WO2023173803A1 - Rail en acier résistant à la fatigue au contact de roulement pour chemin de fer voyageurs et fret mixte, et son procédé de production - Google Patents

Rail en acier résistant à la fatigue au contact de roulement pour chemin de fer voyageurs et fret mixte, et son procédé de production Download PDF

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Publication number
WO2023173803A1
WO2023173803A1 PCT/CN2022/134335 CN2022134335W WO2023173803A1 WO 2023173803 A1 WO2023173803 A1 WO 2023173803A1 CN 2022134335 W CN2022134335 W CN 2022134335W WO 2023173803 A1 WO2023173803 A1 WO 2023173803A1
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Prior art keywords
rail
cooling
temperature
rolling
contact fatigue
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PCT/CN2022/134335
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English (en)
Chinese (zh)
Inventor
费俊杰
周剑华
刘芳鸣
朱敏
何文骥
欧阳珉路
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武汉钢铁有限公司
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Publication of WO2023173803A1 publication Critical patent/WO2023173803A1/fr

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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
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • 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
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
    • E01B5/00—Rails; Guard rails; Distance-keeping means for them
    • E01B5/02—Rails
    • 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 belongs to the field of metallurgical technology, and specifically relates to a rolling contact fatigue resistant steel rail for a mixed passenger and freight railway and a production method thereof.
  • the rail is subjected to huge contact stress, and the maximum shear stress distribution will appear inside the rail head material.
  • the maximum shear stress far exceeds the yield strength limit of the rail material, and the rail material will Due to the ratchet-shaped hysteresis effect of the stress-strain cycle, the material undergoes trace plastic deformation and forms work hardening. As the plastic deformation continues to accumulate, the material hardens to a certain extent, plastic exhaustion occurs, and irreversible plastic flow occurs. When the material The plastic flow exceeds the deformation limit, causing micro-cracks in the rail, and eventually develops into rolling contact fatigue damage.
  • Patent CN 100471974C provides a bainitic steel rail with excellent fatigue resistance and a production method thereof. Its chemical composition (wt%), C: 0.10 ⁇ 0.35%, Si: 0.80 ⁇ 2.00%, Mn: 0.80 ⁇ 3.30%, Cr: ⁇ 2.00%, Mo: 0.05 ⁇ 0.80%, N: 10 ⁇ 100ppm, add Nb and Ti in composite, Nb: 0.005 ⁇ 0.10%, Ti: 0.005 ⁇ 0.13%, and Nb+Ti ⁇ 0.16 %, the rest is Fe and unavoidable impurities. After hot rolling, the rail is naturally cooled in the air, so that the rail has excellent fatigue resistance. In the rail fatigue test, it has been intact for more than 2 million times.
  • Patent CN 102534403A discloses a bainitic heat-treated rail that can improve the toughness and plasticity of the rail and its heat treatment method.
  • the chemical composition is as follows in weight percentage: C: 0.10%-0.40%, Si: 0.80%-2.00%, Mn: 0.80%-2.60%, Cr: 0.1-2.00%, Nb: 0.005%-0.100%, V: 0.01% -0.26%, Ti: 0.001%-0.070%, W: 0.01-0.70%, the balance is Fe and inevitable impurities.
  • the heat treatment method adopts online heat treatment.
  • the rail head is accelerated to cool at a cooling rate of 0.4-8°C/s, and stops when the temperature reaches 200°C. Accelerate cooling, and then air cool to room temperature; or use offline heat treatment to perform full-section austenitization or rail head austenitization.
  • the austenitization temperature is between 880-930°C, and when cooled to the temperature range of 700-890°C , implement accelerated cooling of the rail, the cooling rate is 0.4-8°C/s, stop accelerated cooling when cooling to 200°C, and then air-cool to room temperature.
  • Patent CN 106086622A provides a heat treatment production method for rails for mixed passenger and freight railways.
  • the production method includes sequentially accelerated cooling, slow cooling and Air cooled.
