Thin-wall seamless steel tube and preparation process thereof

Abstract

The invention relates to a thin-wall seamless steel pipe and a preparation process thereof, and belongs to the related field of seamless steel pipes and treatment, and the thin-wall seamless steel pipe comprises the following components in percentage by weight: 0.23%-0.27% of C, 1.10%-1.30% of Si, 0.70%-0.90% of Mn, 0.30%-0.40% of Cr, 0.25%-0.35% of Ni, 0.25%-0.35% of Mo, 0.20%-0.30% of Nb, 0.15%-0.25% of V, less than or equal to 0.01% of P, less than or equal to 0.015% of S and the balance of Fe and inevitable impurities. The prepared product is uniform in thickness, and the quality of the thin-wall seamless steel pipe is improved.

Description

Technical Field

[0001] The invention belongs to the field of seamless steel pipes and related processing, and in particular relates to a thin-wall seamless steel pipe and a preparation process thereof. Background Art

[0002] Compared with stainless steel, the surface of ordinary carbon steel is extremely easy to be oxidized, and a layer of hard and brittle iron oxide scale (mainly Fe3O4) will be formed on the surface, and its melting point is above 1500℃.

[0003] When using ordinary carbon steel to prepare thin-walled seamless steel pipes, especially during the hole expansion process, the oxidized iron scale will fall off, making the pipe wall rough and uneven. In addition, the oxidized iron scale that falls off is easy to accumulate on the pipe wall, resulting in uneven thickness of the pipe wall, which has a great impact on product quality. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies in the prior art, the present invention provides a thin-wall seamless steel pipe and a preparation process thereof.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A thin-walled seamless steel pipe comprises the following components by weight percentage: C: 0.23%-0.27%, Si: 1.10%-1.30%, Mn: 0.70%-0.90%, Cr: 0.30%-0.40%, Ni: 0.25%-0.35%, Mo: 0.25%-0.35%, Nb: 0.20%-0.30%, V: 0.15%-0.25%, P: ≤0.01%, S: ≤0.015%, and the rest is Fe and unavoidable impurities.

[0009] A thin-walled seamless steel pipe, comprising the following components by weight percentage:

[0010] C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest are Fe and unavoidable impurities.

[0011] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0012] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1670-1730℃, and the refining time is 40-80min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0013] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1200-1240°C and the piercing speed is 0.6-0.8 m / s.

[0014] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1080-1120°C;

[0015] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0016] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be lowered to below 200°C within 30 minutes to obtain a tube blank;

[0017] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to a temperature of 200-240°C, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe.

[0018] The temperature of the heating section of the heating furnace in S2 is 1250-1270° C., the temperature of the soaking section is 1220-1260° C., and the soaking time is 3-5 hours.

[0019] The preparation of the lubricant comprises the following steps:

[0020] A1: By weight, add 0.3-0.5 parts of sodium benzoate to 20-30 parts of water, stir until completely dissolved, then add 2-4 parts of potassium fluorozirconate, stir for 20-30 minutes to obtain intermediate 1;

[0021] A2: Add 0.05-0.1 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 10-20 minutes, add 5-7 parts of modified boron glass powder, and ultrasonically vibrate the solution for 4-6 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0022] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 55-65° C., stir for 0.5-1.5 h, evaporate, dry, and crush to obtain the lubricant.

[0023] The preparation of the modified boron glass powder comprises the following steps:

[0024] B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling adopts a sulfuric acid solution with a mass concentration of 10% to 20%;

[0025] B2: By weight, weigh 20 parts of the acid-washed boron glass powder prepared in B1, add it to 80-120 parts of ethanol, stir to make it evenly dispersed, then add 3-5 parts of soluble phenolic resin, heat to 45-55° C., stir for 20-40 minutes, add 0.8-1.2 parts of nano magnesium borate, stir for 10-20 minutes, and obtain a mixed solution;

[0026] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0027] During sizing in S4, the inlet temperature of sizing is 900-980°C, and the final rolling temperature is 860-940°C.

[0028] In the S6, the quenching heating temperature is 900±10°C, and the holding time is controlled at 7-9 min / mm; the tempering temperature is controlled at 600±10°C, and the holding time is controlled at 11-13 min / mm.

[0029] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0030] 1. Adding niobium to thin-walled seamless steel pipes during the rolling process can improve the oxidation resistance of steel, reduce the amount of iron oxide scale generated to a certain extent, and reduce the influence of iron oxide scale on the thickness uniformity of the pipe. At the same time, niobium can delay the recrystallization of austenite and strongly refine the grains, which can significantly improve the plastic deformation ability of the pipe, slow down the hard friction between the mandrel and the inner wall of the steel pipe billet, and help to improve the thickness uniformity of the obtained thin-walled seamless steel pipe.

