Rare earth microalloyed weather-proof seamless steel pipe for low-residual-stress locomotive bogie and manufacturing method of rare earth microalloyed weather-proof seamless steel pipe

Abstract

The invention discloses a rare earth microalloyed weather-resistant seamless steel pipe for a low-residual-stress locomotive bogie. The weather-resistant seamless steel pipe comprises the following chemical elements in percentage by mass: 0.12-0.16% of C, 0.12-0.16% of B, 0.12-0.16% of C, 0.12-0.16% of Cr, 0.30% to 0.50% of Si; 1.00 to 1.10% of Mn; less than or equal to 0.020% of P; s is less than or equal to 0.010%; 0.45 to 0.70 percent of Cr; v < = 0.10%; 0.30% or less of Cu; ni < = 0.40%; ti is less than or equal to 0.04%; re < = 0.002%; and the balance Fe and impurities. The invention also discloses a manufacturing method thereof. Through reasonable component design, alloy elements such as Cu, Cr, Ni, V, Ti and Re are added on the basis of low-carbon steel, the corrosion-resistant seamless tube Q355NH for the locomotive bogie is produced through the processes such as steelmaking, tube rolling and heat treatment, and the performance of the corrosion-resistant seamless tube Q355NH meets the requirements of the standard GB / T4171-2008.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical materials, and in particular relates to a rare earth micro-alloyed weather-resistant seamless steel pipe for a low residual stress locomotive bogie and a manufacturing method thereof. Background Art

[0002] The sources of residual stress cover all industrial fields and nature, and they are generated, accompanied and affected by the entire manufacturing process and service life cycle of materials and equipment. At this stage, China has put forward new requirements for high-quality development. In the fields of materials and equipment, residual stress is one of the important factors of failure and is closely related to it. According to data, the cost increase caused by residual stress distortion in Europe accounts for more than 4% of the total manufacturing cost; in the bearing industry alone, the additional cost caused by residual stress distortion is estimated to exceed US$1 billion per year. According to a survey by the Federation of German Industries (VDMA), the additional manufacturing cost for eliminating residual stress distortion in the power transmission manufacturing field in Germany is as high as 850 million euros per year. Therefore, the American Society for Metals regards "striving to achieve zero deformation and maximum uniformity of heat-treated parts" as its main research and development goal. The present invention relates to a production method for a low residual stress seamless steel pipe.

[0003] Weathering steel refers to low-alloy high-strength structural steel with good corrosion resistance, which is made by adding a small amount of alloying elements (such as Cu, P, Cr, Ni, Mo, etc.) to improve the rust layer structure under the action of atmospheric corrosion, forming a dense internal rust layer, thereby effectively preventing further penetration of corrosive media. Every year, metal equipment and materials scrapped due to corrosion in the world account for about 20% to 40% of the annual output of metal materials, and the metal loss due to corrosion is more than 100 million tons. The metal lost due to atmospheric corrosion accounts for more than 50% of the total metal corrosion, and the amount of steel used in the atmosphere generally exceeds 60% of its total production. That is to say, more than 30 million tons of steel are scrapped due to atmospheric corrosion every year in the world.

[0004] The demand for steel in my country will continue to grow in the future. With such a large demand and use of steel, the amount of metal corrosion cannot be ignored. The experience of industrialized countries in the world has shown that the peak period of infrastructure investment is often the peak period of frequent corrosion problems a few decades later. Therefore, the quality of corrosion control work is directly related to the century-long plan of national construction.

[0005] Weathering steel can be used as structural steel for railways, bridges, towers and other construction facilities that are exposed to the atmosphere for a long time. They often serve for a long time in industrial atmosphere, marine atmosphere, acid rain, haze and other environments. The corrosion of steel has become the main reason for its damage and failure. With the progress of society and the development of technology, people have also put forward more and higher requirements for weathering steel, that is, from the original single pursuit of high strength to excellent comprehensive performance, mainly in terms of high strength and toughness, good weldability and corrosion resistance.

