High impact seamless steel pipe and method of making same

Abstract

The application provides a high-impact-resistance seamless steel pipe and a preparation method thereof, and belongs to the technical field of alloy steel pipes. The seamless steel pipe comprises an impact-resistant material and a steel body material, and the mass ratio of the two is (0.8-1):100. The impact-resistant material comprises irregularly fired rock powder and sodium bicarbonate powder, and the mass ratio of the two is (7-8):1. The chemical composition of the steel body material comprises, in percentage by mass, C: 0.32-0.35%, Si: 0.40-0.42%, Mn: 1.04-1.15%, V: 0.08-0.10%, Ti: 0.05-0.07%, Mo: 0.06-0.08%, Al: 0.04-0.05%, Cu: 0.12-0.14%, Cr: 0.16-0.20%, Ni: 0.03-0.05%, P≤0.014%, S≤0.008%, and the rest is Fe and inevitable impurities. The application ensures that the product has high hardness, and improves the impact resistance and corrosion resistance of the product.

Description

Technical Field

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

[0002] In modern industry, seamless steel pipes are widely used in various fields due to their remarkable characteristics, such as smooth interior, uniform wall thickness, high tensile strength, strong pressure resistance, and high manufacturing precision. In particular, seamless steel pipes play an irreplaceable role in areas with high requirements for impact resistance.

[0003] In the preparation of seamless steel pipes, the increase in the carbon content in the chemical composition of the steel used will significantly improve the strength and hardness of the steel. This is because carbon atoms form carbides (such as Fe3C) in the iron lattice, which enhances the steel's ability to resist deformation and thus increases hardness.

[0004] However, the excessive presence of these hard phases makes the material more susceptible to brittle fracture when impacted, affecting the steel's impact resistance. Furthermore, excessive carbon content results in a low hydrogen diffusion coefficient and high hydrogen solubility. Carbides exhibit electrochemically cathodic properties, accelerating the anodic dissolution reaction around the matrix. This makes the steel more susceptible to hydrogen adsorption in corrosive environments. The accumulation of hydrogen atoms within the steel leads to the formation and expansion of microcracks, which in turn triggers hydrogen embrittlement and significantly reduces the steel's impact resistance. Summary of the Invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a high-impact seamless steel pipe and a preparation method thereof, which ensures that the hardness of the product is high while improving its impact resistance and corrosion resistance.

[0006] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a high-impact-resistant seamless steel pipe, comprising an impact-resistant material and a steel body material, wherein the mass ratio of the impact-resistant material to the steel body material is (0.8-1):100;

[0007] The impact-resistant material comprises irregularly fired rock powder and sodium bicarbonate fine powder, wherein the mass ratio of the irregularly fired rock powder to the sodium bicarbonate fine powder is (7-8):1;

[0008] The chemical composition of the steel body material includes, in terms of mass percentage, C: 0.32-0.35%, Si: 0.40-0.42%, Mn: 1.04-1.15%, V: 0.08-0.10%, Ti: 0.05-0.07%, Mo: 0.06-0.08%, Al: 0.04-0.05%, Cu: 0.12-0.14%, Cr: 0.16-0.20%, Ni: 0.03-0.05%, P≤0.014%, S≤0.008%, and the rest is Fe and inevitable impurities.

[0009] Further, the preparation method of the irregularly calcined rock powder is as follows:

[0010] A1, crushing the rock by a jaw crusher, and passing through a 200-mesh sieve to obtain a rock powder;

[0011] A2, putting the rock powder obtained in A1 into a high-temperature resistance furnace, calcining at 1200-1300°C for 1-1.2h, discharging, and naturally cooling to room temperature to obtain a calcined rock powder;

[0012] A3, immersing the calcined rock powder obtained in A2 into an acid pickling solution, ultrasonic cleaning for 2-3h, filtering out, washing with water for multiple times until neutral, and drying to obtain the irregularly calcined rock powder.

[0013] Further, in A1, the rock is basalt.

[0014] Further, in A3, the acid pickling solution is a hydrofluoric acid solution with a mass concentration of 5-7%.

[0015] Further, in A3, the ultrasonic cleaning frequency is 40-60KHz.

[0016] Further, the sodium bicarbonate micro powder is JJ-100-B type ultra-fine sodium bicarbonate.

[0017] Further, the mass ratio of the irregularly calcined rock powder and the sodium bicarbonate micro powder is 7.4:1.

[0018] Further, the mass ratio of the impact-resistant material and the steel body material is 0.9:100.

