Turnout steel rail with uniformly distributed hardness of central section of rail web and production method of turnout steel rail

Abstract

The invention relates to the technical field of steel rail production, and particularly discloses a turnout steel rail with uniformly distributed hardness of a rail waist central section and a production method of the turnout steel rail. The production method comprises the steps that on-line heat treatment is conducted on the rolled steel rail, and the on-line heat treatment comprises the accelerated cooling stage, specifically, when the temperature of the rail top face of the rolled steel rail ranges from 700 DEG C to 800 DEG C, the long leg side rail web and the short leg side rail web of the rolled steel rail are accelerated to be cooled to 490 DEG C to 570 DEG C, the accelerated cooling speed of the short leg side rail waist is higher than that of the long leg side rail waist; and an air cooling stage, wherein the steel rail cooled in the accelerated cooling stage is air-cooled to the room temperature. The production method can be used for producing the turnout steel rail with the hardness of the central section of the rail web uniformly distributed, and the stability of the turnout steel rail in the service process is improved.

Description

Technical Field

[0001] This invention relates to the field of rail production technology, specifically to a turnout rail with uniform hardness distribution at the center cross-section of the rail web and its production method. Background Technology

[0002] Globally, with the rapid economic development of various countries, railway construction has entered a new peak period. Train speeds and load capacities, as well as the volume and frequency of train services, have all increased significantly. This has made the operating conditions of railway tracks more demanding and has also placed higher requirements on the quality of steel rails, a crucial component of railway tracks.

[0003] As a core material of railway turnouts, a crucial component of railway tracks, the quality of turnout rails directly affects the safety and stability of train operation. Furthermore, turnout rails typically require assembly by specialized manufacturers before they can be used on railways. Therefore, the performance of turnout rails has always been a key focus in the railway industry, and the performance requirements for turnout rails are gradually increasing. For turnout rails used in the fabrication of turnout switch rails, the problem of insufficient hardness at the center section of the rail web, leading to a shortened switch rail life, has also become a major concern for turnout manufacturing companies.

[0004] In recent years, domestic and international rail manufacturers have primarily employed online heat treatment to improve the performance of turnout rails. This process refines the pearlite lamellar spacing and optimizes the pearlite pellet distribution, thereby increasing the rail's strength and hardness, and ultimately enhancing its safety, stability, and service life. Specific patented technologies involving online heat treatment to optimize the microstructure and properties of turnout rails are as follows: Patent CN 20121059.0752.9 – "A Heat Treatment Method for Turnout Rails and Turnout Rails" discloses a heat treatment method for turnout rails. This method includes accelerating the cooling of turnout rails with a rail head tread temperature of 650-900℃ to obtain a turnout rail with a full pearlitic microstructure. The accelerated cooling rate of the working side of the rail head is higher than that of the non-working side. The method also includes producing turnout rails with a working side that has a hardness 1-3 HRC higher and a tensile strength 20-50 MPa higher than the non-working side. However, this invention employs a technique to avoid the risk of abnormal microstructure in the rail when the cooling rates on both sides of the rail head are the same. This results in turnout rails with inconsistent hardness and strength on both sides of the rail head, which is insufficient to meet the current requirements for high strength and hardness across the entire rail section in turnout manufacturing, thus hindering its large-scale application in actual turnout rail production.

[0005] Patent CN 201811378013.7, "Online Heat Treatment Method and Constraint Device for Turnout Rail Web," discloses an online heat treatment method and constraint device for turnout rail web. The method involves controlling the rail temperature at 700-800℃ and the carbon content (by mass percentage) between 0.7% and 0.90%. The rail is then fed into a constraint device, which applies an accelerating cooling medium to the center of the rail head tread, both sides of the rail head, and the center of the rail base at a cooling rate of 1-5℃ / s. Finally, when the rail temperature drops to 450-500℃, the rail is removed from the constraint device. This invention can reduce residual stress in the turnout rail web and improve the overall performance of the rail web. However, this patent does not specify the detailed heat treatment process for the rail, making it impossible to guarantee the hardness of the center section of the rail web of the resulting turnout rail. Furthermore, the additional heat treatment leads to increased product costs and reduced production efficiency.