[0031] 2. During the preparation of the lubricant, the overall performance of the lubricant is improved by improving the compatibility between components.

[0032] Graphite powder has a lubricating effect and can reduce the friction of the contact surface; potassium fluorozirconate is a film-forming agent, which can improve the wettability and adhesion of the lubricant to the core rod and improve the stability of the lubricant during the hole expansion process; boron glass powder is a melting aid material, which can lower the melting point of the iron oxide scale on the surface of the pipe, causing it to gradually soften from a hard and brittle solid state, reducing its offset effect on the steel pipe billet, thereby ensuring uniform thickness of the pipe wall.

[0033] At high temperatures, boron glass powder has a certain viscosity and fluxing effect. By modifying it, its adhesion ability on the core rod at low temperatures can be improved; at the same time, boron glass powder has good antioxidant ability under high temperature conditions, which can improve the stability of boron glass powder in high temperature environments.

[0034] In addition, potassium fluorozirconate and modified boron glass powder can quickly produce a lubricating film with a flaky network structure of boron-oxygen triangles under high temperature conditions, which can reduce the viscosity of the lubricant and make it tightly adhere to the surface of the blank, thereby achieving lubrication, isolation, protection and other protective effects, and greatly improving the thickness uniformity of the pipe. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1: A thin-walled seamless steel pipe, comprising the following components in weight percentage: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest is Fe and unavoidable impurities.

[0037] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0038] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1700℃ and the refining time is 60min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0039] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1220°C and the piercing speed is 0.7 m / s.

[0040] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1100°C;

[0041] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0042] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 180°C within 30 minutes to obtain a tube blank;

[0043] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 220℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe. The prepared thin-walled seamless steel pipe has an outer diameter of 219mm and a wall thickness of 7.5mm.

[0044] The temperature of the heating section of the heating furnace in S2 is 1260° C., the temperature of the soaking section is 1240° C., and the soaking time is 4 hours.

[0045] The preparation of the lubricant comprises the following steps:

[0046] A1: By weight, add 0.4 parts of sodium benzoate to 25 parts of water, stir until completely dissolved, then add 3 parts of potassium fluorozirconate, stir for 25 minutes to obtain intermediate 1;

[0047] A2: Add 0.08 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 15 minutes, add 6 parts of modified boron glass powder, and ultrasonically vibrate the solution for 5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0048] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 60° C., stir for 1 hour, evaporate, dry, and crush to obtain the lubricant.

[0049] The preparation of the modified boron glass powder comprises the following steps:

[0050] B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling is carried out using a sulfuric acid solution with a mass concentration of 15%;

[0051] B2: 20 parts by weight of the acid-washed boron glass powder prepared in B1 were weighed and added to 100 parts of ethanol, stirred to make it evenly dispersed, then 4 parts of soluble phenolic resin were added, heated to 50°C, stirred for 30 minutes, and 1 part of nano magnesium borate was added, stirred for 15 minutes to obtain a mixed solution;

[0052] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0053] During sizing in S4, the inlet temperature of sizing is 940°C, and the final rolling temperature is 900°C.

[0054] In the S6, the quenching heating temperature is 900° C., and the holding time is controlled at 8 min / mm; the tempering temperature is controlled at 600° C., and the holding time is controlled at 12 min / mm.

[0055] Example 2: A thin-walled seamless steel pipe, comprising the following components in weight percentage: C: 0.23%, Si: 1.10%, Mn: 0.70%, Cr: 0.30%, Ni: 0.25%, Mo: 0.25%, Nb: 0.20%, V: 0.15%, P: 0.005%, S: 0.008%, and the rest is Fe and unavoidable impurities.

[0056] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0057] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1670℃ and the refining time is 40min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0058] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1200°C and the piercing speed is 0.6 m / s.

[0059] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 to obtain a rough tube, the rolling temperature is 1080℃;

[0060] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0061] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 100°C within 30 minutes to obtain a tube blank;

[0062] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 200℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe.

[0063] The temperature of the heating section of the heating furnace in S2 is 1250° C., the temperature of the soaking section is 1220° C., and the soaking time is 3 hours.