[0019] In a second aspect, the present application provides a preparation method of the high-impact-resistance seamless steel pipe as described above, comprising the following steps:

[0020] S1, smelting according to the chemical composition of the steel body material to produce a steel body material;

[0021] S2, uniformly mixing the irregularly calcined rock powder and the sodium bicarbonate micro powder to obtain an impact-resistant material;

[0022] S3, placing the impact-resistant material in a container, adding the molten steel body material, stirring and mixing, adding the material into a heating furnace, and hot rolling at 1200-1260°C to form a tube billet;

[0023] S4. Heat the tube blank to 1240-1280°C in a heating furnace, keep it warm for 30 minutes, then take it out of the furnace and perforate it to φ450×30mm to obtain a steel pipe;

[0024] S5. Cool the steel pipe to 450-500℃ by air cooling at a cooling rate of 1-1.5℃ / S, then reheat it to 900-950℃ in a heating furnace, cool it to 800-850℃, and then cool it to 550-600℃ by air cooling at a cooling rate of 2±0.2℃ / S. Move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0025] This application has the following beneficial effects:

[0026] 1. The carbon content of the present invention is 0.32-0.35%, which is high enough to ensure that the hardness of the product is high enough; the addition of impact-resistant materials can demonstrate its strong adsorption capacity, forming a complex contact network with relatively high carbon density nodes, thereby improving the impact resistance and corrosion resistance of the product.

[0027] 2. After crushing, firing and acid washing, basalt is made into irregular fired rock powder, and the irregular fired rock powder is mixed with sodium bicarbonate powder to make impact-resistant material.

[0028] Among them, the rock powder made by crushing basalt itself has a fine pore structure and a certain adsorption capacity. It can form a contact network through adsorption, thereby improving the impact resistance and corrosion resistance of the product; the temperature is raised to 1200-1300℃ for sintering, and the rock powder minerals produce a large amount of glass phase. At the same time, internal reactions occur to release bubbles. The boundaries between the rock powder layers are not obvious, but they have not completely disappeared. The surface is relatively smooth, and there are many pores inside, but most of the pores are not connected. The fired rock powder obtained in this way has a stronger adsorption capacity for carbon and is easy to form a more complex contact network, thereby providing better buffering performance under impact loads; pickling can increase the surface roughness, and coarse particles have higher impact resistance than fine particles, which may be related to their greater internal friction.

[0029] Sodium bicarbonate powder will block the pores on the irregular fired rock powder. When heated, sodium bicarbonate decomposes. On the one hand, it absorbs heat and forms a local temperature gradient, thereby promoting the diffusion of C and facilitating adsorption; on the other hand, it produces gas, forms pore micro-pressure, and enhances adsorption capacity, thereby achieving the effect of improving the impact resistance and corrosion resistance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Fig. 1 , a comparative trend chart of Brinell hardness test data of the products obtained in Examples 1-4 of the present invention and Comparative Examples 1-8;

[0031] Fig. 2 , a comparative trend chart of impact absorption energy test data of the products obtained in Examples 1-4 of the present invention and Comparative Examples 1-8;

[0032] Fig. 3 , a comparative trend diagram of the impact resistance loss rate of the products prepared in Examples 1-4 of the present invention and Comparative Examples 1-8 before and after being placed in a salt spray environment. DETAILED DESCRIPTION

[0033] The present application is further described in detail below with reference to the embodiments.

[0034] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0035] Example 1: (1) Preparation of irregularly fired rock powder, the preparation method is as follows:

[0036] A1. Crush the basalt with a jaw crusher and pass it through a 200-mesh sieve to obtain rock powder.

[0037] A2. Place the rock powder obtained in A1 into a high-temperature resistance furnace and sinter at 1200°C for 1 hour. Discharge the material, cool it naturally to room temperature, and grind it to obtain sintered rock powder.

[0038] A3. Immerse the fired rock powder obtained in A2 in a hydrofluoric acid solution with a mass concentration of 5%, and ultrasonically clean it at a frequency of 40 kHz. After ultrasonic cleaning for 2 hours, filter it out, wash it with water several times until it is neutral, and dry it to obtain irregular fired rock powder.

[0039] Among them, basalt (item number DZ-206) was purchased from Shijiazhuang Deze Mineral Products Co., Ltd.