[0006] Patent CN 202411097828.3 – “A Hypoeutectoid Turnout Rail for High-Altitude Cold Regions and its Heat Treatment Production Method” discloses a method for producing hypoeutectoid turnout rails for high-altitude cold regions. This patent uses steel billets with a C content of 0.5-0.7%, 0.25%≤Cr+V≤0.50%, Cu≥2.5% or Ni≤3.5% to heat-roll the turnout rails. An online heat treatment device is used, employing a multi-stage heat treatment and step-by-step cooling process to cool the rails to 450-550℃ before cooling them to room temperature. After straightening and processing, the resulting turnout rails are manufactured for high-altitude cold regions. The tensile strength of these turnout rails is 1105-1212 MPa, the elongation is 12-18%, and the surface hardness is 320-360 HB. However, the online heat treatment production method described in the patent uses four different processes in the accelerated cooling stage, which has high requirements for equipment, personnel and operation level, making production organization difficult. Moreover, the produced hypoeutectoid turnout rails have low strength and hardness, making it difficult to promote and apply them on a large scale in domestic and foreign markets.

[0007] Patent CN 202411170382.2 – "An Online Heat Treatment Device and Method for Turnout Rails" discloses an online heat treatment device and method for turnout rails. This patent designs an online heat treatment device for turnout rails that can eliminate the heat-blind zone at the turnout rail end, especially the working side, by adjusting the distribution and orientation of the nozzles on the working side. This enhances the online heat treatment cooling intensity on the working side of the turnout while ensuring improved turnout rail strength, thereby improving the surface hardness and strength of turnout rails used for small-radius curves. However, the device described in this patent has a complex operating mechanism, requiring the adjustment of multiple parameters to obtain the turnout rails, making large-scale application difficult.

[0008] In summary, most of the currently published patents related to improving the performance of turnout rails through online heat treatment only differentiate the performance of the working and non-working sides of the turnout rails. No technology addresses the stable improvement of the hardness of the rail web section, making it difficult to ensure stable service life of the turnout rails during manufacturing and online operation. Furthermore, existing production technologies and equipment are relatively complex, requiring high levels of skill and experience from operators, hindering large-scale application. Significant shortcomings remain in the exploration of production methods for turnout rails that achieve uniform hardness distribution at the center of the rail web section. Summary of the Invention

[0009] To overcome the aforementioned defects of existing rails, this invention provides a turnout rail with uniform hardness distribution at the center cross-section of the rail web and its manufacturing method.

[0010] To achieve the above objectives, the present invention adopts the following technical solution.

[0011] According to a first aspect of the present invention, a method for producing a turnout rail with uniform hardness distribution at the center cross-section of the rail web is provided, comprising: performing online heat treatment on the rolled rail, wherein the online heat treatment includes: Accelerated cooling stage: When the temperature of the top surface of the rolled rail is between 700 and 800°C, the long leg side rail web and the short leg side rail web of the rolled rail are accelerated to 490 to 570°C. Among them, the accelerated cooling rate of the short leg side rail web is higher than that of the long leg side rail web. Air cooling stage: The rails that have undergone accelerated cooling stage are air cooled to room temperature.

[0012] As a further implementation, the difference between the accelerated cooling rate of the short-leg side rail and the accelerated cooling rate of the long-leg side rail is 0.1~0.5℃ / s.

[0013] As a further implementation, the accelerated cooling rate of the long-leg side rail is 1.0~2.0℃ / s, and the accelerated cooling rate of the short-leg side rail is 1.0~2.5℃ / s.

[0014] As a further implementation method, during the accelerated cooling stage, when the temperature of the top surface of the rolled rail is between 700 and 800°C, the top surface of the rolled rail and both sides of the rail head are accelerated to 490 to 570°C, wherein the accelerated cooling rate of the top surface is 1.5 to 2.0°C / s, and the accelerated cooling rate of both sides of the rail head is 2.0 to 2.5°C / s.

[0015] As a further implementation, the cooling medium used in the accelerated cooling stage is compressed air and / or water mist.

[0016] As a further implementation method, the air cooling stage is carried out by placing the rails on a cooling bed.

[0017] As a further embodiment, before performing online heat treatment, the production method further includes: sequentially performing converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, and rolling; after performing online heat treatment, the production method further includes: straightening and processing.

[0018] As a further embodiment, the chemical composition of the turnout rail, by weight percentage, is: C: 0.70~0.90%, Si: 0.15~0.80%, Mn: 0.75~1.20%, Cr: 0.01~0.20%, V: 0.001~0.030%, P: 0.005~0.015%, S: 0.005~0.015%, with the balance being Fe and unavoidable impurities.

