Bainite steel rail with excellent tempering resistance and production method thereof

Abstract

The invention discloses a bainite steel rail with excellent tempering resistance and a production method thereof, and the bainite steel rail adopts a composite microalloy component design of 0.10-0.40% of carbon and more than or equal to 0.05% and less than or equal to 0.50% of V, Ti and Nb by mass percent. While the obdurability of the existing on-line heat treatment bainite steel rail is ensured, the tempering resistance of the bainite steel rail and a turnout is remarkably improved, the running safety of the steel rail is improved, and the steel rail for a heavy haul railway or a turnout railway is met.

Description

Technical Field

[0001] The invention relates to the technical field of rail production, and in particular to a bainite rail with excellent tempering resistance and a production method thereof. Background Art

[0002] Rails are key components of railways, and their performance is directly related to the transportation efficiency and driving safety of railways. As an emerging steel for railway tracks, bainitic steel is gradually used in railway rails due to its excellent performance and longer life. In order to improve the service performance of bainitic rails, including wear resistance and contact fatigue resistance, that is, to improve the strength and hardness of bainitic rails and turnout rails. Usually, alloying + heat treatment is used to form bainite + martensite + residual austenite, and the strength and toughness indicators of high-strength and high-toughness bainitic rails and turnouts are adjusted.

[0003] Tempering is a key step in metal heat treatment, which affects the decomposition and final structure of martensite. After quenching, martensite may transform into different tempered structures, such as tempered martensite, tempered troostite and tempered troostite. The hardness of these structures is usually lower than that of martensite, so the hardness and strength of the material will decrease after tempering.

[0004] Tempering stability is a measure of the stability of this hardness change, that is, the difference between the hardness after tempering and the hardness after tempering again at the same temperature. The higher the stability, the smaller the drop in hardness after multiple tempering. Alloying elements play an important role in steel. They can slow down the decomposition of martensite, inhibit the growth of carbides, form hard carbides, and hinder the recovery and recrystallization of phases, thereby enhancing the tempering stability of quenched steel and making it less likely to reduce hardness with increasing temperature.

[0005] Tempering stability also involves the material's resistance to the rate of strength and hardness loss when the tempering temperature rises, which is usually measured by the tempering temperature-hardness curve of steel. The curve shows that materials with slow hardness loss have higher tempering stability and stronger resistance to tempering softening. This stability is closely related to the change of structure during tempering, and together with the thermal stability of steel at high temperatures, it determines its organizational stability in high temperature environments and the mold's ability to resist high-temperature deformation.

[0006] Tempering stability refers to the ability of a material to maintain stable composition, structure and performance during the tempering process. Tempering is a method of changing the structure, shape and performance of a metal material through a heat treatment process under certain temperature, time and environmental conditions. Tempering stability is of great significance to metal materials, and it is one of the important considerations for materials to obtain more stable performance through tempering.

[0007] Tempering stability is mainly affected by the thermodynamic and mechanical properties of the material, and its changes are affected by temperature, time and environment. The stability of the material decreases with the increase of temperature. If the temperature is too high, the organizational structure of the material will change, affecting the performance of the material. The heating time will also affect the tempering stability of the material. If the heating time is too long, the organization will be destroyed, causing deformation of the material, which will also affect the performance. In addition, the tempering stability is also affected by the heating environment, such as carbon oxides, etc., which will affect the stability of the material.

[0008] Therefore, how to improve the anti-tempering performance of the rail while ensuring its high strength and toughness has become a technical problem that needs to be solved urgently by those skilled in the art.

[0009] Based on this, the existing technology still needs to be improved. Summary of the invention

[0010] In order to solve the above technical problems, the embodiments of the present invention provide a bainite rail with excellent tempering resistance and a production method thereof, so as to solve the technical problem that the bainite rail in the prior art has poor tempering resistance.

[0011] To solve the above technical problems, on the one hand, some embodiments of the present invention disclose a method for producing a bainitic rail with excellent tempering resistance, which is designed with a carbon content of 0.10-0.40% and a composite micro-alloy composition of 0.05%≤V+Ti+Nb≤0.50% in terms of mass percentage.

[0012] In some embodiments, 40-80 ppm of N is introduced during the smelting process.

[0013] In some embodiments, after smelting and casting, the steel billet is heated and kept warm at 1200-1280° C., and rolled after dephosphorization.

[0014] In some embodiments, after rolling, the steel is cooled to room temperature at a cooling rate of 3-8° C. / min.

[0015] In some embodiments, the rolling is performed by universal rolling, and the rolling reduction ratio is not less than 11:1.

