• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a bainitic steel rail containing traces of carbides. The bainitic steel rail is mainly composed of bainitic structures, the carbides have a length of 0.05 to 0.5 μm, the major axis of carbides is oriented in a direction forming an angle of 50 to 70 ° inclusive with respect to the direction of the major axis of bainitic ferrite plates, and the carbides constitute 1% to 5% by volume. The present invention further relates to a method of producing a bainitic steel rail containing traces of carbides, comprising: cooling a steel rail with residual heat after finishing rolling by cooling by air, until the temperature in the center of the rail head race surface reaches 420 to 450 ° C, cooling the rail head portion of the steel rail by accelerated cooling at a cooling rate of 2.0 to 5, 0 C / s, until the temperature at the center of the running surface of the rail head reaches 220 to 240 C, the loading of the steel rail in a furnace of income and an income at 300 to 350 C during 4 at 6 o'clock, then cooling the steel rail by air cooling to room temperature.
    公开号:FR3020816A1
    申请号:FR1554102
    申请日:2015-05-07
    公开日:2015-11-13
    发明作者:Zhenyu Han；Ming Zou；Jihai Jia；Hua Guo；Dadong Li；Yong Deng；Chunjian Wang；Jun Yuan
    申请人:Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd；
    IPC主号:
    专利说明:

    [0001] The present invention relates to a bainitic steel rail containing traces of carbides and a method of producing said bainitic steel rail containing traces of carbides. Currently, most of the steel rails generally used for railroads are made of eutectoid steel, whose microscopic structure consists mainly of pearlite and contains traces of ferrite, characterized by a good correspondence of toughness and moderate performance, etc. . However, as traffic density and axle load on track rails increase steadily, existing steel rail products can no longer meet the lane service requirement, particularly in the railway sections. railways in which line conditions are difficult. In this context, the extremely rapid wear of the wheel-rail contact part has gradually become a major factor affecting the service life of steel rails on heavy-duty railways, particularly steel rails at parts with a small radius bend. In order to solve this problem, researchers have conducted work to develop new steel rail products, to meet the demand of railroad engineering.
    [0002] After years of research, it has been discovered that there are mainly two processes that can meet the requirement mentioned above: one method is to further increase the carbon content in the rail steel and add elements of alloy in an appropriate amount as a complement, to take full advantage of the carbon-enhancing effect of the wear resistance of the steel rails, and to obtain a better match of toughness and better overall properties of the steel rails by means of a post-rolling cooling process; the other method consists in using bainitic steel rails having a high content of alloying elements and obtaining bainitic steel rails having a high wear resistance property by controlling a post-rolling cooling process, so to improve the wear resistance property by taking full advantage of the remarkable resistance to contact fatigue. It has been proven in practice that the additional increase in carbon content in existing steel rail products has adverse effects on the safety of application of steel rails due to inadequate toughness and plasticity and secondary precipitation of cementite. In recent years, the practice of applying bainitic steel for railroad steel rails has introduced a new idea for the development of new steel rail products. However, as with existing bainitic steel rails, it is difficult to solve the problem of achieving high wear resistance while maintaining the excellent fatigue resistance property of steel rails. For example, in the case of the bainitic steel rail described in patent document CN-C-1074058, the rail head portion has a Vickers hardness of 230 to 320, and can not effectively withstand wheel-wheel wear. rail because of the low hardness; therefore, the steel rail must be replaced early before reaching its nominal life because it is severely worn. The steel rails described in patent documents CN-C-1101856, CN-C-1219904, CN-C-4040660, and CN-B-1012906, etc. are similar to the steel rail described above. In CN-C-1086743, a bainitic steel rail which has high resistance to damage due to surface fatigue and high wear resistance is described. The microscopic structure of the bainitic steel rail is characterized in that on the basis of the total area of a given cross section of the bainitic structure, the total area of carbides with a major axis in the range of 100 nm to 1 000 nm represents 10 to 50 'Vo. This technique has the following obvious drawbacks: As a hard phase in steel, the carbides represent a percentage which is too high and, therefore, the cracks formed in the stressed steel rail develop preferentially over time. long carbides, which leads to fatigue damage such as cracking and chipping, or even fractures of the steel rail that would compromise service safety. Although steps have been taken to decrease the carbide sizes in the invention to avoid the above problems, these problems can not yet be effectively solved at the root because the percentage of carbides is too high. In patent documents CN-C-100471974 and CN-C-1166804, a bainitic steel rail under air cooling conditions and its production method are described. The production procedures for the bainitic steel rail are very different from those of the present invention because the method uses air cooling after rolling. In summary, with regard to the bainitic steel rails and their production processes which have been described so far, although the contact fatigue resistance of bainitic steel rails is fully exploited, the problem of resistance to the wear of the bainitic steel rails has not been solved at the root. There is an urgent need for a bainitic steel rail which has excellent wear resistance and fatigue damage resistance properties, in order to satisfy the service requirement on heavy duty railways, in particularly in railway sections in which the conditions are demanding.
