CN108342647B - Axle steel for railway vehicles and production method thereof - Google Patents
Axle steel for railway vehicles and production method thereof Download PDFInfo
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- CN108342647B CN108342647B CN201810168830.3A CN201810168830A CN108342647B CN 108342647 B CN108342647 B CN 108342647B CN 201810168830 A CN201810168830 A CN 201810168830A CN 108342647 B CN108342647 B CN 108342647B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- 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
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
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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
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
-
- 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
- C21D2211/005—Ferrite
-
- 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
Abstract
The invention discloses axle steel for railway vehicles and a production method thereof, wherein the axle steel comprises the following chemical components in percentage by weight: 0.33-0.38% of C, 0.15-0.40% of Si, 0.90-1.05% of Mn, less than or equal to 0.020% of P, less than or equal to 0.020% of S, 0.030-0.050% of V, 0.015-0.035% of Als, 0.0040-0.0090% of N, 0.020-0.050% of RE in molten steel, and the balance of Fe and inevitable impurity elements. The production process comprises the following steps: smelting → LF + RH refining → protective pouring → pressure processing → rough machining → heat treatment → fine machining → inspection and warehousing. The method disclosed by the invention can overcome the defects of high rejection rate of magnetic marks on the surface of the existing axle and low transverse impact power, can obviously reduce the magnetic mark waste on the surface of the axle of the railway vehicle, improves the comprehensive mechanical property of the axle, particularly improves the transverse impact power of the axle, and ensures that the transverse impact power guarantee value is more than or equal to 40J, thereby improving the use safety of the axle.
Description
Technical Field
The invention relates to structural steel for machine manufacturing and a production method thereof, in particular to axle steel for railway vehicles and a production method thereof.
Background
Railway vehicle axles are important components for ensuring the safety of railway vehicles, and the quality state of the railway vehicle axles is closely related to the safety of railway transportation. With the rapid development of Chinese railway transportation, the quality requirement on the axle of the railway vehicle is higher and higher. In the running process of the railway vehicle, the axle bears bending force, torsional force and impact force, and is used under the condition of alternating stress for a long time, and the stress condition is complex. When the axle is used, the stress condition of the surface of the axle is the worst, so that the improvement of the surface quality is particularly important on the premise of ensuring the qualified comprehensive performance of the axle.
The requirement of urban rail transit train axles, passenger car axles and the like on the operation safety is very high, so that the railway vehicle axles in Europe, India and other countries adopt the design of lower carbon content and put strict requirements on the impact toughness of the axles.
In European wheel set and bogie-axle-product Standard (EN13261-2003), the axle steel adopts EA1N material, and the chemical composition (weight percentage) is as follows: less than or equal to 0.40 percent of C, less than or equal to 0.50 percent of Si, less than or equal to 1.20 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.30 percent of Cr, less than or equal to 0.30 percent of Ni, less than or equal to 0.30 percent of Cu, less than or equal to 0.08 percent of Mo and less than or. Required yield strength of the axle is not less than 320MPa, tensile strength is 550-650MPa, and elongation (A)5) More than or equal to 22^ percent, the longitudinal U-shaped impact energy (the notch depth is 5mm) at 20 ℃ is more than or equal to 30J, and the transverse U-shaped impact energy at 20 ℃ is more than or equal to 25J.
The axle steel in the specification of the India passenger and freight train forged steel axle railway standard (R16-95) comprises the following chemical components in percentage by weight: less than or equal to 0.37 percent of C, 0.15 to 0.46 percent of Si, less than or equal to 1.12 percent of Mn, less than or equal to 0.040 percent of P, less than or equal to 0.040 percent of S, less than or equal to 0.07 percent of P + S, less than or equal to 0.30 percent of Cr, less than or equal to 0.30 percent of Ni, less than or equal to 0.05 percent of Mo, less than or equal to 0.30 percent of Cu and less. For normalized axles, the yield strength is required to be not less than 320MPa, the tensile strength is required to be 550-5) More than or equal to 22^ percent, and the longitudinal U-shaped impact value (the notch depth is 5mm) at 20 ℃ is more than or equal to 25J/cm2(impact energy 31.3J).
However, most of the axle steel produced according to the standards at present has surface magnetic mark defects, and has low and unstable transverse impact energy.