[0006] Baotou Steel has rich rare earth reserves, so in recent years, it has vigorously researched and developed rare earth steel, because rare earth elements play an important role in steel. Studies have shown that after rare earth elements are added to steel, it is beneficial to purify the molten steel, refine the grains, increase the resistance to grain growth, inhibit the growth of columnar crystals, change the nature, morphology and distribution of inclusions, reduce the corrosion source points, and thus improve the various properties of steel. There have been many studies on the effect of rare earth on the corrosion resistance of steel at home and abroad. It is generally believed that adding an appropriate amount of rare earth to steel can effectively improve the corrosion resistance of steel. Some researchers have conducted four years of exposure corrosion tests at test points in different atmospheric environments such as Qingdao, Jiangjin, Beijing, Wuhan, Qionghai, Guangzhou, and Wanning, and found that the corrosion rate of ordinary carbon steel at different test points is higher than that of weathering steel. Weathering steel with the addition of rare earth elements has better corrosion resistance than the original weathering steel.

[0007] By searching the data, no relevant literature or reports on weather-resistant seamless steel pipes for low residual stress locomotive bogies have been found. Q355NH is the steel grade for weather-resistant structural steel in the standard GB / T 4171-2008. The development of weather-resistant structural steel pipe Q355NH is of great significance. It can not only fill the gap in atmospheric corrosion-resistant seamless pipes for locomotive bogies, but also lay the foundation for the next step of developing higher steel grade weather-resistant seamless pipes. At the same time, it can also give play to the advantages of Baosteel's rich rare earth resources and have good economic benefits.

[0008] The present invention relates to a rare earth micro-alloyed weather-resistant seamless steel pipe for locomotive bogies and a production method thereof, which can fill the gap in atmospheric corrosion-resistant seamless pipes for locomotive bogies and lay a foundation for the next step of developing higher-grade weather-resistant seamless pipes. At the same time, it can also give play to the advantage of Baosteel's rich rare earth resources and have good economic benefits. Summary of the invention

[0009] The purpose of the present invention is to provide a rare earth micro-alloyed weather-resistant seamless steel pipe for a low residual stress locomotive bogie and a manufacturing method thereof. By adding alloy elements such as Cu, Cr, Ni, V, Ti, Re, etc. to low carbon steel through reasonable composition design, the corrosion-resistant seamless pipe Q355NH for locomotive bogie is produced through steelmaking, pipe rolling, heat treatment and other processes, and the performance meets the requirements of standard GB / T 4171-2008.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] The invention discloses a rare earth microalloyed weather-resistant seamless steel pipe for a low residual stress locomotive bogie. The chemical elements and their mass percentages of the weather-resistant seamless steel pipe are as follows: C 0.12-0.16%; Si 0.30-0.50%; Mn 1.00-1.10%; P≤0.020%; S≤0.010%; Cr 0.45-0.70%; V≤0.10%; Cu≤0.30%; Ni≤0.40%; Ti≤0.04%; Re≤0.002%; the rest are Fe and unavoidable impurities, and the mass fraction is 100% in total.