    [0003] To solve a disadvantage of the existing steel rails, that is to say obtain excellent properties of wear resistance and resistance to fatigue damage, which can not be achieved simultaneously in these steel rails, The present invention relates to a bainitic steel rail which has excellent wear resistance and fatigue resistance properties and a method of producing the same. Similar to the case of carbides in pearlitic steel rails, the size and percentage of carbides in bainitic steel rails have significant influences on the wear resistance and service life of steel rails. In the process of use, the steel rail is subjected to the alternating action of complex stresses exerted by the wheels, and the wheel-rail contact portion of the rail head of a steel rail is subjected to wear continuous by the friction force generated between the steel rail and the wheels. Analyzed under the microscope, bainitic ferrite in the steel rail is a soft phase in the steel, and it may still not have sufficient strength to withstand the wear caused by the wheels although it has been reinforced in the accelerated cooling process after rolling. While carbides, which constitute a hard phase in steel, progressively precipitate in bainite ferrite and concentrate as the surface layer of the rail head is worn during the process of use, and thus resist the stress exerted by the wheels together and can improve the wear resistance of the steel. In the course of his research, the inventor of the present invention has discovered that the carbides that precipitate in the bainitic ferrite matrix are rod-shaped or strip-like, with a length not exceeding 0.5 μm, and are oriented in a direction at an angle of 50 to 70 ° inclusive with respect to the long axis direction of the ferrite plates, and these carbides can effectively improve the wear resistance property of the steel rail, with little effect undesirable properties on the rolling contact fatigue resistance property of the steel rail. To achieve the object described above, in one aspect, the present invention relates to a bainitic steel rail containing traces of carbides, characterized in that the bainitic steel rail is mainly constituted by bainitic structures, the carbides have a length from 0.05 to 0.5 μm, the major axis of the carbides is oriented in a direction at an included angle of 50 to 70 ° with respect to the direction of the major axis of bainitic ferrite plates, and the carbides represent 1% to 5% by volume. In another aspect, the present invention further relates to a method for producing a bainitic steel rail containing traces of carbides, comprising cooling a steel rail with residual heat after finishing rolling by air cooling, until the temperature in the center of the rail head tread surface reaches 420 to 450 ° C, the cooling of the rail head portion of the steel rail by accelerated cooling at a cooling rate of 2.0 to 5.0 ° C / s, until the temperature at the center cb the running surface of the rail head reaches 220 to 240 ° C, loading the steel ral in a furnace of income and income at 300 to 350 ° C for 4 to 6 hours, then cooling the steel rail by air cooling to room temperature. Other features and advantages of the present invention are described in more detail in the embodiments presented below. The appended FIG. 1 is presented to facilitate the further understanding of the present invention. It is used in combination with the following embodiments to explain the present invention, but should not be construed as constituting any limitation of the present invention. Figure 1 shows the microscopic structure of the bainitic steel track containing traces of carbides described in the present invention under a transmission electron microscope (TEM) after the thickness has been reduced by double jet electropolishing. Hereinafter, embodiments of the present invention are detailed with reference to the accompanying figure. It should be noted that the presently described embodiments are presented only to describe and explain the present invention, but should not be construed as constituting any limitation of the present invention. According to one aspect, the present invention relates to a bainitic steel rail containing traces of carbides, characterized in that the bainitic steel rail is mainly composed of bainitic structures, the carbides have a length of 0.05 to 0.5 the large The carbide axis is oriented in a direction at an angle of 50 to 70 ° inclusive with the long axis direction of the bainitic ferrite plates, and the carbides represent 1% to 5% by volume. In the research, the inventor of the present invention has found that if the percentage of carbides is too high, for example, greater than 5%, although the wear resistance property of the steel rail can be effectively improved, cracks can easily occur in the steel rail under the stress exerted by