WO2025044324A1 - Pearlitic steel rail having tensile strength uniformly distributed in full cross-section, and production method therefor - Google Patents
Pearlitic steel rail having tensile strength uniformly distributed in full cross-section, and production method therefor Download PDFInfo
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- WO2025044324A1 WO2025044324A1 PCT/CN2024/094836 CN2024094836W WO2025044324A1 WO 2025044324 A1 WO2025044324 A1 WO 2025044324A1 CN 2024094836 W CN2024094836 W CN 2024094836W WO 2025044324 A1 WO2025044324 A1 WO 2025044324A1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Definitions
- the invention relates to the technical field of rail production, and in particular to a pearlite rail with uniform tensile strength distribution over the entire section and a production method thereof.
- Patent CN116371908 "A method for rolling medium-strength rails of American standard” discloses a rail with tensile strength ⁇ 1065MPa, yield strength ⁇ 723MPa, elongation ⁇ 10%, and rail tread hardness ⁇ 350HB after heat treatment. Its chemical composition, calculated by mass percentage, includes: C: 0.70-0.85; Si: 0.30-0.57; Mn0.9-1.18; P ⁇ 0.020; S ⁇ 0.020; Cr: 0.10-0.3; the remainder is Fe and unavoidable impurities.
- the rail has high internal hardness and tensile strength within the depth range of 0-25mm, but the hardness difference between the rail waist and the rail bottom reaches 3-4HRC, which shows that the tensile strength difference is also large, and it is easily affected by external injuries during use, resulting in rail damage.
- the large difference in tensile strength between the rail waist and rail bottom may cause transverse cracks at this position after being subjected to external force, resulting in rail breakage and affecting the service safety of the rail.
- Patent CN102220545 "High-carbon, high-strength, heat-treated rail with excellent wear resistance and plasticity and its manufacturing method” discloses a high-carbon, high-strength, heat-treated rail with excellent performance in wear resistance and plasticity, with a rail head tensile strength ⁇ 1330MPa, an elongation ⁇ 9%, a rail head hardness ⁇ 380HB, a hardened layer depth of more than 25mm, and excellent performance in wear resistance and plasticity.
- Its chemical composition includes by weight percentage: C: 0.80% ⁇ 1.20%, Si: 0.20% ⁇ 1.20%, Mn: 0.20% ⁇ 1.60%, Cr: 0.15% ⁇ 1.20%, V: 0.01% ⁇ 0.20%, Ti: 0.002% ⁇ 0.050%, P ⁇ 0.030%, S ⁇ 0.030%, Al ⁇ 0.010%, N ⁇ 0.0100%, and the rest is Fe and unavoidable impurities.
- C 0.80% ⁇ 1.20%
- Si 0.20% ⁇ 1.20%
- Mn 0.20% ⁇ 1.60%
- Cr 0.15% ⁇ 1.20%
- V 0.01% ⁇ 0.20%
- Ti 0.002% ⁇ 0.050%
- Patent CN104060075 "Heat Treatment Method for Increasing the Depth of Rail Hardening Layer" discloses a heat treatment method for naturally cooling the rail after final rolling to a center temperature of 660-730°C on the rail head tread, accelerating cooling at a cooling rate of 1.5-3.5°C/s to a center temperature of 500-550°C on the rail head tread, and then increasing the cooling rate by 1.0-2.0°C/s. When the center temperature of the rail head tread drops below 450°C, stop accelerating cooling and air cool to room temperature.
- This method can make the rail head part obtain a deep hardening layer of more than 25mm, and the 25mm below the surface of the rail head has a hardness value equivalent to that of the surface of the rail head, and the entire cross section of the rail head is pearlite, which is conducive to improving the good service performance of the rail after continuous wear due to wheel-rail contact.
- the heat treatment method described in the patent only aims to improve the hardness and tensile strength of the rail head part, and does not take into account the simultaneous improvement of the hardness and tensile strength of the rail waist and rail bottom.
- the main purpose of the present invention is to provide a pearlite rail with uniform tensile strength distribution over the entire cross section and a production method thereof, so as to solve the technical problem that the prior art fails to comprehensively improve the tensile strength of the rail.
- a method for producing a pearlite rail with uniform tensile strength distribution over the entire cross section comprising: performing an online heat treatment on the rolled rail, wherein the online heat treatment adopts a part-by-part accelerated cooling process, comprising:
- Accelerated cooling stage when the rail top surface temperature after final rolling is between 680 and 810°C, accelerated cooling is carried out in different parts until the rail top surface temperature is between 480 and 590°C; among which, the cooling rate of the rail top surface is 2.0 to 5.0°C/s, the cooling rate of both sides of the rail head is 1.5 to 4.0°C/s, the cooling rate of both sides of the upper part of the rail waist is 1.0 to 3.0°C/s, the cooling rate of both sides of the middle part of the rail waist is 0.8 to 2.5°C/s, and the cooling rate of the center of the rail bottom is 1.5 to 3.0°C/s;
- Air cooling stage the rails that have undergone the accelerated cooling stage are air cooled to room temperature.
- the cooling speed of the rail top surface, the cooling speed of both sides of the rail head, the cooling speed of both sides of the upper part of the rail waist, and the cooling speed of both sides of the middle part of the rail waist are reduced in sequence.
- accelerated cooling is performed in sections until the rail top surface temperature is between 490 and 560° C.
- the cooling rate of the rail top surface is 3.3-4.3°C/s
- the cooling rate of both sides of the rail head is 2.9-3.7°C/s
- the cooling rate of both sides of the upper part of the rail waist is 2.4-3.0°C/s
- the cooling rate of both sides of the middle part of the rail waist is 1.5-2.1°C/s
- the cooling rate of the center of the rail bottom is 1.8-2.5°C/s.
- the cooling medium used is water mist and/or compressed air.
- the method before performing the online heat treatment, further comprises: sequentially performing converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, and rolling.
- the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ⁇ 0.025%, S: ⁇ 0.020%, and the remainder is Fe and unavoidable impurities.
- a pearlite having uniform tensile strength distribution over the entire cross section has the following chemical compositions, measured by weight percentage: C: 0.65-0.82%, Si: 0.10-0.60%, Mn: 0.65-1.25%, Cr: 0.05-0.25%, Mn+Cr: 0.75-1.50%, Mn/Cr: 7.0-10.0, P: ⁇ 0.030%, S: ⁇ 0.025%, and the remainder is Fe and unavoidable impurities; the tensile strength of the fillet on the rail head, the center of the rail head, the center of the rail waist, and the center of the rail bottom of the steel rail are all ⁇ 1080MPa, and the difference is ⁇ 80MPa.
- the tensile strength of the rounded corner on the rail head is ⁇ 1180MPa, and the elongation is ⁇ 10.0%; the hardness of the rail top surface is 350-390HB; the tensile strength of the center of the rail head, the center of the rail waist, and the center of the rail bottom are all ⁇ 1080MPa, and the elongation is ⁇ 10.0%.
- the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ⁇ 0.025%, S: ⁇ 0.020%, and the remainder is Fe and unavoidable impurities.
- a pearlite rail with uniform tensile strength distribution over the entire cross-section can be prepared without adding multiple micro-alloying elements, which can improve the rail's ability to resist external force damage during transportation, storage and service, can significantly reduce the negative impact of external damage on the service performance of the rail, can improve the service life and safety of the rail, and thus improve the overall transportation efficiency and safety of the railway.
- FIG1 is a schematic diagram showing accelerated cooling and tensile strength testing of a rail with uniform tensile strength distribution over the entire cross section according to an embodiment of the present invention.