[0064] The preparation of the lubricant comprises the following steps:

[0065] A1: By weight, add 0.3 parts of sodium benzoate to 20 parts of water, stir until completely dissolved, then add 2 parts of potassium fluorozirconate, stir for 20 minutes to obtain intermediate 1;

[0066] A2: Add 0.05 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 10 minutes, add 5 parts of modified boron glass powder, and ultrasonically vibrate the solution for 4 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0067] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 55° C., stir for 0.5 h, evaporate, dry, and crush to obtain the lubricant.

[0068] The preparation of the modified boron glass powder comprises the following steps:

[0069] B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling is carried out using a sulfuric acid solution with a mass concentration of 10%;

[0070] B2: By weight, 20 parts of the acid-washed boron glass powder prepared in B1 were weighed and added to 80 parts of ethanol, stirred to make it evenly dispersed, and then 3 parts of soluble phenolic resin were added, heated to 45°C, stirred for 20 minutes, and 0.8 parts of nano magnesium borate were added, and stirred for 10 minutes to obtain a mixed solution;

[0071] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0072] During sizing in S4, the inlet temperature for sizing is 900°C, and the final rolling temperature is 860°C.

[0073] In the S6, the quenching heating temperature is 890° C., and the holding time is controlled at 7 min / mm; the tempering temperature is controlled at 590° C., and the holding time is controlled at 11 min / mm.

[0074] Example 3: A thin-walled seamless steel pipe, comprising the following components in weight percentage: C: 0.24%, Si: 1.15%, Mn: 0.75%, Cr: 0.33%, Ni: 0.28%, Mo: 0.28%, Nb: 0.23%, V: 0.18%, P: 0.006%, S: 0.009%, and the rest is Fe and unavoidable impurities.

[0075] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0076] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1690℃ and the refining time is 50min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0077] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1210°C and the piercing speed is 0.65 m / s.

[0078] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 to obtain a rough tube, the rolling temperature is 1090°C;

[0079] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0080] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 150°C within 30 minutes to obtain a tube blank;

[0081] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, it enters the cold chain cooling bed for cooling to 210℃, and then enters the straightening machine for straightening to obtain a thin-walled seamless steel pipe.

[0082] The temperature of the heating section of the heating furnace in S2 is 1255° C., the temperature of the soaking section is 1230° C., and the soaking time is 3.5 h.

[0083] The preparation of the lubricant comprises the following steps:

[0084] A1: By weight, add 0.35 parts of sodium benzoate to 22 parts of water, stir until completely dissolved, then add 2.5 parts of potassium fluorozirconate, stir for 23 minutes to obtain intermediate 1;

[0085] A2: Add 0.06 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 13 minutes, add 5.5 parts of modified boron glass powder, and ultrasonically vibrate the solution for 4.5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0086] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 58° C., stir for 0.8 h, evaporate, dry, and crush to obtain the lubricant.

[0087] The preparation of the modified boron glass powder comprises the following steps:

[0088] B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling is carried out using a sulfuric acid solution with a mass concentration of 12%;

[0089] B2: By weight, 20 parts of the acid-washed borosilicate glass powder prepared in B1 were weighed and added to 90 parts of ethanol, stirred to make it evenly dispersed, and then 3.5 parts of soluble phenolic resin were added, heated to 48°C, stirred for 25 minutes, and 0.9 parts of nano magnesium borate were added, stirred for 11 minutes to obtain a mixed solution;

[0090] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0091] The sizing inlet temperature during sizing in S4 is 920°C, and the final rolling temperature is 870°C.

[0092] In the S6, the quenching heating temperature is 898° C., and the holding time is controlled at 7.5 min / mm; the tempering temperature is controlled at 598° C., and the holding time is controlled at 11.5 min / mm.

[0093] Example 4: A thin-walled seamless steel pipe, comprising the following components in weight percentage: C: 0.27%, Si: 1.30%, Mn: 0.90%, Cr: 0.40%, Ni: 0.35%, Mo: 0.35%, Nb: 0.28%, V: 0.25%, P: 0.009%, S: 0.012%, and the rest is Fe and unavoidable impurities.

[0094] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0095] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1730℃ and the refining time is 80min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0096] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1240°C and the piercing speed is 0.8 m / s.

[0097] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 to obtain a rough tube, the rolling temperature is 1120℃;

[0098] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0099] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 190°C within 30 minutes to obtain a tube blank;

[0100] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, it enters the cold chain cooling bed for cooling to 240℃, and then enters the straightening machine for straightening to obtain a thin-walled seamless steel pipe.

[0101] The temperature of the heating section of the heating furnace in S2 is 1270° C., the temperature of the soaking section is 1260° C., and the soaking time is 5 hours.