the wheels, and cracks develop in the steel preferably along the carbides; therefore, the steel rail fractures in a short time, and the service safety can not be assured. The direction of the major axis of the carbides forms an angle of 50 to 70 ° inclusive with respect to the major axis of the bainitic ferrite plates, which is advantageous for ensuring that the property of resistance to fatigue damage of the steel rail will not be degraded even after plastic deformation occurs at the wheel-rail contact portion. According to the present invention, the bainitic steel rail contains: 0.15% by weight to 0.30% by weight of C, 1.00% by weight to 1.80% by weight of Si, 1.50% by weight 2.50 (3% by weight of Mn, 0.50% by weight to 1.00% by weight of Cr, 0.20% by weight to 0.50% by weight of Mo, and Fe which constitutes the remainder with unavoidable impurities, and the total weight percentage of Mn and Cr satisfies 2.2% Mn + Cr 3.0%.
    [0004] Hereinafter, the reasons for confining the major chemical elements in the steel rail described in the present invention in the above ranges are explained: Carbon (C) is the most important element in bainitic steel to obtain excellent toughness and overall mechanical matching properties. When the carbon content is less than 0.15% by weight, it is unable to fully produce its reinforcing effect, and the rigidity of the steel rail is too low and, therefore, the percentage of carbides in the steel and the wear resistance property of the steel can not be insured; when the carbon content is greater than 0.30% by weight, with the process described in the present invention, the strength of the steel is too high, while the toughness and the plasticity are too low; therefore, the contact fatigue strength of the steel is severely affected because the percentage of carbides is too high, and the safety of application of the steel rail is compromised. Therefore, the carbon content is confined to 0.15 to 0.30% by weight. As a major additional element in steel, silicon (Si) generally exists in solid solution ferrite, and can improve the strength of the structure. For bainitic steel, when the silicon content is less than 1.00% by weight, on the one hand the reinforcing effect is not significant because the concentration in solid solution is low; on the other hand, fine carbides can not be obtained and, therefore, the structural control objective of the present invention can not be achieved; when the silicon content is greater than 1.80% by weight, the precipitation of the carbides is totally inhibited; instead, residual austenite is present and surface defects can easily occur, therefore the regularity of operation of the trains can not be ensured. Therefore, the silicon content is confined to 1.00 to 1.80% by weight.
    [0005] Manganese (Mn) can significantly decrease the initial transition temperature of the bainitic structure, improve the hardness of carbides, and is an important addition element in bainitic steel. During the course of the research, the inventor has discovered that when the manganese content is less than 1.50% by weight, it is difficult to obtain the effect of improving the hardness of the carbides; when the manganese content is greater than 2.50% by weight, the hardness of the carbides is too high, and the fatigue strength property of the steel rail is severely degraded. Therefore, the manganese content is confined to 1.50 to 2.50% by weight. As a forming element for medium-sized carbides, chromium (Cr) can bind to carbon in steel to form different carbides; in addition, chromium is useful for a uniform carbon distribution in steel, and can decrease the size of carbides, and thus improve the wear resistance property of the steel rail. When the chromium content is less than 0.50% by weight, the hardness and the percentage of the carbides formed in the steel are too low, and the carbides are concentrated in the form of flakes, which is detrimental to the performance of use of steel rail; when the chromium content is greater than 1.00% by weight, the percentage of martensite in the steel is greatly increased and, therefore, the safety of use of the steel rail can not be ensured. Therefore, the chromium content is confined to 0.50 to 1.00% by weight. Molybdenum (Mo) has a remarkable effect in decreasing the initial transition temperature of the bainitic structure, and is advantageous for stabilizing and reinforcing a bainitic structure. When the molybdenum content is less than 0.20% by weight, it will be difficult to obtain the effects mentioned above; when the molybdenum content is greater than 0.50% by weight, the transition efficiency of the bainitic structure will be greatly reduced and, therefore, an ideal bainitic structure can not be obtained in the accelerated cooling process. Therefore, the molybdenum content is confined to 0.20 to 0.50% by weight.