  • the opening cooling temperature of accelerated cooling is 650-950°C
  • the cooling rate is 2.5-7.0°C/s
  • the final cooling temperature is 400-600°C
  • the cooling rate of slow cooling is 0.1-1.5°C/s
  • the final cooling temperature is 180- 300°C.
  • This method can control the hardness within the appropriate range of 350-380HB suitable for mixed passenger and freight railways while ensuring the tensile properties of the rails.
  • Patent CN101646795A provides a high-hardness pearlite rail and a manufacturing method thereof.
  • the chemical composition of the rail includes 0.73-0.85 mass% C, 0.50-0.75 mass% Si, 0.30-1.0 mass% Mn, 0.035 mass% % or less P, 0.0005-0.012 mass% S, 0.2-1.3 mass% Cr, and the remainder is Fe and inevitable impurities.
  • the final rolling temperature of the rail is 850-950°C, and then the temperature above the pearlite phase transformation starting temperature is rapidly cooled to 400-650°C at a cooling rate of 1.2-5°C/s to obtain the rail head surface to a depth range of at least 25mm.
  • the Vickers hardness is HV380-HV480.
  • Patent CN 1793403A provides a pearlite heat-treated rail and its production method. Its chemical composition includes by weight: C: 0.70% ⁇ 0.95%, Si: 0.20% ⁇ 1.10%, Mn: 0.50% ⁇ 1.50%, V : 0.01% ⁇ 0.20%, Cr: 0.15% ⁇ 1.20%, P: ⁇ 0.035%, S: ⁇ 0.035% and Al: ⁇ 0.005%.
  • the method includes the following steps: 1) smelting, 2) casting and rolling, 3) cooling the rail steel from 650 to 880°C to 400 to 500°C at a cooling rate of 1 to 10°C/s or cooling it to room temperature.
  • Patent CN 102220545A provides a high-carbon, high-strength heat-treated rail with excellent wear resistance and plasticity and a production method.
  • the chemical composition of the high-carbon, high-strength heat-treated rail 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%, the rest is iron and unavoidable impurities. After rolling, the residual temperature of the hot rail is 680-900°C.
  • the rail is cooled to 400-500°C at a cooling rate of 1.5-10°C/s, and then naturally cooled to room temperature.
  • the rail tensile strength is ⁇ 1330MPa, and the elongation is ⁇ 9 %, the rail head hardness is ⁇ 380HB, the depth of the hardened layer is more than 25mm, the structure is fine pearlite, has excellent wear resistance and plasticity, and can meet the requirements of heavy-haul railways.
  • the existing technology focuses on improving the tensile strength and hardness of rails through online heat treatment processes, and does not involve improving the yield strength of rails.
  • Yield strength is an important factor affecting the initiation of rolling contact fatigue micro-cracks in rails.
  • a high yield-strength ratio is important for improving the rail's yield strength.
  • it is of great significance to reduce rolling contact fatigue damage; at the same time, as the strength of the rail increases, its toughness and plasticity will decrease, especially the impact performance of the rail waist part is poor, and the risk of fracture during use increases. Therefore, there is an urgent need to develop a rail with high rail head yield-to-strength ratio and good rail waist impact toughness that is resistant to rolling contact fatigue.
  • the present invention provides a rolling contact fatigue-resistant high-strength and toughness rail and its production method.
  • the invention realizes the rail
  • the rail head yield ratio and the rail waist impact toughness are well matched to improve the comprehensive performance and service life of the rail and meet the needs of railway development.
  • a kind of rolling contact fatigue resistant steel rail for mixed passenger and freight railways is 0.75-0.88% C, 0.10-0.60% Si, 0.75-1.30% Mn, 0.20-0.55% Ni, 0.10 in weight percentage. -0.20% V, 0.03-0.06% Nb, ⁇ 0.025% P, ⁇ 0.025% S, the rest is Fe and inevitable impurities.