In order to reduce the magnetic mark waste products on the surface of the existing railway vehicle axle and improve the comprehensive mechanical properties, especially the transverse impact energy, it is necessary to develop a new axle steel with lower carbon content for the railway vehicle and a production method thereof, so as to overcome the defects of the existing axle for the railway vehicle and improve the use safety of the axle.
Disclosure of Invention
The invention provides axle steel for railway vehicles and a production method thereof, which can overcome the defects of high rejection rate of magnetic marks on the surface of the existing axle and low transverse impact power, obviously reduce the magnetic mark wastes on the surface of the axle of the railway vehicle, improve the comprehensive mechanical property of the axle, particularly improve the transverse impact power of the axle, and ensure that the transverse impact power has a guaranteed value of more than or equal to 40J, thereby improving the use safety of the axle.
The technical scheme adopted by the invention is as follows:
the axle steel for the railway vehicles comprises the following chemical components in percentage by weight: 0.33-0.38% of C, 0.15-0.40% of Si, 0.90-1.05% of Mn, less than or equal to 0.020% of P, less than or equal to 0.020% of S, 0.030-0.050% of V, 0.015-0.035% of Als, 0.0040-0.0090% of N, 0.020-0.050% of RE in molten steel, and the balance of Fe and inevitable impurity elements.
Further, the chemical components with the following weight percentages are preferably contained: 0.33-0.38% of C, 0.20-0.35% of Si, 0.90-1.00% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.035-0.045% of V, 0.020-0.030% of Als, 0.0050-0.0080% of N, 0.020-0.035% of RE in molten steel, and the balance of Fe and inevitable impurity elements.
Still further, it is preferable that the chemical composition comprises the following weight percentages: 0.33-0.38% of C, 0.20-0.30% of Si, 0.92-0.98% of Mn0.92, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.035-0.045% of V, 0.020-0.030% of Als, 0.0050-0.0080% of N, and 0.020-0.025% of RE in the molten steel. The balance of iron and inevitable impurity elements.
The effects of the chemical components are as follows:
carbon is an important element in steel to improve strength, and a suitable carbon content range is 0.33 to 0.38%, too low reduces strength and hardness, and too high reduces plasticity and toughness.
Silicon is mainly present in the form of a solid solution in the steel in ferrite or austenite, and can improve the strength of the steel, and is also a deoxidizing element for steel making, but the content is not too high so as not to reduce the toughness of the steel. Therefore, the content is controlled to be 0.15-0.40%.
Manganese is an important element for improving strength, and the suitable manganese content range is 0.90-1.05%.
V is added to refine the structure after normalizing, the tempering stability is properly improved, and N is controlled to be beneficial to better play the role of V.
Aluminum is a deoxidizer in steel and can refine the structure of steel.
The addition of a proper amount of RE can purify steel, reduce the total amount of inclusions, make the inclusions become fine and disperse, obviously improve anisotropy and improve transverse impact performance. And can greatly reduce surface magnetic mark waste products caused by longitudinally distributed inclusions.
The invention also provides a production method of the axle steel for the railway vehicle, which comprises the following process steps: smelting → LF + RH refining → protective pouring → pressure processing → rough machining → heat treatment → fine machining → inspection and warehousing.
Further, adding lanthanum-cerium-rare earth alloy blocks with the purity of more than or equal to 95 percent before breaking empty in the final stage of RH refining treatment; or feeding lanthanum-cerium-rare earth alloy wires with the purity of more than or equal to 98 percent after the RH refining treatment is carried out to break the air.
The heat treatment step comprises 1 normalizing and 1 tempering treatment.
Further, normalizing and heating at 850-900 ℃, and keeping the temperature for 3-5 hours. When the normalizing heating temperature is higher than 900 ℃, the normalized structure is thick and large, and the plasticity and the toughness of the steel are not good; if the normalizing heating temperature is lower than 850 ℃, the austenitizing of the steel is not complete.
Further, tempering and heating are carried out at 480-580 ℃, and heat preservation is carried out for 3-5 hours. The tempering heating temperature higher than 580 ℃ lowers the strength, while the tempering temperature lower than 480 ℃ is insufficient, which is unfavorable for the plasticity and toughness of the steel.
