CN113637914A - High-strength and high-toughness steel rail and preparation method thereof - Google Patents
High-strength and high-toughness steel rail and preparation method thereof Download PDFInfo
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
- B21B1/085—Rail sections
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
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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
- C22C38/04—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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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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
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Abstract
The invention discloses a preparation method of a high-strength and high-toughness steel rail, which comprises the following steps: preparing a steel rail casting blank; heating the steel rail casting blank to 1230-1280 ℃, wherein the soaking time is 2-4 h; rolling the heated steel rail casting blank into a steel rail, wherein the initial rolling temperature is 1120-1180 ℃, the final rolling temperature is 900-950 ℃, and the final rolling deformation is 10-15%; and carrying out on-line heat treatment on the rolled steel rail by using waste heat, cooling the steel rail by standing the steel rail by using the waste heat in air, and blowing a cooling medium to the rail head of the steel rail when the central temperature of the top surface of the steel rail is less than or equal to 800 ℃ so as to accelerate the cooling of the rail head of the steel rail to 400-500 ℃, and then continuously cooling the steel rail to room temperature in the air. The invention also discloses a high-strength and high-toughness steel rail prepared by the method. According to the invention, through the steel rail component optimization and controlled rolling and controlled cooling process, the pearlite lamella refinement of the steel rail is realized, so that the toughness and plasticity of the steel rail are improved.
Description
Technical Field
The invention belongs to the technical field of steel rail manufacturing, and particularly relates to a high-strength and high-toughness steel rail and a preparation method thereof.
Background
With the rapid development of the heavy-load line transportation in China, the axle weight of a train is gradually upgraded from 27t to 30t which is common at present, and meanwhile, the requirement on the strength and hardness of a steel rail is more severe. Therefore, in order to meet the requirement of railways on the wear resistance of the rails, the strength and hardness of the rails are continuously improved, for example, the original 1180MPa grade U75V rail of the large-Qin heavy load line is gradually transited to 1280MPa grade U78CrV rail, and part of lines are trial paved with 1330MPa grade U95Cr hypereutectoid steel rails. However, increasing the strength and hardness of the steel rail is often accompanied by a decrease in the ductility and toughness of the steel rail, which can bring about a significant risk to the driving safety of the train.
The method for improving the strength and hardness of the steel rail mainly comprises the steps of strengthening a pearlite structure by alloy, reducing interlayer spacing of pearlite sheets, controlling the proportion of ferrite and cementite and the like. On the premise of ensuring the strength and hardness of the steel rail, the toughness and plasticity of the steel rail can be improved by adjusting the components of the steel rail, controlling and refining the structure of the steel rail and the like, and the reduction of the toughness and plasticity caused by the high strength and hardness of the steel rail is reduced. Both the coarse pearlite interlamellar spacing and the pellets reduce rail fracture toughness. For a specific steel rail component, the steel rail pearlite sheet interlayer spacing is mainly influenced by the phase transition temperature and is inversely proportional to the supercooling degree in the heat treatment process. Furthermore, the influence of transformation temperature on the size of pearlite pellets is similar to the lamella spacing, i.e. the lower the transformation temperature, the smaller the pellet size. Therefore, to realize the matching of the strength and the hardness of the heavy-duty steel rail, a method for optimally combining the components and the structure of the steel rail is required.
Chinese patent CN112239831A discloses a high-toughness and high-cold railway steel rail and a production method thereof, wherein the steel rail comprises the following design components in percentage by mass: 0.40-0.65%, Si: 0.10 to 0.60%, Mn: 0.50-1.10%, Cr: 0.1-0.3%, P is less than or equal to 0.020%, S is less than or equal to 0.020%, V: 0.004-0.006% of iron and inevitable impurities as the rest; according to the invention, the foaming agent is used in the LF heating process, and the whole-process protection pouring is adopted, so that the impact load bearing capacity and the low-temperature impact crack propagation resistance capacity of the steel rail are improved. However, the carbon content of the steel rail with the composition is low, and the high hardness is not enough to meet the development requirement of the large axle weight of the existing heavy-duty line.
Chinese patent CN112501418A discloses a steel rail for heavy haul railway and a preparation method thereof, wherein the rail bottom and the rail web part of the steel rail after heat preservation treatment are heated and cooled for multiple times, austenite grain size is reduced through multiple accelerated cooling, and finally the steel rail for heavy haul railway with smaller pellet size is obtained, and the toughness of the steel rail is greatly improved. However, the method needs to repeatedly heat the steel rail and accelerate cooling, and has high energy consumption and large difficulty in industrial production and operation.
