CN111961963A - Medium-carbon niobium-vanadium microalloyed high-speed wheel steel and wheel preparation method - Google Patents
Medium-carbon niobium-vanadium microalloyed high-speed wheel steel and wheel preparation method Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/34—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tyres; for rims
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- 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
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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Abstract
The invention discloses medium-carbon niobium-vanadium microalloyed high-speed wheel steel and a wheel preparation method, and belongs to the field of railway wheel preparation. Aiming at the problems of poor adaptability and lower strength and hardness of high-speed wheel steel in the prior art, the invention provides medium-carbon niobium-vanadium microalloyed high-speed wheel steel which comprises the following components in percentage by weight: c: 0.52-0.56%, Si: 0.15-0.40%, Mn: 0.50-0.80%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Nb: 0.01-0.03%, V: 0.10-0.20%, and the balance of Fe and inevitable impurity elements. According to the invention, a brand-new component design system is formed by adding Nb and V elements, and corresponding heat treatment processes are matched, so that the strength and hardness of the wheel are improved by more than 5% compared with those of an ER8 wheel on the premise of not reducing the toughness index, the contact fatigue resistance and the wear resistance are also improved, and the adaptability of the wheel is stronger.
Description
Technical Field
The invention belongs to the technical field of railway wheel preparation, and particularly relates to medium-carbon niobium-vanadium microalloyed high-speed wheel steel and a wheel preparation method.
Background
China has attracted attention for the development of high-speed railways, and key parts of high-speed trains are independently innovated. At present, the high-speed wheel in China is mainly an ER8 wheel in European standard EN13262, the wheel made of medium carbon steel has high fracture toughness (more than or equal to 70 MPa-m)1/2) And the service safety is ensured. The structure of the ER8 wheel is a small amount of discontinuous reticular ferrite + lamellar pearlite, wherein the ferrite is a soft phase, the toughness is good, the yield strength is low, the pearlite strength is high, but the toughness is poor, and the matching relationship of the contents of the two determines the final performance of the material. The rim yield strength of ER8 wheel is generally not more than 600MPa, the rolling contact stress between wheel rails is large and alternate when the wheel runs at high speed, so that the secondary surface of the wheel rim tread generates plastic deformation in the running process, and because the steel contains inclusions, cementite and other brittle phases, the rim is easy to generate micro cracks, and the micro cracks generate damages such as peeling and the like under the action of the rolling contact fatigue of the wheel during running. The hardness of the ER8 wheel is generally not more than 265HB, and is relatively low, so that regular vibration is generated in the high-speed movement process of the train, and the polygonal shape of the wheel is generated along with the abrasion of the wheel. From the probability of polygon generation of the high-speed wheel and the statistical result of wheel hardness, the hardness improvement can reduce the polygon generation, and therefore, the service performance of the wheel can be improved by improving the hardness level. In addition, from the relationship of rail hardness matching, the wheel hardness cannot be higher than the rail hardness. In general, the yield strength and tensile strength of the material are correspondingly improved after the hardness is improved, and the effect of plastic deformation of the surface layer of the wheel under the contact stress of the wheel and the rail can be reduced, so that the initiation source of the micro-cracks is reduced. However, the improvement of strength and hardness tends to bring about an index of toughnessAnd the running risk of the vehicle is influenced. Meanwhile, the European high-speed railway has relatively single line, relatively short continuous high-speed running time and no obvious change in climatic conditions, and the ER8 wheel shows better service performance. The service of ER8 wheels has obvious inadaptability due to long-term high-speed railway lines, long trains running at high speed for a long time, large temperature difference between south and north, and large change of east-west service conditions in China, and particularly, the damage problems of wheel tread stripping, multiple changes and the like are more in high-speed trains with the speed of 300 kilometers per hour, so that the maintenance frequency of the wheels is greatly increased, the service life of the wheels is shortened, and the comprehensive cost is improved.
Through research for decades, the comprehensive performance of carbon steel wheels is basically exerted to a limit level, and the further improvement through the optimization of a heat treatment process is difficult. The addition of other elements and alloying become the most direct and effective method for improving the performance of the wheel. In the North American AAR M107/M208 standard, the upper line of Si content is put to 1.0 percent and is obviously higher than 0.40 percent of carbon steel, which is mainly because the AAR M107/M208 standard is mainly used for wheels of trucks, the wheels are braked by brake shoes, the wheel treads are easy to generate heat cracks, and the addition of Si improves the material phase change point and reduces the production of the heat cracks. The 12 national standards of GOST 10791 such as Russia and the like put the line of V content to 0.15%, play the role of V reinforcement and grain refinement, and improve the comprehensive performance of the wheel. Therefore, the characteristics of the high-speed railway in China are combined, component innovation and performance improvement are realized by adding alloy elements on the basis of ER8 wheel component design and performance indexes, and the method has great significance for realizing high-speed wheel products with independent intellectual property rights.