[0012] Furthermore, the chemical elements and their mass percentages of the weathering seamless steel pipe are as follows: C 0.14%; Si 0.32%; Mn 1.03%; P 0.014%; S 0.005%; Cr 0.47%; V 0.09%; Cu 0.29%; Ni 0.39%; Ti 0.029%; Re 0.0004%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0013] Furthermore, the chemical elements and their mass percentages of the weathering seamless steel pipe are as follows: C 0.14%; Si 0.33%; Mn 1.09%; P 0.013%; S 0.006%; Cr 0.47%; V 0.08%; Cu 0.28%; Ni 0.35%; Ti 0.038%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0014] Furthermore, the chemical elements and their mass percentages of the weathering seamless steel pipe are as follows: C 0.13%; Si 0.32%; Mn 1.05%; P 0.012%; S 0.005%; Cr 0.45%; V 0.08%; Cu 0.27%; Ni 0.39%; Ti 0.035%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0015] Furthermore, the chemical elements and their mass percentages of the weathering seamless steel pipe are as follows: C 0.14%; Si 0.30%; Mn 1.05%; P 0.011%; S 0.004%; Cr 0.46%; V 0.09%; Cu 0.26%; Ni 0.35%; Ti 0.038%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0016] Furthermore, the chemical elements and their mass percentages of the weathering seamless steel pipe are as follows: C 0.13%; Si 0.31%; Mn 1.07%; P 0.014%; S 0.005%; Cr 0.48%; V 0.08%; Cu 0.29%; Ni 0.32%; Ti 0.037%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0017] Functions of each element:

[0018] Carbon (C): is detrimental to the atmospheric corrosion resistance of steel. At the same time, C affects the welding performance, cold brittleness and stamping performance of steel. For the present invention, the C content is 0.12-0.16%.

[0019] Silicon (Si): It exists in the steel mainly in the solid solution state, mainly for solid solution strengthening, without forming carbonitrides, and can significantly increase the volume fraction of ferrite and strengthen the ferrite structure. For the present invention, the Si content is 0.30-0.50%.

[0020] Manganese (Mn): There is no consensus on the effect of manganese on corrosion resistance. Most scholars believe that manganese can improve the corrosion resistance of steel to marine atmosphere, but has almost no effect on corrosion resistance in industrial atmosphere. Usually, w(Mn) in weathering steel is 0.5% to 2.0%. Therefore, for the present invention, the Mn content ranges from 1.00 to 1.10%.

[0021] Chromium (Cr): The alloy element Cr can react with the steel matrix to produce a passivation film, making the rust layer on the steel surface denser, increasing its corrosion potential, and reducing the self-corrosion current, thereby achieving the purpose of improving the passivation ability of the metal material. Therefore, the Cr content is 0.45-0.70%.

[0022] Vanadium (V): V mainly forms stable carbides and nitrides, refines austenite grains, and improves strength and low-temperature toughness after normalizing, improves tempering stability of materials, and ensures that the strength and toughness of materials match. Therefore, V in the present invention is ≤0.10%.

[0023] Copper (Cu): It is the most effective alloying element in weathering steel. Cu was first added to weathering steel. When 0.2% to 0.4% Cu is added to steel, it has superior corrosion resistance than ordinary carbon steel in rural atmosphere, industrial atmosphere or marine atmosphere. Cu can form secondary precipitation products on its surface when added to steel, and act as a cathode to produce anodic passivation on the steel surface, thereby achieving the purpose of improving its corrosion resistance. The effect of Cu in offsetting the harmful effects of S in steel is very obvious. Its action characteristic is that the higher the S content in steel, the more significant the relative effect of Cu in reducing the corrosion rate. This is because Cu and S generate insoluble sulfides. Therefore, in the present invention, Cu≤0.30%.

[0024] Nickel (Ni): It is a relatively stable element. Adding Ni can change the self-corrosion potential of steel in a positive direction, thus increasing the stability of the steel. Atmospheric exposure tests show that when the Ni content is about 4%, the atmospheric corrosion resistance of coastal weathering steel can be significantly improved. The excellent corrosion resistance of the Cr-free 3% Ni coastal weathering steel recently developed in Japan proves that the enrichment of Ni in the stable rust layer can effectively inhibit the intrusion of chloride ions, promote the formation of protective rust layer, and reduce the corrosion rate of steel. Therefore, in the present invention, Ni≤0.40%.