- the present invention provides a method for producing a pearlite rail with uniform tensile strength distribution over the entire cross section, comprising: performing online heat treatment on the rolled rail, wherein the online heat treatment comprises:
- Accelerated cooling stage when the rail top surface temperature after final rolling is between 680 and 810°C, accelerated cooling is performed in different parts until the rail top surface temperature is between 480 and 590°C; wherein, the cooling rate of the rail top surface is 2.0 to 5.0°C/s, the cooling rate of both sides of the rail head is 1.5 to 4.0°C/s, the cooling rate of both sides of the upper part of the rail waist is 1.0 to 3.0°C/s, the cooling rate of both sides of the middle part of the rail waist is 0.8 to 2.5°C/s, and the cooling rate of the center of the rail bottom is 1.5 to 3.0°C/s;
- Figure 1 shows the accelerated cooling of various parts;
- Air cooling stage the rails that have undergone the accelerated cooling stage are air cooled to room temperature on a cooling bed.
- the cooling speed of the rail top surface should be the largest, which is controlled within the range of 2.0-5.0°C/s, while the cooling speeds of the two sides of the rail head, the two sides of the upper part of the rail waist, and the two sides of the center of the rail waist are reduced in turn, which are controlled within the range of 1.5-4.0°C/s, 1.0-3.0°C/s, and 0.8-2.5°C/s, respectively.
- the cross-sectional area of the center of the rail bottom is between the two sides of the rail head and the two sides of the upper part of the rail waist, and the cooling speed is controlled within the range of 1.5-3.0°C/s.
- accelerated cooling is performed in sections until the rail top surface temperature is between 490°C and 560°C.
- the cooling rate of the rail top surface is 3.3-4.3°C/s
- the cooling rate on both sides of the rail head is 2.9-3.7°C/s
- the cooling rate on both sides of the upper rail waist is 2.4-3.0°C/s
- the cooling rate on both sides of the middle rail waist is 1.5-2.1°C/s
- the cooling rate at the center of the rail bottom is 1.8-2.5°C/s.
- the cooling medium used is water mist and/or compressed air.
- the method before the online heat treatment is performed, the method further comprises: sequentially performing converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, and rolling.
- the rails may be processed.
- the complete production process of the rails may be: using low-sulfur vanadium-containing molten steel, smelting in a converter or electric furnace, LF refining, RH or VD vacuum treatment, large square billet protection continuous casting, billet heating furnace heating, high-pressure water descaling before billet rolling, universal rolling mill rolling, rail online heat treatment, room temperature air cooling on a step-type cooling bed, horizontal and vertical composite straightening, rail specification inspection, processing line processing, surface inspection and warehousing.
- the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ⁇ 0.025%, S: ⁇ 0.020%, and the remainder is Fe and unavoidable impurities.
- C is the most important and cheapest element in pearlite rails that enables them to obtain good comprehensive mechanical properties and promote pearlite transformation.
- the C content is less than 0.65%, under the production process described in the present invention, it is impossible to ensure that the rails have appropriate hardness and resistance to external damage;
- the C content is greater than 0.82%, under the production process described in the present invention, the strength index of the rails is excessive but the toughness and plasticity are too low, and the carbide ratio is too high, which affects the toughness and plasticity of the rails and has an adverse effect on the safe use of the rails. Therefore, the carbon content in the present invention is limited to 0.65-0.82%.
- the main role of Si in steel is to inhibit the formation of cementite and act as a solid solution strengthening element to improve iron
- the Si content increases the hardness of the matrix and improves the strength and hardness of the steel.
- the Si content is less than 0.10%, the solid solution content is too low, resulting in an insignificant strengthening effect; when the Si content is greater than 0.60%, local segregation is likely to occur, which will reduce the toughness and plasticity of the steel and have an adverse effect on the safe use of the rail. Therefore, the Si content in the present invention is limited to 0.10-0.60%.
- Mn is essential for improving the strength of ferrite and austenite in steel.
- the Mn content is less than 0.65%, it is difficult to increase the hardness of carbides and thus increase the strength of steel; when the Mn content is greater than 1.25%, it will coarsen the grain size and significantly reduce the toughness and plasticity of steel; at the same time, Mn has a significant effect on the diffusion of C in steel, and abnormal structures such as bainite or martensite may be produced in the Mn segregation area, which will affect the welding performance of the rail. Therefore, the Mn content in the present invention is limited to 0.65-1.25%.
- Cr as a carbide-forming element, can form a variety of carbides with carbon in steel; at the same time, Cr can evenly distribute carbides in steel, reduce the size of carbides, increase the strength and hardness of rails, and improve the wear resistance of rails.
- the Cr content is less than 0.05%, the hardness and proportion of the formed carbides are relatively low; when the Cr content is greater than 0.25%, the hardenability of the rails is too high, which can easily cause the rails to produce harmful bainite and martensite structures, and it is impossible to ensure that the rails are pearlite structures, which has an adverse effect on the safe use of the rails. Therefore, the Cr content in the present invention is limited to 0.05-0.25%.
- Mn and Cr are strengthening elements that increase the hardness and hardenability of rails, their total content needs to be limited to control the microstructure of the rails so that abnormal structures such as martensite do not appear, and to ensure that the performance of the finished rails meets the requirements.
- Mn+Cr content is less than 0.75%, it is difficult to provide sufficient carbides, the strengthening effect is weak, and it is impossible to ensure that the hardness of the rails meets the design indicators; when the Mn+Cr content is greater than 1.45%, since both Mn and Cr can improve the hardenability of rails, there is a greater risk of abnormal structures appearing in the rails. Therefore, the Mn+Cr content in the present invention is limited to 0.75-1.45%.
- Mn/Cr In rail steel, controlling the balance of Mn and Cr content is crucial for the comprehensive regulation of rail structure and hardness. If only the Mn content is increased, the rail structure is relatively stable, but the internal hardness is low. If the Cr content is increased, the internal hardness of the rail can be improved, but abnormal structure is prone to occur.
- Mn/Cr is less than 7.0, the Cr content in the rail is relatively high. Although a higher hardness can be obtained, the risk of abnormal structure is relatively high; when Mn/Cr is greater than 10.0, the Mn content in the rail is relatively high. Although the full pearlite structure can be maintained, the internal hardness is relatively low. Therefore, the Mn/Cr value in the present invention is limited to 7.0-10.0.
- Figure 1 shows a schematic diagram of tensile strength testing, wherein position 1 is the tensile strength testing position for the fillet on the rail, position 2 is the tensile strength testing position for the center of the rail head, position 3 is the tensile strength testing position for the center of the rail waist, and position 4 is the tensile strength testing position for the center of the rail bottom.
- the tensile strength of the rounded corners on the rail head is ⁇ 1180MPa, and the elongation is ⁇ 10.0%; the hardness of the rail top surface is 350-390HB; the tensile strength of the center of the rail head, the center of the rail waist, and the center of the rail bottom are all ⁇ 1080MPa, and the elongation is ⁇ 10.0%.
- the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ⁇ 0.025%, S: ⁇ 0.020%, and the remainder is Fe and unavoidable impurities.
- the present invention adopts a method of controlling the chemical composition of the rail and the online heat treatment process, and the obtained pearlite rail has a tensile strength uniformly distributed over the entire section without adding multiple microalloying elements, which can improve the rail's ability to resist external damage during transportation, storage and service, and can significantly reduce the negative impact of external damage on the service performance of the rail, and can improve the service life and safety of the rail, thereby improving the overall transportation efficiency and safety of the railway.