Corresponding improvement is also carried out aiming at the problems, for example, Chinese patent application No. CN201310736261.5, the publication date is 2014, 4, 23, the patent discloses a medium carbon steel wheel steel for railway locomotives and a wheel preparation method, the medium carbon steel wheel steel for railway locomotives and the wheel preparation method improve the fracture toughness, and the weight percentages of chemical components are as follows: 0.46-0.53% of C, 0.20-0.37% of Si, 0.70-0.85% of Mn, 0.10-0.25% of Ni, 0.24-0.32% of Cr, 0.020-0.040% of Als, less than or equal to 0.008% of P, less than or equal to 0.008% of S, and the balance of Fe and inevitable impurity elements, wherein the heat treatment process comprises the following steps: heating the rolled and roughly processed wheel to 860-880 ℃ along with a furnace, preserving heat for 3-3.5 hours, discharging the wheel out of the furnace, and air cooling the wheel to room temperature; heating the wheels to 840-860 ℃ along with the furnace, preserving heat for 4 hours, and then taking the wheels out of the furnace and spraying water for cooling for 400 s; and then putting the mixture into a furnace at 480-500 ℃, preserving heat for 5 hours, and then discharging the mixture out of the furnace for air cooling.
As another example, chinese patent application No. CN201410247587.6, published as 2014, 9, and 3, discloses a medium-carbon low-alloy wheel steel for subways and a manufacturing method thereof, and the steel comprises the following chemical components in percentage by weight: 0.50-0.60% of C, 0.80-1.20% of Si, 0.90-1.10% of Mn0.15-0.35% of Cr0.15-0.35%, 0.010-0.030% of Als, less than or equal to 0.015% of P, less than or equal to 0.015% of S, and the balance of Fe and inevitable impurity elements. The manufacturing method comprises the following steps: an electric furnace smelting process, an ingot cutting and rolling process and a heat treatment process.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems of poor adaptability and lower strength and hardness of high-speed wheel steel in the prior art. The invention provides medium-carbon niobium-vanadium microalloyed high-speed wheel steel and a preparation method thereof. According to the invention, a brand-new component design system is formed by adding Nb and V elements, and corresponding heat treatment processes are matched, so that the strength and hardness of the wheel are improved by more than 5% compared with those of an ER8 wheel on the premise of not reducing the toughness index, the contact fatigue resistance and the wear resistance are also improved, and the adaptability of the wheel is stronger.
2. Technical scheme
In order to solve the above problems, the present invention adopts the following technical solutions.
The medium-carbon niobium-vanadium microalloyed high-speed wheel steel comprises the following components in percentage by weight: c: 0.52-0.56%, Si: 0.15-0.40%, Mn: 0.50-0.80%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Nb: 0.01-0.03%, V: 0.10-0.20%, and the balance of Fe and inevitable impurity elements.
When the weight percentage content of Nb is 0.010-0.020%, the content of V element is controlled at 0.15-0.20%; when the content of Nb in percentage by weight is 0.020-0.030%, the content of V element is controlled to be 0.10-0.15%.
Furthermore, the paint comprises the following components in percentage by weight: c: 0.56%, Si: 0.25%, Mn: 0.65%, P: 0.003%, S: 0: 05%, Nb: 0.01%, V: 0.20 percent, and the balance of Fe and inevitable impurity elements.
A method for preparing a medium carbon niobium vanadium micro-alloyed high speed wheel steel as claimed in any one of the preceding claims, comprising a heat treatment process comprising the steps of:
s1: heating the wheel at 850-880 ℃, and preserving heat for 2.0-3.5 hours after heating;
s2: spraying water to cool the heat-insulated wheel;
s3: and tempering the cooled wheel.
Further, the wheel is cooled to below 550 ℃ in S2 and then the next step is carried out.