[0025] Titanium (Ti): The characteristic of Ti in steel is that it has a very strong affinity for oxygen, nitrogen, sulfur and carbon, and has significant deoxidation, denitrification, sulfur bonding, and significant carbide formation. It plays a stable role in resisting intergranular corrosion as a carbide former. It also has the characteristic of refining grains. Therefore, in the present invention, Ti≤0.04%.

[0026] Rare earth (Re): When appropriate rare earth elements are added to steel, it is beneficial to purify the molten steel, refine the grains, increase the resistance to grain growth, inhibit the growth of columnar crystals, change the properties, morphology and distribution of inclusions, reduce the corrosion source points, and thus improve the various properties of steel. Adding a proper amount of rare earth to steel can effectively improve the corrosion resistance of steel. Therefore, in the present invention, Re≤0.002%.

[0027] A method for manufacturing a rare earth microalloyed weather-resistant seamless steel pipe for a low residual stress locomotive bogie, comprising:

[0028] Steelmaking process: blast furnace molten iron → molten iron pretreatment → converter smelting → LF refining → VD vacuum treatment → continuous casting → slow cooling of ingots → storage; Among them:

[0029] Desulfurized hot metal is used, and the basicity of the final slag of converter smelting is ≥3.0. The final carbon must be controlled, and overoxidation and ultra-low carbon steelmaking are not allowed. The steelmaking temperature is 1615-1635℃; ferrosilicon and ferromanganese are used for deoxidation and alloying, and the final deoxidation adopts an aluminum deoxidation process; an appropriate amount of white ash is added during the steelmaking process; in the LF refining process, argon is blown normally as required throughout the process, and the temperature is raised by gradually increasing the heating rate from a low level to a high level to make white slag; copper alloys and nickel alloys are added in the converter process, and other alloys are added in the middle and late stages of refining. The composition is fine-tuned in the late stage of refining, and rare earth alloys are added in proportion; an appropriate amount of high calcium wire is fed before the end of refining; VD deep vacuum degree ≤0 .12KPa, deep vacuum time ≥10 minutes, during the vacuuming process, attention should be paid to the boiling of molten steel at any time and the argon pressure should be adjusted in time; the soft blowing time after vacuum treatment should be ≥10min, and the weak stirring effect should be paid attention to, and the molten steel should not be exposed; the continuous casting process adopts electromagnetic stirring technology, and the superheat of the continuous casting molten steel is controlled within the range of 20℃~30℃ to ensure constant drawing speed casting; each nozzle of the secondary cooling water should ensure uniform spraying, and no interruption and water column spraying are allowed; the billet should be sent to the slow cooling pit in time for slow cooling, and the slow cooling time is greater than 48 hours. The billet temperature drops below 100℃ before it can be taken out of the pit; high-quality round billets with low P, low S and uniform composition are obtained by this method;

[0030] Pipe making process: continuous casting → sawing → ring furnace heating → perforation → PQF three-roller limited mandrel continuous rolling → tube removal → diameter reduction → cooling → sawing → heat treatment → straightening; Among them:

[0031] Before loading the tube into the furnace, the tube billet should be inspected. The surface quality of the tube billet should meet the requirements of Q / BG 524. Severe slag pits and scars should be repaired and ground. Check the quality of the sawn end face, and remove the tube billet with defects such as center cracks and center shrinkage holes that exceed the standard in time. The temperature of the insulation section of the annular furnace is 1260±20℃. During piercing, the piercing machine body and the front and back rolling center lines must be consistent. The head extension should be strictly controlled as required. The temperature of the round billet after piercing is 1200±20℃. The continuous rolling inlet temperature is 1110±20℃. During the rolling process, the outer surface quality of the rough tube and the mandrel should be checked, and high-pressure water descaling should be turned on. The pressure range of high-pressure descaling water is 9-12MPa. The temperature after fixed tension reduction is 940±20℃. Adjust the spray direction of the roller cooling water to ensure that it is not sprayed onto the inner surface of the tube body. High-precision high-quality tube bodies of different sizes are obtained by combining the three-roller limited mandrel continuous rolling unit PQF with high-end hot rolling control technology.