- the production method of the pearlite rail with uniform tensile strength distribution over the entire section provided by the present invention is simple, easy to operate, and conducive to promotion and application.
- the microstructure, tensile properties and rail top surface hardness of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 3.
- the tensile strength measurement positions are shown in Figure 1, where position 1 is the tensile strength test position for the rounded corner of the rail, position 2 is the tensile strength test position for the center of the rail head, position 3 is the tensile strength test position for the center of the rail waist, and position 4 is the tensile strength test position for the center of the rail bottom.
- GB/T 228.1 "Tensile Test of Metallic Materials Part 1: Room Temperature Test Method”
- the rail top surface hardness of the rails obtained by the method of the present invention is within the range of 350-390HB, and the tensile strength at the fillet on the rail head, the center of the rail head, the center of the rail waist, and the center of the rail bottom is relatively high, and the difference is less than 80MPa, and the distribution is uniform, which can effectively reduce the wide range of the impact of the surface and shallow surface damage of the rails on the service performance and safety of the rails; while in the comparative example, the rail top surface hardness of the rails obtained by the method of the present invention is within the range of 350-390HB, and the tensile strength at the fillet on the rail head, the center of the rail head, the center of the rail waist, and the center of the rail bottom is relatively
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Abstract
Description
本发明涉及钢轨生产技术领域，具体涉及一种全断面抗拉强度分布均匀的珠光体钢轨及其生产方法。The invention relates to the technical field of rail production, and in particular to a pearlite rail with uniform tensile strength distribution over the entire section and a production method thereof.
随着高速铁路、重载铁路均向着更加专业化的方向发展，现有铁路网也面临着进一步升级改造，向着高速化、高效率的方向发展，这对钢轨提出了更高的要求。同时由于铁路网的整体发展，铁路运营环境逐渐复杂化，导致钢轨整体材料在运输、储存及服役过程中同样面临着更加容易导致钢轨各位置表面及浅表面出现伤损的情况，而钢轨表面伤损会对其服役寿命和安全性均造成负面影响。因此，只有采用全断面均有更高抗拉强度的钢轨，才能够保证钢轨在生命全周期内的稳定性，提高铁路的运输效率。As high-speed railways and heavy-duty railways develop in a more specialized direction, the existing railway network is also facing further upgrading and transformation, and is developing in the direction of high speed and high efficiency, which puts higher requirements on rails. At the same time, due to the overall development of the railway network, the railway operating environment has gradually become more complicated, resulting in the overall material of the rails being more prone to damage on the surface and shallow surface of the rails during transportation, storage and service. Surface damage to the rails will have a negative impact on their service life and safety. Therefore, only by using rails with higher tensile strength across the entire section can the stability of the rails be guaranteed throughout their life cycle and the transportation efficiency of the railway be improved.
近年来，国内外钢轨生产企业为提升钢轨的硬度，主要采用离线或在线热处理的方式，对钢轨轨头进行加速冷却，以此来细化钢轨轨头部分珠光体组织，通过细化晶粒的方式获得更高的强度和硬度，涉及的相关专利技术具体如下：In recent years, domestic and foreign rail manufacturers have mainly adopted offline or online heat treatment to accelerate the cooling of the rail head in order to improve the hardness of the rails, so as to refine the pearlite structure of the rail head and obtain higher strength and hardness by refining the grains. The relevant patent technologies involved are as follows:
专利CN116371908《一种美标中强度钢轨的轧制方法》公布了一种热处理后抗拉强度≥1065MPa、屈服强度≥723MPa、伸长率≥10％、钢轨踏面硬度≥350HB的钢轨，其以质量百分计，化学成分包括：C：0.70～0.85；Si：0.30～0.57；Mn0.9～1.18；P≤0.020；S≤0.020；Cr：0.10～0.3；余量为Fe及不可避免的杂质。该钢轨在0～25mm深度范围内具有较高的内部硬度以及抗拉强度，但其轨腰与轨底之间硬度差达到3～4HRC，由此可看出其抗拉强度差也较大，在使用过程中易受外伤影响产生钢轨伤损，同时 其轨腰、轨底位置抗拉强度差较大的情况可能导致受外力作用后在该位置产生横向裂纹，导致钢轨断裂，影响钢轨服役安全性。Patent CN116371908 "A method for rolling medium-strength rails of American standard" discloses a rail with tensile strength ≥1065MPa, yield strength ≥723MPa, elongation ≥10%, and rail tread hardness ≥350HB after heat treatment. Its chemical composition, calculated by mass percentage, includes: C: 0.70-0.85; Si: 0.30-0.57; Mn0.9-1.18; P≤0.020; S≤0.020; Cr: 0.10-0.3; the remainder is Fe and unavoidable impurities. The rail has high internal hardness and tensile strength within the depth range of 0-25mm, but the hardness difference between the rail waist and the rail bottom reaches 3-4HRC, which shows that the tensile strength difference is also large, and it is easily affected by external injuries during use, resulting in rail damage. The large difference in tensile strength between the rail waist and rail bottom may cause transverse cracks at this position after being subjected to external force, resulting in rail breakage and affecting the service safety of the rail.
专利CN102220545《耐磨性和塑性优良的高碳高强热处理钢轨及其制造方法》公布了一种轨头抗拉强度≥1330MPa，延伸率≥9％，轨头硬度≥380HB，硬化层深度达到25mm以上，在耐磨性和塑性方面性能优良的高碳高强热处理钢轨，其化学成分按重量百分比包括：C：0.80％～1.20％、Si：0.20％～1.20％、Mn：0.20％～1.60％、Cr：0.15％～1.20％、V：0.01％～0.20％、Ti：0.002％～0.050％、P≤0.030％、S≤0.030％、Al≤0.010％、N≤0.0100％，其余为Fe和不可避免的杂质。但该钢轨在生产过程中仅考虑轨头、轨底的在线热处理强化，未对最容易受外力影响而伤损的轨腰采取任何强化措施。Patent CN102220545 "High-carbon, high-strength, heat-treated rail with excellent wear resistance and plasticity and its manufacturing method" discloses a high-carbon, high-strength, heat-treated rail with excellent performance in wear resistance and plasticity, with a rail head tensile strength ≥1330MPa, an elongation ≥9%, a rail head hardness ≥380HB, a hardened layer depth of more than 25mm, and excellent performance in wear resistance and plasticity. Its chemical composition includes by weight percentage: C: 0.80%~1.20%, Si: 0.20%~1.20%, Mn: 0.20%~1.60%, Cr: 0.15%~1.20%, V: 0.01%~0.20%, Ti: 0.002%~0.050%, P≤0.030%, S≤0.030%, Al≤0.010%, N≤0.0100%, and the rest is Fe and unavoidable impurities. However, during the production process of this rail, only the rail head and rail bottom were strengthened by online heat treatment, and no strengthening measures were taken for the rail waist which is most susceptible to damage by external forces.