Further, in the step S2, the wheel is horizontally placed on the wheel cooling platform, and the wheel is self-transmitted on the wheel cooling platform in the clockwise direction at a speed of 20r/min to 30r/min, and the wheel is subjected to water spray cooling treatment by using a nozzle on the wheel cooling platform.
Furthermore, a plurality of nozzles are uniformly distributed on the wheel cooling platform at intervals around the circumference of the wheel tread.
Further, the wheel in S3 is tempered at 480-520 ℃ for 4.5-6.0 hours.
Furthermore, before the heat treatment process, the method also sequentially comprises an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, a round billet continuous casting process and an ingot cutting and rolling process; the heat treatment process also comprises a processing process and a finished product detection process.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the invention, the components of the wheel steel are optimized, and Nb and V are added, so that Nb can be combined with C to form niobium carbide, and the effect of refining pearlite colonies is achieved during steel rolling and heat treatment; v can be combined with N to form a precipitate to play a role in grain refinement, and can be combined with C to reduce the content of cementite in pearlite and promote the precipitation of ferrite; on the premise of not reducing the toughness index of the wheel, the strength and hardness levels are improved by more than 5 percent compared with those of an ER8 wheel, and the contact fatigue resistance and the wear resistance are also improved;
(2) according to the invention, the contents of Nb and V are further designed, and as C is respectively combined with Nb and V to form second phase particles, the content of cementite in a matrix is reduced, ferrite precipitation is promoted, and thus the toughness index is improved; meanwhile, the generated VC second phase particles can be dissolved in ferrite to play a role in strengthening, and the improvement on the strength and the hardness is greater than the reduction caused by the reduction of matrix cementite, so that the strength and the toughness are improved, and the material performance is improved;
(3) the invention optimizes the heating temperature in the heat treatment process, fully exerts the functions of Nb and V, and leads the formed second phase particles to be dissolved in austenite, thereby improving the strong hardness and the toughness of the material; meanwhile, the cooling speed of the wheel is selected within 2 ℃/s-5 ℃/s, the rim structure of the wheel is ensured to be a pearlite + ferrite structure at the cooling speed, a bainite structure can be generated due to overhigh cooling speed, the cooling speed is overlow, the spacing between generated pearlite pieces is overlarge, the content of precipitated ferrite is high, and the comprehensive performance of the wheel is reduced;
(4) compared with ER8 wheels, the wheel prepared by the invention has the advantages that the toughness is not reduced basically, but the strength and the hardness are improved, so that better comprehensive mechanical properties are obtained, meanwhile, under the laboratory conditions, the wear resistance and the contact fatigue resistance of the material are better than those of the ER8 wheel material, the ferrite and pearlite tissue states of the original wheel can be maintained, the wheel preparation difficulty is not increased, the wheel hardness is still in the wheel rail hardness matching range, and the use of steel rails is not influenced.
Drawings
FIG. 1 is a microstructure of a wheel rim according to example 1 of the present invention;
FIG. 2 is a microstructure of a wheel rim according to example 2 of the present invention;
FIG. 3 is a microstructure of a wheel rim according to example 3 of the present invention;
fig. 4 is a microstructure diagram of ER8 wheel rim.
Detailed Description
The invention is further described with reference to specific embodiments and the accompanying drawings.