[0032] Heat treatment process: normalizing + air cooling; the heating temperature of normalizing treatment is usually 30-50℃ above AC3, the normalizing temperature is 930℃±10℃, and the insulation time is 70±5 minutes; straightening is required after normalizing, and the straightening force should be strictly controlled during straightening to ensure the bending requirements of the steel pipe, and no concave, elliptical or cracking should occur.

[0033] Compared with the prior art, the beneficial technical effects of the present invention are:

[0034] The reasonable selection of alloy elements and the appropriate ratio of element content in the present invention make the steel have a lower carbon equivalent, and at the same time have excellent weather resistance, good weldability, low cost, and reasonable smelting and continuous casting process, rolling process and heat treatment process make the steel pipe have higher dimensional accuracy. The product of the present invention can be used without painting, which greatly reduces the maintenance cost of the product and reduces the environmental pollution problems caused by the painting process; further, it also reduces the requirements for maintenance of steel structures during service, greatly reduces direct maintenance costs and indirect costs of traffic interruption, and extends the service life, which is of great significance to the promotion of steel structures. The present invention is the first domestic application of weathering steel seamless steel pipes in the field of locomotive bogies. It has the characteristics of high strength, high toughness, low temperature resistance, easy welding, and good atmospheric corrosion resistance. It has made outstanding contributions to building a resource-saving and environmentally friendly society and achieving carbon peak and carbon neutrality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below in conjunction with the accompanying drawings.

[0036] Figure 1 This is the metallographic structure of the finished steel pipe of Example 1. DETAILED DESCRIPTION

[0037] A rare earth microalloyed weather-resistant seamless steel pipe for locomotive bogies with low residual stress

[0038] The steel pipe obtained by the present invention, taking the production specification of Φ307×13mm as an example, has a chemical composition as shown in Table 1:

[0039] Table 1 Statistical results of chemical composition of steel pipe of the present invention wt%

[0040]

[0041] As can be seen from Table 1, the deviation of the chemical composition content of the steel pipe is very small, which fully meets the design requirements of the present invention for the steel type. The stable component content is conducive to temperature control during heat treatment, thus providing a prerequisite for the pipe to have good organization and performance.

[0042] Steelmaking process: To produce steel pipes with specifications of Φ307×13mm, the continuous casting machine equipment shall be inspected before production to ensure that the casting machine is well aligned with the arc and the center; the pressure of the straightening machine shall be reduced to ensure the normal straightening of the billet; the nozzle plugging in the second cooling zone shall be replaced to ensure the uniformity of the billet in the second cooling zone, and the pulling speed shall be appropriately increased. When the pulling speed cannot be guaranteed, the flow shall be shut down in a tight sequence to ensure the pouring speed; the straightening temperature of the billet shall be increased to not less than 930℃; the superheat of the molten steel shall be controlled at 30℃ to ensure that the protective slag of the crystallizer is well melted and the slag is evenly discharged. The copper tube of the crystallizer in the middle and early stages shall be selected to ensure the inverted taper of the crystallizer. After the billet leaves the second cooling zone, it shall be covered with asbestos board for insulation to increase the straightening temperature of the billet. The billet shall be sent to the slow cooling pit in time for slow cooling, and the slow cooling time shall be greater than 48 hours. Through the above measures, high-quality round billets are obtained.

[0043] Pipe rolling process: The round billet is heated in a ring furnace with a furnace temperature of 1280℃. It is very important whether the temperature range of the round billet during hot rolling is in the plastic deformation zone of the steel grade, which is related to the inner and outer surface quality of the steel pipe and the load of the rolling mill. During production, the heating temperature of the ring furnace is strictly controlled to not exceed 1270℃. The round billet is in the optimal temperature range and plastic deformation zone. The time in the furnace should not be too long. The perforation adopts the process of low-speed biting and high-speed rolling. The temperature after perforation is 1200℃, the temperature entering the continuous rolling mill is 1100℃, the temperature after sizing is 925℃, cooling, and sawing.