专利CN104060075《提高钢轨硬化层深度的热处理方法》公布了一种将终轧后的钢轨自然冷却至轨头踏面中心温度为660～730℃，以1.5～3.5℃/s的冷却速度加速冷却至轨头踏面中心温度为500～550℃，冷却速度再增加1.0～2.0℃/s，当轨头踏面中心温度降至450℃以下时，停止加速冷却，空冷至室温，能够使钢轨轨头部位获得超过25mm的深硬化层，且轨头表层下方25mm具有与轨头表层相当的硬度值，并且轨头全断面均为珠光体组织，有利于提高钢轨因轮轨接触不断磨耗后良好的服役性能的热处理方法。但该专利所述热处理方法只针对钢轨轨头部位的硬度及抗拉强度提升，未考虑到钢轨轨腰及轨底的硬度、抗拉强度的同步提升。Patent CN104060075 "Heat Treatment Method for Increasing the Depth of Rail Hardening Layer" discloses a heat treatment method for naturally cooling the rail after final rolling to a center temperature of 660-730℃ on the rail head tread, accelerating cooling at a cooling rate of 1.5-3.5℃/s to a center temperature of 500-550℃ on the rail head tread, and then increasing the cooling rate by 1.0-2.0℃/s. When the center temperature of the rail head tread drops below 450℃, stop accelerating cooling and air cool to room temperature. This method can make the rail head part obtain a deep hardening layer of more than 25mm, and the 25mm below the surface of the rail head has a hardness value equivalent to that of the surface of the rail head, and the entire cross section of the rail head is pearlite, which is conducive to improving the good service performance of the rail after continuous wear due to wheel-rail contact. However, the heat treatment method described in the patent only aims to improve the hardness and tensile strength of the rail head part, and does not take into account the simultaneous improvement of the hardness and tensile strength of the rail waist and rail bottom.
可见，目前的改善珠光体钢轨抗拉强度的相关专利中，部分专利能够提升钢轨的轨头上圆角及轨顶面抗拉强度，但均未涉及到钢轨轨腰及轨底的抗拉强度均匀提升，在提高钢轨的实际服役性能上，仍然存在明显的不足。It can be seen that among the current patents related to improving the tensile strength of pearlite rails, some patents can improve the rounded corners on the rail head and the tensile strength of the rail top surface, but none of them involve uniformly improving the tensile strength of the rail waist and rail bottom. There are still obvious deficiencies in improving the actual service performance of the rails.
发明内容Summary of the invention
本发明的主要目的在于提供一种全断面抗拉强度分布均匀的珠光体钢轨及其生产方法，以解决现有技术未能全面地提升钢轨抗拉强度的技术问题。 The main purpose of the present invention is to provide a pearlite rail with uniform tensile strength distribution over the entire cross section and a production method thereof, so as to solve the technical problem that the prior art fails to comprehensively improve the tensile strength of the rail.
根据本发明的一个方面，提出一种全断面抗拉强度分布均匀的珠光体钢轨的生产方法，包括：对轧制后钢轨进行在线热处理，其中所述在线热处理采用分部位加速冷却工艺，包括：According to one aspect of the present invention, a method for producing a pearlite rail with uniform tensile strength distribution over the entire cross section is provided, comprising: performing an online heat treatment on the rolled rail, wherein the online heat treatment adopts a part-by-part accelerated cooling process, comprising:
加速冷却阶段：待终轧后钢轨的轨顶面温度在680～810℃之间时，进行分部位加速冷却至轨顶面温度为480～590℃；其中，轨顶面冷却速度为2.0～5.0℃/s、轨头两侧冷却速度为1.5～4.0℃/s、轨腰上部两侧冷却速度为1.0～3.0℃/s、轨腰中部两侧冷却速度为0.8～2.5℃/s、轨底中心冷却速度为1.5～3.0℃/s；Accelerated cooling stage: when the rail top surface temperature after final rolling is between 680 and 810°C, accelerated cooling is carried out in different parts until the rail top surface temperature is between 480 and 590°C; among which, the cooling rate of the rail top surface is 2.0 to 5.0°C/s, the cooling rate of both sides of the rail head is 1.5 to 4.0°C/s, the cooling rate of both sides of the upper part of the rail waist is 1.0 to 3.0°C/s, the cooling rate of both sides of the middle part of the rail waist is 0.8 to 2.5°C/s, and the cooling rate of the center of the rail bottom is 1.5 to 3.0°C/s;
空冷阶段：将经过所述加速冷却阶段的钢轨空冷至室温。Air cooling stage: the rails that have undergone the accelerated cooling stage are air cooled to room temperature.
根据本发明的一个实施例，轨顶面冷却速度、轨头两侧冷却速度、轨腰上部两侧冷却速度、轨腰中部两侧冷却速度依次降低。According to one embodiment of the present invention, the cooling speed of the rail top surface, the cooling speed of both sides of the rail head, the cooling speed of both sides of the upper part of the rail waist, and the cooling speed of both sides of the middle part of the rail waist are reduced in sequence.
根据本发明的一个实施例，在所述加速冷却阶段，待终轧后钢轨的轨顶面温度在740～800℃之间时，进行分部位加速冷却至轨顶面温度为490～560℃。According to one embodiment of the present invention, in the accelerated cooling stage, when the rail top surface temperature of the steel rail after final rolling is between 740 and 800° C., accelerated cooling is performed in sections until the rail top surface temperature is between 490 and 560° C.
根据本发明的一个实施例，在所述加速冷却阶段，轨顶面冷却速度为3.3～4.3℃/s、轨头两侧冷却速度为2.9～3.7℃/s、轨腰上部两侧冷却速度为2.4～3.0℃/s、轨腰中部两侧冷却速度为1.5～2.1℃/s、轨底中心冷却速度为1.8～2.5℃/s。According to one embodiment of the present invention, in the accelerated cooling stage, the cooling rate of the rail top surface is 3.3-4.3°C/s, the cooling rate of both sides of the rail head is 2.9-3.7°C/s, the cooling rate of both sides of the upper part of the rail waist is 2.4-3.0°C/s, the cooling rate of both sides of the middle part of the rail waist is 1.5-2.1°C/s, and the cooling rate of the center of the rail bottom is 1.8-2.5°C/s.
根据本发明的一个实施例，进行所述在线热处理时，采用的冷却介质为水雾和/或压缩空气。According to one embodiment of the present invention, when performing the online heat treatment, the cooling medium used is water mist and/or compressed air.
根据本发明的一个实施例，在进行所述在线热处理之前，所述方法还包括：依次进行转炉冶炼、LF炉精炼、RH真空处理、连铸、轧制。According to one embodiment of the present invention, before performing the online heat treatment, the method further comprises: sequentially performing converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, and rolling.
根据本发明的一个实施例，以重量百分比计，所述钢轨的化学成分为：C:0.68～0.80％、Si:0.25～0.60％、Mn:0.75～1.20％、Cr:0.05～0.20％、Mn+Cr:0.85～1.45％、Mn/Cr:7.5～10.0、P:≤0.025％、S:≤0.020％，余量为Fe和不可避免的杂质。According to one embodiment of the present invention, the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ≤0.025%, S: ≤0.020%, and the remainder is Fe and unavoidable impurities.
根据本发明的另一方面，提出一种全断面抗拉强度分布均匀的珠光体 钢轨，以重量百分比计，所述钢轨的化学成分为：C:0.65～0.82％、Si:0.10～0.60％、Mn:0.65～1.25％、Cr:0.05～0.25％、Mn+Cr:0.75～1.50％、Mn/Cr:7.0～10.0、P:≤0.030％、S:≤0.025％，余量为Fe和不可避免的杂质；所述钢轨的轨头上圆角、轨头中心部、轨腰中心部、轨底中心部的抗拉强度均≥1080MPa，且差值＜80MPa。According to another aspect of the present invention, a pearlite having uniform tensile strength distribution over the entire cross section is provided. The steel rail has the following chemical compositions, measured by weight percentage: C: 0.65-0.82%, Si: 0.10-0.60%, Mn: 0.65-1.25%, Cr: 0.05-0.25%, Mn+Cr: 0.75-1.50%, Mn/Cr: 7.0-10.0, P: ≤0.030%, S: ≤0.025%, and the remainder is Fe and unavoidable impurities; the tensile strength of the fillet on the rail head, the center of the rail head, the center of the rail waist, and the center of the rail bottom of the steel rail are all ≥1080MPa, and the difference is <80MPa.