  • the invention also provides the production method of the above-mentioned rolling contact fatigue resistant rail, which includes the following processes: hot metal desulfurization, converter smelting, LF refining, vacuum treatment, continuous casting, slab heating, rolling, accelerated cooling, and straightening;
  • the desulfurization of molten iron adopts the magnesium powder desulfurization process
  • Converter smelting adopts top-bottom double blowing process, and the tapping temperature is controlled at 1660 ⁇ 1680°C;
  • the alkalinity of the slag refined outside the LF furnace is controlled at 1.8-2.5;
  • RH adopts deep vacuum treatment, bottom blowing argon pressure is 0.40 ⁇ 0.55MPa, and soft blowing time is 8 ⁇ 12min;
  • the long nozzle of the large tank and the immersed nozzle of the crystallizer are used to protect the casting.
  • the immersion depth is 60 ⁇ 70mm, and the casting speed is controlled at 0.4 ⁇ 0.6m/min;
  • a walking beam heating furnace is used to heat the slab, with a heating temperature of 1200-1250°C and a holding time of 170-210 minutes;
  • the opening rolling temperature is 1080-1130°C
  • the compression ratio in the rough rolling stage is ⁇ 5.8
  • the final rolling temperature is 830-860°C
  • the compression ratio in the finishing rolling stage is ⁇ 2.2;
  • the starting cooling temperature is 700-720°C
  • the cooling speed of the rail head is 2-5°C/s
  • the cooling speed of the rail waist and rail bottom is 1-2°C/s.
  • the off-site temperature of LF refining outside the furnace is controlled at 1585 ⁇ 1600°C.
  • the processing time for RH vacuum pressure ⁇ 50Pa is not less than 15 minutes
  • the temperature of RH molten steel leaving the station is controlled to 1540 ⁇ 1565°C
  • the hydrogen content of molten steel is ⁇ 1.2ppm
  • the total oxygen content of molten steel is ⁇ 12ppm.
  • the continuous casting billet is slowly cooled, and the cooling rate is controlled at 0.05°C/s ⁇ 0.1°C/s.
  • the opening rolling temperature is 1100-1130°C
  • the compression ratio in the rough rolling stage is ⁇ 6.0
  • the final rolling temperature is 830-850°C
  • the compression ratio in the finishing rolling stage is ⁇ 2.3.
  • the starting cooling temperature during accelerated cooling is controlled to 705-720°C
  • the rail head cooling rate is 2.5-4°C/s
  • the rail waist and rail bottom cooling rate is 1.5-2°C/s
  • the rail head surface temperature is When the temperature drops below 430°C, the accelerated cooling is stopped and then air-cooled to room temperature.
  • the rail waist and rail bottom also stop cooling accordingly;
  • the cooling medium for accelerated cooling includes but is not limited to water, polymer solution, oil, compressed air, water mist or oil mist mixture. gas.
  • This invention achieves a good match between the rail head yield ratio and the rail waist impact toughness by reasonably setting the chemical composition and the smelting and rolling processes, while simultaneously performing accelerated cooling at different cooling rates on the rolled rail head, rail waist and rail bottom. , thereby improving the comprehensive performance and service life of the rail and meeting the needs of railway development; the method is simple, highly operable, and easy to promote and apply.
  • the rolling contact fatigue-resistant high-strength and toughness rail obtained by the method of the present invention has a rail head metallographic structure of fine pearlite and a small amount of ferrite, a rail tensile strength ⁇ 1200 MPa, an elongation ⁇ 12%, and a rail head yield ratio ⁇ 0.72, rail waist room temperature impact energy Aku ⁇ 10J.
  • the specific embodiment provides a rolling contact fatigue resistant steel rail for mixed passenger and freight railways, the chemical composition of which is: 0.75-0.88% C, 0.10-0.60% Si, 0.75-1.30% Mn, 0.20% by weight. -0.55% Ni, 0.15-0.30% Cr, 0.03-0.06% Nb, ⁇ 0.025% P, ⁇ 0.025% S, the rest is Fe and inevitable impurities.