Chinese patent CN111485171A discloses a steel rail material for heavy haul railway and a production method thereof; the percentage content of the steel rail is C: 0.75-0.80%, Si: 0.62 to 0.70%, Mn: 0.92-0.98%, P is less than or equal to 0.025%, S is less than or equal to 0.025%, V: 0.04-0.12% of Fe, and the balance of Fe; the steel rail is rolled by adopting a billet with the section of 280mm multiplied by 380mm, and the strength and the hardness of the steel rail are improved by optimizing C, Si and Mn elements and adding V alloy elements; after rolling, the steel rail is subjected to heat treatment by utilizing the waste heat of the steel rail, and is rapidly cooled to refine pearlite rail tissue lamellar of the steel rail, so that the strength and the toughness of the steel rail are improved. However, the invention mainly ensures the fixed length of the steel rail by the billet size and the controlled rolling process, and does not clearly determine the heat treatment cooling rate.
Chinese patent CN109207691A discloses a method for producing a steel rail for heavy haul railway; after the steel rail is subjected to primary heat treatment by using rolling waste heat, the steel rail is heated to 650-700 ℃ again by using a heating device, and the steel rail is returned to be subjected to secondary heat treatment, so that the heavy-load steel rail with the tensile strength of above 1380MPa, the-20 ℃ low-temperature fracture toughness of not less than 38 MPa-m 1/2 and excellent wear resistance and contact fatigue resistance can be obtained. However, the steel rail needs to be reheated and subjected to secondary heat treatment, and the requirements on equipment and process control are high.
Chinese patent CN104195433B discloses a high-strength and high-toughness pearlitic steel rail and a production method thereof; the steel rail comprises the following components: 0.75 to 0.84%, Si: 0.3-0.8%, Mn: 0.5-1.5%, V: 0.04-0.12%, Ti: 0.004-0.02%, 0.1-0.25% of V +10Ti, 30ppm of N, 0.02% of P, 0.008% of S, V: 0.04-0.12%, and the balance of Fe and inevitable impurities; the rolling temperature of the steel rail is 1120-1180 ℃, the finishing temperature is 840-880 ℃, the steel rail is cooled to below 600 ℃ at the speed of less than or equal to 2 ℃/s after rolling, and then air cooling is carried out, so that pearlite grains of the obtained steel rail are refined, and the steel rail has good toughness. However, the invention requires narrow temperature control windows for initial rolling and final rolling, and has high requirements on the process.
Chinese patent CN104480390A discloses a high impact toughness steel rail and a production method thereof; the spacing between steel rail layers is 0.05-0.09 mu m, the normal-temperature impact energy is 30-35J, and the steel rail comprises the following components: c: 0.71-0.82%, Si: 0.25 to 0.45%, Mn: 0.75-1.05%, V: 0.03-0.15%, P is less than or equal to 0.030%, S is less than or equal to 0.035%, Al is less than or equal to 0.020%, and the balance of Fe and inevitable impurities; the tensile strength of the obtained steel rail is more than 1300MPa, the U-shaped impact toughness of the rail head can reach more than 30J, and the steel rail has good toughness matching. However, the method is mainly suitable for improving the low-temperature impact toughness of the steel rail of the alpine line, and the pearlite interlamellar spacing fluctuation range of the steel rail is large.
Therefore, the toughness and plasticity of the existing heavy-duty steel rail are poor, and the toughness and plasticity of the steel rail needs to be further improved.
Disclosure of Invention
The invention provides a steel rail with high strength and toughness and a preparation method thereof, aiming at the problem of poor toughness and plasticity of heavy-duty steel rails. The method realizes the pearlite lamellar refinement of the steel rail by improving the alloy content in the steel rail and combining the controlled rolling and controlled cooling process, thereby achieving the purpose of improving the toughness and the plasticity of the steel rail. The invention is suitable for domestic heavy-load lines.