[0016] In some embodiments, the starting rolling temperature is between 1100-1150°C, and the final rolling temperature is between 850-950°C.

[0017] In some embodiments, after smelting and casting, tempering is performed at a temperature of 200-400° C. for 5-12 hours.

[0018] In some embodiments, the invention includes: 40-80ppm of N is introduced during the smelting process; After smelting and casting, the steel billet is heated and kept at 1200-1280℃. After dephosphorization, the steel billet is subjected to universal rolling with a compression ratio of ≥11:1, a starting rolling temperature of 1100-1150℃, and a final rolling temperature of 850-950℃. After rolling, the steel billet is cooled to room temperature at a cooling rate of 3-8℃ / min. Finally, the tempering temperature is 200-400℃ and the tempering time is 5-12h.

[0019] On the other hand, an embodiment of the present invention further discloses a bainite steel rail with excellent tempering resistance, which is produced by the aforementioned method for producing a bainite steel rail with excellent tempering resistance.

[0020] In some embodiments, the tensile strength is not less than 1280 MPa, the elongation is not less than 12%, and the surface hardness is not less than 400 HB.

[0021] By adopting the above technical solution, the present invention has at least the following beneficial effects: The present invention provides a bainite rail with excellent tempering resistance and a production method thereof, which significantly improves the tempering resistance of the bainite rail and the turnout while ensuring the strength and toughness of the existing online heat-treated bainite rail, improves the rail operation safety, and meets the requirements of heavy-load railway rails or turnout railway rails. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a diagram showing changes in tempering temperature and Rockwell hardness at different (V+Ti+Nb) contents in a method for producing a bainitic rail with excellent tempering resistance disclosed in some embodiments of the present invention. DETAILED DESCRIPTION

[0024] The following is a further detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0025] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0026] It should be noted that, in the description of the present disclosure, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0027] In addition, the words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0028] It should also be noted that in the description of the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0029] All terms used in the present disclosure have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0030] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0031] Some embodiments of the present invention disclose a bainite rail with excellent tempering resistance and a production method thereof, which is designed with a carbon content of 0.10-0.40% and a composite microalloy composition of 0.05%≤V+Ti+Nb≤0.50% in terms of mass percentage. It adopts the introduction of 40-80ppm of N during the smelting process, and the introduction of N (nitrogen) can be achieved by not using a special N removal process during the smelting process and retaining the N content in the original components; after smelting and casting, heating and heat preservation at 1200-1280℃ are adopted, and after the steel billet is dephosphorized, the universal rolling compression ratio is ≥11:1, the starting rolling temperature is between 1100-1150℃, and the final rolling temperature is between 850-950℃; after rolling, it is cooled to room temperature at a cooling rate of 3-8℃ / min; finally, it is tempered at 200-400℃, and the tempering time is 5-12h. The produced bainite rail with excellent tempering resistance has a tensile strength of not less than 1280MPa, an elongation of not less than 12%, a surface hardness of not less than 400HB, and has excellent tempering resistance, and is particularly suitable for heavy-load railway rails or switch railway rails.

[0032] The above production method, while ensuring the toughness of the existing online heat-treated bainitic rails, significantly improves the tempering resistance of the bainitic rails and turnouts, improves the running safety of the rails, and meets the requirements of heavy-load railway rails or turnout railway rails.

[0033] The researchers found in the study that the retained austenite in steel can effectively improve the plasticity and toughness of the material. Silicon can significantly inhibit the precipitation of carbides during the bainite transformation, increase the carbon concentration in the untransformed austenite, and reduce the Ms point, which is conducive to the increase of the volume fraction of retained austenite at room temperature. A higher silicon mass fraction can obtain more retained austenite and help improve its stability, which is conducive to the occurrence of the TRIP effect. In addition, part of the carbon-rich austenite between or within the bainitic ferrite laths is retained in a film-like form, and the retained austenite with good toughness replaces the brittle cementite, and the toughness of the steel is significantly improved. Studies have shown that retained austenite exists in the structure of steel as a metastable phase. When the local stress exceeds a certain critical value, the metastable retained austenite undergoes a phase transformation induced plasticity (TRIP) effect, which can effectively absorb load energy and reduce stress concentration, thereby delaying the occurrence of necking during tensile deformation and greatly improving the plasticity of steel. It is generally believed that the blocky retained austenite in steel is less stable than the filmy retained austenite. The volume fraction, morphology and size of the retained austenite in bainitic steel can be regulated by the bainite phase transformation heat treatment process, so as to give full play to the influence of the microstructure on the mechanical properties of the steel. In addition, according to the needs, the tempering process can be used to obtain samples with different strength, plasticity, toughness and hardness. Tempering heat treatment has become an important means to improve the comprehensive mechanical properties of bainitic steel.