[0044] Heat treatment: The production of atmospheric corrosion resistant seamless pipes for locomotive bogies requires normalizing treatment. When producing large-diameter thick-walled steel pipes, low strength is likely to occur. The normalizing system is 930℃ + insulation for 70min. If the normalizing insulation time is too short, it will have a negative impact on the temperature uniformity of the steel pipe when it is heated, so it is advisable to be no less than 70 minutes. The normalizing furnace process is 930℃ for the heating section, 920℃ for the insulation section, 70min for the insulation section, and air cooling.

[0045] The mechanical properties of the steel pipe of the present invention are shown in Table 2. As can be seen from Table 2, the steel pipe with a specification of Φ307×13mm produced by the method of the present invention can well meet the requirements of the Q355NH steel grade in the national standard GB / T 4171-2008, with excellent low-temperature impact toughness and a longitudinal impact of greater than 27J at -40°C. Generally, structural steel will change from toughness to brittleness as the temperature decreases. If the structural steel is used at the transition temperature or in a brittle state, low-stress failure is inevitable even at a lower stress level. For materials used at low temperatures, in addition to requiring a certain strength, sufficient toughness must be required. The seamless pipe Q355NH has very high requirements for low-temperature impact. The full-size impact energy (-40°C) of the steel pipe requires KV2≥27J. As can be seen from Table 2, the low-temperature impact performance of the steel pipe is very good, far exceeding the standard requirement of 27J, reaching 230J, and the toughness is very excellent.

[0046] Table 2 Mechanical properties of the steel pipe of the present invention

[0047]

[0048] The steel pipe of the present invention is sampled for laboratory analysis. After grinding and polishing, the sample is corroded with 4% nitric acid alcohol, and the organizational morphology is observed under an optical microscope. The grain size is graded according to the requirements of GB / T 6394-2002 standard, and the grade is not less than 8.5. The non-metallic inclusions are graded according to A in GB / T 10561-2005. The results are shown in Table 3.

[0049] Table 3: Impurities and grain size of the steel pipe of the present invention

[0050]

[0051] Note: F stands for ferrite and P stands for pearlite.

[0052] After heat treatment, the metallographic structure of the steel pipe in Example 1 is as follows: Figure 1 .from Figure 1 It can be seen that the steel pipe structure is ferrite and pearlite, which is uniform and fine, with a grain size of 10. The steel pipe contains an appropriate amount of V and Ti. When austenite is transformed into ferrite, precipitates will precipitate. The precipitates can not only inhibit the growth of ferrite grains and improve the strength of the matrix, but also inhibit the transformation of bainite, making the structure more uniform. Heat treatment further refines the grains. The uniform and fine structure makes the steel pipe have good strength and toughness.

[0053] The existence of residual stress reduces the strength and fatigue resistance of the material. In a corrosive environment, stress corrosion will occur, causing material failure. At the same time, during processing or use, the shape and size of the material will change due to the release of internal stress, and even cause the material to crack. The residual stress of steel pipe Examples 1 to 5 of the present invention is measured by the residual stress ring cutting opening displacement measurement method in the national standard GB / T 43898-2024, and the residual stress is 75 to 95 MPa, which is lower than the recommended minimum limit of residual stress of 100 MPa in the standard, effectively improving the corrosion resistance of the steel pipe. It can be seen that the weather-resistant seamless pipe for bogies produced by the present invention is a low residual stress seamless steel pipe.