[0019] According to a second aspect of the present invention, a turnout rail with uniform hardness distribution at the center cross-section of the rail web is provided, which is obtained by the above-described production method.

[0020] As a further implementation method, the hardness of the web center section of the turnout rail is in the range of 29~33HRC, and the difference between the maximum and minimum hardness values ​​is ≤1.0HRC. The tensile strength of the turnout rail is ≥1200MPa, the elongation after fracture is ≥10%, the surface hardness is ≥340HB, and the microstructure of the entire rail section is pearlite.

[0021] By adopting the above technical solution, the present invention can achieve the following technical effects: This invention optimizes the online heat treatment process, enabling turnout rails with uniform hardness distribution at the center of the rail web without restricting other rail production processes. During turnout manufacturing and track service, the uniformly distributed hardness at the center of the rail web improves the strength and consistency of the turnout switch rails, extending the overall service life of the turnout and enhancing its safety and stability.

[0022] Furthermore, the production method of turnout rails with uniform hardness distribution at the center section of the rail web provided by this invention is simple, easy to operate, and conducive to large-scale promotion and application. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram showing the location of the cooling medium spraying during the accelerated cooling stage of the turnout rails. Figure 2 This is a schematic diagram showing the location for testing the hardness of the central section of the web of a turnout rail. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] This invention proposes a method for producing turnout rails with uniform hardness distribution at the center cross-section of the rail web, comprising: performing online heat treatment on the rolled rail, wherein the online heat treatment includes: an accelerated cooling stage: when the temperature of the top surface of the rolled rail is between 700 and 800°C, the long leg side rail web and the short leg side rail web of the rolled rail are accelerated to 490 to 570°C, wherein the accelerated cooling rate of the short leg side rail web is higher than that of the long leg side rail web; and an air cooling stage: the rail cooled in the accelerated cooling stage is air cooled to room temperature.

[0028] The inventors of this invention discovered through extensive research that: ① Only when the starting temperature of accelerated cooling of the rail (i.e., the center surface temperature of the rail top after rolling) is between 700 and 800℃, and the accelerated cooling rate of the short leg side rail web is higher than that of the long leg side rail web, can it be ensured that the rail web of the asymmetrical turnout rail is fully and uniformly cooled during the heat treatment process, so that the cross-sectional hardness of the entire rail web can be increased and evenly distributed, and the hardness difference of the entire rail web center cross-section can be controlled to be ≤1.0HRC. At the same time, the other mechanical properties and microstructure of the rail meet the requirements. ② When the rail cools to 490~570℃, the pearlite transformation inside the rail head is completed. Continuing to accelerate cooling will not improve the rail performance. On the contrary, it will greatly increase the possibility of abnormal structures such as martensite appearing on the rail surface. Therefore, at this temperature, accelerated cooling should be stopped. ③ After the rail stops accelerating cooling, in order to control the deformation and residual stress of the rail, air cooling is used to continue cooling the rail to room temperature without any other heat preservation measures.

[0029] The accelerated cooling start temperature can typically, but not limited to, be set to 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, or 800°C; the accelerated cooling stop temperature can typically, but not limited to, be set to 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, or 570°C.

[0030] The production method described in this invention is applicable to asymmetric cross-section turnout rails. Asymmetric cross-section turnout rails have a short leg side and a long leg side, with the rail head correspondingly having a short leg side and a long leg side, and the rail web correspondingly having a short leg side rail web and a long leg side rail web. This invention optimizes the online heat treatment process, controlling the accelerated cooling rate of the short leg side rail web to be higher than that of the long leg side rail web. This ensures that the actual internal temperature of the two sides of the rail web, which have different metal mass distributions, remains at the same level during heat treatment, precisely compensating for the difference in thermal inertia between the two sides, thereby achieving a uniform hardness distribution in the center section of the rail web.

[0031] In some embodiments, the difference between the accelerated cooling rate of the short-leg side rail and the accelerated cooling rate of the long-leg side rail is 0.1~0.5℃ / s. The difference between the accelerated cooling rates of the short-leg side rail and the long-leg side rail can typically, but not limitedly, be set to 0.1℃ / s, 0.2℃ / s, 0.3℃ / s, 0.4℃ / s, or 0.5℃ / s.