In order to achieve the purpose, the invention adopts the following technical scheme:
according to an aspect of the present invention, there is provided a method for producing a high-toughness steel rail, comprising the steps of:
the method comprises the following steps: preparing a steel rail casting blank;
step two: heating the steel rail casting blank obtained in the first step to 1230-1280 ℃, wherein the soaking time is 2-4 h;
step three: rolling the steel rail casting blank obtained in the step two into a steel rail, wherein the initial rolling temperature is 1120-1180 ℃, the final rolling temperature is 900-950 ℃, and the final rolling deformation is 10-15%;
step four: and (3) carrying out online heat treatment on the steel rail obtained in the step three by using waste heat, cooling the steel rail by standing the steel rail with the waste heat in air, and blowing a cooling medium to the rail head of the steel rail when the central temperature of the top surface of the steel rail is less than or equal to 800 ℃ so as to accelerate the cooling of the rail head of the steel rail to 400-500 ℃, and then continuously cooling the steel rail to room temperature in the air.
According to one embodiment of the invention, the steel rail casting blank prepared in the first step comprises the following components in percentage by mass: c: 0.65-0.85%, Si: 0.3-0.8%, Mn: 0.5-1.0%; cr: 0.5-1.2%; v: 0.05-0.13 percent of Fe, less than or equal to 0.008 percent of S, less than or equal to 0.025 percent of P, and the balance of Fe and inevitable impurities.
According to an embodiment of the invention, the preparation of the steel rail casting blank in the first step comprises the following steps: the steel rail casting blank is prepared through a molten iron pretreatment process, a converter smelting process, an LF furnace refining process, an RH vacuum treatment process and a continuous casting process.
According to an embodiment of the invention, the preparation of the steel rail casting blank in the first step comprises the following steps: the molten steel is fed into a furnace by adopting low-S molten iron, and soft argon blowing is carried out on the molten steel under the protection of high-alkalinity refining slag to homogenize alloy components.
According to one embodiment of the invention, the argon blowing time is 5min to 10 min.
According to one embodiment of the invention, a universal rolling line is used in the third step to roll the steel rail casting blank into the steel rail.
According to one embodiment of the invention, the cooling rate of the rail head accelerated cooling in the fourth step is 4.0-6.0 ℃/s.
According to an embodiment of the present invention, the cooling medium in the fourth step is compressed air or a water mist mixture.
According to one embodiment of the invention, the step four of blowing the cooling medium to the rail head comprises blowing the cooling medium to the tread of the rail head, two sides of the rail head and the lower jaw of the rail head.
According to another aspect of the present invention, there is provided a high-toughness steel rail, which comprises the following components by mass: c: 0.65-0.85%, Si: 0.3-0.8%, Mn: 0.5-1.0%; cr: 0.5-1.2%; v: 0.05-0.13 percent of Fe, less than or equal to 0.008 percent of S, less than or equal to 0.025 percent of P, and the balance of Fe and inevitable impurities.
Compared with the prior art, the technical scheme of the invention realizes the pearlite lamella refinement of the steel rail through the steel rail component optimization and the controlled rolling and controlled cooling process, thereby improving the toughness and the plasticity of the steel rail. The spacing between pearlite sheets of the steel rail produced by the method is 65-85 nm, and the tensile strength (R) ism) Not less than 1350MPa, elongation (A) not less than 12%, and excellent strength, toughness and plasticity, and is suitable for heavy load railway.
Drawings
FIG. 1 is a schematic cross-sectional view of a steel rail;
fig. 2 is an SEM image of a microscopic lamellar pearlite structure of the high-toughness steel rail provided by the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As required, detailed embodiments of the present invention are disclosed in the present specification; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. In the following description, various operating parameters and components are described in various embodiments as contemplated. These specific parameters and components are used in this specification as examples only and are not meant to be limiting.
The invention provides a preparation method of a high-strength and high-toughness steel rail, which comprises the following steps:
(1) and (3) feeding low-S molten iron into a furnace, and carrying out soft argon blowing on the molten steel under the protection of the high-alkalinity refining slag to homogenize alloy components, wherein the argon blowing time is 5-10 min.
(2) And (2) performing electric heating refining on the molten steel subjected to argon blowing in the step (1) in an LF furnace, accurately regulating and controlling main alloy components, performing RH vacuum circulation degassing treatment after LF refining is finished, and forming the obtained molten steel into a steel rail casting blank through a continuous casting process. The steel rail casting blank comprises the following components in percentage by mass: c: 0.65-0.85%, Si: 0.3-0.8%, Mn: 0.5-1.0%; cr: 0.5-1.2%; v: 0.05-0.13 percent of Fe, less than or equal to 0.008 percent of S, less than or equal to 0.025 percent of P, and the balance of Fe and inevitable impurities.
