WO2024027264A1 - 一种具有高屈服强度的中等强度钢轨及其生产方法 - Google Patents
一种具有高屈服强度的中等强度钢轨及其生产方法 Download PDFInfo
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- WO2024027264A1 WO2024027264A1 PCT/CN2023/093537 CN2023093537W WO2024027264A1 WO 2024027264 A1 WO2024027264 A1 WO 2024027264A1 CN 2023093537 W CN2023093537 W CN 2023093537W WO 2024027264 A1 WO2024027264 A1 WO 2024027264A1
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- Prior art keywords
- rail
- strength
- cooling
- medium
- high yield
- Prior art date
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 35
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 34
- 239000010959 steel Substances 0.000 title claims abstract description 34
- 238000010438 heat treatment Methods 0.000 claims abstract description 30
- 238000000034 method Methods 0.000 claims abstract description 24
- 230000008569 process Effects 0.000 claims abstract description 16
- 238000001816 cooling Methods 0.000 claims description 61
- 239000000203 mixture Substances 0.000 claims description 15
- 229910001562 pearlite Inorganic materials 0.000 claims description 12
- 238000005096 rolling process Methods 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 11
- 229910052717 sulfur Inorganic materials 0.000 claims description 9
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 229910052748 manganese Inorganic materials 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 238000003723 Smelting Methods 0.000 claims description 6
- 239000003595 mist Substances 0.000 claims description 6
- 239000002826 coolant Substances 0.000 claims description 5
- 238000012545 processing Methods 0.000 claims description 5
- 238000009749 continuous casting Methods 0.000 claims description 4
- 238000007670 refining Methods 0.000 claims description 4
- 238000009489 vacuum treatment Methods 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 abstract description 3
- 239000000956 alloy Substances 0.000 abstract description 3
- 230000002708 enhancing effect Effects 0.000 abstract 1
- 239000012535 impurity Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- 150000001247 metal acetylides Chemical class 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 239000007769 metal material Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 238000007550 Rockwell hardness test Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- 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
-
- 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
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- 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
-
- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- 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 field of rail production, specifically to a medium-strength rail with high yield strength and a production method thereof.
- high-performance heat-treated pearlite rails are mainly used to improve the tensile strength and hardness of the rails through online or offline heat treatment to achieve Improve the wear resistance and contact fatigue resistance, but the existing medium-strength pearlite heat-treated rails rarely take into account the improvement of the rail's plastic deformation resistance brought by high yield strength and its fundamental reduction in the occurrence of surface contact fatigue damage.
- high-strength heat-treated pearlite rails with high yield strength to take into account the reduced safety caused by issues such as increased wheel wear due to their excessive tensile strength and hardness when used on mixed passenger and freight lines.
- Patent CN 106086622A "A heat treatment production method for rails for mixed passenger and freight railways and the resulting rails" discloses a rail for mixed passenger and freight transportation and its production method.
- the chemical composition of the rail includes: C: 0.71 ⁇ 0.82 %, Si: 0.13 ⁇ 0.60%, Mn: 0.65 ⁇ 1.25%, Cr: 0.05 ⁇ 0.25%, P: ⁇ 0.020%, S: ⁇ 0.015%, Al: ⁇ 0.1%, the balance is Fe and inevitable impurities .
- This patent uses an online heat treatment method to treat the rail head tread center, Both sides of the rail head and the center of the rail bottom undergo accelerated cooling, slow cooling and air cooling in sequence.
- the opening cooling temperature of the accelerated cooling is 650-950°C, the cooling rate is 2.5-7°C/s, and the final cooling temperature is 400-630°C. °C, the cooling rate of the slow cooling is 0.1 ⁇ 1.5°C/s, and the final cooling temperature is 180-300°C.
- the aluminum content in the rails described in this patent is relatively high, which can easily lead to rail core damage and fracture; and the production of this rail
- the method requires accelerated cooling of the rail bottom, which requires high equipment and complicated production methods.
- Patent CN 104988405A "A Rail for Mixed Use of Passengers and Freight and Its Production Method and Application” discloses a kind of rail for mixed use of passengers and freight and its preparation method.
- the chemical composition of the rail includes: C: 0.71 ⁇ 0.78%, Si : 0.30 ⁇ 0.80%, Mn: 0.80 ⁇ 1.1%, Cr: 0.1 ⁇ 0.3%, V: 0.04 ⁇ 0.2%, P: ⁇ 0.020%, S: ⁇ 0.015%, the balance is Fe and inevitable impurities.
- the rails adopt an online heat treatment method: the final rolled rails are rapidly cooled, and then the gauge corners are rapidly heated and insulated; the conditions for rapid cooling include: the opening cooling temperature is 800-880°C, and the cooling rate is 2-6°C.