[0032] In some embodiments, the accelerated cooling rate of the long-leg side rail is 1.0~2.0℃ / s, and the accelerated cooling rate of the short-leg side rail is 1.0~2.5℃ / s. The accelerated cooling rate of the long-leg side rail web can typically, but not limited to, be set to 1.0℃ / s, 1.1℃ / s, 1.2℃ / s, 1.3℃ / s, 1.4℃ / s, 1.5℃ / s, 1.6℃ / s, 1.7℃ / s, 1.8℃ / s, 1.9℃ / s, or 2.0℃; the accelerated cooling rate of the short-leg side rail web can typically, but not limited to, be set to 1.0℃ / s, 1.1℃ / s, 1.2℃ / s, 1.3℃ / s, 1.4℃ / s, 1.5℃ / s, 1.6℃ / s, 1.7℃ / s, 1.8℃ / s, 1.9℃ / s, 2.0℃, 2.1℃ / s, 2.2℃ / s, 2.3℃ / s, 2.4℃ / s, or 2.5℃ / s.

[0033] In some embodiments, during the accelerated cooling stage, when the temperature of the top surface of the rolled rail is between 700 and 800°C, the top surface and both sides of the rail head of the rolled rail are accelerated to 490 to 570°C. The accelerated cooling rate of the top surface is 1.5 to 2.0°C / s, and the accelerated cooling rate of both sides of the rail head is 2.0 to 2.5°C / s. The accelerated cooling rate of the top surface can typically, but is not limited to, be set to 1.5°C / s, 1.6°C / s, 1.7°C / s, 1.8°C / s, 1.9°C / s, or 2.0°C / s; the accelerated cooling rate of both sides of the rail head can typically, but is not limited to, be set to 2.0°C / s, 2.1°C / s, 2.2°C / s, 2.3°C / s, 2.4°C / s, or 2.5°C / s.

[0034] In this invention, accelerated cooling is achieved by spraying a cooling medium onto the corresponding parts. Specifically, as shown in the example... Figure 1 As shown, accelerated cooling of these parts is achieved by spraying cooling medium onto the top surface of the rail, both sides of the rail head (i.e., the short leg side and the long leg side of the rail head), the long leg side rail web, and the short leg side rail web.

[0035] In some embodiments, the cooling medium used in the accelerated cooling phase is compressed air and / or water mist.

[0036] In some embodiments, the air-cooling stage is performed by placing the rails on a cooling bed.

[0037] In some embodiments, prior to online heat treatment, the production method further includes: sequentially performing converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, and rolling. After online heat treatment, the production method further includes: straightening and machining. In some embodiments, the production method sequentially includes: converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, universal rolling, online heat treatment, straightening, and machining.

[0038] For example, the complete manufacturing process of turnout rails can be as follows: using low-sulfur vanadium-containing molten steel, smelting it in a converter or electric furnace, refining it with LF, vacuum treating it with RH, and continuously casting it with large billet protection to obtain steel billets. After the steel billets are heated in a heating furnace, they are descaled with high-pressure water before rolling, then rolled on a universal rolling mill, heat treated online, cooled by room temperature and air in a walking beam cooling bed, straightened by a combination of flat and vertical straightening, inspected for rail specifications, processed on the processing line, inspected for surface, and put into storage.

[0039] In some embodiments, the chemical composition of the turnout rail, by weight percentage, is: C: 0.70~0.90%, Si: 0.15~0.80%, Mn: 0.75~1.20%, Cr: 0.01~0.20%, V: 0.001~0.030%, P: 0.005~0.015%, S: 0.005~0.015%, with the balance being Fe and unavoidable impurities.

[0040] The following details the reasons for limiting the content of the main chemical elements in the rails of this invention.

[0041] Carbon (C) is a key element in the formation of pearlite. Through the formation of a lamellar structure of cementite (Fe3C) and ferrite, it directly determines the lamellar spacing and cementite thickness, thus affecting strength and hardness. When the C content is <0.70%, the proportion of pearlite in the rail is insufficient, resulting in low strength and hardness, affecting wear resistance. When the C content is >0.90%, the cementite lamellars thicken, the pearlite becomes brittle, the elongation after fracture decreases, increasing the risk of rail fracture and affecting the rail's fatigue performance and safety. Therefore, the C content in this invention is limited to 0.70~0.90%.