[0102] The preparation of the lubricant comprises the following steps:

[0103] A1: By weight, add 0.5 parts of sodium benzoate to 30 parts of water, stir until completely dissolved, then add 4 parts of potassium fluorozirconate, stir for 30 minutes to obtain intermediate 1;

[0104] A2: Add 0.1 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 20 minutes, add 7 parts of modified boron glass powder, and ultrasonically vibrate the solution for 6 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0105] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 65° C., stir for 1.5 hours, evaporate, dry, and crush to obtain the lubricant.

[0106] The preparation of the modified boron glass powder comprises the following steps:

[0107] B1: by weight, pickling and water washing boron glass powder with a particle size less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling is carried out using a sulfuric acid solution with a mass concentration of 20%;

[0108] B2: 20 parts by weight of the acid-washed borosilicate glass powder prepared in B1 were weighed and added to 120 parts of ethanol, stirred to make it evenly dispersed, and then 5 parts of soluble phenolic resin were added, heated to 55°C, stirred for 40 minutes, and 1.2 parts of nano magnesium borate were added, stirred for 20 minutes to obtain a mixed solution;

[0109] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0110] The inlet temperature of sizing in S4 is 980°C, and the final rolling temperature is 940°C.

[0111] In the S6, the quenching heating temperature is 910° C., and the holding time is controlled at 9 min / mm; the tempering temperature is controlled at 610° C., and the holding time is controlled at 13 min / mm.

[0112] Example 5: A thin-walled seamless steel pipe, comprising the following components in weight percentage: C: 0.26%, Si: 1.25%, Mn: 0.85%, Cr: 0.38%, Ni: 0.32%, Mo: 0.32%, Nb: 0.28%, V: 0.23%, P: 0.095%, S: 0.014%, and the rest is Fe and unavoidable impurities.

[0113] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0114] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1720℃ and the refining time is 70min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0115] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1230°C and the piercing speed is 0.75 m / s.

[0116] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 to obtain a rough tube, the rolling temperature is 1110°C;

[0117] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0118] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 100°C within 30 minutes to obtain a tube blank;

[0119] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, it enters the cold chain cooling bed for cooling to 230℃, and then enters the straightening machine for straightening to obtain a thin-walled seamless steel pipe.

[0120] The temperature of the heating section of the heating furnace in S2 is 1265° C., the temperature of the soaking section is 1250° C., and the soaking time is 4.5 h.

[0121] The preparation of the lubricant comprises the following steps:

[0122] A1: By weight, add 0.45 parts of sodium benzoate to 28 parts of water, stir until completely dissolved, then add 3.5 parts of potassium fluorozirconate, stir for 28 minutes to obtain intermediate 1;

[0123] A2: Add 0.08 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 18 minutes, add 6.5 parts of modified boron glass powder, and ultrasonically vibrate the solution for 5.5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0124] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 62° C., stir for 1.3 h, evaporate, dry, and crush to obtain the lubricant.

[0125] The preparation of the modified boron glass powder comprises the following steps:

[0126] B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling is carried out using a sulfuric acid solution with a mass concentration of 18%;

[0127] B2: By weight, 20 parts of the acid-washed boron glass powder prepared in B1 were weighed and added to 110 parts of ethanol, stirred to make it evenly dispersed, and then 4.5 parts of soluble phenolic resin were added, heated to 52°C, stirred for 35 minutes, and 1.1 parts of nano magnesium borate were added, stirred for 18 minutes to obtain a mixed solution;

[0128] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0129] The sizing inlet temperature during sizing in S4 is 970°C, and the final rolling temperature is 930°C.

[0130] In the S6, the quenching heating temperature is 908° C., and the holding time is controlled at 8.5 min / mm; the tempering temperature is controlled at 608° C., and the holding time is controlled at 12.5 min / mm.

[0131] Comparative Example 1: The only difference from Example 1 is that the composition of the thin-walled seamless steel pipe does not contain niobium.

[0132] A thin-wall seamless steel pipe comprises the following components by weight percentage: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest is Fe and inevitable impurities.

[0133] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0134] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1700℃ and the refining time is 60min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0135] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1220°C and the piercing speed is 0.7 m / s.

[0136] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1100°C;

[0137] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0138] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 180°C within 30 minutes to obtain a tube blank;

[0139] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 220℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe. The prepared thin-walled seamless steel pipe has an outer diameter of 219mm and a wall thickness of 7.5mm.

[0140] The temperature of the heating section of the heating furnace in S2 is 1260° C., the temperature of the soaking section is 1240° C., and the soaking time is 4 hours.