- the final cooling temperature is 430-470°C; the conditions for rapid heating and heat preservation include: raising the track angle temperature to 700-800°C at a heating rate of 3.0-4.0°C/s and keeping it warm for 2-4 minutes.
- the rails described in this patent need to add high-priced alloy elements such as V, which is costly.
- the rail head is heated multiple times during the rail production process. The production method is complicated, and the secondary heating has a greater impact on the performance stability of the rail head. It has a huge negative impact and seriously affects the safety performance of rail lines in service.
- Patent CN 112301205A "A High Yield Ratio Pearlitic Rail Rail and its Preparation Method” discloses a high yield ratio pearlitic rail rail and its manufacturing method.
- the composition of the rail is based on weight percentage: C: 0.70 ⁇ 0.85%, Si: 0.2 ⁇ 0.8%, Mn: 0.8 ⁇ 1.1%, Cr: 0.5 ⁇ 0.7%, Cu: 0.01 ⁇ 0.1%, Nb: 0.01 ⁇ 0.05%, P: ⁇ 0.020%, S: ⁇ 0.015%, Al ⁇ 0.005 %, the balance is Fe and inevitable impurities.
- the rail uses an online heat treatment method.
- the heat treatment is a multi-stage cooling process, and the rail is cooled from 850 to 950°C to room temperature at different cooling rates.
- the rail described in this patent has a high yield strength, but its tensile strength exceeds 1300MPa, which can easily lead to rapid wheel wear when used on a low-axle load mixed passenger and freight line, which increases line maintenance costs.
- the rail contains a large amount of Cr, Alloying elements such as Cu and Nb have high production costs and are difficult to promote production.
- the purpose of the present invention is to provide a medium-strength rail with high yield strength and a production method thereof to meet the standard sound insulation and shock absorption requirements, with faster construction speed, stronger adhesion and lower cost. Lower and more stable sound insulation effect.
- a medium-strength steel rail with high yield strength has: yield strength ⁇ 820MPa, tensile strength 1200-1300MPa, and elongation ⁇ 10%.
- the microstructure of the rail head of the medium strength rail is full pearlite.
- the surface hardness of the rail top surface of the medium-strength rail is 350-390HB, and the 10mm depth section hardness of the rail top surface and rail gauge corner is 35.5-41.0HRC.
- the chemical composition of the rail should be: C: 0.65-0.85%, Si: 0.15-0.60%, Mn: 0.50-1.30%, Cr: 0.05-0.20%, P : ⁇ 0.020%, S: ⁇ 0.015%, the balance is Fe.
- the invention also provides a production method based on medium-strength rails with high yield strength, which sequentially includes: converter smelting, LF furnace refining, RH vacuum treatment, continuous casting to obtain steel billet, rolling of steel billet, online heat treatment and processing.
- in-line heat treatment includes:
- the first stage of cooling cooling the rail after final rolling.
- the cooling process includes accelerated cooling of the top surface of the rail, the two upper fillets of the rail head, the two sides of the rail head, and the two lower fillets of the rail head to the rail.
- the top surface temperature is 630-750°C;
- Second stage cooling Cool the rail after step a at a cooling rate of 3.0-6.0°C/s.
- the rail top surface, the two upper fillets of the rail head, the two sides of the rail head, and the two lower fillets of the rail head are accelerated and cooled until the temperature of the rail top surface is 400-500°C;
- step c Place the rail cooled in step c on the cooling bed, and air-cool the rail to room temperature.
- the cooling medium used in the online heat treatment is at least one of water mist, compressed air, and a mixture of compressed air and water mist.
- step a when the temperature of the rail top surface after final rolling is between 800-950°C, cooling care is performed.
- the temperature in the cooling process, is lowered at a cooling rate of 1.0-3.0°C/s.
- the cooling medium used in the online heat treatment is compressed air.
- the invention adopts the method of controlling the chemical composition of the rail and the online heat treatment process, and can obtain a medium-strength rail with high yield strength without adding multiple alloy elements.
- the yield strength is ⁇ 820MPa and the tensile strength is 1200-1300MPa. , elongation ⁇ 10%. Therefore, the medium-strength steel rail of the present invention can effectively reduce the probability of contact fatigue damage when used on mixed passenger and freight lines, can effectively improve the service performance and service life of the rail, and improve the safety of train operation.
- this patent provides The production method of medium-strength rails with high yield strength is simple and easy to operate, which is conducive to its large-scale promotion and application in mixed passenger and freight lines.
- the invention provides a medium-strength steel rail with high yield strength.
- the medium-strength steel rail has high yield strength, with a yield strength of ⁇ 820MPa, a tensile strength of 1200-1300MPa, and an elongation of ⁇ 10%.