  • its chemical composition is: 0.76-0.86% C, 0.20-0.60% Si, 0.90-1.10% Mn, 0.35-0.55% Ni, 0.15-0.20% Cr, 0.04-0.06 % Nb, ⁇ 0.025% P, ⁇ 0.025% S, and the rest is Fe and inevitable impurities.
  • C is the main element that forms pearlite and carbide, and is also the main element that determines the strength of steel. If the C content is too low, the density of the lamellar cementite in the pearlite structure cannot be guaranteed, and the basic strength and hardness of the rail are insufficient, which affects Usage effect; if the C content is too high, on the one hand, the hardness of the rail will be too high, which will accelerate the expansion of fatigue cracks and also reduce the welding performance. Therefore, the present invention controls the C content in the range of 0.75-0.88% by weight.
  • Si As the main additive element of steel, Si usually exists in ferrite and austenite in the form of solid solution to improve the strength of the matrix structure, inhibit the formation of cementite in steel, and promote the transformation of ferrite.
  • Si content in steel gradually increases When it is high, local segregation is prone to occur, and the Si content is controlled within the range of 0.10-0.60% by weight.
  • Mn is a solid solution strengthening element in steel. It can improve the strength of ferrite and is also a carbide-forming element. After entering cementite, it can partially replace Fe atoms and improve the strength and hardness of steel. Increased Mn content will significantly reduce the weldability of the steel, coarsen the grain size, and increase the susceptibility to the formation of white spots and slab segregation. Therefore, the Mn content is controlled within the range of 0.75-1.30% by weight.
  • V is a precipitation strengthening element that improves the strength and hardness of the rail. However, as the V content is increased, the strength and hardness of the rail will further increase while the toughness will decrease.
  • the V content is controlled within the range of 0.08-0.15% by weight.
  • Nb is an important micro-alloying element in steel. Its mechanism for improving strength is grain refinement strengthening and precipitation strengthening. Through the pinning effect of precipitates, it prevents the austenite grains from growing during the rolling process and refines the grains. Grain, improves strength but does not reduce the impact toughness of steel.
  • niobium reduces the high-temperature thermoplasticity of steel, thereby increasing the tendency of hot cracking of niobium-containing steel billets. The content should not be too high, so the Nb content is controlled within the range of 0.03-0.06% by weight.
  • Ni can improve the hardenability of steel and improve the strength of rails after heat treatment while maintaining good plasticity and toughness.
  • solid solution in steel it increases stacking fault energy, promotes dislocation slip, increases the work consumed by crack propagation, and improves toughness.
  • the Nb content is controlled within the range of 0.20-0.55% by weight.
  • P and S are generally considered to be harmful residual elements in steel, which will greatly increase the crack sensitivity of steel, increase the low-temperature brittle transition temperature of steel, and reduce the impact performance of steel. Therefore, without affecting the performance of the rail, it is required The lower the content of P and S, the better. According to the current relevant standards for rails, it should be controlled at a level of ⁇ 0.025% by weight.
  • the production method of rolling contact fatigue resistant rails described in the specific embodiment includes the following processes: hot metal desulfurization, converter smelting, LF refining, vacuum treatment, continuous casting, billet heating, rolling, accelerated cooling, and straightening;
  • the desulfurization of molten iron adopts the magnesia powder desulfurization process; the converter smelting adopts the top-bottom double blowing process, and the tapping temperature is controlled at 1660-1680°C; the alkalinity of the slag refined outside the LF furnace is controlled at 1.8-2.5, which improves low melting point inclusions.
  • the proportion of materials makes it easy to float and remove and has a certain deformation ability during the rolling process, thereby improving the fatigue resistance and service life of the rail.
  • RH adopts deep vacuum treatment, bottom blowing argon pressure is 0.40 ⁇ 0.55MPa, and soft blowing time is 8 ⁇ 12 minutes.
  • the continuous casting billet should be Slow cooling treatment, the cooling rate is controlled at 0.05°C/s ⁇ 0.1°C/s.