根据本发明的一个实施例，所述钢轨轨头上圆角处的抗拉强度≥1180MPa，延伸率≥10.0％；轨顶面硬度为350～390HB；轨头中心部、轨腰中心部、轨底中心部的抗拉强度均≥1080MPa，延伸率≥10.0％。According to one embodiment of the present invention, the tensile strength of the rounded corner on the rail head is ≥1180MPa, and the elongation is ≥10.0%; the hardness of the rail top surface is 350-390HB; the tensile strength of the center of the rail head, the center of the rail waist, and the center of the rail bottom are all ≥1080MPa, and the elongation is ≥10.0%.
根据本发明的一个实施例，以重量百分比计，所述钢轨的化学成分为：C:0.68～0.80％、Si:0.25～0.60％、Mn:0.75～1.20％、Cr:0.05～0.20％、Mn+Cr:0.85～1.45％、Mn/Cr:7.5～10.0、P:≤0.025％、S:≤0.020％，余量为Fe和不可避免的杂质。According to one embodiment of the present invention, the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ≤0.025%, S: ≤0.020%, and the remainder is Fe and unavoidable impurities.
通过本发明的技术方案，可以在无需添加多种微合金元素的情况下制备获得全断面抗拉强度分布均匀的珠光体钢轨，能够提高钢轨在运输、储存及服役过程中的抗外力损伤能力，能够显著降低外部伤害对钢轨服役性能的负面影响，能够提升钢轨的服役寿命和安全性，从而提高铁路整体的运输效率和安全性。Through the technical solution of the present invention, a pearlite rail with uniform tensile strength distribution over the entire cross-section can be prepared without adding multiple micro-alloying elements, which can improve the rail's ability to resist external force damage during transportation, storage and service, can significantly reduce the negative impact of external damage on the service performance of the rail, can improve the service life and safety of the rail, and thus improve the overall transportation efficiency and safety of the railway.
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。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.
图1示出根据本发明实施例的全断面抗拉强度分布均匀钢轨加速冷却及抗拉强度检验示意图。FIG1 is a schematic diagram showing accelerated cooling and tensile strength testing of a rail with uniform tensile strength distribution over the entire cross section according to an embodiment of the present invention.
为使本发明的目的、技术方案和优点更加清楚明白，以下结合具体实施例，并参照附图，对本发明实施例进一步详细说明。In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.
需要说明的是，本发明实施例中所有使用“第一”和“第二”的表述均是为了区分两个相同名称非相同的实体或者非相同的参量，可见“第一”“第二”仅为了表述的方便，不应理解为对本发明实施例的限定，后续实施例对此不再一一说明。It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.
本发明提出一种全断面抗拉强度分布均匀的珠光体钢轨的生产方法，包括：对轧制后钢轨进行在线热处理，其中所述在线热处理包括：The present invention provides a method for producing a pearlite rail with uniform tensile strength distribution over the entire cross section, comprising: performing online heat treatment on the rolled rail, wherein the online heat treatment comprises:
加速冷却阶段：待终轧后钢轨的轨顶面温度在680～810℃之间时，进行分部位加速冷却至轨顶面温度为480～590℃；其中，轨顶面冷却速度为2.0～5.0℃/s、轨头两侧冷却速度为1.5～4.0℃/s、轨腰上部两侧冷却速度为1.0～3.0℃/s、轨腰中部两侧冷却速度为0.8～2.5℃/s、轨底中心冷却速度为1.5～3.0℃/s；图1示出对各部位进行加速冷却；Accelerated cooling stage: when the rail top surface temperature after final rolling is between 680 and 810°C, accelerated cooling is performed in different parts until the rail top surface temperature is between 480 and 590°C; wherein, the cooling rate of the rail top surface is 2.0 to 5.0°C/s, the cooling rate of both sides of the rail head is 1.5 to 4.0°C/s, the cooling rate of both sides of the upper part of the rail waist is 1.0 to 3.0°C/s, the cooling rate of both sides of the middle part of the rail waist is 0.8 to 2.5°C/s, and the cooling rate of the center of the rail bottom is 1.5 to 3.0°C/s; Figure 1 shows the accelerated cooling of various parts;
空冷阶段：将经过所述加速冷却阶段的钢轨在冷床上空冷至室温。Air cooling stage: the rails that have undergone the accelerated cooling stage are air cooled to room temperature on a cooling bed.
本发明的发明人经过大量研究发现：The inventors of the present invention have found through extensive research that:
①针对加速冷却阶段：在钢轨轨头踏面温度为680～810℃时，为抑制钢轨中的先共析铁素体或先共析渗碳体析出，获得具有较高抗拉强度的钢轨，需要在高温阶段对其进行加速冷却，同时由于轨顶面截面积最大、轨头两侧次之、轨腰上部及轨底中心再次之、轨腰中心截面积最小，需要控制不同部位加速冷却速度不同，以使各部位获得分布更加分布均匀的抗拉强度，轨顶面冷却速度应最大，控制在2.0～5.0℃/s范围内，而轨头两侧、轨腰上部两侧、轨腰中心两侧的冷却速度依次降低，分别控制在1.5～4.0℃/s、1.0～3.0℃/s、0.8～2.5℃/s范围内，而轨底中心截面积介于轨头两侧和轨腰上部两侧之间，冷却速度控制在1.5～3.0℃/s范围内。① For the accelerated cooling stage: when the rail head and tread temperature is 680-810℃, in order to inhibit the precipitation of proeutectoid ferrite or proeutectoid cementite in the rail and obtain a rail with higher tensile strength, it is necessary to accelerate the cooling in the high temperature stage. At the same time, since the cross-sectional area of the rail top surface is the largest, the two sides of the rail head are second, the upper part of the rail waist and the center of the rail bottom are third, and the cross-sectional area of the center of the rail waist is the smallest, it is necessary to control the accelerated cooling speed of different parts to make each part obtain a more evenly distributed tensile strength. The cooling speed of the rail top surface should be the largest, which is controlled within the range of 2.0-5.0℃/s, while the cooling speeds of the two sides of the rail head, the two sides of the upper part of the rail waist, and the two sides of the center of the rail waist are reduced in turn, which are controlled within the range of 1.5-4.0℃/s, 1.0-3.0℃/s, and 0.8-2.5℃/s, respectively. The cross-sectional area of the center of the rail bottom is between the two sides of the rail head and the two sides of the upper part of the rail waist, and the cooling speed is controlled within the range of 1.5-3.0℃/s.
②针对空冷阶段：在加速冷却阶段将钢轨冷却至480～590℃后，钢轨各部位已完成珠光体相变，此时继续加速冷却已无明显意义，可将钢轨空冷至室温以进行后续工序处理。 ② For the air cooling stage: After the rail is cooled to 480-590℃ in the accelerated cooling stage, the pearlite phase transformation has been completed in all parts of the rail. At this time, there is no obvious meaning to continue accelerated cooling. The rail can be air-cooled to room temperature for subsequent processing.
在一些实施例中，在所述加速冷却阶段，待终轧后钢轨的轨顶面温度在740～800℃之间时，进行分部位加速冷却至轨顶面温度为490～560℃。In some embodiments, during the accelerated cooling stage, when the rail top surface temperature of the rail after final rolling is between 740°C and 800°C, accelerated cooling is performed in sections until the rail top surface temperature is between 490°C and 560°C.