[0141] The preparation of the lubricant comprises the following steps:

[0142] A1: By weight, add 0.4 parts of sodium benzoate to 25 parts of water, stir until completely dissolved, then add 3 parts of potassium fluorozirconate, stir for 25 minutes to obtain intermediate 1;

[0143] A2: Add 0.08 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 15 minutes, add 6 parts of modified boron glass powder, and ultrasonically vibrate the solution for 5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0144] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 60° C., stir for 1 hour, evaporate, dry, and crush to obtain the lubricant.

[0145] The preparation of the modified boron glass powder comprises the following steps:

[0146] B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling is carried out using a sulfuric acid solution with a mass concentration of 15%;

[0147] B2: 20 parts by weight of the acid-washed boron glass powder prepared in B1 were weighed and added to 100 parts of ethanol, stirred to make it evenly dispersed, then 4 parts of soluble phenolic resin were added, heated to 50°C, stirred for 30 minutes, and 1 part of nano magnesium borate was added, stirred for 15 minutes to obtain a mixed solution;

[0148] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0149] During sizing in S4, the inlet temperature of sizing is 940°C, and the final rolling temperature is 900°C.

[0150] In the S6, the quenching heating temperature is 900° C., and the holding time is controlled at 8 min / mm; the tempering temperature is controlled at 600° C., and the holding time is controlled at 12 min / mm.

[0151] Comparative Example 2: The only difference from Example 1 is that no modified boron glass powder is added to the lubricant.

[0152] A thin-walled seamless steel pipe comprises the following components by weight percentage: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest is Fe and unavoidable impurities.

[0153] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0154] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1700℃ and the refining time is 60min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0155] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1220°C and the piercing speed is 0.7 m / s.

[0156] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1100°C;

[0157] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0158] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 180°C within 30 minutes to obtain a tube blank;

[0159] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 220℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe. The prepared thin-walled seamless steel pipe has an outer diameter of 219mm and a wall thickness of 7.5mm.

[0160] The temperature of the heating section of the heating furnace in S2 is 1260° C., the temperature of the soaking section is 1240° C., and the soaking time is 4 hours.

[0161] The preparation of the lubricant comprises the following steps:

[0162] A1: By weight, add 0.4 parts of sodium benzoate to 25 parts of water, stir until completely dissolved, then add 3 parts of potassium fluorozirconate, stir for 25 minutes to obtain intermediate 1;

[0163] A2: Add 0.08 parts of dimethylpolysiloxane by weight to the intermediate 1 obtained in A1, stir for 15 minutes, and ultrasonically vibrate the solution for 5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0164] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 60° C., stir for 1 hour, evaporate, dry, and crush to obtain the lubricant.

[0165] During sizing in S4, the inlet temperature of sizing is 940°C, and the final rolling temperature is 900°C.

[0166] In the S6, the quenching heating temperature is 900° C., and the holding time is controlled at 8 min / mm; the tempering temperature is controlled at 600° C., and the holding time is controlled at 12 min / mm.

[0167] Comparative Example 3: The only difference from Example 1 is that potassium fluorozirconate is not added to the lubricant.

[0168] A thin-walled seamless steel pipe comprises the following components by weight percentage: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest is Fe and unavoidable impurities.

[0169] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0170] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1700℃ and the refining time is 60min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0171] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1220°C and the piercing speed is 0.7 m / s.

[0172] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1100°C;

[0173] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0174] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 180°C within 30 minutes to obtain a tube blank;

[0175] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 220℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe. The prepared thin-walled seamless steel pipe has an outer diameter of 219mm and a wall thickness of 7.5mm.

[0176] The temperature of the heating section of the heating furnace in S2 is 1260° C., the temperature of the soaking section is 1240° C., and the soaking time is 4 hours.

[0177] The preparation of the lubricant comprises the following steps:

[0178] A1: Add 0.4 parts of sodium benzoate to 25 parts of water by weight and stir until completely dissolved to obtain intermediate 1;

[0179] A2: Add 0.08 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 15 minutes, add 6 parts of modified boron glass powder, and ultrasonically vibrate the solution for 5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0180] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 60° C., stir for 1 hour, evaporate, dry, and crush to obtain the lubricant.

[0181] The preparation of the modified boron glass powder comprises the following steps:

[0182] B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling is carried out using a sulfuric acid solution with a mass concentration of 15%;

[0183] B2: 20 parts by weight of the acid-washed boron glass powder prepared in B1 were weighed and added to 100 parts of ethanol, stirred to make it evenly dispersed, then 4 parts of soluble phenolic resin were added, heated to 50°C, stirred for 30 minutes, and 1 part of nano magnesium borate was added, stirred for 15 minutes to obtain a mixed solution;

[0184] B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

[0185] During sizing in S4, the inlet temperature of sizing is 940°C, and the final rolling temperature is 900°C.