[0034] Because high-strength and high-toughness bainitic rails and turnouts contain martensite and residual austenite, tempering must be used to eliminate the residual stress generated during quenching of the workpiece, prevent deformation and cracking; adjust the hardness, strength, plasticity and toughness of the workpiece to meet the performance requirements; stabilize the organization and size to ensure accuracy; and improve and enhance processing performance. Therefore, tempering is the last important process for high-strength and high-toughness bainitic rails and turnouts to obtain the required performance, but many alloy steels will experience low-temperature and high-temperature temper brittleness.

[0035] Low temperature temper brittleness is the embrittlement phenomenon that occurs during tempering at 250-400℃. The embrittlement that has occurred cannot be eliminated by reheating, so it is also called irreversible temper brittleness. It is generally believed that when quenched steel is tempered in the range of 250-400℃, cementite precipitates at the original austenite grain boundary or on the martensite interface to form a thin shell, which is the main cause of low temperature temper brittleness.

[0036] High temperature temper brittleness is the brittleness that occurs when tempering between 500 and 550°C, or when tempering at a temperature above 600°C and then cooling slowly through the 500-550°C range. If it is reheated to a temperature above 600°C and then cooled rapidly, toughness can be restored, so it is also called reversible temper brittleness.

[0037] In order to improve the structure and performance of high-strength and high-toughness bainitic rails and turnouts, and at the same time improve their tempering resistance, the present invention adopts (V, Ti, Nb) (C, N) composite microalloying to improve their tempering resistance. By adding (V, Ti, Nb) (C, N) to bainitic rails and turnouts, their tempering resistance stability is improved, thereby ensuring the performance of the steel in use. At the same time, through the precipitation of (V, Ti, Nb) (C, N) composite microalloying, the structure and grain size are refined, and the strength and toughness are improved.

[0038] Tempering stability refers to the speed at which the strength and hardness of a material decrease as the tempering temperature increases. It is also called tempering resistance or resistance to tempering softening. It is usually represented by the tempering temperature-hardness curve of steel. A slow decrease in hardness indicates high tempering stability or high tempering resistance. Tempering stability is also related to the change in structure during tempering. Together with the thermal stability of steel, it characterizes the degree of structural stability of steel at high temperatures and the deformation resistance of the mold at high temperatures. The influence of alloying elements on the tempering transformation of quenched steel improves the tempering stability of steel: This is mainly manifested in that alloying elements delay the decomposition of martensite and the transformation of residual austenite during tempering, increase the recrystallization temperature of ferrite, make it difficult for carbides to aggregate and grow and maintain a large dispersion, thereby improving the resistance of steel to tempering softening, that is, improving the tempering stability of steel.

[0039] In alloy steel, due to the effect of alloying elements, the decomposition temperature of martensite will be pushed to high temperature, that is, tempering at a higher temperature can still maintain a certain degree of supersaturation and fine carbides in the α phase, so that the steel maintains higher strength and hardness.

[0040] Tempering stability is a measure of the stability of this hardness change, that is, the difference between the hardness after tempering and the hardness after tempering again at the same temperature. The higher the stability, the smaller the drop in hardness after multiple tempering. Alloying elements play an important role in steel. They can slow down the decomposition of martensite, inhibit the growth of carbides, form hard carbides, and hinder the recovery and recrystallization of phases, thereby enhancing the tempering stability of quenched steel and making it less likely to reduce hardness with increasing temperature.

[0041] Tempering stability also involves the material's resistance to the rate of strength and hardness loss when the tempering temperature rises, which is usually measured by the tempering temperature-hardness curve of steel. The curve shows that materials with slow hardness loss have higher tempering stability and stronger resistance to tempering softening. This stability is closely related to the change of structure during tempering, and together with the thermal stability of steel at high temperatures, it determines its organizational stability in high temperature environments and the mold's ability to resist high-temperature deformation.

[0042] In order to improve the tempering stability of the material, the surface of the material should be treated with high purity to ensure the extreme tempering process. In addition, the heat treatment temperature of the material should be determined according to the yield strength, hardness and other physical properties of the material, and should be as low as possible below the phase change temperature of the material, and a lower temperature, so that the material structure can be stable. During the tempering process, the heating time should be controlled to be short to prevent the material from changing after a long period of heating and affecting the performance. In addition, in the tempering environment, oxygen should be avoided as much as possible to prevent oxidation.