[0040] (2) Preparation of high impact resistant seamless steel pipe, the preparation method is as follows:

[0041] S1. Prepare steel body material; smelt it according to existing technology to obtain the steel body; its chemical composition, by mass percentage, includes C: 0.32%, Si: 0.40%, Mn: 1.04%, V: 0.08%, Ti: 0.05%, Mo: 0.06%, Al: 0.04%, Cu: 0.12%, Cr: 0.16%, Ni: 0.03%, P: 0.014%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0042] S2. Prepare an impact-resistant material: Irregularly fired rock powder and sodium bicarbonate fine powder are mixed in a mass ratio of 7:1 and mixed evenly to obtain an impact-resistant material. The sodium bicarbonate fine powder is JJ-100-B ultrafine sodium bicarbonate, 1800 mesh, industrial grade, purchased from Weifang Jiejia New Materials Co., Ltd.

[0043] S3. Place the impact-resistant material in a container, add molten steel body material, the mass ratio of the impact-resistant material to the steel body material is 0.8:100, stir and mix, add to the heating furnace, hot roll at 1200°C to make a tube blank.

[0044] S4. Heat the tube billet to 1240℃ in a heating furnace, keep it warm for 30 minutes and then take it out of the furnace. Use a piercing machine to pierce it to φ450×30mm. The final piercing temperature is 1080℃ to obtain a steel pipe.

[0045] S5. Cool the steel pipe to 460℃ with air cooling at a cooling rate of about 1℃ / S. Then reheat it to 910℃ in a heating furnace, cool it to 810℃, and then cool it to 560℃ with air cooling at a cooling rate of about 1.9℃ / S. Move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0046] Example 2: (1) Preparation of irregularly fired rock powder, the preparation method is as follows:

[0047] A1. Crush the basalt with a jaw crusher and pass it through a 200-mesh sieve to obtain rock powder.

[0048] A2. The rock powder obtained in A1 was placed in a high-temperature resistance furnace and fired at 1250°C for 1.1 hours. The material was discharged and naturally cooled to room temperature to obtain fired rock powder.

[0049] A3. Immerse the fired rock powder obtained in A2 in a hydrofluoric acid solution with a mass concentration of 6%, and ultrasonically clean it at a frequency of 50 kHz. After ultrasonic cleaning for 2.5 hours, filter it out, wash it with water several times until it is neutral, and dry it to obtain irregular fired rock powder.

[0050] Among them, basalt (item number DZ-206) was purchased from Shijiazhuang Deze Mineral Products Co., Ltd.

[0051] (2) Preparation of high impact resistant seamless steel pipe, the preparation method is as follows:

[0052] S1. Prepare a steel body material; its chemical composition, by mass percentage, includes C: 0.33%, Si: 0.41%, Mn: 1.08%, V: 0.09%, Ti: 0.06%, Mo: 0.07%, Al: 0.045%, Cu: 0.13%, Cr: 0.18%, Ni: 0.04%, P: 0.012%, S: 0.008%, and the remainder is Fe and unavoidable impurities. Smelting is carried out according to existing technology to obtain the steel body material.

[0053] S2, preparing the impact-resistant material; irregularly calcined rock powder and sodium bicarbonate powder are mixed in a mass ratio of 7.4:1, and uniformly mixed to obtain the impact-resistant material. The sodium bicarbonate powder is JJ-100-B type superfine sodium bicarbonate, 1800 mesh, industrial grade, purchased from Weifang Jiejia New Material Co., Ltd.

[0054] S3, placing the impact-resistant material in a container, adding molten steel body material, and stirring and mixing the impact-resistant material and the steel body material in a mass ratio of 0.9:100, then adding to a heating furnace, hot rolling at 1240°C to form a pipe blank.

[0055] S4, heating the pipe blank in the heating furnace to 1260°C, holding for 30 min, then taking out of the furnace, piercing to φ450x30mm, and the final piercing temperature is 1110°C, to obtain a steel pipe.

[0056] S5, cooling the steel pipe to 480°C at a cooling rate of about 1.3°C / s, then heating to 930°C in a heating furnace, cooling to 820°C, then cooling to 570°C at a cooling rate of about 2°C / s, then moving to a cooling bed and air cooling to room temperature, to obtain a high impact-resistant seamless steel pipe.

[0057] Example 3: (1) preparing irregularly calcined rock powder, the preparation method is as follows:

[0058] A1, crushing basalt by a jaw crusher, and passing through a 200 mesh sieve to obtain rock powder.

[0059] A2, placing the rock powder obtained in A1 into a high-temperature resistance furnace, calcining at 1290°C for 1.1h, discharging, and naturally cooling to room temperature to obtain calcined rock powder.