[0042] As a solid solution strengthening element, silicon (Si) can improve the strength of the ferrite matrix, reduce oxide inclusions in steel, and optimize the pearlite microstructure. When the Si content is <0.15%, its solid solution strengthening effect is insufficient; when the Si content is >0.80%, it increases carbon activity, promotes premature precipitation of vitamin C, affects the effect of subsequent heat treatment, and reduces weldability. Therefore, the Si content in this invention is limited to 0.15~0.80%.

[0043] Mn significantly improves the hardenability of steel by lowering the austenite transformation temperature and increasing undercooling, and can refine the pearlite lamellar spacing, thereby enhancing the mechanical properties of rails. When the Mn content is <0.75%, insufficient pearlite refinement and reduced hardenability result in insufficient improvement in the strength and hardness of the steel. When the Mn content is >1.20%, the risk of grain coarsening increases, which may reduce the toughness and plasticity of the rail, and bainite or martensite may form in the Mn segregation zone, affecting weldability. Therefore, the Mn content in this invention is limited to 0.75~1.20%.

[0044] As a carbide-forming element, Cr can form various carbides with carbon in steel, while also improving hardenability, strength, and wear resistance of the rail. When the Cr content is <0.01%, hardenability is insufficient, and the strengthening effect is not obvious; when the Cr content is >0.20%, a σ phase may form, causing a sharp decrease in impact toughness and affecting the safe use of the rail. Therefore, the Cr content in this invention is limited to 0.01~0.20%.

[0045] V (V) inhibits austenite grain growth and refines pearlite lamellar spacing by forming carbonitrides, significantly improving the strength and toughness of rails. When the V content is <0.001%, the grain refinement effect is insufficient, the pearlite lamellar spacing is large, and the strength and wear resistance of the rail decrease. When the V content is >0.030%, excessive carbonitride precipitation may reduce plasticity and toughness and affect the processing performance of the rail. Therefore, the V content in this invention is limited to 0.001~0.030%.

[0046] Phosphorus (P) is a harmful element that is difficult to completely remove from steel. It tends to segregate at grain boundaries, reducing the toughness of the rail. Therefore, the P content in this invention must be strictly controlled below 0.015% to ensure the impact toughness of the rail.

[0047] Sulfide (S) readily forms MnS inclusions in steel, affecting the fatigue performance and wear resistance of rails. Therefore, the S content in this invention needs to be controlled below 0.015% to reduce the size and quantity of sulfide inclusions.

[0048] This invention also proposes a turnout rail with uniformly distributed hardness at the center cross-section of the rail web, obtained using the aforementioned production method. The hardness of the rail web center cross-section is within the range of 29-33 HRC, and the difference between the maximum and minimum hardness values ​​is ≤1.0 HRC. The hardness test location at the center cross-section of the rail web is on the extended line of the rail head centerline, between the intersection of the extended lines of the straight sections of the lower jaws on both sides of the rail head and the intersection of the extended lines of the straight sections of the upper surface of the rail base. Figure 2 As shown in the dashed box, the cross-sectional hardness test can be performed at regular intervals (e.g., 10mm) from top to bottom within the dashed box area. For example, a total of 5 points are tested, labeled as position 1#, position 2#, position 3#, position 4#, and position 5# from top to bottom. The resulting turnout rail has a tensile strength ≥1200MPa, elongation after fracture ≥10%, surface hardness ≥340HB, and the microstructure of the entire rail cross-section is pearlite.

[0049] In summary, this invention, by optimizing the online heat treatment process and combining it with a redesigned content of key strengthening elements in the rail, can produce turnout rails with uniform hardness distribution at the center of the rail web, without restricting other rail production processes. The hardness of the center of the rail web is within the range of 29-33 HRC, and the range between the maximum and minimum hardness values ​​at each inspection point is ≤1.0 HRC. Therefore, the turnout rails with uniform hardness distribution at the center of the rail web provided by this invention can improve the strength and consistency of the turnout switch rails during turnout manufacturing and track service, thereby extending the overall service life of the turnout and improving its safety and stability. Furthermore, the production method of the turnout rails with uniform hardness distribution at the center of the rail web provided by this invention is simple and easy to operate, facilitating large-scale application.

[0050] The present invention will be described in detail below through embodiments, but the scope of the present invention is not limited thereto.

[0051] Examples 1-3 and Comparative Examples 1-3 use steel rails with chemical compositions of A, B, and C, respectively, as shown in Table 1.