在一些实施例中，在所述加速冷却阶段，轨顶面冷却速度为3.3～4.3℃/s、轨头两侧冷却速度为2.9～3.7℃/s、轨腰上部两侧冷却速度为2.4～3.0℃/s、轨腰中部两侧冷却速度为1.5～2.1℃/s、轨底中心冷却速度为1.8～2.5℃/s。In some embodiments, during the accelerated cooling stage, the cooling rate of the rail top surface is 3.3-4.3°C/s, the cooling rate on both sides of the rail head is 2.9-3.7°C/s, the cooling rate on both sides of the upper rail waist is 2.4-3.0°C/s, the cooling rate on both sides of the middle rail waist is 1.5-2.1°C/s, and the cooling rate at the center of the rail bottom is 1.8-2.5°C/s.
在一些实施例中，进行所述在线热处理时，采用的冷却介质为水雾和/或压缩空气。In some embodiments, when performing the online heat treatment, the cooling medium used is water mist and/or compressed air.
在一些实施例中，在进行所述在线热处理之前，所述方法还包括：依次进行转炉冶炼、LF炉精炼、RH真空处理、连铸、轧制。在所述在线热处理之后，可以对钢轨进行加工。在一些实施例中，钢轨的完整生产工艺可以为：采用低硫含钒钢水、经转炉或电炉进行冶炼、经LF精炼、RH或VD真空处理、大方坯保护连铸、钢坯加热炉加热、钢坯轧制前高压水除鳞、万能轧机轧制、钢轨在线热处理、步进式冷床室温空气冷却、平立复合矫直、钢轨规格检查、加工线处理、表面检查及入库。In some embodiments, before the online heat treatment is performed, the method further comprises: sequentially performing converter smelting, LF furnace refining, RH vacuum treatment, continuous casting, and rolling. After the online heat treatment, the rails may be processed. In some embodiments, the complete production process of the rails may be: using low-sulfur vanadium-containing molten steel, smelting in a converter or electric furnace, LF refining, RH or VD vacuum treatment, large square billet protection continuous casting, billet heating furnace heating, high-pressure water descaling before billet rolling, universal rolling mill rolling, rail online heat treatment, room temperature air cooling on a step-type cooling bed, horizontal and vertical composite straightening, rail specification inspection, processing line processing, surface inspection and warehousing.
在一些实施例中，以重量百分比计，所述钢轨的化学成分为：C:0.68～0.80％、Si:0.25～0.60％、Mn:0.75～1.20％、Cr:0.05～0.20％、Mn+Cr:0.85～1.45％、Mn/Cr:7.5～10.0、P:≤0.025％、S:≤0.020％，余量为Fe和不可避免的杂质。In some embodiments, the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ≤0.025%, S: ≤0.020%, and the remainder is Fe and unavoidable impurities.
以下详细说明本发明中所述钢轨主要化学元素含量的限定理由。The reasons for limiting the contents of main chemical elements in the rail of the present invention are described in detail below.
C是珠光体钢轨中使钢轨获得良好综合力学性能、促进珠光体转变的最重要、最廉价的元素。当C含量＜0.65％时，在本发明所述生产工艺下，无法保证钢轨具有合适的强硬度、无法保证钢轨抗外力损伤性能；当C含量＞0.82％时，在本发明所述生产工艺下，钢轨的强度指标过剩而韧塑性过低，碳化物比例过高，影响钢轨的韧塑性，对钢轨的安全使用有不利影响。因此，本发明中的碳含量限定在0.65～0.82％。C is the most important and cheapest element in pearlite rails that enables them to obtain good comprehensive mechanical properties and promote pearlite transformation. When the C content is less than 0.65%, under the production process described in the present invention, it is impossible to ensure that the rails have appropriate hardness and resistance to external damage; when the C content is greater than 0.82%, under the production process described in the present invention, the strength index of the rails is excessive but the toughness and plasticity are too low, and the carbide ratio is too high, which affects the toughness and plasticity of the rails and has an adverse effect on the safe use of the rails. Therefore, the carbon content in the present invention is limited to 0.65-0.82%.
Si在钢中的主要作用是抑制渗碳体形成和作为固溶强化元素，提高铁 素体基体硬度，改善钢的强度和硬度。当Si含量＜0.10％时，其固溶量偏低导致强化效果不明显；当Si含量＞0.60％时，易产生局部偏析，会降低钢的韧塑性，对钢轨的安全使用有不利影响。因此，本发明中的Si含量限定在0.10～0.60％。The main role of Si in steel is to inhibit the formation of cementite and act as a solid solution strengthening element to improve iron The Si content increases the hardness of the matrix and improves the strength and hardness of the steel. When the Si content is less than 0.10%, the solid solution content is too low, resulting in an insignificant strengthening effect; when the Si content is greater than 0.60%, local segregation is likely to occur, which will reduce the toughness and plasticity of the steel and have an adverse effect on the safe use of the rail. Therefore, the Si content in the present invention is limited to 0.10-0.60%.
Mn是提高钢中铁素体和奥氏体强度所必不可少的。当Mn含量＜0.65％时，其难以达到增加碳化物硬度从而增加钢的强硬度的作用；当Mn含量＞1.25％时，其会粗化晶粒尺寸，明显降低钢的韧塑性；同时Mn在钢中对C的扩散影响显著，在Mn偏析区域有可能产生贝氏体或马氏体等异常组织，同时影响钢轨的焊接性能。因此，本发明中的Mn含量限定在0.65～1.25％。Mn is essential for improving the strength of ferrite and austenite in steel. When the Mn content is less than 0.65%, it is difficult to increase the hardness of carbides and thus increase the strength of steel; when the Mn content is greater than 1.25%, it will coarsen the grain size and significantly reduce the toughness and plasticity of steel; at the same time, Mn has a significant effect on the diffusion of C in steel, and abnormal structures such as bainite or martensite may be produced in the Mn segregation area, which will affect the welding performance of the rail. Therefore, the Mn content in the present invention is limited to 0.65-1.25%.
Cr作为碳化物形成元素，与钢中的碳可形成多种碳化物；同时，Cr能均匀钢中碳化物分布，减小碳化物尺寸，提高钢轨的强度、硬度，改善钢轨的耐磨性能。当Cr含量＜0.05％时，形成的碳化物硬度及比例较低；当Cr含量＞0.25％，钢轨的淬透性过高，易使钢轨生产有害的贝氏体和马氏体组织，无法保证钢轨为珠光体组织，对钢轨安全使用有不利影响。因此，本发明中的Cr含量限定在0.05～0.25％。Cr, as a carbide-forming element, can form a variety of carbides with carbon in steel; at the same time, Cr can evenly distribute carbides in steel, reduce the size of carbides, increase the strength and hardness of rails, and improve the wear resistance of rails. When the Cr content is less than 0.05%, the hardness and proportion of the formed carbides are relatively low; when the Cr content is greater than 0.25%, the hardenability of the rails is too high, which can easily cause the rails to produce harmful bainite and martensite structures, and it is impossible to ensure that the rails are pearlite structures, which has an adverse effect on the safe use of the rails. Therefore, the Cr content in the present invention is limited to 0.05-0.25%.