[0060] A3, immersing the calcined rock powder obtained in A2 into a 7% mass concentration hydrofluoric acid solution, ultrasonic cleaning at a frequency of 60KHz for 2.5h, then filtering, washing with water for multiple times until neutral, and drying to obtain irregularly calcined rock powder.

[0061] The basalt (item number DZ-206) is purchased from Shijiazhuang Dezhe Mineral Products Co., Ltd.

[0062] (2) preparing a high impact-resistant seamless steel pipe, the preparation method is as follows:

[0063] S1. Prepare steel body material; smelt it according to the existing technology to obtain the steel body; its chemical composition, by mass percentage, includes C: 0.34%, Si: 0.41%, Mn: 1.12%, V: 0.09%, Ti: 0.06%, Mo: 0.07%, Al: 0.05%, Cu: 0.14%, Cr: 0.19%, Ni: 0.04%, P: 0.013%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0064] S2. Prepare an impact-resistant material: Irregularly fired rock powder and sodium bicarbonate fine powder are mixed in a mass ratio of 8:1 and mixed evenly to obtain an impact-resistant material. The sodium bicarbonate fine powder is JJ-100-B ultrafine sodium bicarbonate, 1800 mesh, industrial grade, purchased from Weifang Jiejia New Materials Co., Ltd.

[0065] S3. Place the impact-resistant material in a container, add molten steel body material, the mass ratio of the impact-resistant material to the steel body material is 1:100, stir and mix, add to the heating furnace, hot roll at 1250℃, and make a tube blank.

[0066] S4. Heat the tube billet to 1270°C in a heating furnace, keep it warm for 30 minutes, then take it out of the furnace and perforate it to φ450×30mm. The final perforation temperature is 1100°C to obtain a steel pipe.

[0067] S5. Cool the steel pipe to 490℃ with air cooling at a cooling rate of about 1.5℃ / S. Then reheat it to 940℃ in a heating furnace, cool it to 830℃, and then cool it to 590℃ with air cooling at a cooling rate of about 2.2℃ / S. Then move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0068] Example 4: (1) Preparation of irregularly fired rock powder, the preparation method is as follows:

[0069] A1. Crush the basalt with a jaw crusher and pass it through a 200-mesh sieve to obtain rock powder.

[0070] A2. The rock powder obtained in A1 was placed in a high-temperature resistance furnace and fired at 1300°C for 1.2 hours. The material was discharged and naturally cooled to room temperature to obtain fired rock powder.

[0071] A3. Immerse the fired rock powder obtained in A2 in a hydrofluoric acid solution with a mass concentration of 7%, and ultrasonically clean it at a frequency of 60 kHz. After ultrasonic cleaning for 3 hours, filter it out, wash it with water several times until it is neutral, and dry it to obtain irregular fired rock powder.

[0072] Among them, basalt (item number DZ-206) was purchased from Shijiazhuang Deze Mineral Products Co., Ltd.

[0073] (2) Preparation of high impact resistant seamless steel pipe, the preparation method is as follows:

[0074] S1. Prepare steel base material; smelt it according to existing technology to obtain the steel base material; its chemical composition, by mass percentage, includes C: 0.35%, Si: 0.42%, Mn: 1.15%, V: 0.10%, Ti: 0.07%, Mo: 0.08%, Al: 0.05%, Cu: 0.14%, Cr: 0.20%, Ni: 0.05%, P: 0.012%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0075] S2. Prepare an impact-resistant material: Irregularly fired rock powder and sodium bicarbonate fine powder are mixed in a mass ratio of 8:1 and mixed evenly to obtain an impact-resistant material. The sodium bicarbonate fine powder is JJ-100-B ultrafine sodium bicarbonate, 1800 mesh, industrial grade, purchased from Weifang Jiejia New Materials Co., Ltd.

[0076] S3. Place the impact-resistant material in a container, add molten steel body material, the mass ratio of the impact-resistant material to the steel body material is 1:100, stir and mix, add to the heating furnace, and hot roll at 1260°C to make a tube billet.

[0077] S4. Heat the tube blank to 1280°C in a heating furnace, keep it warm for 30 minutes, then take it out of the furnace and perforate it to φ450×30mm. The final perforation temperature is 1130°C to obtain a steel pipe.

[0078] S5. Cool the steel pipe to 500℃ by air cooling at a cooling rate of about 1.5℃ / S, then reheat it to 950℃ in a heating furnace, cool it to 850℃, and then cool it to 600℃ by air cooling at a cooling rate of about 2.2℃ / S. Then move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0079] Comparative Example 1: The difference between this comparative example and Example 1 is that the C content in the steel body material is as low as 0.2%.