(3) And (3) heating the steel rail casting blank obtained in the step (2) to 1230-1280 ℃ (namely the heating temperature is 1230-1280 ℃), and keeping the temperature for 2-4 h.
(4) And (3) rolling the steel rail casting blank heated in the step (3) by using a universal rolling mill, wherein the initial rolling temperature is 1120-1180 ℃, the final rolling temperature is 900-950 ℃, and the final rolling deformation is 10-15%.
(5) Carrying out on-line heat treatment on the steel rail rolled in the step (4) by using waste heat, and specifically comprising the following steps: and (3) cooling the steel rail by waste heat in air, entering an online heat treatment unit when the central temperature of the top surface of the steel rail is less than or equal to 800 ℃ (namely the opening temperature is less than or equal to 800 ℃), and blowing cooling media to the tread, the two sides and the lower jaw of the steel rail head for accelerated cooling so that the steel rail head is accelerated and cooled to 400-500 ℃ (namely the final cooling temperature is 400-500 ℃) at a cooling rate of 4.0-6.0 ℃/s. After that, the rail is stopped from accelerated cooling and continues to cool to room temperature in air.
For ease of understanding, fig. 1 shows a schematic cross-sectional view of a rail, as shown, the rail comprises a head 1, a web 2 and a foot 3, the head 1 comprising a head tread 11, a head side 12 and a head chin 13. In the process of online heat treatment, cooling media are sprayed on the railhead tread 11, the two railhead side surfaces 12 and the railhead lower jaw 13 to accelerate the cooling of the rail head of the steel rail.
The second aspect of the invention provides a high-strength and high-toughness steel rail prepared by the preparation method. The steel rail comprises the following components in percentage by mass: c: 0.65-0.85%, Si: 0.3-0.8%, Mn: 0.5-1.0%; cr: 0.5-1.2%; v: 0.05-0.13 percent of Fe, less than or equal to 0.008 percent of S, less than or equal to 0.025 percent of P, and the balance of Fe and inevitable impurities.
The spacing between pearlite sheets of the steel rail produced by the preparation method provided by the invention is 65-85 nm, and the tensile strength (R) ism) The steel rail has the advantages of not less than 1350MPa, the elongation (A) of not less than 12 percent and good toughness, and is suitable for domestic heavy-load lines.
The present invention will be specifically described below with reference to specific examples.
The invention selects seven groups of steel rail samples with different chemical compositions and production processes for comparison. In examples 1 to 5, the method of the present invention was used as described above, and the specific rail components and rolling and heat treatment process parameters are shown in tables 1 to 3 below. Examples 1 to 5 were the same in step (1) except that the argon blowing time was different. Examples 1-5 argon blowing times in step one were 5min, 7min, 8min, 10min, 6min, respectively. Comparative examples 1-2 were designed according to conventional rail requirements. Specifically, preparing a steel rail casting blank according to a conventional method, heating the obtained steel rail casting blank to a heating temperature, and preserving heat for a certain heat preservation time; rolling the heated steel rail casting blank by using a universal rolling mill; and (3) carrying out online heat treatment on the rolled steel rail by utilizing waste heat, cooling the steel rail by standing the steel rail with the waste heat in air, entering an online heat treatment unit when the central temperature of the top surface of the steel rail reaches the start cooling temperature, accelerating the cooling to the final cooling temperature at a certain cooling rate, and then carrying out air cooling to room temperature to obtain the steel rail in the comparative example 1-2. The steel rail composition and rolling and heat treatment process parameters of comparative examples 1-2 are shown in tables 1-3 below.
The compositions of the rail slabs in examples 1 to 5 and comparative examples 1 to 2 are shown in Table 1.