Further preferably, the normalizing heating temperature is 860-880 ℃, and the heat preservation time is 3-5 hours; tempering and heating at 500-530 ℃, and preserving heat for 3-5 hours.
The current axles with lower carbon content have the following problems:
1. when the surface of magnetic powder after finish machining of an axle is subjected to flaw detection, the defect of magnetic marks with the length of 0.5-30mm and the fineness of the surface is often found, the proportion can reach 1-6%, the axle is scrapped, the axle is shown in figure 1, the magnetic marks are mainly caused by impurities distributed along the longitudinal direction through analysis, the axle is shown in figure 2, and the defect of the magnetic marks is difficult to completely eliminate by adopting common smelting measures.
2. In the rolling and forging processes of the railway vehicle axle, the orientation distribution and the banded structure of the inclusions can cause the performance to generate directionality, so that the transverse toughness is obviously reduced, and the transverse impact energy is generally 30 to 50 percent lower than the longitudinal impact energy. Therefore, the lateral impact work of the axle is often low and unstable.
The microstructure morphology of the axle steel for the railway vehicle obtained by the method disclosed by the invention is ferrite plus pearlite, and the grain size grade detected according to GB/T6394 is smaller than 6.5 grade; the mechanical properties are as follows: the yield strength is more than or equal to 350MPa, the tensile strength is more than or equal to 600MPa, the longitudinal impact energy is more than or equal to 65J, and the transverse impact energy is more than or equal to 45J.
The axle steel for the railway vehicle and the production method thereof provided by the invention can overcome the defects of high rejection rate of magnetic marks on the surface of the existing axle and low transverse impact power, can obviously reduce the magnetic mark wastes on the surface of the railway vehicle axle, reduce the production cost and reduce the quality objections. But also can improve the comprehensive mechanical property, especially the transverse impact energy, and the guarantee value of the transverse impact energy is more than or equal to 40J, thereby improving the use safety of the axle.
Drawings
FIG. 1 shows a magnetic mark defect found during magnetic powder surface inspection after finish machining of an existing railway vehicle axle;
fig. 2 is a scanning electron microscope image of magnetic mark defects, and it can be seen that the magnetic marks are mainly caused by inclusions distributed along the longitudinal direction.
Detailed Description
The present invention will be described in detail with reference to examples.
The chemical components and weight percentages of the axle steel of examples 1 to 6 and comparative examples 1 to 2 are shown in table 1.
TABLE 1
The production process comprises the following steps:
110 ton electric furnace smelting → LF + RH refining → continuous casting → pressure processing (rolling cogging → rapid forging machine forging) → rough machining → heat treatment → fine machining → inspection and warehousing. In the embodiments 1-4, the lanthanum-cerium-rare earth alloy blocks with the purity of 99 percent are added before the blank breaking at the final stage of the RH refining treatment. In the embodiment 5-6, after the RH refining treatment is broken, a lanthanum-cerium-rare earth alloy wire with the purity of 99 percent is fed, and the weak argon blowing is carried out for soft blowing.
The heat treatment process parameters of each example and comparative example are shown in table 2.
TABLE 2
The rating (GB/T10561) of the axle inclusions prepared in each example and comparative example is shown in Table 3
TABLE 3
As can be seen from table 3, the inclusion grade of the examples is significantly reduced.
Table 4 shows the results of the surface magnetic powder flaw detection tests of the finished axle of examples and comparative examples. As can be seen from Table 3, the magnetic powder tests on the surfaces of the axles of the examples are all qualified, while the axles of the comparative examples have unqualified phenomena, so that the technical scheme of the invention has advantages, and the rejection rate and quality objections can be reduced.
TABLE 4
The mechanical properties and microstructure of the axles produced in the examples and comparative examples are shown in Table 5, and the grain size was examined in accordance with GB/T6394.
TABLE 5
Injecting: f is ferrite and P is pearlite.
As can be seen from the comparison between examples 1-6 and comparative examples 1 and 2, the impact energy of the axles prepared in examples 1-6 is improved, especially the transverse impact energy is improved more, and the impact energy can be ensured to be more than or equal to 40J. The axle structures produced in examples 1-6 and ratios 1 and 2 were all F + P, but the axle produced in examples 1-6 had a finer grain size.