由于Mn、Cr均为增加钢轨强硬度、提高钢轨淬透性的强化元素，需要限定其总含量以控制钢轨的显微组织中不会出现马氏体等异常组织，并保证钢轨成品性能满足要求。当Mn+Cr含量＜0.75％时，难以提供足够的碳化物，强化效果较弱，无法保证钢轨的硬度符合设计指标；当Mn+Cr含量＞1.45％时，由于Mn、Cr均能够提高钢轨的淬透性，钢轨中出现异常组织风险较大。因此，本发明中的Mn+Cr含量限定在0.75～1.45％。Since Mn and Cr are strengthening elements that increase the hardness and hardenability of rails, their total content needs to be limited to control the microstructure of the rails so that abnormal structures such as martensite do not appear, and to ensure that the performance of the finished rails meets the requirements. When the Mn+Cr content is less than 0.75%, it is difficult to provide sufficient carbides, the strengthening effect is weak, and it is impossible to ensure that the hardness of the rails meets the design indicators; when the Mn+Cr content is greater than 1.45%, since both Mn and Cr can improve the hardenability of rails, there is a greater risk of abnormal structures appearing in the rails. Therefore, the Mn+Cr content in the present invention is limited to 0.75-1.45%.
在钢轨钢中，控制Mn、Cr含量的平衡对钢轨的组织、硬度综合调控至关重要，仅提高Mn含量，钢轨组织较为稳定，但内部硬度较低，提高Cr含量，钢轨内部硬度能够提高，但易出现异常组织。当Mn/Cr＜7.0时，钢轨中Cr含量较高，虽然能够获得较高的硬度，但异常组织风险较大；当Mn/Cr＞10.0时，钢轨中Mn含量较高，虽然能够保持全珠光体组织，但内部硬度较低。因此，本发明中Mn/Cr值限定在7.0～10.0。In rail steel, controlling the balance of Mn and Cr content is crucial for the comprehensive regulation of rail structure and hardness. If only the Mn content is increased, the rail structure is relatively stable, but the internal hardness is low. If the Cr content is increased, the internal hardness of the rail can be improved, but abnormal structure is prone to occur. When Mn/Cr is less than 7.0, the Cr content in the rail is relatively high. Although a higher hardness can be obtained, the risk of abnormal structure is relatively high; when Mn/Cr is greater than 10.0, the Mn content in the rail is relatively high. Although the full pearlite structure can be maintained, the internal hardness is relatively low. Therefore, the Mn/Cr value in the present invention is limited to 7.0-10.0.
P和S均为钢轨中无法完全除去的杂质元素。P会在钢轨组织晶界处偏 聚，严重降低钢轨的韧性；S在钢中易形成MnS夹杂，对钢轨耐磨耗性能和耐接触疲劳性能有害。因此，本发明中的P含量需控制在0.030％以下；S含量需控制在0.030％以下。P and S are impurity elements that cannot be completely removed from the rail. The P content in the present invention should be controlled below 0.030%; the S content should be controlled below 0.030%.
本发明还提出一种全断面抗拉强度分布均匀的珠光体钢轨，该钢轨采用上述方法制备，以重量百分比计，所述钢轨的化学成分为：C:0.65～0.82％、Si:0.10～0.60％、Mn:0.65～1.25％、Cr:0.05～0.25％、Mn+Cr:0.75～1.50％、Mn/Cr:7.0～10.0、P:≤0.030％、S:≤0.025％，余量为Fe和不可避免的杂质；所述钢轨的轨头上圆角、轨头中心部、轨腰中心部、轨底中心部的抗拉强度均≥1080MPa，且差值＜80MPa。图1示出抗拉强度检验示意图，其中位置①为钢轨上圆角抗拉强度检验位置、位置②为轨头中心抗拉强度检验位置，位置③为轨腰中心抗拉强度检验位置、位置④为轨底中心抗拉强度检验位置。The present invention also provides a pearlite rail with uniform tensile strength distribution over the entire cross section. The rail is prepared by the above method. The chemical composition of the rail is, by weight percentage, C: 0.65-0.82%, Si: 0.10-0.60%, Mn: 0.65-1.25%, Cr: 0.05-0.25%, Mn+Cr: 0.75-1.50%, Mn/Cr: 7.0-10.0, P: ≤0.030%, S: ≤0.025%, and the remainder is Fe and unavoidable impurities; the tensile strength of the fillet on the rail head, the center of the rail head, the center of the rail waist, and the center of the rail bottom of the rail are all ≥1080MPa, and the difference is <80MPa. Figure 1 shows a schematic diagram of tensile strength testing, wherein position ① is the tensile strength testing position for the fillet on the rail, position ② is the tensile strength testing position for the center of the rail head, position ③ is the tensile strength testing position for the center of the rail waist, and position ④ is the tensile strength testing position for the center of the rail bottom.
在一些实施例中，所述钢轨轨头上圆角处的抗拉强度≥1180MPa，延伸率≥10.0％；轨顶面硬度为350～390HB；轨头中心部、轨腰中心部、轨底中心部的抗拉强度均≥1080MPa，延伸率≥10.0％。In some embodiments, the tensile strength of the rounded corners on the rail head is ≥1180MPa, and the elongation is ≥10.0%; the hardness of the rail top surface is 350-390HB; the tensile strength of the center of the rail head, the center of the rail waist, and the center of the rail bottom are all ≥1080MPa, and the elongation is ≥10.0%.
在一些实施例中，以重量百分比计，所述钢轨的化学成分为：C:0.68～0.80％、Si:0.25～0.60％、Mn:0.75～1.20％、Cr:0.05～0.20％、Mn+Cr:0.85～1.45％、Mn/Cr:7.5～10.0、P:≤0.025％、S:≤0.020％，余量为Fe和不可避免的杂质。In some embodiments, the chemical composition of the rail is, by weight percentage, C: 0.68-0.80%, Si: 0.25-0.60%, Mn: 0.75-1.20%, Cr: 0.05-0.20%, Mn+Cr: 0.85-1.45%, Mn/Cr: 7.5-10.0, P: ≤0.025%, S: ≤0.020%, and the remainder is Fe and unavoidable impurities.
综上所述，本发明采用了控制钢轨化学成分和在线热处理工艺的方法，所得到的珠光体钢轨在无需添加多种微合金元素的情况下具有全断面均匀分布的抗拉强度，能够提高钢轨在运输、储存及服役过程中的抗外力损伤能力，能够显著降低外部伤害对钢轨服役性能的负面影响，能够提升钢轨的服役寿命和安全性，从而提高铁路整体的运输效率和安全性。同时本发明提供的全断面抗拉强度分布均匀的珠光体钢轨生产方法简单、易操作，利于推广应用。In summary, the present invention adopts a method of controlling the chemical composition of the rail and the online heat treatment process, and the obtained pearlite rail has a tensile strength uniformly distributed over the entire section without adding multiple microalloying elements, which can improve the rail's ability to resist external damage during transportation, storage and service, and can significantly reduce the negative impact of external damage on the service performance of the rail, and can improve the service life and safety of the rail, thereby improving the overall transportation efficiency and safety of the railway. At the same time, the production method of the pearlite rail with uniform tensile strength distribution over the entire section provided by the present invention is simple, easy to operate, and conducive to promotion and application.
下面根据具体的实施例进行说明。 The following is a description based on specific embodiments.
实施例1～3和对比例1～3对应选用以下编号1～3化学成分的钢轨，具体化学成分如表1所示，余量为Fe和不可避免的杂质。Examples 1 to 3 and Comparative Examples 1 to 3 correspond to steel rails with chemical compositions numbered 1 to 3 below, and their specific chemical compositions are shown in Table 1, with the remainder being Fe and unavoidable impurities.