[0043] In addition, from a technological point of view, improving the tempering stability of materials also requires a reasonable process flow. During the tempering process of materials, control should be strengthened during the heating and cooling process, and strict inspections should be carried out to maintain the performance of the materials and ensure the stability of tempering.

[0044] In short, tempering stability is an important consideration for materials to obtain performance and stable performance during the tempering process. Tempering stability is affected by temperature, time and environmental conditions, and can be ensured by high-purity treatment, selection of reasonable temperature, time and environmental conditions, and reasonable process flow.

[0045] Composite microalloying is an important development direction of microalloying technology. From a thermodynamic point of view, microalloyed nitrides are more stable than carbides. Through strict control of chemical composition and production process, the beneficial effects of different microalloying elements can be fully utilized.

[0046] The main functions of vanadium in steel are: (1) Refine the structure and grain of steel, increase the grain coarsening temperature, thereby reducing overheating sensitivity and improving the strength and toughness of steel.

[0047] (2) When dissolved into austenite at high temperature, it increases the hardenability of steel; on the contrary, when it exists as carbide, it reduces the hardenability of steel.

[0048] (3) Increase the hardenability and tempering stability of quenched steel, refine the grains, and produce a secondary hardening effect.

[0049] (4) The solid solubility product of vanadium carbide and vanadium nitride in austenite is relatively high. Therefore, cracks caused by precipitation are not easily generated at high temperatures, and the tendency of cracks to appear in the steel billet during solidification is relatively small.

[0050] (5) The precipitation temperature of vanadium carbonitride is low, and it is dissolved in austenite, so the drag force of grain boundary migration is low. This will be beneficial to the recrystallization of austenite, making it easy to implement recrystallization controlled rolling, and uniform organization along the cross section of the steel. Uniform recrystallized grains can be obtained in a wide temperature range, and the final rolling temperature has little effect on the mechanical properties. Compared with other microalloyed steels and alloy steels, the rolling resistance of vanadium-containing steel is small, which is equivalent to that of carbon manganese steel.

[0051] (6) It precipitates in ferrite or martensite, producing precipitation strengthening. Generally, the precipitation strengthening increment in ferrite is 50MPa to 100MPa. By increasing the nitrogen content in steel, the precipitation of vanadium can be promoted to obtain a greater precipitation strengthening effect. This is a good technology in the production of high-strength hot-rolled ribbed steel bars, which can save the use of vanadium and increase the amount of precipitation strengthening.

[0052] (7) Vanadium and nitrogen have a strong binding force and can form vanadium nitride, which is beneficial to reduce the strain aging of steel. This property is very important for steel bars that have undergone cold deformation during service.

[0053] (8) Adding vanadium to martensitic steel can increase the steel's resistance to tempering softening, allowing the steel to maintain the martensitic lath morphology during tempering, or precipitate vanadium carbide during tempering to produce a secondary hardening effect.

[0054] That is to say, adding vanadium to steel can deoxidize and denitrify on the one hand, and improve the performance of steel on the other hand, ultimately achieving the goal of reducing production costs or reducing the amount of steel used. At present, most of vanadium is used as an additive to steel to produce high-strength low-alloy steel, high-speed steel, tool steel, stainless steel, spring steel, bearing steel, etc. Vanadium steel has the characteristics of high strength, toughness, good wear resistance and corrosion resistance. It is widely used in machinery manufacturing, automobiles, aviation, railway transportation vehicles, bridges and other industries.

[0055] The earliest purpose of adding Nb to steel was to accelerate the bainite phase transformation. Nb is insoluble in cementite. It can reduce the activity coefficient of carbon in ferrite, increase the solid solubility of carbon in ferrite, and inhibit the precipitation of carbides. Nb can increase the starting temperature of cementite. Through its influence on the magnetic and non-magnetic parts of the phase transformation driving force, the driving force of the phase transformation is increased, thereby accelerating the bainite phase transformation. At the same time, Nb can greatly increase the Ms temperature. Adding Nb to carbide-free bainitic steel can move the curve to the high temperature zone on the right. After adding Nb, the curve moves to the right. Bainitic steel with Nb added has a greater degree of undercooling, that is, by adding Nb, the driving force for bainite nucleation can be increased, and then the nucleation density of bainite is increased, which plays a role in refining bainite laths. Therefore, the appropriate addition of Nb can greatly reduce the hydrogen embrittlement sensitivity of bainitic steel.