[0080] Specifically, a high-impact seamless steel pipe is prepared by the following method:

[0081] S1. Prepare steel body material; smelt it according to existing technology to obtain the steel body; its chemical composition, by mass percentage, includes C: 0.2%, Si: 0.40%, Mn: 1.04%, V: 0.08%, Ti: 0.05%, Mo: 0.06%, Al: 0.04%, Cu: 0.12%, Cr: 0.16%, Ni: 0.03%, P: 0.014%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0082] S2. Prepare an impact-resistant material: Irregularly fired rock powder and sodium bicarbonate fine powder are mixed in a mass ratio of 7:1 and mixed evenly to obtain an impact-resistant material. The sodium bicarbonate fine powder is JJ-100-B ultrafine sodium bicarbonate, 1800 mesh, industrial grade, purchased from Weifang Jiejia New Materials Co., Ltd.

[0083] S3. Place the impact-resistant material in a container, add molten steel body material, the mass ratio of the impact-resistant material to the steel body material is 0.8:100, stir and mix, add to the heating furnace, hot roll at 1200°C to make a tube blank.

[0084] S4. Heat the tube blank to 1240℃ in a heating furnace, keep it warm for 30 minutes, then take it out of the furnace, pierce it to φ450×30mm, and the final piercing temperature is 1080℃ to obtain a steel pipe.

[0085] S5. Cool the steel pipe to 460℃ with air cooling at a cooling rate of about 1℃ / S. Then reheat it to 910℃ in a heating furnace, cool it to 810℃, and then cool it to 560℃ with air cooling at a cooling rate of about 1.9℃ / S. Move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0086] Comparative Example 2: The difference between this comparative example and Example 1 is that the C content in the steel base material is as low as 0.2%; and the impact-resistant material is deleted in the preparation of the high-impact-resistant seamless steel pipe.

[0087] Specifically, a high-impact seamless steel pipe is prepared by the following method:

[0088] S1. Prepare steel body material; smelt it according to existing technology to obtain the steel body; its chemical composition, by mass percentage, includes C: 0.2%, Si: 0.40%, Mn: 1.04%, V: 0.08%, Ti: 0.05%, Mo: 0.06%, Al: 0.04%, Cu: 0.12%, Cr: 0.16%, Ni: 0.03%, P: 0.014%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0089] S2. Add the steel body material into the heating furnace and hot-roll it at 1200°C to make a tube billet.

[0090] S3. Heat the tube blank to 1240℃ in a heating furnace, keep it warm for 30 minutes, then take it out of the furnace, pierce it to φ450×30mm, and the final piercing temperature is 1080℃ to obtain a steel pipe.

[0091] S4. Cool the steel pipe to 460℃ with air cooling at a cooling rate of about 1℃ / S, then reheat it to 910℃ in a heating furnace, cool it to 810℃, and then cool it to 560℃ with air cooling at a cooling rate of about 1.9℃ / S. Then move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0092] Comparative Example 3: The difference between this comparative example and Example 1 is that the impact-resistant material is deleted in the preparation of the high-impact-resistant seamless steel pipe.

[0093] Specifically, a high-impact seamless steel pipe is prepared by the following method:

[0094] S1. Prepare steel body material; smelt it according to existing technology to obtain the steel body; its chemical composition, by mass percentage, includes C: 0.32%, Si: 0.40%, Mn: 1.04%, V: 0.08%, Ti: 0.05%, Mo: 0.06%, Al: 0.04%, Cu: 0.12%, Cr: 0.16%, Ni: 0.03%, P: 0.014%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0095] S2. Add the steel body material into the heating furnace and hot-roll it at 1200°C to make a tube billet.

[0096] S3. Heat the tube blank to 1240℃ in a heating furnace, keep it warm for 30 minutes, then take it out of the furnace, pierce it to φ450×30mm, and the final piercing temperature is 1080℃ to obtain a steel pipe.

[0097] S4. Cool the steel pipe to 460℃ with air cooling at a cooling rate of about 1℃ / S, then reheat it to 910℃ in a heating furnace, cool it to 810℃, and then cool it to 560℃ with air cooling at a cooling rate of about 1.9℃ / S. Then move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0098] Comparative Example 4: The difference between this comparative example and Example 1 is that the irregularly fired rock powder is replaced by acid-washed rock powder; that is, in the preparation of the original irregularly fired rock powder, the firing treatment of the original A2 step is not performed.

[0099] Specifically, the acid-washed rock powder is prepared as follows:

[0100] A1. Crush the basalt with a jaw crusher and pass it through a 200-mesh sieve to obtain rock powder.