The above detailed description of an axle steel for railway vehicles and a method for producing the same with reference to the embodiments is illustrative and not restrictive, and several embodiments may be cited within the scope of the present invention, so that changes and modifications that do not depart from the general concept of the present invention are intended to be included within the scope of the present invention.
Claims (5)
1. The axle steel for the railway vehicles is characterized by comprising the following chemical components in percentage by weight: 0.33-0.38% of C, 0.15-0.40% of Si, 0.90-1.05% of Mn, less than or equal to 0.020% of P, less than or equal to 0.020% of S, 0.030-0.050% of V, 0.015-0.035% of Als, 0.0040-0.0090% of N, 0.020-0.050% of RE added in the molten steel, and the balance of Fe and inevitable impurity elements;
the production method of the axle steel for the railway vehicle comprises the following process steps: smelting → LF + RH refining → protective casting → pressure processing → rough machining → heat treatment → fine machining → inspection and warehousing,
adding lanthanum-cerium-rare earth alloy blocks with the purity of more than or equal to 95 percent before breaking empty in the final stage of RH refining treatment; or feeding lanthanum-cerium-rare earth alloy wires with the purity of more than or equal to 98 percent after the RH refining treatment is carried out to break the space;
the heat treatment step comprises 1 normalizing and 1 tempering treatment;
normalizing and heating at 850-900 ℃, and keeping the temperature for 3-5 hours; tempering and heating at 480-580 ℃, and preserving heat for 3-5 hours;
the structure morphology of the axle steel for the railway vehicle is ferrite plus pearlite, and the grain size grade is smaller than 6.5 grade.
2. The road vehicle axle steel according to claim 1, comprising the following chemical components in percentage by weight: 0.33-0.38% of C, 0.20-0.35% of Si, 0.90-1.00% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.035-0.045% of V, 0.020-0.030% of Als, 0.0050-0.0080% of N, 0.020-0.035% of RE in molten steel, and the balance of Fe and inevitable impurity elements.
3. The road vehicle axle steel according to claim 1, comprising the following chemical components in percentage by weight: 0.33-0.38% of C, 0.20-0.30% of Si, 0.92-0.98% of Mn0.92, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.035-0.045% of V, 0.020-0.030% of Als, 0.0050-0.0080% of N, 0.020-0.025% of RE in molten steel, and the balance of iron and inevitable impurity elements.
4. The axle steel for road vehicles according to claim 1, wherein the normalizing heating temperature is 860 to 880 ℃, and the heat preservation time is 3 to 5 hours; tempering and heating at 500-530 ℃, and preserving heat for 3-5 hours.
5. The axle steel for road vehicles according to claim 1, wherein the mechanical properties of the axle steel for railway vehicles are as follows: the yield strength is more than or equal to 350MPa, the tensile strength is more than or equal to 600MPa, the longitudinal impact energy is more than or equal to 65J, and the transverse impact energy is more than or equal to 45J.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810168830.3A CN108342647B (en) | 2018-02-28 | 2018-02-28 | Axle steel for railway vehicles and production method thereof |
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| CN201810168830.3A CN108342647B (en) | 2018-02-28 | 2018-02-28 | Axle steel for railway vehicles and production method thereof |
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| CN108342647B true CN108342647B (en) | 2019-12-27 |
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| CN109338228B (en) * | 2018-11-21 | 2019-09-27 | 钢铁研究总院 | A kind of high conductivity anode steel claw steel and preparation method thereof |
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| CN101928878B (en) * | 2010-09-17 | 2012-02-01 | 攀钢集团钢铁钒钛股份有限公司 | Axle shaft steel and production method thereof |
| CN102876982A (en) * | 2011-07-14 | 2013-01-16 | 宝山钢铁股份有限公司 | Axle steel and its manufacturing method |
| CN102644033A (en) * | 2012-04-17 | 2012-08-22 | 中国铁道科学研究院金属及化学研究所 | Axle steel used for railway vehicle and preparation method for axle steel |
| CN102719749B (en) * | 2012-06-28 | 2013-09-04 | 宝山钢铁股份有限公司 | Steel for railway axle and production process for steel |
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