    [0006] To further improve the operating performance of the steel rail in the present invention, the manganese content and the chromium content must satisfy 2.2% by weight Mn + Cr 3.0% by weight. Mn and Cr have similar effects in bainitic steel; when Mn + Cr <2.20% by weight, the strength, size, and percentage of carbides in the steel can not meet the requirement described in the present invention; moreover, the hardness of the carbides is low, and a moderate property of resistance to wear can not be obtained; when Mn + Cr> 3.00% by weight, on the one hand, the hardness of the carbides is too high; on the other hand, a strong segregation occurs locally in the steel rail and, consequently, the uniformity of the bainitic structure and the performances of the bainitic structure in the steel rail can not be assured. Therefore, a condition of "2.2 wt% Mn + Cr 3.0 wt%" must be satisfied. Currently, "Mn + Cr" refers to the sum of Mn content and Cr content. According to another aspect, the present invention further relates to a method of producing a bainitic steel rail containing traces of carbides, comprising cooling a steel rail with residual heat after cooling finishing rolling. air, until the temperature at the center of the running surface of the rail head reaches 420 to 450 ° C, the cooling of the rail head part of the steel rail by accelerated cooling at a cooling rate of 2 , 0 to 5.0 ° C / s, until the temperature at the center cb the running surface of the rail head reaches 220 to 240 ° C, loading the steel ral in a furnace of income and income at 300 to 350 ° C for 4 to 6 hours, then cooling the steel rail by cooling in air at room temperature. According to the method described in the present invention, a steel rail with residual heat after finish rolling is used, the rail head portion of the steel rail is cooled by accelerated cooling at a cooling rate of 2.0 to 5, 0 ° C / s; when the temperature at the center of the railhead tread decreases to 220 ° C-240 ° C, the steel rail is loaded into a furnace and returned to 300 to 350 ° C for 4-6 hours ; then, the steel rail is cooled to room temperature by air cooling; in this manner, rod-shaped carbides can precipitate in the bainitic ferrite matrix, where the rod-shaped carbides have a length of 0.05 to 0.5 μm and are oriented in a direction at an angle of 50 to 50 μm. 70 ° included with respect to the major axis of the bainitic ferrite plates, and represent 1 ° / 0 to 5% by volume. According to the method described in the present invention, the steel rail with residual heat after finishing rolling can be produced with a method common in the art; for example, the process may comprise: treating a steel material having a suitable chemical composition by melting in a converter or an electric oven, refining in a pocket oven, vacuum treatment RH or in a ladle, and casting, to produce a continuously cast steel billet having appropriate cross-sectional dimensions; then, the steel billet is loaded into a movable beam furnace and heated at 1200 to 1300 ° C, and held at that temperature for 2 hours or longer; then, the steel billet is rolled into a steel rail having the required cross-sectional dimensions; here, the finishing rolling temperature of the steel rail is 850 to 950 ° C. The steel rail with residual heat after finishing rolling is placed on a roller conveyor and kept in the air for air cooling; when the temperature of the surface layer of the steel rail head decreases to 420-450 ° C, an accelerated cooling medium is applied to the upper surface and both sides of the rail head. Here, the accelerated cooling medium may be a cooling medium commonly used in the art. For example, the accelerated cooling medium may be selected from at least one of compressed air, a water-air mixture, and an oil-gas mixture.