[0056] The three elements V, Ti and Nb have different characteristics in terms of precipitation, microstructure and performance, and service. Figure 1 The figure shows the change of tempering temperature and Rockwell hardness under different (V+Ti+Nb) contents. Based on this, the present invention adopts composite microalloying of V, Ti and Nb to maximize the strength and toughness of bainite rails and improve the tempering resistance.

[0057] The following specific embodiments and comparative examples are listed to explain the technical effects of the present invention in detail. In Examples 1 to 5, a (V, Ti, Nb) (C, N) composite microalloyed bainitic rail with excellent tempering resistance and a production method thereof are disclosed. A composite microalloy composition design of 0.10-0.40% carbon content and 0.05%≤V+Ti+Nb≤0.50% is adopted, 40-80ppm N is introduced during the smelting process, and after smelting and casting, 1200-1280℃ is used for heating and insulation. After dephosphorization of the steel billet, the universal rolling compression ratio is ≥11:1, the starting rolling temperature is between 1100-1150℃, and the final rolling temperature is between 850-950℃; after rolling, it is cooled to room temperature at a cooling rate of 3-8℃ / min. Finally, it is tempered at 200-400℃, and the tempering time is 5-12h. The bainitic rail produced by the method has a tensile strength of ≥1280MPa, an elongation of ≥12%, a surface hardness of ≥400HB, and excellent tempering resistance, and is particularly suitable for heavy-duty railway rails or turnout railway rails. The specific composition design and process control parameters are shown in Table 1 and Table 2, respectively. At the same time, the present invention also lists comparative examples 1 and 2 to compare and demonstrate the technical effects of the present invention. The specific composition design and process control parameters are shown in Table 1 and Table 2, respectively. Each embodiment and comparative example is subjected to tensile and surface hardness tests in accordance with the requirements of TB / T2344 "Technical Conditions for Ordering 43kg / m~75kg / m Rails", and the tensile and hardness data statistics are shown in Table 3.

[0058] Table 1

[0059] Table 2

[0060] Table 3

[0061] In summary, the bainitic rail with excellent tempering resistance and the production method thereof disclosed in the embodiments of the present invention can significantly improve the tempering resistance of the bainitic rail and the turnout while ensuring the strength and toughness of the existing online heat-treated bainitic rail, thereby improving the operating safety of the rail and meeting the requirements for heavy-duty railway rails or turnout railway rails.

[0062] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0063] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A method for producing a bainite rail with excellent tempering resistance, characterized in that: Calculated by mass percentage, the carbon content is 0.10-0.40% and the composite micro-alloy composition is designed to be 0.05%≤V+Ti+Nb≤0.50%.

2. The method for producing a bainite rail having excellent tempering resistance according to claim 1, characterized in that: 40-80 ppm of N is introduced during the smelting process.

3. The method for producing a bainite rail having excellent tempering resistance according to claim 1, characterized in that: After smelting and casting, the steel is heated and kept warm at 1200-1280℃. After dephosphorization, the steel billet is rolled.

4. The method for producing a bainite rail having excellent tempering resistance according to claim 1, characterized in that: After rolling, the steel was cooled to room temperature at a cooling rate of 3-8°C / min.

5. The method for producing a bainite rail having excellent tempering resistance according to claim 3, characterized in that: The rolling adopts universal rolling, and the rolling compression ratio is not less than 11:

1.

6. The method for producing a bainite rail having excellent tempering resistance according to claim 3, characterized in that: The starting rolling temperature is between 1100-1150°C, and the final rolling temperature is between 850-950°C.

7. The method for producing a bainite rail having excellent tempering resistance according to claim 1, characterized in that: After smelting and casting, it is tempered at 200-400℃ for 5-12h.

8. The method for producing a bainite rail having excellent tempering resistance according to claim 1, characterized in that: include: 40-80ppm of N is introduced during the smelting process; After smelting and casting, the steel billet is heated and kept at 1200-1280℃. After dephosphorization, the steel billet is subjected to universal rolling with a compression ratio of ≥11:1, a starting rolling temperature of 1100-1150℃, and a final rolling temperature of 850-950℃. After rolling, the steel billet is cooled to room temperature at a cooling rate of 3-8℃ / min. Finally, the tempering temperature is 200-400℃ and the tempering time is 5-12h.

9. A bainite rail with excellent tempering resistance, characterized in that: The bainite rail having excellent tempering resistance is produced by the production method of any one of claims 1 to 7.

10. The bainite rail having excellent tempering resistance according to claim 9, characterized in that: The tensile strength is not less than 1280MPa, the elongation is not less than 12%, and the surface hardness is not less than 400HB.

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