[0101] A2. Immerse the rock powder obtained in A1 in a hydrofluoric acid solution with a mass concentration of 5%, and ultrasonically clean it at a frequency of 40 kHz. After ultrasonic cleaning for 2 hours, filter it out, wash it with water several times until it is neutral, and dry it to obtain acid-washed rock powder.

[0102] Comparative Example 5: The difference between this comparative example and Example 1 is that the irregularly fired rock powder is replaced by fired rock powder; that is, in the preparation of the original irregularly fired rock powder, the acid washing treatment of the original step A3 is not performed.

[0103] Specifically, the fired rock powder is prepared as follows:

[0104] A1. Crush the basalt with a jaw crusher and pass it through a 200-mesh sieve to obtain rock powder.

[0105] A2. Place the rock powder obtained in A1 into a high-temperature resistance furnace, sinter at 1200°C for 1 hour, discharge, and naturally cool to room temperature to obtain sintered rock powder.

[0106] Comparative Example 6: The difference between this comparative example and Example 1 is that the irregularly fired rock powder is replaced by rock powder; that is, in the preparation of the original irregularly fired rock powder, neither the firing treatment of the original A2 step nor the pickling treatment of the original A3 step is performed.

[0107] Specifically, the rock powder is prepared as follows: basalt is crushed by a jaw crusher and passed through a 200-mesh sieve to obtain rock powder.

[0108] Comparative Example 7: The difference between this comparative example and Example 1 is that the impact-resistant material is replaced by sodium bicarbonate powder, that is, the irregularly fired rock powder is deleted.

[0109] Specifically, a high-impact seamless steel pipe is prepared by the following method:

[0110] S1. Prepare steel body material; smelt it according to existing technology to obtain the steel body; its chemical composition, by mass percentage, includes C: 0.32%, Si: 0.40%, Mn: 1.04%, V: 0.08%, Ti: 0.05%, Mo: 0.06%, Al: 0.04%, Cu: 0.12%, Cr: 0.16%, Ni: 0.03%, P: 0.014%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0111] S2. Sodium bicarbonate powder is placed in a container, and molten steel body material is added, with the mass ratio of sodium bicarbonate powder to steel body material being 0.1:100. After stirring and mixing, the mixture is added into a heating furnace and hot rolled at 1200°C to form a tube blank.

[0112] S4. Heat the tube billet to 1240℃ in a heating furnace, keep it warm for 30 minutes and then take it out of the furnace. Use a piercing machine to pierce it to φ450×30mm. The final piercing temperature is 1080℃ to obtain a steel pipe.

[0113] S5. Cool the steel pipe to 460℃ with air cooling at a cooling rate of about 1℃ / S. Then reheat it to 910℃ in a heating furnace, cool it to 810℃, and then cool it to 560℃ with air cooling at a cooling rate of about 1.9℃ / S. Move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0114] Comparative Example 8: The difference between this comparative example and Example 1 is that the impact-resistant material is replaced by irregularly fired rock powder, that is, the sodium bicarbonate powder is deleted.

[0115] Specifically, a high-impact seamless steel pipe is prepared by the following method:

[0116] S1. Prepare steel body material; smelt it according to existing technology to obtain the steel body; its chemical composition, by mass percentage, includes C: 0.32%, Si: 0.40%, Mn: 1.04%, V: 0.08%, Ti: 0.05%, Mo: 0.06%, Al: 0.04%, Cu: 0.12%, Cr: 0.16%, Ni: 0.03%, P: 0.014%, S: 0.007%, and the rest is Fe and unavoidable impurities.

[0117] S3. Place the irregularly fired rock powder in a container, add molten steel body material, the mass ratio of the irregularly fired rock powder to the steel body material is 0.7:100, stir and mix, add to the heating furnace, hot roll at 1200°C to make a tube blank.

[0118] S4. Heat the tube billet to 1240℃ in a heating furnace, keep it warm for 30 minutes and then take it out of the furnace. Use a piercing machine to pierce it to φ450×30mm. The final piercing temperature is 1080℃ to obtain a steel pipe.

[0119] S5. Cool the steel pipe to 460℃ with air cooling at a cooling rate of about 1℃ / S. Then reheat it to 910℃ in a heating furnace, cool it to 810℃, and then cool it to 560℃ with air cooling at a cooling rate of about 1.9℃ / S. Move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

[0120] Test example: Test objects: Products prepared in Examples 1-4 and Comparative Examples 1-8.

[0121] Test items: 1. Hardness.