    [0007] Hereinafter, the reason why the initial accelerated cooling temperature is adjusted to 420 to 450 ° C is explained. As discussed in the inventor's investigation of the present invention, under post-air cooling conditions, the phase transition temperature of the bainitic steel rails is generally in the range of 350 to 400 ° C. If the accelerated cooling is initiated from the temperature range of the austenitic phase domain, a longer cooling time will be required and a larger amount of energy from the cooling medium will be consumed, since the initial cooling temperature accelerated is far from the phase transition temperature; more importantly, in the accelerated cooling process, heat from the central part of the rail head and the web core portion diffuses to the surface layer of the rail head by heat transfer, while the top layer of the fungus rail is subjected to accelerated cooling by the external cooling medium; therefore, the mushroom portion of the rail can not undergo a phase transition to a higher degree of supercooling, finally, the stiffness on the railhead cross-section decreases progressively from the surface layer to the central portion, and the steel rail can not be fully cured. By adjusting the initial cooling temperature to 420 to 450 ° C, the following benefit can be obtained: the initiation of accelerated cooling in the temperature range of the austenitic phase domain at 450 ° C has a small contribution to improvement. overall performance of the steel rail. When the steel rail is cooled to 420-450 ° C, the rail core temperature and the base temperature of the rail are less than 480 ° C. If the accelerated cooling is initiated at this temperature, the temperature of the surface layer of the rail head is significantly reduced, while it is difficult for the heat from the central part of the rail head to effectively compensate for the heat loss in the superficial layer; in addition, since the initial cooling temperature is close to the phase transition point, the total cross section of the rail head, in particular towards the central portion of the rail head, can undergo a phase transition to a degree of over-cooling higher. The reason why the cooling rate is adjusted to 2.0 at 5.0 ° C / s in this process is as follows: if the cooling rate is below 2.0 ° C / s, the temperature of the layer surface of the rail head can not be cooled quickly, and the cooling effect can not be effectively transferred to the central part; in addition, the heat from the central part is retroceded to the surface layer, which is detrimental to improving the overall performance of the steel rail; more importantly, the carbides in the steel rail can not sufficiently precipitate and, therefore, the object of the present invention can not be realized; if the cooling rate is greater than 5.0 ° C / sec, a greater amount of martensite is produced because the surface layer is cooled too rapidly, therefore the stiffness of the steel rail is too high; although martensite can be converted to martensite partially returned by the following process of income, residual martensite is still present and eventually forms martensitic structures at room temperature, which are detrimental to the safe use of steel rail. The accelerated cooling is stopped when the surface layer of the steel rail is cooled to 220 to 240 ° C. The reason why the final accelerated cooling temperature is adjusted to 220 to 240 ° C is as follows: if the final cooling temperature is higher than 240 ° C, fine bainitic structures are obtained in the surface layer of the mushroom. rail, coarse bainitic structures are formed in the central part of the rail head due to the high temperature, and coarse bainitic structures influence the performance of the steel rail at room temperature and are detrimental to the uniformity of performance of the rail. total cross section; if the cooling temperature is below 220 ° C, a large amount of martensite is formed, and can not be removed, even with the aid of the subsequent treatment of income; therefore, the toughness and plasticity of the steel rail will be highly compromised, or even the steel rail can not be used. In addition, once the accelerated cooling is complete, the steel rail is loaded into a heating oven and returned to 300-350 ° C for 4-6 hours, and is then cooled to room temperature by air cooling. The reason for the above procedure is as follows: if the tempering temperature is below 300 ° C, the toughness and plasticity of the steel, particularly the low temperature impact toughness, is greatly degraded, therefore the high tenacity property of the low temperature bainitic steel rail can not be used; moreover, since the carbides can not precipitate sufficiently in the steel, the wear resistance property of the steel rail can not be improved; if the tempering temperature is above 350 ° C, although the toughness and plasticity further increase, the strength and hardness decrease, therefore, it will be difficult to obtain a steel rail having excellent overall properties. The reason why the duration of income is adjusted to 4 to 6 hours is as follows: when the duration of income is less than 4 hours, carbides in steel, especially carbides in the deep zone of the rail head, can not rush enough; when the duration of income is greater than 6 hours, the excessively long treatment time will bring few benefits, because the precipitation of carbides in the steel is already completed and the objective of the income process has already reached state. After the treatment of income, the steel rail is removed and cooled to room temperature by air cooling, so as to obtain a finished product of steel rail.
    [0008] According to the method described in the present invention, the steel rail contains: 0.15% by weight to 0.30% by weight of C, 1.00% by weight to 1.80% by weight of Si, 1.50 % by weight to 2.50% by weight of Mn, 0.50% by weight to 1.00% by weight of Cr, 0.20% by weight to 0.50% by weight of Mo, and Fe which constitutes the remains with unavoidable impurities, and the percentage by total weight of Mn and Cr satisfies 2.2% Mn + Cr 3.0%.