The steel for train wheels at home and abroad is medium and high carbon steel with a ferrite-pearlite structure, and compared with other structures, the steel has the best wear resistance at the same hardness level, so the steel for train wheels of the invention has a ferrite-pearlite structure state. The currently commonly used ER8 wheel steel comprises the following components in percentage by weight: less than or equal to 0.56 percent of C, less than or equal to 0.40 percent of Si, less than or equal to 0.80 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.025 percent of S, less than or equal to 0.08 percent of Mo, less than or equal to 0.06 percent of V, 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, and. The wheel steel disclosed by the invention is applied to a high-speed motor train unit, has the advantages of high running speed, long mileage and large temperature change of a service environment, and needs high toughness indexes, particularly low-temperature toughness. Therefore, the specific scheme of the invention is as follows: the medium-carbon niobium-vanadium microalloyed high-speed wheel steel comprises the following components in percentage by weight: c: 0.52-0.56%, Si: 0.15-0.40%, Mn: 0.50-0.80%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Nb: 0.01-0.03%, V: 0.10 to 0.20%, and the balance of Fe and inevitable impurity elements, wherein the following are described for each component:
c element: in the aspect of improving the hardness of the wheel, C contributes most to the strength and the hardness, the strength and hardness index of the wheel can be obviously improved along with the increase of the carbon content, the wear resistance of the wheel is improved, but the toughness of the wheel is reduced along with the increase of the carbon content, so that the range of C is determined to be between 0.52 and 0.56 percent in order to ensure that the toughness of the wheel is not reduced compared with ER8, and a basic condition is created for improving the performance by alloying;
mn element: the strength and hardness of the wheel can be effectively improved, the content of Mn element in the ER8 carbon steel wheel is generally 0.50-0.80%, and the Mn content is controlled between 0.50-0.90% according to the design of the invention;
si element: the increase of the content of the Si element can not only increase the phase change point of the material, but also improve the strength and the hardness, but the over-high Si can increase the thermal sensitivity and the brittleness of the material, and the content of the Si is controlled between 0.15 and 0.40 percent;
nb element: the alloy element is added in the invention, Nb can be combined with C to form niobium carbide, and the niobium carbide has the function of refining pearlite colony during steel rolling and heat treatment. However, higher Nb content, combined with higher C content, tends to result in a reduction in cementite and a reduction in the level of strength. In order to effectively match with the V element, the Nb content is controlled to be 0.01-0.03%, a small amount of niobium carbide is formed to play a role in refining grains and pearlite colonies, on the other hand, the content of cementite in pearlite cannot be greatly reduced due to the combination of C and Nb, and a certain amount of ferrite is precipitated, so that the toughness matching is improved;
v element: the V can be combined with the N to form a precipitate, so that the V plays a role in grain refinement, can be combined with the C, reduces the content of cementite in pearlite and promotes the precipitation of ferrite. The content of the V element is controlled between 0.10 and 0.20 percent;
p and S are impurity elements, so that the content thereof should be controlled to not more than 0.015%.
Furthermore, when the composition design is carried out, when the weight percentage content of Nb is 0.010-0.020%, the content of V element is controlled at 0.15-0.20%; when the content of Nb in percentage by weight is 0.020-0.030%, the content of V element is controlled to be 0.10-0.15%. Under the design, Nb forms Nb (CN) second phase particles, V forms VC second phase particles, and C, Nb and V are combined to form second phase particles, so that the content of cementite in a matrix is reduced, ferrite precipitation is promoted, and toughness indexes are improved.
The preparation method of the medium-carbon niobium-vanadium microalloyed high-speed wheel steel by using the medium-carbon niobium-vanadium microalloyed high-speed wheel steel comprises a heat treatment process, wherein the heat treatment process comprises the following steps of:
s1: the wheel is kept warm for 2.0-3.5 hours at the temperature of 850-; the main reason is that the addition of Nb and V elements makes it necessary to raise the heating temperature to make the formed second phase particles dissolve in austenite in order to fully exert the action of Nb and V. When the Nb and V contents are lower than the lower line, the temperature is 850 ℃, the temperature is increased along with the increase of the Nb and V contents, but the temperature exceeds 880 ℃, and the austenite grains can obviously grow. Therefore, the heat treatment temperature is designed to be 850-880 ℃;
s2: spraying water to cool the heat-insulated wheel; specifically, the wheel kept warm in the step S1 is horizontally placed on a wheel cooling table, the wheel is automatically transmitted on the wheel cooling table in the clockwise direction at the speed of 20 r/min-30 r/min, and a nozzle on the wheel cooling table is used for carrying out water spraying cooling treatment on the wheel, so that metal in the wheel is accelerated and cooled to below 550 ℃ at the cooling speed of 2 ℃/S-5 ℃/S; in the cooling process, martensite and bainite structures are not generated, and the section of the wheel is ensured to be a pearlite + ferrite structure; furthermore, in the step, a plurality of nozzles are uniformly distributed on the wheel cooling table at intervals around the circumferential direction of the wheel tread, the nozzles are inclined nozzles, the inclined nozzles are arranged above the wheel, and the inclined nozzles are inclined downwards to spray water for cooling the wheel, so that the wheel can be uniformly cooled in all directions in multiple directions, and the uniform performance of the circumferential organization of the wheel is better;
s3: the cooled wheel is tempered at 480-520 ℃ for 4.5-6.0 hours.