- microstructure of the rail head of medium-strength rails is full pearlite.
- the surface hardness of the rail top surface of medium-strength rails is 350-390HB, and the 10mm depth section hardness of the rail top surface and rail gauge angle is 35.5-41.0HRC.
- the chemical composition of the rails in weight percentage should be: C: 0.65-0.85%, Si: 0.15-0.60%, Mn: 0.50-1.30%, Cr: 0.05-0.20 %, P: ⁇ 0.020%, S: ⁇ 0.015%, the balance is Fe and inevitable impurities.
- the chemical composition of the rail in terms of weight percentage, is: C: 0.70-0.85%, Si: 0.30-0.60%, Mn: 0.95-1.25%, Cr: 0.05-0.20%, P: ⁇ 0.020%, S : ⁇ 0.015%, the balance is Fe and inevitable impurities.
- C is the most important and cheapest element in pearlitic rails that enables the rails to obtain good comprehensive mechanical properties and promotes the transformation of pearlite.
- the C content is ⁇ 0.65%, under the production process of the present invention, it is impossible to ensure that the rail has appropriate hardness and the anti-contact fatigue performance of the rail; when the C content is >0.85%, under the production process of the present invention, the rail's resistance to contact fatigue cannot be guaranteed.
- the proportion of carbides is too high, the tensile strength is too high, and the strength index is excessive, which reduces the anti-contact fatigue performance of the rail during service and has an adverse effect on the safe use of the rail; therefore, the carbon content in the present invention is limited to 0.65-0.85%.
- the main role of Si in steel is to inhibit the formation of cementite and serve as a solid solution strengthening element to increase the hardness of the ferrite matrix and improve the strength and hardness of the steel.
- Si content is less than 0.15%, its solid solution content is low and the strengthening effect is not obvious.
- abnormal structures such as martensite are prone to appear in the rails.
- Si content is >0.60%, local segregation is likely to occur, which will reduce the toughness of the steel. Plasticity and weldability have a negative impact on the safe use of rails. Therefore, the Si content in the present invention is limited to 0.15-0.60%.
- Mn is essential to improve the strength of ferrite and austenite in steel.
- the Mn content is ⁇ 0.50%, it is difficult to increase the hardness of carbides and thereby increase the hardness of the steel; when the Mn content is >1.30%, it will coarsen the grain size and affect the structural changes of rail steel during the heat treatment process.
- Mn has a significant impact on the diffusion of C in the steel, and abnormal structures such as bainite or martensite may be produced in the Mn segregation area, which also affects the welding performance of the rail. Therefore, the Mn content in the present invention is limited to 0.50-1.30%.
- Cr can form a variety of carbides with carbon in steel; at the same time, Cr can Uniform carbide distribution in steel, reduce carbide size, and improve rail wear resistance.
- the Cr content is ⁇ 0.05%, the hardness and proportion of the carbides formed are low; when the Cr content is >0.20%, the hardenability of the rail is too high, which can easily lead to the production of harmful bainite and martensite structures in the rail. While improving the mechanical properties of the rail, there is no guarantee that the rail will have a full pearlite structure. Therefore, the Cr content in the present invention is limited to 0.05-0.20%.
- P and S are impurity elements that cannot be completely removed from rails. P will segregate at the grain boundaries of the rail structure, seriously reducing the toughness of the rail; S easily forms MnS inclusions in the steel, which is harmful to the wear resistance and contact fatigue resistance of the rail. Therefore, the P content in the present invention needs to be controlled below 0.020%; the S content needs to be controlled below 0.015%.
- the invention also provides a production method for the above-mentioned medium-strength rail with high yield strength, which sequentially includes: converter smelting, LF furnace refining, RH vacuum treatment, continuous casting to obtain steel billet, rolling of steel billet, online heat treatment and processing.
- the online heat treatment includes:
- First stage cooling When the temperature of the rail top surface after final rolling is between 800-950°C, use a cooling rate of 1.0-3.0°C/s to round the rail top surface, rail head and rail head. The two side surfaces and the two lower corners of the rail head are subjected to accelerated cooling until the temperature of the rail top surface is 630-750°C;
- the second stage of cooling use the cooling speed of 3.0-6.0°C/s to perform filleting on the top surface of the rail, the two upper corners of the rail head, the two sides of the rail head, and the two lower corners of the rail head after cooling in step a. Accelerate the cooling process until the rail top surface temperature is 400-500°C;
- step c Place the rail cooled in step c on the cooling bed, and air-cool the rail to room temperature.
- the cooling medium used in the online heat treatment of this patent is at least one of water mist, compressed air, and a mixture of compressed air and water mist.
- the temperature of the rail head tread is 800-950°C
- the rail has not yet started the pearlite phase transformation.