[0186] In the S6, the quenching heating temperature is 900° C., and the holding time is controlled at 8 min / mm; the tempering temperature is controlled at 600° C., and the holding time is controlled at 12 min / mm.

[0187] Comparative Example 4: The only difference from Example 1 is that neither modified boron glass powder nor potassium fluorozirconate is added to the lubricant.

[0188] A thin-walled seamless steel pipe comprises the following components by weight percentage: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest is Fe and unavoidable impurities.

[0189] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0190] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1700℃ and the refining time is 60min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0191] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1220°C and the piercing speed is 0.7 m / s.

[0192] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1100°C;

[0193] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0194] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 180°C within 30 minutes to obtain a tube blank;

[0195] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 220℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe. The prepared thin-walled seamless steel pipe has an outer diameter of 219mm and a wall thickness of 7.5mm.

[0196] The temperature of the heating section of the heating furnace in S2 is 1260° C., the temperature of the soaking section is 1240° C., and the soaking time is 4 hours.

[0197] The preparation of the lubricant comprises the following steps:

[0198] A1: Add 0.4 parts of sodium benzoate to 25 parts of water by weight and stir until completely dissolved to obtain intermediate 1;

[0199] A2: Add 0.08 parts of dimethylpolysiloxane by weight to the intermediate 1 obtained in A1, stir for 15 minutes, and ultrasonically vibrate the solution for 5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0200] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 60° C., stir for 1 hour, evaporate, dry, and crush to obtain the lubricant.

[0201] During sizing in S4, the inlet temperature of sizing is 940°C, and the final rolling temperature is 900°C.

[0202] In the S6, the quenching heating temperature is 900° C., and the holding time is controlled at 8 min / mm; the tempering temperature is controlled at 600° C., and the holding time is controlled at 12 min / mm.

[0203] Comparative Example 5: The only difference from Example 1 is that the boron glass powder in the lubricant is not modified.

[0204] A thin-walled seamless steel pipe comprises the following components by weight percentage: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest is Fe and unavoidable impurities.

[0205] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0206] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1700℃ and the refining time is 60min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0207] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1220°C and the piercing speed is 0.7 m / s.

[0208] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1100°C;

[0209] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0210] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 180°C within 30 minutes to obtain a tube blank;

[0211] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 220℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe. The prepared thin-walled seamless steel pipe has an outer diameter of 219mm and a wall thickness of 7.5mm.

[0212] The temperature of the heating section of the heating furnace in S2 is 1260° C., the temperature of the soaking section is 1240° C., and the soaking time is 4 hours.

[0213] The preparation of the lubricant comprises the following steps:

[0214] A1: By weight, add 0.4 parts of sodium benzoate to 25 parts of water, stir until completely dissolved, then add 3 parts of potassium fluorozirconate, stir for 25 minutes to obtain intermediate 1;

[0215] A2: Add 0.08 parts of dimethylpolysiloxane by weight to the intermediate 1 obtained in A1, stir for 15 minutes, add 6 parts of boron glass powder, and ultrasonically vibrate the solution for 5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0216] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 60° C., stir for 1 hour, evaporate, dry, and crush to obtain the lubricant.

[0217] Comparative Example 6: The only difference from Example 1 is that potassium fluorozirconate is not added to the lubricant and the boron glass powder is not modified.

[0218] A thin-walled seamless steel pipe comprises the following components by weight percentage: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest is Fe and unavoidable impurities.

[0219] A method for preparing a thin-wall seamless steel pipe comprises the following steps:

[0220] S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1700℃ and the refining time is 60min. After refining, continuous casting and billet drawing are carried out to form steel billets;

[0221] S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1220°C and the piercing speed is 0.7 m / s.

[0222] S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1100°C;

[0223] S4: Sizing: The rough tube in S3 is sized in a sizing machine;

[0224] S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be reduced to 180°C within 30 minutes to obtain a tube blank;

[0225] S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, enter the cold chain cooling bed for cooling to 220℃, and then enter the straightening machine for straightening to obtain a thin-walled seamless steel pipe. The prepared thin-walled seamless steel pipe has an outer diameter of 219mm and a wall thickness of 7.5mm.

[0226] The temperature of the heating section of the heating furnace in S2 is 1260° C., the temperature of the soaking section is 1240° C., and the soaking time is 4 hours.