Of course, the heat treatment is only a part of the wheel prepared by using the medium-carbon aluminum-controlled nitrogen-controlled vanadium microalloyed high-speed wheel steel, and the finished process steps are as follows: an electric furnace steelmaking process → an LF furnace refining process → an RH vacuum treatment process → a round billet continuous casting process → an ingot cutting and rolling process → a heat treatment process → a processing process → a finished product detection process. Since other processes are conventional in the art, the steps will not be described in detail in the present invention. The preparation method is simple and convenient to operate, and parameters of the heat treatment process are optimized, so that the toughness of the prepared wheel is basically not reduced compared with that of the ER8 wheel, but the strength and the hardness are improved, and better comprehensive mechanical properties are obtained.
Example 1
The medium-carbon niobium-vanadium microalloyed high-speed wheel steel comprises the following components in percentage by weight: c: 0.52%, Si: 0.25%, Mn: 0.65%, P: 0.003%, S: 0.005%, Nb: 0.01%, V: 0.20 percent, and the balance of Fe and inevitable impurity elements, and the preparation method of the wheel comprises the following steps: the molten steel containing the components is formed by an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, a round billet continuous casting process, an ingot cutting and rolling process, a heat treatment process, a processing process and a finished product detection process, wherein the heat treatment process comprises the following steps: firstly heating at 860 ℃, preserving heat after heating, cooling the wheel by spraying water after preserving heat for 2.5 hours, accelerating the cooling of the metal in the wheel to below 550 ℃ at the cooling speed of 2 ℃/s-5 ℃/s, and finally tempering at 500 ℃ for 4.5 hours. As a comparative example of the invention, in the implementation, the composition of the ER8 wheel steel comprises the following components in percentage by weight: c: 0.56%, Si: 0.40%, Mn: 0.80%, P: 0.015%, S: 0.025%, Mo: 0.08%, V: 0.06%, Cr: 0.30%, Ni: 0.30%, Cu: 0.30 percent, and the balance of Fe and inevitable impurity elements.
As shown in fig. 1 and 4, the metallographic structure of the rim of the wheel prepared in this example and the ER8 wheel were both pearlite + reticulated ferrite, but the ferrite content of the wheel in this example was about 20%, the ferrite content of the ER8 wheel was about 6%, and about 14% more than that of the ER8 wheel. The mechanical properties of the wheel in this example are shown in Table 1, with toughness levels substantially the same as those of the ER8 wheel, while strength and hardness are significantly improved over those of the ER8 wheel. A wear performance and contact fatigue performance comparison test is carried out on an MMS-2A type microcomputer control testing machine, under the same test conditions, main samples in the test process are the wheel sample prepared in the embodiment and an ER8 wheel sample, all the matched samples are U71Mn steel rail samples with the same hardness, and the diameters of the main samples and the matched samples are both 60 mm. And (3) wear test: the rotation speed of a main sample is 360rpm, the rotation speed of a matched sample is 400rpm, the corresponding rotation slip rate is 0.75%, the contact stress is 1100MPa, and the cycle frequency is 50 ten thousand times. Contact fatigue test: the rotating speed of a group of 6 samples is 2000rpm, the corresponding rotating slip ratio is 0.3 percent, the contact stress is 1100-. Meanwhile, the cycle frequency of the contact fatigue of the wheel is obviously higher than that of the ER8 wheel, which shows that the rolling contact fatigue resistance of the wheel material in the embodiment is better than that of the ER8 wheel.
Meanwhile, under the same test conditions, the abrasion weight loss of the U71Mn steel rail sample ground by the wheel sample prepared in the embodiment is obviously lower than that of the U71Mn steel rail sample ground by the ER8 wheel sample, which is more beneficial to prolonging the service life of the steel rail.
Example 2
The medium-carbon niobium-vanadium microalloyed high-speed wheel steel comprises the following components in percentage by weight: c: 0.54%, Si: 0.30%, Mn: 0.65%, P: 0.003%, S: 0.006%, Nb: 0.02%, V: 0.15 percent, and the balance of Fe and inevitable impurity elements, and the preparation method of the wheel comprises the following steps: molten steel containing the components is formed through an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, a round billet continuous casting process, an ingot cutting and rolling process, a heat treatment process, a processing process and a finished product detection process. The heat treatment process comprises the following steps: firstly heating at 870 ℃, preserving heat after heating, spraying water to cool the wheel after preserving heat for 3.0 hours, accelerating to cool the metal in the wheel to below 550 ℃ at the cooling speed of 2 ℃/s-5 ℃/s, and finally tempering at 500 ℃ for 5.5 hours. The composition of the ER8 wheel steel in this example was identical to that of example 1.