[0122] 2. Impact resistance.

[0123] 3. Corrosion resistance.

[0124] Test method / basis: 1. Hardness test: measure Brinell hardness (HBW).

[0125] 2. Impact resistance test: The test was performed according to GB / T 229-2007. The test temperature was room temperature. The greater the impact absorption energy value, the stronger the impact resistance.

[0126] 3. Corrosion resistance test: The test was performed by the impact resistance loss rate. The smaller the impact resistance loss rate value, the stronger the corrosion resistance. The impact resistance loss rate = (impact absorption energy of the sample before salt spray corrosion treatment-impact absorption energy of the sample after salt spray corrosion treatment) / impact absorption energy of the sample before salt spray corrosion treatment*100%, wherein the sample before salt spray corrosion treatment and the sample after salt spray corrosion treatment were two different samples of the same test object. The salt spray corrosion treatment method: the sample was placed at an inclination angle of 15°-30° in a salt spray test chamber. The salt solution in the salt spray test chamber was a 7% sodium chloride solution with a temperature of 40°C and a relative humidity of 95%. The placement (treatment) time was 8 days.

[0127] Test results: see Table 1.

[0128] Table 1. Test data of test examples

[0129]

[0130] Result analysis: analysis of examples 1-4 and combination of Table 1 data and Figs. 1-3 It can be seen that the product prepared by the application has high hardness, and strong impact resistance and corrosion resistance.

[0131] Analysis of examples 1 and comparative examples 1-3 and combination of Table 1 data and Figs. 1-3 It can be seen from the comparison of comparative example 2 and comparative example 3 that when the C content is high (0.32%), the hardness is high, and the impact resistance and corrosion resistance are low; when the C content is low (0.2%), the hardness is low, and the impact resistance and corrosion resistance are high. It shows that the increase of C content (from 0.2% to 0.32%) can improve the hardness of the prepared product, but at the same time, it will also cause the impact resistance and corrosion resistance of the prepared product to decrease.

[0132] It can be seen from the comparison of example 1 and comparative example 3 that when the C content is high (0.32%), the addition of the impact-resistant material has no obvious effect on the hardness of the prepared product, but it can significantly improve the impact resistance and corrosion resistance of the prepared product. It can be seen from the comparison of comparative example 1 and comparative example 2 that when the C content is low (0.2%), the addition of the impact-resistant material also has no obvious effect on the hardness of the prepared product, but it will cause the impact resistance and corrosion resistance of the prepared product to decrease slightly. It shows that only when the C content is high enough, the impact-resistant material can improve the impact resistance and corrosion resistance of the prepared product.

[0133] This is because only when the C content is high enough, the strong adsorption capacity of the impact-resistant material can be fully exhibited, and a complex contact network of relatively high C density nodes can be formed, thereby improving the impact resistance and corrosion resistance of the product. When the C content is too low, the strong adsorption capacity of the impact-resistant material will instead lead to the appearance of multiple local C-containing network sections, insufficient network continuity, and a decrease in the buffering performance provided under impact load.

[0134] Example 1, Comparative Examples 3 and 7-8 are analyzed in combination with the data in Table 1 and Figs. 1-3 It can be seen that when the C content is high (0.32%), the addition of irregularly fired rock powder alone can improve the impact resistance and corrosion resistance of the product, as shown by the comparison between Comparative Example 3 and Comparative Example 8. In combination with Example 1, it can be seen that under the premise of the presence of irregularly fired rock powder, the addition of mixed sodium bicarbonate powder can further improve the impact resistance and corrosion resistance of the product. As shown by the comparison between Comparative Example 3 and Comparative Example 7, the addition of sodium bicarbonate powder alone can instead lead to a decrease in the impact resistance and corrosion resistance of the product.

[0135] This is because when irregularly fired rock powder is added together with sodium bicarbonate powder, the sodium bicarbonate powder will block the pores on the irregularly fired rock powder. Upon heating, the sodium bicarbonate decomposes, on the one hand, absorbing heat and forming a temperature gradient in the local area, thereby promoting the diffusion of C and facilitating adsorption. On the other hand, gas is generated, forming a pore micro-pressure and enhancing the adsorption capacity. This in turn achieves the effect of improving the impact resistance and corrosion resistance of the product. When sodium bicarbonate powder is added alone, the gas generated by the decomposition upon heating will increase the local pressure inside the material, and the lack of adsorption and buffering effect of the pores on the irregularly fired rock powder will cause stress concentration inside, thereby causing micro-cracks, not only reducing the impact resistance of the steel, but also forming more corrosion initiation points in the corrosion environment and accelerating the corrosion process.