TABLE 1 composition of steel rail casting blank (%)
| Item | Rail numbering | C | Si | Mn | P | S | Cr | V | Fe |
| Example 1 | 1# | 0.71 | 0.70 | 0.60 | 0.020 | 0.007 | 0.85 | 0.08 | Balance of |
| Example 2 | 2# | 0.80 | 0.64 | 0.84 | 0.019 | 0.006 | 1.00 | 0.13 | Balance of |
| Example 3 | 3# | 0.65 | 0.50 | 1.00 | 0.015 | 0.008 | 1.20 | 0.07 | Balance of |
| Example 4 | 4# | 0.75 | 0.80 | 0.50 | 0.025 | 0.004 | 0.65 | 0.12 | Balance of |
| Example 5 | 5# | 0.85 | 0.30 | 0.75 | 0.010 | 0.005 | 0.50 | 0.05 | Balance of |
| Comparative example 1 | D1# | 0.79 | 0.55 | 0.70 | 0.010 | 0.007 | 0.23 | - | Balance of |
| Comparative example 2 | D2# | 0.78 | 0.56 | 0.73 | 0.011 | 0.007 | 0.22 | - | Balance of |
A cast rail slab containing the above components was heated and rolled to 60kg/m rail, and the heating and rolling process parameters are shown in Table 2. The heat treatment process parameters after rolling are shown in table 3.
TABLE 2 Steel rail heating and rolling technological parameter table
TABLE 3 Steel rail heat treatment process parameter table
| Rail numbering | Cold start temperature/. degree C | Cooling Rate/. degree.C/s | Final cooling temperature/. |
| 1# | 735 | 4.0 | 500 |
| 2# | 800 | 5.5 | 430 |
| 3# | 750 | 5.2 | 400 |
| 4# | 740 | 5.0 | 480 |
| 5# | 780 | 6.0 | 450 |
| D1# | 780 | 0.8 | 500 |
| D2# | 750 | 0.9 | 500 |
And air-cooling the steel rail subjected to heat treatment to room temperature, and respectively carrying out structure analysis and tensile property test. A metallographic sample with the size of 10mm multiplied by 10mm is taken below the steel rail head tread of 1mm, the metallographic sample is subjected to sample preparation and corrosion on the longitudinal surface of the position 11mm away from the steel rail tread, the longitudinal surface is observed by a scanning electron microscope, data not less than 1000 lamellar spacing data are counted by using a line cutting method, and the mean value of the data is used for representing the pearlite lamellar spacing of the steel rail sample. Fig. 2 shows an SEM image of the micro lamellar pearlite structure of the # 1 steel rail. The tensile property of the tensile sample is tested by sampling according to the requirements of TB/T2344 technical conditions for ordering steel rails from 43kg/m to 75 kg/m. The results of the tissue analysis and performance testing are shown in Table 4.
TABLE 4 Steel Rail organization and tensile Property Table
| Rail numbering | Lamella spacing/nm | Yield strength/MPa | Tensile strength/MPa | A/％ | Z/％ |
| 1# | 81 | 984 | 1392 | 12.8 | 35.5 |
| 2# | 78 | 996 | 1408 | 13.6 | 36.8 |
| 3# | 85 | 970 | 1356 | 13.2 | 36.2 |
| 4# | 73 | 989 | 1387 | 13.8 | 37.2 |
| 5# | 65 | 1011 | 1415 | 14.1 | 37.0 |
| D1# | 136 | 785 | 1032 | 11.3 | 33.8 |
| D2# | 128 | 823 | 1083 | 10.4 | 32.1 |
As can be seen from table 4: the interlayer spacing of the pearlite plates of the steel rail produced by the preparation method provided by the invention is 65-85 nm, which is smaller than the interlayer spacing of the pearlite plates of the steel rail designed according to the requirements of conventional steel rails; the yield strength of the steel rail produced by the preparation method provided by the invention is more than or equal to 970MPa, the tensile strength is more than or equal to 1350MPa, the elongation (A) is more than or equal to 12%, the reduction of area (Z) is more than or equal to 35%, and the steel rail is obviously superior to the steel rail designed according to the requirements of the conventional steel rail. That is, the pearlite lamella of the steel rail designed according to the requirements of the conventional steel rail is thick and thick, and the toughness of the steel rail is poor, but the lamella spacing of the steel rail produced by the method is refined, so that the steel rail has good toughness matching performance, and the service condition of the steel rail on a heavy-load line can be effectively improved.
It should be understood that although the steps of such methods, etc., are described as occurring in a certain order, such methods may perform operations using the described steps which are performed in an order other than the order described herein. It is further understood that certain steps may be performed simultaneously, that other steps may be added, or that certain steps described herein may be omitted. In other words, the description of the methods herein is provided for the purpose of illustrating certain embodiments and should not be construed as limiting the claimed invention in any way.