As shown in fig. 2, the metallographic structure of the wheel rim prepared in this example and the ER8 wheel were both pearlite + reticulated ferrite, but the ferrite content of the wheel in this example was about 19%, which was about 13% more than that of the ER8 wheel. The mechanical properties of the wheel in this example are shown in Table 1, with toughness levels substantially the same as those of the ER8 wheel, while strength and hardness are significantly improved over those of the ER8 wheel. A wear performance and contact fatigue performance comparison test is carried out on an MMS-2A type microcomputer control testing machine, under the same test conditions, main samples in the test process are the wheel sample prepared in the embodiment and an ER8 wheel sample, all the matched samples are U71Mn steel rail samples with the same hardness, and the diameters of the main samples and the matched samples are both 60 mm. And (3) wear test: the rotation speed of a main sample is 360rpm, the rotation speed of a matched sample is 400rpm, the corresponding rotation slip rate is 0.75%, the contact stress is 1100MPa, and the cycle frequency is 50 ten thousand times. Contact fatigue test: the rotating speed of a group of 6 samples is 2000rpm, the corresponding rotating slip ratio is 0.3 percent, the contact stress is 1100-. Meanwhile, the cycle frequency of the contact fatigue of the wheel is obviously higher than that of the ER8 wheel, which shows that the rolling contact fatigue resistance of the wheel material in the embodiment is better than that of the ER8 wheel.
Meanwhile, under the same test conditions, the abrasion weight loss of the U71Mn steel rail sample ground by the wheel sample prepared in the embodiment is obviously lower than that of the U71Mn steel rail sample ground by the ER8 wheel sample, which is more beneficial to prolonging the service life of the steel rail.
Example 3
The medium-carbon niobium-vanadium microalloyed high-speed wheel steel comprises the following components in percentage by weight: c: 0.56%, Si: 0.38%, Mn: 0.65%, P: 0.006%, S: 0.007%, Nb: 0.03%, V: 0.12 percent, and the balance of Fe and inevitable impurity elements, and the preparation method of the wheel comprises the following steps: molten steel containing the components is formed through an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, a round billet continuous casting process, an ingot cutting and rolling process, a heat treatment process, a processing process and a finished product detection process. The heat treatment process comprises the following steps: firstly heating at 875 ℃, preserving heat after heating, spraying water to cool the wheel after preserving heat for 3.5 hours, accelerating to cool the metal in the wheel to below 550 ℃ at the cooling speed of 2 ℃/s-5 ℃/s, and finally tempering at 520 ℃ for 5.5 hours. The composition of the ER8 wheel steel in this example was identical to that of example 1.
As shown in fig. 3, the metallographic structure of the rim of the wheel prepared in this example and the ER8 wheel were both pearlite + reticulated ferrite, but the ferrite content of the wheel in this example was about 15%, which was about 9% more than that of the ER8 wheel. The mechanical properties of the wheel in this example are shown in Table 1, with toughness levels substantially the same as those of the ER8 wheel, while strength and hardness are significantly improved over those of the ER8 wheel. A wear performance and contact fatigue performance comparison test is carried out on an MMS-2A type microcomputer control testing machine, under the same test conditions (in the test process, a main sample is a wheel sample prepared in the embodiment and an ER8 wheel sample, matched samples are U71Mn steel rail samples with the same hardness, the diameters of the main sample and the matched samples are both 60mm, the wear test comprises a group of 3 sets of samples, the rotating speed of the main sample is 360rpm, the rotating speed of the matched samples is 400rpm, the corresponding rotating slip rate is 0.75%, the contact stress is 1100MPa, the cycle times are 50 ten thousand, and the contact fatigue test comprises a group of 6 sets of samples, the rotating speed is 2000rpm, the corresponding rotating slip rate is 0.3%, the contact stress is 1100-1500MPa, and the lubricating is carried out by using 20# engine oil). Meanwhile, the cycle frequency of the contact fatigue of the wheel is obviously higher than that of the ER8 wheel, which shows that the rolling contact fatigue resistance of the wheel material in the embodiment is better than that of the ER8 wheel.
Meanwhile, under the same test conditions, the abrasion weight loss of the U71Mn steel rail sample ground by the wheel sample prepared in the embodiment is obviously lower than that of the U71Mn steel rail sample ground by the ER8 wheel sample, which is more beneficial to prolonging the service life of the steel rail.