[0054] The cyclic infiltration test is used to simulate the actual service conditions of metal materials in the atmosphere, and different industrial environments can be simulated to obtain the corrosion resistance data of the test steel in a shorter period. According to the provisions of the standard "Cyclic Infiltration Corrosion Test Method for Weathering Steel for Railways" TB / T 2375-93, the finished steel pipe of this patent was subjected to a cyclic infiltration test. The test simulated an industrial atmosphere, and the comparison steel was a seamless steel pipe Q345B for ordinary structures of the same strength level. The results of the 72h cyclic infiltration test show that the relative corrosion rate of the finished steel pipe of this patent is 18% lower than that of the seamless steel pipe Q345B for ordinary structures. It can be seen that under the same corrosion environment, the atmospheric corrosion resistance of the finished steel pipe of this patent is better than that of Q345B.

[0055] The seamless steel pipe for weather-resistant locomotive bogie with a specification of Φ307×13mm produced by the present invention has reasonable selection of alloy elements and appropriate element content ratio, so that the steel type is easy to produce and has low cost. Reasonable smelting and continuous casting process, rolling process and heat treatment process make the steel pipe have lower residual stress, higher strength, excellent low-temperature impact toughness and high dimensional accuracy. The product of the present invention has good corrosion resistance, lower residual stress, high dimensional accuracy, good inner and outer surface quality, high strength, uniform and stable performance of the whole pipe, especially excellent low-temperature toughness, which meets the use requirements of low-temperature environment. At the same time, it adopts low-carbon equivalent component design, and the product has excellent welding performance, which can improve the production efficiency of users and fully meet the requirements of national standard GB / T4171-2008.

[0056] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A rare earth microalloyed weather-resistant seamless steel pipe for low residual stress locomotive bogie, characterized in that: The chemical elements and their mass percentages of the weather-resistant seamless steel pipe are as follows: C 0.12-0.16%; Si 0.30-0.50%; Mn 1.00-1.10%; P ≤ 0.020%; S ≤ 0.010%; Cr 0.45-0.70%; V≤0.10%; Cu≤0.30%; Ni≤0.40%; Ti≤0.04%; Re≤0.002%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

2. The rare earth microalloyed weather-resistant seamless steel pipe for locomotive bogie with low residual stress according to claim 1, characterized in that: The chemical elements and their mass percentages of the weather-resistant seamless steel pipe are as follows: C 0.14%; Si 0.32%; Mn 1.03%; P 0.014%; S 0.005%; Cr 0.47%; V 0.09%; Cu 0.29%; Ni 0.39%; Ti 0.029%; Re 0.0004%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

3. The rare earth microalloyed weather-resistant seamless steel pipe for locomotive bogie with low residual stress according to claim 1, characterized in that: The chemical elements and their mass percentages of the weather-resistant seamless steel pipe are as follows: C 0.14%; Si 0.33%; Mn 1.09%; P 0.013%; S 0.006%; Cr 0.47%; V 0.08%; Cu 0.28%; Ni 0.35%; Ti 0.038%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

4. The rare earth microalloyed weather-resistant seamless steel pipe for locomotive bogie with low residual stress according to claim 1, characterized in that: The chemical elements and their mass percentages of the weather-resistant seamless steel pipe are as follows: C 0.13%; Si 0.32%; Mn 1.05%; P 0.012%; S 0.005%; Cr 0.45%; V 0.08%; Cu 0.27%; Ni 0.39%; Ti 0.035%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

5. The rare earth microalloyed weather-resistant seamless steel pipe for locomotive bogie with low residual stress according to claim 1, characterized in that: The chemical elements and their mass percentages of the weather-resistant seamless steel pipe are as follows: C 0.14%; Si 0.30%; Mn 1.05%; P 0.011%; S 0.004%; Cr 0.46%; V 0.09%; Cu 0.26%; Ni 0.35%; Ti 0.038%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

6. The rare earth microalloyed weather-resistant seamless steel pipe for locomotive bogie with low residual stress according to claim 1, characterized in that: The chemical elements and their mass percentages of the weather-resistant seamless steel pipe are as follows: C 0.13%; Si 0.31%; Mn 1.07%; P 0.014%; S 0.005%; Cr 0.48%; V 0.08%; Cu 0.29%; Ni 0.32%; Ti 0.037%; Re 0.0005%; the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