    [0009] Hereinafter, the present invention is detailed in examples, but the scope of the present invention is not limited to these examples. In the examples according to the invention 1 to 6 and comparative examples 1 to 6, the following steel rails 1 to 6 are used, respectively. The chemical compositions of the steel rails are shown in Table 1. No. Chemical Composition /% by Weight C Si Mn PS Cr Mo Mn + Cr 1 0.23 1.58 1.97 0.010 0.006 0.80 0.20 2 , 77 2 0.20 1.20 2.50 0.011 0.005 0.50 0.29 3.00 3 0.15 1.80 1.50 0.011 0.007 1.00 0.42 2.50 4 0.21 1, 45 1.60 0.014 0.009 0.60 0.50 2.20 0.24 1.00 2.05 0.012 0.004 0.63 0.36 2.68 6 0.30 1.30 1.87 0.013 0.006 0.78 0.25 2.65 Table 1: Compositions of the rails of the examples Example 1 according to the invention Steel No. 1 is treated in Table 1 by preparation in a converter, oven-pocket refining, vacuum treatment RH, and casting, to produce a continuous cast steel billet, the steel billet is loaded in a traveling beam furnace and heated to 1300 ° C and maintained at this temperature for at least 2 hours, the billet of steel in the form of a 60 kg / m steel rail, after a finishing lamination, the steel rail is placed on a roller conveyor and holds the steel rail thereon by means of a steel rollover ramp for air cooling until the temperature at the center of the running surface of the rail head reaches 445 ° C, then a cooling medium is applied to the upper surface and both sides of the rail head to start the accelerated cooling, the cooling medium being a water-air mixture, and the steel rail is cooled to an accelerated cooling speed of 4.5 ° C / s, until the temperature of the surface layer of the rail head decreases to 240 ° C, then the accelerated cooling is stopped, the steel rail is loaded into a furnace and an income at 300 ° C for 4.1 h. After the tempering treatment, the steel rail is cooled in air at room temperature; thus, a steel rail Al is finally obtained.
    [0010] Examples 2 to 6 according to the invention and Comparative Examples 1 to 6 The steel rails are prepared in Examples 2 to 6 according to the process described in Example 1, but the control parameters are replaced in the operating process of the Example 1 by those shown in Table 2. The steel rails prepared according to the invention by the method of Examples 2 to 6 are called A2-A6. In the comparative examples, the treatment method is a conventional heat treatment method and the control parameters specific to the operational process are shown in Table 2. The steel rails prepared according to the method of Comparative Examples 1 to 6 are called Dl- D6. Example No. Temperature Temperature Speed Return Temperature / Initial Final Cooling Time ° C Cooling Cooling Recovery / Accelerated Cooling / ° C Accelerated Cooling / Accelerated C ° / ° C / s Examples Al 445 4.5 240 300 4 , According to the invention A2 432 3.0 235 338 4.8 A3 429 3.4 232 350 6.0 A4 420 2.0 227 344 5.1 A5 448 5.0 220 330 4.0 A6 450 4, 1 224 340 5.6 Examples D1 760 1.8 350 comparisons D2 780 2.4 381 D3 820 2.2 364 D4 880 3.1 425 D5 690 2.9 346 D6 870 1.9 315 Table 2: Treatment parameters Test Examples The performances of the steel rails A1 to A6 prepared in Examples 1 to 6 according to the invention and D1 to D6 prepared in Comparative Examples 1 to 6 are tested according to the following method, specifically: The tensile property of Steel rail is measured according to GB / T228-2010 "Tensile Testing Method of Metallic Materials at Room Temperature", and the Rp0.2 measured (conventional yield strength at 0.2% elongation), R, (tensile strength), A (3/0 (elongation), Z% (cross-sectional reduction) are shown in Table 3. Wear tests are conducted on a MM-200 wear test machine to determine the average weight loss resulting from wear. Samples are taken from the railhead portion of the Al to A6 and D1 to D6 steel rails. In all the wear tests, the lower machining samples consist of the same material. The measured values of average weight loss resulting from wear are presented in Table 3. The test parameters are as follows: Sample size: Circular sample 10 mm thick and 36 mm in diameter Load of test: 150 kg Slip: 10% Lower