[0227] The preparation of the lubricant comprises the following steps:

[0228] A1: Add 0.4 parts of sodium benzoate to 25 parts of water by weight and stir until completely dissolved to obtain intermediate 1;

[0229] A2: Add 0.08 parts of dimethylpolysiloxane by weight to the intermediate 1 obtained in A1, stir for 15 minutes, add 6 parts of boron glass powder, and ultrasonically vibrate the solution for 5 minutes using an ultrasonic vibrator to obtain the intermediate 2;

[0230] A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 60° C., stir for 1 hour, evaporate, dry, and crush to obtain the lubricant.

[0231] During sizing in S4, the inlet temperature of sizing is 940°C, and the final rolling temperature is 900°C.

[0232] In the S6, the quenching heating temperature is 900° C., and the holding time is controlled at 8 min / mm; the tempering temperature is controlled at 600° C., and the holding time is controlled at 12 min / mm.

[0233] Test example: Thickness uniformity = (measured maximum thickness - measured minimum thickness) / nominal thickness * 100%. The specific test results are shown in Table 1. The smaller the thickness uniformity value, the better the thickness uniformity.

[0234] Table 1

[0235]

[0236]

[0237] It can be seen from Table 1 that the thin-walled seamless steel pipes prepared in Examples 1 to 5 are of good quality and excellent quality.

[0238] The only difference between Comparative Example 1 and Example 1 is that the composition of the thin-walled seamless steel pipe does not contain niobium.

[0239] The thickness uniformity of the thin-walled seamless steel pipe prepared in Comparative Example 1 is greater than the thickness uniformity of the thin-walled seamless steel pipe prepared in Example 1.

[0240] The above shows that the addition of niobium can improve the thickness uniformity of the thin-walled seamless steel pipe and ensure that the thickness distribution of the obtained thin-walled seamless steel pipe is more uniform.

[0241] The only difference between Comparative Example 2 and Example 1 is that no modified boron glass powder is added to the lubricant.

[0242] The thickness uniformity of the thin-walled seamless steel pipe prepared in Comparative Example 2 is greater than the thickness uniformity of the thin-walled seamless steel pipe prepared in Example 1.

[0243] It shows that the addition of modified boron glass powder can improve the thickness uniformity of thin-walled seamless steel pipes.

[0244] The only difference between Comparative Example 3 and Example 1 is that potassium fluorozirconate is not added to the lubricant.

[0245] The thickness uniformity of the thin-walled seamless steel pipe prepared in Comparative Example 3 is greater than the thickness uniformity of the thin-walled seamless steel pipe prepared in Example 1.

[0246] It shows that the addition of potassium fluorozirconate can improve the thickness uniformity of thin-walled seamless steel pipes.

[0247] The only difference between Comparative Example 4 and Example 1 is that neither modified boron glass powder nor potassium fluorozirconate is added to the lubricant.

[0248] The thickness uniformity of the thin-walled seamless steel pipe prepared in Comparative Example 4 is greater than the thickness uniformity of the thin-walled seamless steel pipe prepared in Example 1.

[0249] Combining Comparative Examples 2 and 3, it can be seen that modified boron glass powder and potassium fluorozirconate can work synergistically to improve the thickness uniformity of thin-walled seamless steel pipes.

[0250] The only difference between Comparative Example 5 and Example 1 is that the boron glass powder in the lubricant is not modified.

[0251] The thickness uniformity of the thin-walled seamless steel pipe prepared in Comparative Example 5 is greater than the thickness uniformity of the thin-walled seamless steel pipe prepared in Example 1.

[0252] Combined with Comparative Example 2, it can be seen that the modification of boron glass powder can enhance the use effect of boron glass powder and further reduce the thickness uniformity of the prepared thin-walled seamless steel pipe, that is, further improve the thickness uniformity of the thin-walled seamless steel pipe.

[0253] The only difference between Comparative Example 6 and Example 1 is that potassium fluorozirconate is not added to the lubricant and the boron glass powder is not modified.

[0254] The thickness uniformity of the thin-walled seamless steel pipe prepared in Comparative Example 6 is greater than the thickness uniformity of the thin-walled seamless steel pipe prepared in Example 1.

[0255] Combined with Comparative Example 4, it can be seen that the synergistic effect of modified boron glass powder and potassium fluorozirconate is better than the synergistic effect of unmodified boron glass powder and potassium fluorozirconate, and the synergistic effect of modified boron glass powder and potassium fluorozirconate is more excellent in reducing the thickness uniformity of thin-walled seamless steel pipes and improving the thickness uniformity of thin-walled seamless steel pipes.