- a lower cooling rate needs to be used to uniformly reduce the temperature of the rail.
- the cooling rate needs to be controlled between 1.0-3.0°C/s;
- the internal temperature of the rail head is in the range of 400-500°C.
- the rail has completed the pearlite phase transformation process, and there is no obvious significance in continuing to accelerate cooling. It can be
- the rails are air-cooled to room temperature for subsequent processing.
- the complete production process of the production method of medium-strength rails with high yield strength of the present invention can be: using low-sulfur vanadium-containing molten steel, smelting through a converter or electric furnace, refining through LF, RH or VD vacuum treatment, and bloom protection continuous casting , billet heating furnace heating, high-pressure water descaling before billet rolling, universal rolling mill rolling, rail online heat treatment, step cooling bed room temperature air cooling, horizontal and vertical composite straightening, rail specification inspection, processing line treatment, surface inspection and Warehousing.
- Examples 1-3 and Comparative Examples 1-3 correspond to the selection of rails with the following chemical compositions numbered 1-3.
- the production process is the same as above, and the specific chemical compositions are shown in Table 1.
- the balance is Fe and unavoidable impurities.
- the yield strength, tensile strength, and elongation after break of the rail are tested in accordance with GB/T 228.1 "Tensile Test of Metal Materials Part 1: Room Temperature Test Method", and in accordance with GB/T 230.1 "Rockwell Hardness Test of Metal Materials Part 1".
- Part 1: Test Method” Test the 10mm section hardness of the rail, and test the surface hardness of the top surface of the rail in accordance with GB/T 231.1 "Brickell Hardness Test of Metal Materials Part 1: Test Method”.
- the tensile properties, rail top surface hardness, and 10mm position section hardness of Examples 1-3 and Comparative Examples 1-3 are shown in Table 3.
- the rails obtained by the method of the present invention have high yield strength, with yield strength ⁇ 820MPa, tensile strength 1200-1300MPa, and elongation ⁇ 10%; while in the comparative example, the rails have yield strength, tensile strength, or microscopic A situation where the organization does not meet the requirements.
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Abstract
Description
Claims (10)
- 一种具有高屈服强度的中等强度钢轨,其特征在于,所述中等强度钢轨具有:屈服强度≥820MPa,抗拉强度为1200-1300MPa,延伸率≥10%。
- 根据权利要求1所述的具有高屈服强度的中等强度钢轨,其特征在于,所述中等强度钢轨的轨头显微组织为全珠光体。
- 根据权利要求1或2所述的具有高屈服强度的中等强度钢轨,其特征在于,所述中等强度钢轨的轨顶面的表面硬度为350-390HB,轨顶面及轨距角处10mm深度断面硬度为35.5-41.0HRC。
- 根据权利要求3所述的具有高屈服强度的中等强度钢轨,其特征在于,以重量百分比计,钢轨的化学成分应为:C:0.65-0.85%、Si:0.15-0.60%、Mn:0.50-1.30%、Cr:0.05-0.20%、P:≤0.020%、S:≤0.015%,余量为Fe。
- 一种具有高屈服强度的中等强度钢轨的生产方法,其特征在于,依次包括:转炉冶炼、LF炉精炼、RH真空处理、连铸获得钢坯、对钢坯进行轧制、在线热处理及加工。
- 根据权利要求5所述的生产方法,其特征在于,所述在线热处理包括:a、第一阶段冷却:将待终轧后钢轨进行冷却处理,所述冷却处理包括对钢轨轨顶面、轨头两上圆角、轨头两侧面、轨头两下圆角进行加速冷却处理至轨顶面温度为630-750℃;b、第二阶段冷却:将经过步骤a冷却后的钢轨以3.0-6.0℃/s的冷却速度对钢轨轨顶面、轨头两上圆角、轨头两侧面、轨头两下圆角进行加速冷却处理至轨顶面温度为400-500℃;c、第三阶段冷却:将经过步骤c冷却后的钢轨放置在冷床上,将钢轨空冷至室温。
- 根据权利要求6所述的生产方法,其特征在于,所述在线热处理所采用的冷却介质为水雾、压缩空气、压缩空气与水雾混合物中的至少一种。
- 根据权利要求6所述的生产方法,其特征在于,步骤a中,所述待终轧后钢轨轨顶面温度在800-950℃之间时,进行冷却护理。
- 根据权利要求6所述的生产方法,其特征在于,所述冷却处理中,以1.0-3.0℃/s的冷却速度降温。
- 根据权利要求6所述的生产方法,其特征在于,所述在线热处理所采用的冷却介质压缩空气。
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WO2022110812A1 (zh) * | 2020-11-30 | 2022-06-02 | 武汉钢铁有限公司 | 一种控轧控冷高强度珠光体钢轨及其生产方法 |
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