machining sample material: steel for wheel with a hardness of 260 to 310 HB Environment: in the air Speed of rotation: 200 rpm Total wear cycles: 100,000 The carbide length, the angle formed between the carbides and the bainitic ferrite, and the percentage of the carbides are measured according to the following method: Samples are taken from the steel rails prepared in the examples according to the invention and the examples Comparative and film samples having a thickness of 50 lm are obtained from the samples. Then, the samples are treated by double jet electropolishing for reduction of the thickness; then, the morphology of the carbides is indexed and observed under a transmission electron microscope (TEM), and the included angle between the carbides and the bainitic ferrite is measured; carbides 0.05 to 0.5 μm in length and oriented in a direction at an angle of 50 to 70 ° inclusive are selected, and the area and percentage of the carbides are measured by rough estimation. Since carbide morphology varies in different fields of view, to ensure measurement accuracy, at least 20 fields of view on a steel rail with the same material, process and sampling position are observed, and the average value is selected, and the percentage of carbides that satisfy the requirement is determined. Examples No. Tensile properties Percent property Length Weight loss due to wear / g Carb resistance average shock /% in vol. carbides / Aku / J Pm Rpo2 / MPa Rp, / MPa A /% Z /% Ambient temperature, 0, 's "Examples Al 1230 1480 16.5 52 95 78 2.8 0.42 0.5466 according to the A2 1280 1510 15.5 48 85 60 4.4 0.08 0.5143 A3 1150 1430 18.0 58 107 81 1.8 0.26 0.5896 A4 1290 1590 16.5 50 98 64 4.2 0 , 32 0.4831 A5 1260 1490 17.0 52 92 72 3.5 0.40 0.4269 A6 1360 1610 15.0 44 78 56 4.9 0.29 0.3987 Examples D1 1025 1340 16.0 52 75 48 S / 0 - 1.0236 comparative D2 1040 1350 15.0 44 54 38 S / 0 - 0.9584 D3 1080 1290 17.5 49 52 40 5/0 - 1.1459 D4 1105 1420 16.5 40 58 40 S / 0 - 0.8562 D5 1060 1310 15.0 46 68 46 S / 0 - 0.7569 D6 1180 1480 14.0 40 66 41 S / 0 - 0.7258 Table 3: Test results The results in Table 3 indicate that under conditions of the same chemical composition and the same process of elaboration and rolling, the post-rolling treatment of the steel rail will have a significant influence on the final properties of the steel rail, represented by: in the rail in steel produced with the pro described in the present invention, rod-shaped or strip-shaped carbides, which are 0.05 to 0.5 μm in length, oriented in a direction at an angle of 50 to 70 ° inclusive by relative to the direction of the major axis of the ferritic plates, and represent 1 to 5% by volume, precipitate in the bainitic ferrite matrix; accordingly, the steel rail gets excellent toughness and property of wear resistance under the same conditions significantly improved. Therefore, the present invention is useful for extending the life of steel rails, particularly curved track section steel rails with demanding operating conditions on heavy duty railroad tracks. Preferred embodiments of the present invention are described above in detail, however, the present invention is not limited to the specific details of the above embodiments, the technical solutions of the present invention may include various modifications. simple in remaining in the technical spirit of the present invention. In addition, it should be noted that each specific technical feature described in the specific embodiments above can be combined in any suitable manner, in the absence of incompatibilities. In order to avoid unnecessary repetition, the various possible combinations are not described further in the present invention.
    权利要求:
    Claims (5)
    [0001]
    REVENDICATIONS1. A bainitic steel rail containing traces of carbides, characterized in that the bainitic steel rail consists mainly of bainitic structures, the carbides have a length of 0.05 to 0.5 the major axis of the carbides is oriented in a direction forming an angle of 50 to 70 ° inclusive with respect to h direction of the major axis of the bainitic ferrite plates, and the carbides constitute 1% to 5% by volume.