[0052] Table 1

[0053] The balance is Fe and unavoidable impurities.

[0054] Examples 1-3 and Comparative Examples 1-3 used chemical components A, B, and C, respectively. The process comparisons are shown in Table 2. The differences between the remaining processes of the examples and comparative examples are negligible.

[0055] Table 2

[0056] The tensile properties, surface hardness, microstructure, and cross-sectional hardness of Examples 1-3 and Comparative Examples 1-3 are shown in Table 3. In this invention, the tensile strength and elongation after fracture of the rail were measured according to GB / T 228.1 "Metallic materials, tensile testing—Part 1: Test methods at room temperature"; the surface hardness of the rail was measured using the Brinell hardness test method as specified in GB / T 231.1 "Metallic materials, Brinell hardness testing—Part 1: Test methods"; the cross-sectional hardness of the rail web center section was measured using the Rockwell hardness test method as specified in GB / T 230.1 "Metallic materials, Rockwell hardness testing—Part 1: Test methods"; and the microstructure of the rail was determined according to TB / T 2344.2-2020 "Railways—Part 2: Asymmetric section rails for turnouts" and GB / T 13298-2015 "Metallic materials, microstructure testing methods".

[0057] Table 3

[0058] Comparing the embodiments and comparative examples, it can be seen that, under the same process conditions, the online heat treatment process of the rail significantly affects the hardness distribution of the rail web center section. Compared with the comparative example, the rail obtained by using the method described in this invention has a higher and more uniformly distributed hardness at the rail web center section, as well as a more stable microstructure and other mechanical properties.

[0059] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Those skilled in the art should understand that various modifications can be made to the present invention without departing from the spirit and scope thereof. All such modifications fall within the protection scope of the present invention.

Claims

1. A method for producing turnout rails with uniform hardness distribution at the center cross-section of the rail web, characterized in that, include: The rolled rails undergo online heat treatment, which includes: Accelerated cooling stage: When the temperature of the top surface of the rolled rail is between 700 and 800°C, the long leg side rail web and the short leg side rail web of the rolled rail are accelerated to 490 to 570°C. Among them, the accelerated cooling rate of the short leg side rail web is higher than that of the long leg side rail web. Air cooling stage: The rails that have undergone accelerated cooling stage are air cooled to room temperature.

2. The production method according to claim 1, characterized in that, The difference between the accelerated cooling rate of the short-leg side rail and the long-leg side rail is 0.1~0.5℃ / s.

3. The production method according to claim 1, characterized in that, The accelerated cooling rate of the long-leg side rail is 1.0~2.0℃ / s, and the accelerated cooling rate of the short-leg side rail is 1.0~2.5℃ / s.

4. The production method according to claim 1, characterized in that, During the accelerated cooling stage, when the temperature of the top surface of the rolled rail is between 700 and 800°C, the top surface and both sides of the rail head of the rolled rail are accelerated to 490 to 570°C. The accelerated cooling rate of the top surface is 1.5 to 2.0°C / s, and the accelerated cooling rate of both sides of the rail head is 2.0 to 2.5°C / s.

5. The production method according to claim 1, characterized in that, The cooling medium used in the accelerated cooling stage is compressed air and / or water mist.

6. The production method according to claim 1, characterized in that, The air-cooling stage is carried out by placing the rails on a cooling bed.

7. The production method according to claim 1, characterized in that, Before online heat treatment, the production method further includes: sequentially performing converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, and rolling; after online heat treatment, the production method further includes: straightening and processing.

8. The production method according to claim 1, characterized in that, The chemical composition of the turnout rail, by weight percentage, is as follows: C: 0.70~0.90%, Si: 0.15~0.80%, Mn: 0.75~1.20%, Cr: 0.01~0.20%, V: 0.001~0.030%, P: 0.005~0.015%, S: 0.005~0.015%, with the balance being Fe and unavoidable impurities.

9. A turnout rail with uniform hardness distribution at the center cross-section of the rail web, characterized in that, Obtained by the production method according to any one of claims 1-8.

10. The turnout rail according to claim 9, characterized in that, The hardness of the web center section of the turnout rail is in the range of 29~33HRC and the difference between the maximum and minimum hardness values ​​is ≤1.0HRC. The tensile strength of the turnout rail is ≥1200MPa, the elongation after fracture is ≥10%, the surface hardness is ≥340HB, and the microstructure of the entire rail section is pearlite.

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