表1：钢轨化学成分(wt％)
Table 1: Rail chemical composition (wt%)
实施例1～3对比例1～3热处理工艺参数如表2所示，实施例和对比例的冶炼工艺和轧制工艺之间的差异是可以忽略不计的。Examples 1 to 3 Comparative Examples 1 to 3 The heat treatment process parameters are shown in Table 2. The differences between the smelting process and the rolling process of the examples and the comparative examples are negligible.
表2：热处理工艺参数
Table 2: Heat treatment process parameters
实施例1～3和对比例1～3的显微组织、拉伸性能及轨顶面硬度如表3所示。其中，抗拉强度测量位置如图1所示，位置①为钢轨上圆角抗拉强度检验位置、位置②为轨头中心抗拉强度检验位置，位置③为轨腰中心抗拉强度检验位置、位置④为轨底中心抗拉强度检验位置。按照GB/T 228.1《金属材料拉伸试验第1部分：室温试验方法》中规定，在各位置取拉伸试样并进行拉伸试验。 The microstructure, tensile properties and rail top surface hardness of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 3. The tensile strength measurement positions are shown in Figure 1, where position ① is the tensile strength test position for the rounded corner of the rail, position ② is the tensile strength test position for the center of the rail head, position ③ is the tensile strength test position for the center of the rail waist, and position ④ is the tensile strength test position for the center of the rail bottom. According to GB/T 228.1 "Tensile Test of Metallic Materials Part 1: Room Temperature Test Method", tensile specimens were taken at each position and tensile tests were performed.
表3：显微组织、轨顶面硬度及拉伸性能
Table 3: Microstructure, rail top surface hardness and tensile properties
通过比较实施例和对比例可以看出，本发明所述的实施例在相同的化学成分和冶炼工艺下，对轧制后钢轨的热处理方式的不同对钢轨的最终性能将产生显著影响，通过采用本发明所述的方法所获得的钢轨的轨顶面硬度处于350～390HB范围内，轨头上圆角、轨头中心、轨腰中心、轨底中心各位置抗拉强度较高，且差值＜80MPa，分布均匀，能够有效降低钢轨表面及浅表面伤损对钢轨服役性能和安全性的幅面影响；而对比例则在未经热 处理的部分出现明显的抗拉强度降低，钢轨在使用中该位置易受外力损伤导致钢轨产生裂纹继而可能断裂。By comparing the embodiments and comparative examples, it can be seen that in the embodiments of the present invention, under the same chemical composition and smelting process, different heat treatment methods for the rolled rails will have a significant impact on the final performance of the rails. The rail top surface hardness of the rails obtained by the method of the present invention is within the range of 350-390HB, and the tensile strength at the fillet on the rail head, the center of the rail head, the center of the rail waist, and the center of the rail bottom is relatively high, and the difference is less than 80MPa, and the distribution is uniform, which can effectively reduce the wide range of the impact of the surface and shallow surface damage of the rails on the service performance and safety of the rails; while in the comparative example, the rail top surface hardness of the rails obtained by the method of the present invention is within the range of 350-390HB, and the tensile strength at the fillet on the rail head, the center of the rail head, the center of the rail waist, and the center of the rail bottom is relatively high, and the difference is less than 80MPa, and the distribution is uniform, which can effectively reduce the wide range of the impact of the surface and shallow surface damage of the rails on the service performance and safety of the rails; The tensile strength of the treated part is significantly reduced, and this position of the rail is easily damaged by external forces during use, causing cracks in the rail and possible breakage.
所属领域的普通技术人员应当理解：以上任何实施例的讨论仅为示例性的，并非旨在暗示本发明实施例公开的范围(包括权利要求)被限于这些例子；在本发明实施例的思路下，以上实施例或者不同实施例中的技术特征之间也可以进行组合，并存在如上所述的本发明实施例的不同方面的许多其它变化，为了简明它们没有在细节中提供。因此，凡在本发明实施例的精神和原则之内，所做的任何省略、修改、等同替换、改进等，均应包括在本发明实施例的保护范围之内。 A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160010188A1 (en) * | 2014-07-14 | 2016-01-14 | Pangang Group Panzhihua Iron & Steel Research Institute Co., Ltd. | Heat treatment method for increasing the depth of hardening layer in a steel rail and steel rail obtained with the method |
| CN111621631A (en) * | 2020-05-29 | 2020-09-04 | 武汉钢铁有限公司 | Efficient heat treatment production method for steel rail and steel rail prepared by same |
| CN113637913A (en) * | 2021-08-18 | 2021-11-12 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for improving corrosion-resistant fracture-resistant capacity of steel rail and steel rail produced by method |
| CN114672730A (en) * | 2022-03-18 | 2022-06-28 | 武汉钢铁有限公司 | Rolling contact fatigue resistant steel rail for passenger-cargo mixed transportation railway and production method thereof |
| CN115466904A (en) * | 2022-08-10 | 2022-12-13 | 包头钢铁（集团）有限责任公司 | Production method of wear-resistant corrosion-resistant steel rail for low-temperature area railway |
| CN116590593A (en) * | 2023-04-13 | 2023-08-15 | 攀钢集团攀枝花钢铁研究院有限公司 | High-corrosion-resistance and high-wear-resistance pearlitic steel rail and preparation method thereof |
| CN117144111A (en) * | 2023-08-31 | 2023-12-01 | 攀钢集团攀枝花钢铁研究院有限公司 | Pearlitic steel rail with uniform full-section tensile strength distribution and production method thereof |
| CN117144110A (en) * | 2023-08-31 | 2023-12-01 | 攀钢集团攀枝花钢铁研究院有限公司 | Pearlite rail with excellent internal hardness distribution and production method thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| DE4319165C1 (en) * | 1993-06-09 | 1994-08-18 | Elektro Thermit Gmbh | Process for the intermediate cast welding of isothermally annealed rails |
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2023
- 2023-08-31 CN CN202311118441.7A patent/CN117144111A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160010188A1 (en) * | 2014-07-14 | 2016-01-14 | Pangang Group Panzhihua Iron & Steel Research Institute Co., Ltd. | Heat treatment method for increasing the depth of hardening layer in a steel rail and steel rail obtained with the method |
| CN111621631A (en) * | 2020-05-29 | 2020-09-04 | 武汉钢铁有限公司 | Efficient heat treatment production method for steel rail and steel rail prepared by same |
| CN113637913A (en) * | 2021-08-18 | 2021-11-12 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for improving corrosion-resistant fracture-resistant capacity of steel rail and steel rail produced by method |
| CN114672730A (en) * | 2022-03-18 | 2022-06-28 | 武汉钢铁有限公司 | Rolling contact fatigue resistant steel rail for passenger-cargo mixed transportation railway and production method thereof |
| CN115466904A (en) * | 2022-08-10 | 2022-12-13 | 包头钢铁（集团）有限责任公司 | Production method of wear-resistant corrosion-resistant steel rail for low-temperature area railway |
| CN116590593A (en) * | 2023-04-13 | 2023-08-15 | 攀钢集团攀枝花钢铁研究院有限公司 | High-corrosion-resistance and high-wear-resistance pearlitic steel rail and preparation method thereof |
| CN117144111A (en) * | 2023-08-31 | 2023-12-01 | 攀钢集团攀枝花钢铁研究院有限公司 | Pearlitic steel rail with uniform full-section tensile strength distribution and production method thereof |
| CN117144110A (en) * | 2023-08-31 | 2023-12-01 | 攀钢集团攀枝花钢铁研究院有限公司 | Pearlite rail with excellent internal hardness distribution and production method thereof |
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| AU2024205069A1 (en) | 2025-03-20 |
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