  • a walking beam heating furnace is used to heat the slab.
  • the heating temperature is 1200-1250°C and the holding time is 170-210 minutes. This is to ensure that the alloy elements are fully dissolved in the austenite and to avoid excessive growth and refinement of the austenite grains.
  • Pearlite group size the opening rolling temperature is 1080-1130°C, the compression ratio in the rough rolling stage is ⁇ 5.8, the final rolling temperature is 830-860°C, and the compression ratio in the finishing rolling stage is ⁇ 2.2, mainly through lower rolling temperature and higher Large compression ratio obtains refined austenite grain size, thereby refining the final pearlite structure and improving mechanical properties.
  • the rail head After rolling, the rail head undergoes online accelerated cooling.
  • the starting cooling temperature is 700-720°C
  • the cooling speed of the rail head is 2-5°C/s
  • the cooling speed of the rail waist and rail bottom is 1-2°C/s.
  • the accelerated cooling is stopped and then air cooled to room temperature.
  • the basic principle of the rail online heat treatment process is to accelerate the cooling of the rolled rail, use the residual temperature of the rolled rail to accelerate the cooling, increase the degree of supercooling for the transformation of austenite to pearlite, and obtain a thinner layer spacing than that of hot-rolled rails. Fine pearlite structure, thereby improving the strength and hardness of the rail.
  • the cooling speed of the rail head is 2-5°C/s.
  • the purpose is to quickly take away the heat from the surface of the rail head, quickly form a stable and refined pearlite layer, ensure the strength and hardness of the rail head, and improve the rolling contact fatigue resistance of the rail head;
  • the rail waist and rail bottom are not directly affected by wheel-rail stress, but as a support and fixed structure, they have higher requirements for impact toughness than the rail head.
  • the cooling rate of the rail waist and rail bottom is 1-2°C/s.
  • the rolling contact fatigue-resistant rail obtained through the specific implementation method has a rail head metallographic structure of fine pearlite and a small amount of ferrite, a rail tensile strength ⁇ 1200 MPa, an elongation ⁇ 12%, and a rail head yield ratio ⁇ 0.72.
  • Examples 1-4 The chemical compositions of Examples 1-4 are shown in Table 1. Comparative Examples 1-2 select U75V rails, which are currently the most widely used in railways, and the chemical compositions are shown in Table 1.
  • the desulfurization of molten iron adopts the magnesia powder desulfurization process; the converter smelting adopts the top-bottom double blowing process, and the tapping temperature is controlled at 1660°C; the basicity of the slag refined outside the LF furnace is controlled at 2.3, and the leaving station temperature is controlled at 1590°C; the RH adopts deep Vacuum degree treatment, the processing time of vacuum pressure ⁇ 50Pa is 18 minutes, the bottom blowing argon pressure is 0.45MPa, and the soft blowing time is 10 minutes; the continuous casting process uses a large tank long nozzle and a crystallizer immersed nozzle to protect the casting, and the immersion depth is 60mm.
  • the billet drawing speed is controlled at 0.45m/min, and the billet is slowly cooled; a walking beam heating furnace is used to heat the billet, with a heating temperature of 1230°C and a holding time of 180min; the opening rolling temperature is 1110°C, and the compression ratio in the rough rolling stage is ⁇ 5.8 , the final rolling temperature is 840°C, and the compression ratio in the finishing rolling stage is ⁇ 2.2; the rolled rail head is subjected to online accelerated cooling, the starting cooling temperature is 700°C, the cooling speed of the rail head is 3°C/s, and the rail waist and rail bottom are cooled The speed is 1.5°C/s. When the surface temperature of the rail head drops below 450°C, the accelerated cooling is stopped and then air-cooled to room temperature.
  • Example 2 The desulfurization of molten iron adopts the magnesia powder desulfurization process; the converter smelting adopts the top-bottom double blowing process, and the tapping temperature is controlled at 1680°C; the alkalinity of the slag refined outside the LF furnace is controlled at 2.0, and the leaving station temperature is controlled at 1600°C.