[0136] Example 1 and Comparative Examples 4-7 are analyzed in combination with the data in Table 1 and Figs. 1-3 It can be seen that when the C content is high (0.32%), the addition of rock powder can improve the impact resistance and corrosion resistance of the product. The firing and pickling treatment of the rock powder can also improve the impact resistance and corrosion resistance of the product, and there is a positive synergistic effect between the two.

[0137] This is because the rock powder made from basalt itself has a fine pore structure and a certain adsorption capacity, and can form a contact network through adsorption, thereby improving the impact resistance and corrosion resistance of the product; when the temperature is raised to 1200-1300℃ for sintering, the rock powder minerals produce a large amount of glass phase, and at the same time, internal reactions occur to release bubbles. The boundaries between the rock powder layers are not obvious, but they have not completely disappeared. The surface is relatively smooth, and there are many pores inside, but most of the pores are not connected. The fired rock powder obtained in this way has a stronger adsorption capacity for carbon and is easy to form a more complex contact network, thereby providing better buffering performance under impact loads; pickling can increase the surface roughness, and coarse particles have higher impact resistance than fine particles, which may be related to their greater internal friction.

[0138] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0139] In addition, the 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 high impact resistant seamless steel pipe, characterized in that: It comprises an impact-resistant material and a steel body material, wherein the mass ratio of the impact-resistant material to the steel body material is (0.8-1):100; The impact-resistant material comprises irregularly fired rock powder and sodium bicarbonate fine powder, wherein the mass ratio of the irregularly fired rock powder to the sodium bicarbonate fine powder is (7-8):1; The chemical composition of the steel body material, calculated by mass percentage, includes C: 0.32-0.35%, Si: 0.40-0.42%, Mn: 1.04-1.15%, V: 0.08-0.10%, Ti: 0.05-0.07%, Mo: 0.06-0.08%, Al: 0.04-0.05%, Cu: 0.12-0.14%, Cr: 0.16-0.20%, Ni: 0.03-0.05%, P≤0.014%, S≤0.008%, and the remainder is Fe and unavoidable impurities; The preparation method of the irregularly fired rock powder is as follows: A1. Crushing the rock with a crusher and passing it through a 200-mesh sieve to obtain rock powder; the rock is basalt; A2. Place the rock powder obtained in A1 into a high-temperature resistance furnace and sinter at 1200-1300°C for 1-1.2 hours, then discharge and allow to cool naturally to room temperature to obtain sintered rock powder. A3. Immerse the fired rock powder obtained in A2 in an acid washing solution, ultrasonically clean for 2-3 hours, filter out, wash with water several times until neutral, and dry to obtain irregular fired rock powder; The method for preparing the high-impact seamless steel pipe comprises the following steps: S1. Smelting the steel body material according to its chemical composition to produce the steel body material; S2. Mixing the irregularly fired rock powder and sodium bicarbonate powder to obtain an impact-resistant material; S3, placing the impact-resistant material in a container, adding the molten steel body material, stirring and mixing, adding the material into a heating furnace, and hot rolling at 1200-1260°C to form a tube billet; S4. Heat the tube blank in a heating furnace to 1240-1280°C, keep it warm for 30 minutes, then take it out of the furnace and perforate it to obtain a steel pipe; S5. Cool the steel pipe to 450-500℃ by air cooling at a cooling rate of 1-1.5℃ / s, then reheat it to 900-950℃ in a heating furnace, cool it to 800-850℃, and then cool it to 550-600℃ by air cooling at a cooling rate of 2±0.2℃ / s. Move it to a cooling bed and air cool it to room temperature to obtain a high-impact seamless steel pipe.

2. The high-impact seamless steel pipe according to claim 1, characterized in that: In A3, the pickling solution is a hydrofluoric acid solution with a mass concentration of 5-7%.

3. The high-impact seamless steel pipe according to claim 1, characterized in that: In A3, the ultrasonic cleaning frequency is 40-60kHz.

4. The high-impact seamless steel pipe according to claim 1, characterized in that: The sodium bicarbonate micropowder is JJ-100-B ultrafine sodium bicarbonate.

5. The high-impact seamless steel pipe according to claim 1, characterized in that: The mass ratio of the irregularly fired rock powder to the sodium bicarbonate fine powder is 7.4:

1.

6. The high-impact seamless steel pipe according to claim 1, characterized in that: The mass ratio of the impact-resistant material to the steel body material is 0.9:100.

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