7. The method for manufacturing a rare earth microalloyed weather-resistant seamless steel pipe for a locomotive bogie with low residual stress according to any one of claims 1 to 6, characterized in that: include: Steelmaking process: blast furnace molten iron → molten iron pretreatment → converter smelting → LF refining → VD vacuum treatment → continuous casting → slow cooling of ingots → storage; Among them: Desulfurized hot metal is used, and the basicity of the final slag of converter smelting is ≥3.

0. The final carbon must be controlled, and overoxidation and ultra-low carbon steelmaking are not allowed. The steelmaking temperature is 1615-1635℃; ferrosilicon and ferromanganese are used for deoxidation and alloying, and the final deoxidation adopts an aluminum deoxidation process; an appropriate amount of white ash is added during the steelmaking process; in the LF refining process, argon is blown normally as required throughout the process, and the temperature is raised by gradually increasing the heating rate from a low level to a high level to make white slag; copper alloys and nickel alloys are added in the converter process, and other alloys are added in the middle and late stages of refining. The composition is fine-tuned in the late stage of refining, and rare earth alloys are added in proportion; an appropriate amount of high calcium wire is fed before the end of refining; VD deep vacuum degree ≤0 .12KPa, deep vacuum time ≥10 minutes, during the vacuuming process, attention should be paid to the boiling of molten steel at any time and the argon pressure should be adjusted in time; the soft blowing time after vacuum treatment should be ≥10min, and the weak stirring effect should be paid attention to, and the molten steel should not be exposed; the continuous casting process adopts electromagnetic stirring technology, and the superheat of the continuous casting molten steel is controlled within the range of 20℃~30℃ to ensure constant drawing speed casting; each nozzle of the secondary cooling water should ensure uniform spraying, and no interruption and water column spraying are allowed; the billet should be sent to the slow cooling pit in time for slow cooling, and the slow cooling time is greater than 48 hours. The billet temperature drops below 100℃ before it can be taken out of the pit; high-quality round billets with low P, low S and uniform composition are obtained by this method; Pipe making process: continuous casting → sawing → ring furnace heating → perforation → PQF three-roller limited mandrel continuous rolling → tube removal → diameter reduction → cooling → sawing → heat treatment → straightening; Among them: Before loading the tube into the furnace, the tube billet should be inspected. The surface quality of the tube billet should meet the requirements of Q / BG 524. Severe slag pits and scars should be repaired and ground. Check the quality of the sawn end face, and remove the tube billet with defects such as center cracks and center shrinkage holes that exceed the standard in time. The temperature of the insulation section of the annular furnace is 1260±20℃. During piercing, the piercing machine body and the front and back rolling center lines must be consistent. The head extension should be strictly controlled as required. The temperature of the round billet after piercing is 1200±20℃. The continuous rolling inlet temperature is 1110±20℃. During the rolling process, the outer surface quality of the rough tube and the mandrel should be checked, and high-pressure water descaling should be turned on. The pressure range of high-pressure descaling water is 9-12MPa. The temperature after fixed tension reduction is 940±20℃. Adjust the spray direction of the roller cooling water to ensure that it is not sprayed onto the inner surface of the tube body. High-precision high-quality tube bodies of different sizes are obtained by combining the three-roller limited mandrel continuous rolling unit PQF with high-end hot rolling control technology. Heat treatment process: normalizing + air cooling; the heating temperature of normalizing treatment is usually 30-50℃ above AC3, the normalizing temperature is 930℃±10℃, and the insulation time is 70±5 minutes; straightening is required after normalizing, and the straightening force should be strictly controlled during straightening to ensure the bending requirements of the steel pipe, and no concave, elliptical or cracking should occur.

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