[0256] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A thin-walled seamless steel pipe, characterized in that: Calculated by weight percentage, it includes the following components: C: 0.23%-0.27%, Si: 1.10%-1.30%, Mn: 0.70%-0.90%, Cr: 0.30%-0.40%, Ni: 0.25%-0.35%, Mo: 0.25%-0.35%, Nb: 0.20%-0.30%, V: 0.15%-0.25%, P: ≤0.01%, S: ≤0.015%, and the rest are Fe and unavoidable impurities.

2. A thin-walled seamless steel pipe according to claim 1, characterized in that: According to weight percentage, it includes the following components: C: 0.25%, Si: 1.20%, Mn: 0.80%, Cr: 0.35%, Ni: 0.30%, Mo: 0.30%, Nb: 0.25%, V: 0.20%, P: 0.01%, S: 0.015%, and the rest are Fe and unavoidable impurities.

3. A process for preparing a thin-walled seamless steel pipe as claimed in claim 1 or 2, characterized in that: The following steps are involved: S1: Smelting: Mix the raw materials of each component of the seamless steel pipe according to weight percentage, and then refine them. The refining temperature is 1670-1730℃, and the refining time is 40-80min. After refining, continuous casting and billet drawing are carried out to form steel billets; S2: Heating: The steel billet prepared in S1 is heated in a heating furnace and then pierced to obtain a steel tube billet. The piercing temperature is 1200-1240°C and the piercing speed is 0.6-0.8 m / s. S3: rolling: applying lubricant on the surface of the mandrel, and then rolling the steel tube blank obtained in S2 into a rough tube, the rolling temperature is 1080-1120°C; S4: Sizing: The rough tube in S3 is sized in a sizing machine; S5: Cooling: After the S4 sizing, the surface temperature of the rough tube is controlled to be lowered to below 200°C within 30 minutes to obtain a tube blank; S6: Heat treatment: After heating the tube blank in S5, use quenching liquid to quench it, and then temper it. After tempering, it enters the cold chain cooling bed for cooling to a temperature of 200-240°C, and then enters the straightening machine for straightening to obtain a thin-walled seamless steel pipe.

4. The process for preparing a thin-walled seamless steel pipe according to claim 3, characterized in that: The temperature of the heating section of the heating furnace in S2 is 1250-1270° C., the temperature of the soaking section is 1220-1260° C., and the soaking time is 3-5 hours.

5. The process for preparing a thin-walled seamless steel pipe according to claim 3, characterized in that: The preparation of the lubricant comprises the following steps: A1: By weight, add 0.3-0.5 parts of sodium benzoate to 20-30 parts of water, stir until completely dissolved, then add 2-4 parts of potassium fluorozirconate, stir for 20-30 minutes to obtain intermediate 1; A2: Add 0.05-0.1 parts of dimethyl polysiloxane by weight to the intermediate 1 obtained in A1, stir for 10-20 minutes, add 5-7 parts of modified boron glass powder, and use an ultrasonic oscillator to ultrasonically oscillate the solution for 4-6 minutes to obtain the intermediate 2; A3: Add 10 parts of graphite powder by weight to the intermediate 2 obtained in A2, heat to 55-65° C., stir for 0.5-1.5 h, evaporate, dry, and crush to obtain the lubricant.

6. A process for preparing a thin-walled seamless steel pipe according to claim 5, characterized in that: The preparation of the modified boron glass powder comprises the following steps: B1: by weight, pickling and water washing boron glass powder with a particle size of less than 20 um, and drying to obtain pickled boron glass powder, wherein the pickling adopts a sulfuric acid solution with a mass concentration of 10% to 20%; B2: By weight, weigh 20 parts of the acid-washed boron glass powder prepared in B1, add it to 80-120 parts of ethanol, stir to make it evenly dispersed, then add 3-5 parts of soluble phenolic resin, heat to 45-55°C, stir for 20-40 minutes, add 0.8-1.2 parts of nano magnesium borate, stir for 10-20 minutes, and obtain a mixed solution; B3: By weight, the mixed solution obtained in B2 is filtered and dried to obtain modified boron glass powder.

7. The process for preparing a thin-walled seamless steel pipe according to claim 3, characterized in that: During sizing in S4, the inlet temperature of sizing is 900-980°C, and the final rolling temperature is 860-940°C.

8. The process for preparing a thin-walled seamless steel pipe according to claim 3, characterized in that: In the S6, the quenching heating temperature is 900±10°C, and the holding time is controlled at 7-9 min / mm; the tempering temperature is controlled at 600±10°C, and the holding time is controlled at 11-13 min / mm.

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