no obvious effect on the yield strength of the obtained product at room temperature, but can obviously reduce the loss rate of the yield strength of the obtained product at 400°C, that is, weaken the decrease in the yield strength of the obtained product at 400°C; indicating that the addition of 4-acryloylhydroxybenzoic acid benzophenone can improve the high temperature resistance of the obtained product.

[0092] Analyze Example 1 and Comparative Example 4 and Comparative Example 6-7 and combine the data in Table 1 and Figure 1-2 It can be seen that in the preparation of the high temperature resistant treatment agent of the present invention, the addition of modified glass powder can improve the high temperature resistance of the obtained product, and the addition of epoxy resin can also improve the high temperature resistance of the obtained product. Moreover, there is a synergistic effect between the two, which can synergistically improve the high temperature resistance of the obtained product.

[0093] Analyze Example 1 and Comparative Example 8 and combine the data in Table 1 and Figure 1-2 It can be seen that in the preparation of the high temperature resistant treatment agent of the present invention, replacing dichloromethane with ethanol will have a negative impact on the effect of improving the high temperature resistance.

[0094] Analyze Example 1 and Comparative Example 9 and combine the data in Table 1 and Figure 1-2 , it can be verified that the conclusion is: the present invention uses a high temperature resistant treatment agent to form a coating on the surface of the seamless steel pipe, thereby forming heat insulation and oxygen isolation protection, and can effectively maintain good uniformity and adhesion at high temperatures, can effectively weaken the decrease in yield strength at high temperatures, and significantly improve the high temperature resistance of the seamless steel pipe.

[0095] Analyze Comparative Examples 9 and 12 and combine the data in Table 1 and Figure 1-2 It can be seen that when the carbon content of the present invention is reduced to C: 0.32%, the yield strength of the product at room temperature will be significantly reduced. At the same time, the decrease in the yield strength of the product at 400°C is also reduced.

[0096] Analyze Example 1, Comparative Example 9, Comparative Example 10 and Comparative Example 12 and combine the data in Table 1 and Figure 1-2 It can be seen that the high temperature resistant treatment agent of the present invention has a better effect on improving the high temperature resistant performance of products with high carbon content (C: 0.65%) than that of products with high carbon content (C: 0.32%).

[0097] Analyze Comparative Examples 10-12 and combine the data in Table 1 and Figure 1-2 It can be seen that when the carbon content of the product is as low as C: 0.32%, the addition of modified glass powder in the preparation of the high-temperature resistant treatment agent will cause the high-temperature resistance of the product to decrease instead of increase.

[0098] This is because when the modified glass powder dotted with the coating cross-linked network is on high carbon steel (C: 0.65%), the surface roughness of the high carbon steel increases relatively greatly at high temperature (400°C), and the glass powder can soften and directionally fill the rough sites, effectively exerting its own performance, while also effectively avoiding the decrease in coating uniformity and adhesion, reducing the decrease in yield strength, and further improving the high temperature resistance of the product. However, when on low carbon steel (C: 0.32%), the surface roughness of low carbon steel changes relatively little at high temperature (400°C), and the glass powder will cause the cross-linking points of the cross-linked network to shift and aggregate together due to softening and flow, thereby reducing the protective effect of the coating, causing the decline in the yield strength of the product to increase instead of decrease, which is not conducive to improving the high temperature resistance of the product.

[0099] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0100] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A process for preparing a high temperature resistant seamless steel pipe, characterized in that: The steps include: S1. Prepare seamless steel pipe body; The composition of the seamless steel pipe body includes, by mass percentage, C: 0.62-0.68%, Si: 0.18-0.23%, Mn: 0.40-0.47%, Al: 0.027-0.038%, Cr: 0.045-0.055%, P≤0.016%, S≤0.014%, and the rest is Fe and unavoidable impurities; S2, preparing high temperature resistant treatment agent; The components of the high temperature resistant treatment agent include 24 parts of polyvinylidene fluoride, 5-7 parts of 4-acryloylhydroxybenzoic acid benzophenone, 0.5-1 parts of benzoyl peroxide, 4-6 parts of modified glass powder, 6-8 parts of epoxy resin, 4-6 parts of ethyl cyanoacrylate and 5-7 parts of solvent by weight; S3, preparing high temperature resistant seamless steel pipe; The high temperature resistant treatment agent prepared by S2 is preheated to 70-80°C, evenly coated on the seamless steel pipe body prepared by S1, and then baked, cured, and cooled to room temperature to form a coating to obtain a high temperature resistant seamless steel pipe.

2. The process for preparing a high temperature resistant seamless steel pipe according to claim 1, characterized in that: The specific operation steps of S2 are as follows: S21, mixing polyvinylidene fluoride and 4-acryloylhydroxybenzoic acid benzophenone, adding benzoyl peroxide and modified glass powder, heating to 70-80° C., stirring for reaction for 1-2 hours, then adding epoxy resin, keeping the temperature and continuing stirring for 50-60 minutes to obtain a composite resin; S22, stirring ethyl cyanoacrylate and solvent at a uniform speed for 15-25 minutes under sealed conditions to obtain a diluted curing solution; S23, mixing the composite resin obtained in S21 with the diluted solidifying liquid obtained in S22, and stirring for 25-35 minutes to obtain a high temperature resistant treatment agent.

3. The process for preparing a high temperature resistant seamless steel pipe according to claim 1 or 2, characterized in that: The preparation method of the modified glass powder is as follows: A1. Immerse the glass powder in a 5-6% hydrofluoric acid aqueous solution, stir at a constant speed of 50-60r / min for 3-5min at room temperature, filter, and wash with water until neutral to obtain roughened glass powder; A2. Immerse the roughened glass powder obtained in A1 in a 10-12% n-butanol solution of silane coupling agent, heat to 75-85°C, stir at a constant speed of 50-60 r / min for 4-5 hours, filter, and dry to obtain the modified glass powder.

4. The process for preparing a high temperature resistant seamless steel pipe according to claim 3, characterized in that: The glass powder has a softening temperature of 350-560° C., a thermal expansion coefficient of 65-125, and a fineness of 2-8 μm.

5. The process for preparing a high temperature resistant seamless steel pipe according to claim 3, characterized in that: The silane coupling agent is KH550.

6. The process for preparing a high temperature resistant seamless steel pipe according to claim 1 or 2, characterized in that: The solvent includes any one of acetone, butanone or dichloromethane.

7. The process for preparing a high temperature resistant seamless steel pipe according to claim 1, characterized in that: In S3, coating is performed 2-3 times, and the coating thickness is 0.3-0.5 mm.

8. The process for preparing a high temperature resistant seamless steel pipe according to claim 1, characterized in that: In S3, baking is performed at 165-175° C. for 40-60 min.

9. A high temperature resistant seamless steel pipe, characterized in that: The method is prepared by the preparation process according to any one of claims 1 to 8.

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