  • RH adopts deep vacuum treatment, the processing time of vacuum pressure ⁇ 50Pa is 20 minutes, the bottom blowing argon pressure is 0.50MPa, and the soft blowing time is 8 minutes; the continuous casting process uses a large tank long nozzle and a crystallizer immersed nozzle to protect the casting, and the immersion depth At 65mm, the billet drawing speed is controlled at 0.50m/min, and the billet is slowly cooled; a walking beam heating furnace is used to heat the billet, the heating temperature is 1220°C, and the holding time is 200min; the opening rolling temperature is 1090°C, and the rough rolling stage The compression ratio is ⁇ 5.8, the final rolling temperature is 850°C, and the compression ratio in the finishing rolling stage is ⁇ 2.2; the rolled rail head is accelerated and cooled online, the starting cooling temperature is 720°C, the cooling speed of the rail head is 4°C/s, and the rail waist The cooling rate of the rail bottom is 1.2°C/s. When the surface temperature of the rail head drops below 450°C, the 450
  • Example 3 The desulfurization of molten iron adopts the magnesia powder desulfurization process; the converter smelting adopts the top-bottom double blowing process, and the tapping temperature is controlled at 1660°C; the alkalinity of the slag refined outside the LF furnace is controlled at 1.9, and the leaving station temperature is controlled at 1590°C.
  • RH adopts deep vacuum treatment, the processing time of vacuum pressure ⁇ 50Pa is 16 minutes, the bottom blowing argon pressure is 0.40MPa, and the soft blowing time is 11 minutes; the continuous casting process uses a large tank long nozzle and a crystallizer immersed nozzle to protect the casting, and the immersion depth At 65mm, the billet drawing speed is controlled at 0.55m/min, and the billet is slowly cooled; a walking beam heating furnace is used to heat the billet, the heating temperature is 1240°C, and the holding time is 210min; the opening rolling temperature is 1120°C, and the rough rolling stage The compression ratio is ⁇ 5.8, the final rolling temperature is 855°C, and the compression ratio in the finishing rolling stage is ⁇ 2.2; the rolled rail head is accelerated and cooled online, the starting cooling temperature is 710°C, the cooling speed of the rail head is 2°C/s, and the rail waist The cooling rate of the rail bottom is 1.8°C/s. When the surface temperature of the rail head drops below 450°C,
  • Example 4 The desulfurization of molten iron adopts the magnesia powder desulfurization process; the converter smelting adopts the top-bottom double blowing process, and the tapping temperature is controlled at 1670°C; the alkalinity of the slag refined outside the LF furnace is controlled at 2.2, and the leaving station temperature is controlled at 1590°C.
  • RH adopts deep vacuum treatment, the processing time of vacuum pressure ⁇ 50Pa is 17 minutes, the bottom blowing argon pressure is 0.45MPa, and the soft blowing time is 10 minutes; the continuous casting process uses a large tank long nozzle and a crystallizer immersed nozzle to protect the casting, and the immersion depth
  • the billet drawing speed is controlled at 0.6m/min, and the billet is slowly cooled; a walking beam heating furnace is used to heat the billet, the heating temperature is 1240°C, and the holding time is 210min; the opening rolling temperature is 1120°C, and the rough rolling stage
  • the compression ratio is ⁇ 5.8, the final rolling temperature is 860°C, and the compression ratio in the finishing rolling stage is ⁇ 2.2; the rolled rail head is accelerated and cooled online, the starting cooling temperature is 720°C, the cooling speed of the rail head is 3°C/s, and the rail waist
  • the cooling rate of the rail bottom is 1.6°C/s.
  • Comparative Examples 1-2 were carried out according to the production method of Example 1, and the tensile strength, yield strength, elongation and rail head of the rail heads of the Examples and Comparative Examples were measured according to the methods specified in the national railway industry standard TB/T 2344-2012. Performance indicators such as waist room temperature impact energy A ku are shown in Table 2.