    [0002]
    2. bainitic steel rail according to claim 1, characterized in that the bainitic steel rail contains: 0.15% by weight to 0.30% by weight of C, 1.00% by weight to 1.80 ( 3/0 by weight of Si, 1.50% by weight to 2.50% by weight of Mn, 0.50% by weight to 1.00% by weight of Cr, 0.20% by weight at 0.50 % by weight of Mo, and Fe which constitutes the remainder with unavoidable impurities, and the percentage by total weight of Mn and Cr satisfies 2.2% Mn + Cr 3.0 'Vo.
    [0003]
    A method of producing the bainitic steel track containing traces of carbides according to claim 1, comprising: cooling a steel rail with residual heat after finishing rolling by air cooling, until the temperature at the center of the rail mushroom running surface reaches 420 to 450 ° C, the cooling of the rail rail part of the steel rail by accelerated cooling at a cooling rate of 2.0 to 5.0 ° C / s, until the temperature in the center of the running surface of the rail head reaches 220 to 240 ° C, the loading of the steel rail in a furnace of income, and a revenue at 300 to 350 ° C for 4 to 6 hours, then cooling the steel rail by air cooling to room temperature.
    [0004]
    4. Production process according to claim 3, characterized in that the accelerated cooling medium is selected from at least one of compressed air, a water-air mixture, and an oil-gas mixture.
    [0005]
    Production method according to claim 3, characterized in that the steel rail contains: 0.15% by weight to 0.30% by weight of C, 1.00% by weight to 1.80% by weight of Si, 1.50% by weight to 2.50% by weight of Mn, 0.50% by weight to 1.00% by weight of Cr, 0.20% by weight to 0.50% by weight of Mo , and Fe which constitutes the remainder with unavoidable impurities, and the total weight percentage of Mn and Cr satisfies 2.2% Mn + Cr 3.0 'Vo.
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    同族专利:
    公开号 | 公开日
    US20150322553A1|2015-11-12|
    CN103966520B|2016-07-06|
    FR3020816B1|2017-03-03|
    CN103966520A|2014-08-06|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JPH05271875A|1992-03-30|1993-10-19|Nippon Steel Corp|Wear resistant roll material for hot rolling|
    US5759299A|1994-05-10|1998-06-02|Nkk Corporation|Rail having excellent resistance to rolling fatigue damage and rail having excellent toughness and wear resistance and method of manufacturing the same|
    US6254696B1|1998-01-14|2001-07-03|Nippon Steel Corporation|Bainitic type rail excellent in surface fatigue damage resistance and wear resistance|
    JP2007197776A|2006-01-27|2007-08-09|Jfe Steel Kk|High-strength steel material superior in delayed fracture resistance and fatigue-crack propagation resistance, and manufacturing method therefor|
    CN102839268B|2012-08-28|2014-08-13|攀钢集团攀枝花钢铁研究院有限公司|Heat treatment method of bainite switch rail|
    CN102899471B|2012-10-17|2014-08-06|攀钢集团攀枝花钢铁研究院有限公司|Heat treatment method for bainite steel rail|CN103993237B|2014-05-22|2016-07-06|攀钢集团攀枝花钢铁研究院有限公司|A kind of anti abrasive bainite turnout rail and production method thereof|
    PL234098B1|2016-06-27|2020-01-31|Arcelormittal Poland Spolka Akcyjna|Multi-phase steel, preferably for the production of standard-gauge rails|
    CN106435367B|2016-11-23|2018-07-10|攀钢集团攀枝花钢铁研究院有限公司|A kind of bainite rail and preparation method thereof|
    JP6610844B1|2018-03-30|2019-11-27|Ｊｆｅスチール株式会社|rail|
    CN110541125A|2019-09-12|2019-12-06|北京交通大学|High-wear-resistance bainite complex phase structure steel rail for heavy haul railway and manufacturing method thereof|
    CN110885950A|2019-10-30|2020-03-17|鞍钢股份有限公司|High-strength and high-toughness steel rail for crane and manufacturing method thereof|
    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
    CN201410192490.XA|CN103966520B|2014-05-08|2014-05-08|A kind of bainite rail containing trace carbon compound and production method thereof|
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