The above-described embodiments, particularly any "preferred" embodiments, are possible examples of implementations, and are presented merely for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiments without departing substantially from the spirit and principles of the technology described herein. All such modifications are intended to be included within the scope of this disclosure.
Claims (10)
1. The preparation method of the high-strength and high-toughness steel rail is characterized by comprising the following steps of:
the method comprises the following steps: preparing a steel rail casting blank;
step two: heating the steel rail casting blank obtained in the first step to 1230-1280 ℃, wherein the soaking time is 2-4 h;
step three: rolling the steel rail casting blank obtained in the step two into a steel rail, wherein the initial rolling temperature is 1120-1180 ℃, the final rolling temperature is 900-950 ℃, and the final rolling deformation is 10-15%;
step four: and (3) carrying out online heat treatment on the steel rail obtained in the step three by using waste heat, cooling the steel rail by standing the steel rail with the waste heat in air, and blowing a cooling medium to the rail head of the steel rail when the central temperature of the top surface of the steel rail is less than or equal to 800 ℃ so as to accelerate the cooling of the rail head of the steel rail to 400-500 ℃, and then continuously cooling the steel rail to room temperature in the air.
2. The method for preparing the high-strength and high-toughness steel rail according to claim 1, wherein the steel rail casting blank prepared in the step one comprises the following components in percentage by mass: c: 0.65-0.85%, Si: 0.3-0.8%, Mn: 0.5-1.0%; cr: 0.5-1.2%; v: 0.05-0.13 percent of Fe, less than or equal to 0.008 percent of S, less than or equal to 0.025 percent of P, and the balance of Fe and inevitable impurities.
3. The method for preparing a high-toughness steel rail according to claim 1, wherein the preparation of the steel rail casting blank in the first step comprises the following steps: the steel rail casting blank is prepared through a molten iron pretreatment process, a converter smelting process, an LF furnace refining process, an RH vacuum treatment process and a continuous casting process.
4. The method for preparing a high-toughness steel rail according to claim 1, wherein the preparation of the steel rail casting blank in the first step comprises the following steps: the molten steel is fed into a furnace by adopting low-S molten iron, and soft argon blowing is carried out on the molten steel under the protection of high-alkalinity refining slag to homogenize alloy components.
5. The method for producing a high-toughness steel rail according to claim 4, wherein the argon blowing time is 5 to 10 minutes.
6. The method for preparing the high-strength and high-toughness steel rail according to claim 1, wherein a universal rolling line is adopted in the third step to roll the steel rail casting blank into the steel rail.
7. The method for preparing the high-strength and high-toughness steel rail according to claim 1, wherein the cooling rate of the accelerated cooling of the rail head of the steel rail in the fourth step is 4.0-6.0 ℃/s.
8. The method for preparing a high-toughness steel rail according to claim 1, wherein the cooling medium in the fourth step is compressed air or a water mist mixture.
9. The method for preparing a high-strength and high-toughness steel rail according to claim 1, wherein the step four of blowing a cooling medium to the rail head comprises blowing a cooling medium to the tread of the rail head, two sides of the rail head and the jaw of the rail head.
10. A high-strength and high-toughness steel rail is characterized by comprising the following components in percentage by mass: c: 0.65-0.85%, Si: 0.3-0.8%, Mn: 0.5-1.0%; cr: 0.5-1.2%; v: 0.05-0.13 percent of Fe, less than or equal to 0.008 percent of S, less than or equal to 0.025 percent of P, and the balance of Fe and inevitable impurities.
Priority Applications (1)
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| CN115058636A (en) * | 2022-06-27 | 2022-09-16 | 包头钢铁（集团）有限责任公司 | Production method of European standard R370CrHT on-line heat treatment steel rail |
| CN115233503A (en) * | 2022-08-05 | 2022-10-25 | 攀钢集团攀枝花钢铁研究院有限公司 | Medium-strength steel rail with high yield strength and production method thereof |
| CN115261733A (en) * | 2022-08-18 | 2022-11-01 | 攀钢集团攀枝花钢铁研究院有限公司 | Wear-resistant corrosion-resistant steel rail for subway and production method thereof |
| CN115466833A (en) * | 2022-08-10 | 2022-12-13 | 包头钢铁（集团）有限责任公司 | Heat treatment method for improving low-temperature toughness of pearlitic steel rail |
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