  • the M-2000 rolling contact wear testing machine was used to conduct contact fatigue tests on the rails of the Examples and Comparative Examples under the same test conditions.
  • the test was carried out by relatively rolling the cylindrical samples. The samples were taken from the rail head area of the Example and Comparative Examples respectively, and the lower sample was taken from the wheel steel.
  • the sample dimensions are thickness 8mm, inner diameter 10mm, outer diameter 20mm; test load: 500N; rotation speed: upper sample 180r/min, lower sample 200r/min; slip rate: 10%.
  • the rolling contact fatigue test results are shown in Table 3.
  • Example 1 6.2 ⁇ 10 4 2.7 ⁇ 10 5
  • Example 2 6.4 ⁇ 10 4 3.3 ⁇ 10 5
  • Example 3 5.8 ⁇ 10 4 3.1 ⁇ 10 5
  • Example 4 6.1 ⁇ 10 4 2.8 ⁇ 10 5 Comparative example 1 4.5 ⁇ 10 4 1.7 ⁇ 10 5 Comparative example 2 4.2 ⁇ 10 4 1.5 ⁇ 10 5
  • the mechanical properties of the rails obtained in the examples are good. Compared with the comparative example, the tensile strength, yield strength and room temperature impact energy of the rail waist are significantly improved.
  • the rail head yield ratio can be guaranteed to be above 0.72, and the rail waist can be guaranteed to be above 0.72. Room temperature impact energy A ku ⁇ 10J.
  • the rail obtained in the Example showed better rolling contact fatigue resistance, and the number of rolling times where fatigue cracks appeared and pieces peeled off was significantly later than that of the Comparative Example.
  • the method of the present invention achieves a good match between the rail head yield ratio and the rail waist impact toughness on the premise of ensuring various mechanical properties of the heat-treated rail, and improves the rolling contact fatigue life of the rail.

Abstract

La présente invention divulgue un rail en acier résistant à la fatigue au contact de roulement pour un chemin de fer voyageurs et fret mixte, caractérisé en ce qu'il comprend les constituants chimiques suivants en pourcentage en poids : de 0,75 à 0,88 % de C, de 0,10 à 0,60 % de Si, de 0,75 à 1,30 % de Mn, de 0,20 à 0,55 % de Ni, de 0,10 à 0,20 % de V, de 0,03 à 0,06 % de Nb, moins de ou égal à 0,025 % de P, moins de ou égal à 0,025 % de S, et le reste étant constitué de Fe et d'impuretés inévitables. Le procédé de production comprend les étapes suivantes : désulfuration de fer fondu, fusion de convertisseur, raffinage LF, traitement sous vide, coulée continue, chauffage d'ébauche de coulée, laminage, refroidissement accéléré et redressement. La présente invention, au moyen de la configuration raisonnable de constituants chimiques et de processus de fusion et de laminage, ainsi que de la réalisation d'un refroidissement accéléré d'une tête de rail en acier laminé, d'une bande de rail et d'un fond de rail à différents taux de refroidissement, permet d'obtenir une bonne adaptation du rapport de rendement de la tête de rail en acier et de ténacité au choc de la bande de rail, ce qui permet d'améliorer les performances globales de service et la durée de vie du rail en acier, et de répondre aux exigences de développement de chemin de fer ; le procédé est simple, présente une forte aptitude au fonctionnement, et est facile à populariser et à appliquer.
PCT/CN2022/134335 2022-03-18 2022-11-25 Rail en acier résistant à la fatigue au contact de roulement pour chemin de fer voyageurs et fret mixte, et son procédé de production WO2023173803A1 (fr)

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CN115094338B (zh) * 2022-07-27 2023-09-22 内蒙古科技大学 一种过共析钢轨用钢及其制备方法
CN115386799B (zh) * 2022-08-30 2023-11-10 鞍钢股份有限公司 一种高速铁路用强韧热轧钢轨及其生产方法

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