Table 1 examples 1-3 and ER8 wheel rim performance
TABLE 2 comparison of wear Performance of examples 1-3 and ER8 wheels
TABLE 3 comparison of contact fatigue Performance of examples 1-3 and ER8 wheels
It is clear from tables 2 and 3 that under the laboratory conditions, the wear resistance and the contact fatigue resistance of the medium-carbon niobium-vanadium microalloyed high-speed wheel steel are better than those of ER8 wheels, the wheel prepared by the invention can keep the ferrite-pearlite structure state of the original wheel without increasing the difficulty of wheel preparation, and in addition, the hardness of the wheel prepared by the invention is still in the hardness matching range of the wheel rail and does not influence the use of the steel rail.
The examples described herein are merely illustrative of the preferred embodiments of the present invention and do not limit the spirit and scope of the present invention, and various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall within the protection scope of the present invention.
Claims (9)
1. A medium-carbon niobium-vanadium microalloyed high-speed wheel steel is characterized in that: comprises the following components in percentage by weight: c: 0.52-0.56%, Si: 0.15-0.40%, Mn: 0.50-0.80%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Nb: 0.01-0.03%, V: 0.10-0.20%, and the balance of Fe and inevitable impurity elements.
2. A medium carbon niobium vanadium microalloyed high speed wheel steel as claimed in claim 1 wherein: when the weight percentage content of Nb is 0.010-0.020%, the content of V element is controlled at 0.15-0.20%; when the content of Nb in percentage by weight is 0.020-0.030%, the content of V element is controlled to be 0.10-0.15%.
3. A medium carbon niobium vanadium microalloyed high speed wheel steel as claimed in claim 2, wherein: comprises the following components in percentage by weight: c: 0.56%, Si: 0.25%, Mn: 0.65%, P: 0.003%, S: 0: 05%, Nb: 0.01%, V: 0.20 percent, and the balance of Fe and inevitable impurity elements.
4. A method of producing a medium carbon niobium vanadium micro-alloyed high speed wheel using a medium carbon niobium vanadium micro-alloyed high speed wheel steel according to any one of claims 1 to 3, comprising a heat treatment process, characterized in that: the heat treatment process comprises the following steps:
s1: heating the wheel at 850-880 ℃, and preserving heat for 2.0-3.5 hours after heating;
s2: spraying water to cool the heat-insulated wheel;
s3: and tempering the cooled wheel.
5. The method for preparing a medium-carbon niobium-vanadium microalloyed high-speed wheel according to claim 4, wherein: in S2, the wheel is cooled to below 550 ℃ and then the next step is carried out.
6. The method for preparing a medium-carbon niobium-vanadium microalloyed high-speed wheel according to claim 5, wherein: and S2, horizontally placing the wheel on a wheel cooling table, automatically transmitting the wheel on the wheel cooling table at a speed of 20 r/min-30 r/min in a clockwise direction, and performing water spray cooling treatment on the wheel by using a nozzle on the wheel cooling table.
7. The method for preparing a medium-carbon niobium-vanadium microalloyed high-speed wheel according to claim 6, wherein: and a plurality of nozzles are uniformly distributed on the wheel cooling table at intervals around the circumferential direction of the wheel tread.
8. The method for preparing a medium-carbon niobium-vanadium microalloyed high-speed wheel according to claim 4, wherein: in S3, the wheel is tempered at 480-520 ℃ for 4.5-6.0 hours.
9. The method for preparing a medium-carbon niobium-vanadium microalloyed high-speed wheel according to claim 4, wherein: before the heat treatment process, the method also sequentially comprises an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, a round billet continuous casting process and an ingot cutting and rolling process; the heat treatment process also comprises a processing process and a finished product detection process.
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| CN114107823A (en) * | 2021-11-30 | 2022-03-01 | 宝武集团马钢轨交材料科技有限公司 | Steel for high-speed wheel, heat treatment method of steel and method for preparing high-speed wheel by using steel |
| CN115341150A (en) * | 2022-08-25 | 2022-11-15 | 宝武集团马钢轨交材料科技有限公司 | Anti-fatigue crack steel for locomotive wheels, method for producing locomotive wheels and application |
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| CN102534396A (en) * | 2012-03-13 | 2012-07-04 | 北京科技大学 | Method for producing Nb-containing high-speed train wheel steel |
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