High wear resistance and crack resistance wheel steel, wheel and production method thereof

Abstract

The application provides a high-wear-resistance and anti-crack wheel steel and a wheel production method, and the composition comprises the following components: C: 0.58-0.75%, Si: 0.55-1.0%, Mn: 0.70-1.0%, Cr: 0.15-0.35%, V: 0.03-0.06%, P: 0.005-0.010%, S: 0.006-0.015%, T.O: ≤7ppm, [H]: ≤1.5ppm, N: 60-100ppm, and the rest is Fe and inevitable impurity elements. Compared with the prior art, the application is characterized by component design and design of matched wheel production process and heat treatment process, and the rim produced by the application has a tensile strength (Rm) of ≥1200MPa, a yield strength of ≥800MPa, and a rim abrasion limit Brinell hardness of ≥321HBW heavy-load wheel, and the wheel has good high-wear-resistance and anti-crack performance.

Description

Technical Field

[0001] This invention belongs to the field of railway wheel manufacturing technology, specifically relating to a high wear-resistant and crack-resistant wheel steel, a wheel, and a method for producing the same. Background Technology

[0002] A wheel steel disclosed in CN104831158A, published on August 12, 2015, is described in terms of its uses and heat treatment method. The disclosed wheel steel contains the following chemical composition by weight percentage: C 0.68-0.77%, Si≤1.00%, Mn≤1.20%, P≤0.025%, S≤0.025%, with the remainder being Fe and unavoidable impurity elements. It is used to manufacture railway freight car wheels. The heat treatment method includes the following steps: (1) heating the wheel in the furnace to 850-870℃; (2) heat preservation; (3) water spray cooling of the wheel rim; (4) air cooling of the spoke portion when the temperature in the middle of the spoke drops below 730℃; (5) air cooling; (6) heating, tempering, and heat preservation. The wheels manufactured using the above-mentioned components and processes have a tensile strength of 926MPa to 956MPa, which can be used for the manufacture of high-carbon wheels. However, the drawback is that the tensile strength does not exceed 1000MPa, which cannot meet the requirements of high-carbon, high-toughness heavy-duty wheels for railway mining and railway freight.

[0003] Publication No. CN 107245649 A, published on October 13, 2017, discloses a high-strength, high-ductility steel for heavy-duty railway freight car wheels and its production method. The disclosed chemical composition of the wheel (by weight percentage) is: C 0.67-0.77%, Si 0.50-0.70%, Mn 0.70-0.8%, V 0.05-0.15%, N 50-150ppm, Als≤0.025%, P≤0.015%, S≤0.015%, with the remainder being Fe and unavoidable impurity elements. Wheels manufactured using the above composition and corresponding process exhibit good strength and toughness, suitable for heavy-duty wheel manufacturing. However, a drawback is the high content of the microalloying element V, which increases production costs.

[0004] The patent with publication number CN103741033A, which was published on April 23, 2014, discloses a preparation method for high-carbon wheel steel wheels for railway wagons to improve plasticity. The chemical composition of the wheels in weight percentage is as follows: C 0.70 - 0.75%, Si 0.70 - 1.00%, Mn 0.60 - 0.90%, 0 < Cr ≤ 0.35%, Als 0.010 - 0.030%, P ≤ 0.020%, S ≤ 0.040%, and the rest is Fe and inevitable impurity elements. The heat treatment process is as follows: After rolling and rough machining, the wheels are heated in the furnace to 850 - 880°C and then held for a total heating time of 2.5 - 3.0 h, and then taken out of the furnace and air-cooled to room temperature; then the wheels are heated in the furnace to 840 - 860°C and held for a total heating time of 2.5 - 3.0 h, and then taken out of the furnace and sprayed with water for cooling for 450 s; then put into a furnace at 490 - 510°C, held for 4.5 - 5.5 h, and then taken out of the furnace and air-cooled to room temperature to obtain good comprehensive performance. The disadvantage is that compared with the conventional quenching process, an additional normalizing process of heating → air-cooling is added, increasing greenhouse gas emissions. Summary of the Invention

[0005] The present invention provides a highly wear-resistant and crack-resistant wheel steel, and excellent wheel steel is obtained through composition design.

[0006] Another object of the present invention is to provide a wheel and its production method, which are produced using the above-mentioned highly wear-resistant and crack-resistant wheel steel. The produced wheels, compared with traditional AAR-C wheel steel, not only have a higher level of mechanical properties in the rim, can significantly improve the strength of the wheels, effectively enhance the wear resistance of the wheels under heavy-duty service conditions, but also improve the toughness of the wheels and enhance the anti-fracture ability of the wheels under service conditions. The wheels produced by the present invention can be used for railway freight vehicles with an axle load exceeding 30 tons, and the tensile strength and hardness indexes are higher than those of conventional wheels. The wheel design of this application has a greater safety redundancy, making technical reserves for the research and development of wheels with higher strength and toughness requirements for railway mines and railway freight under future heavy-duty conditions.

[0007] The specific technical solution of the present invention is as follows:

[0008] A highly wear-resistant and crack-resistant wheel steel, including the following components in mass percentage:

[0009] C: 0.58 - 0.75%, Si: 0.55 - 1.0%, Mn: 0.70 - 1.0%, Cr: 0.15 - 0.35%, V: 0.03 - 0.06%, P: 0.005 - 0.010%, S: 0.006 - 0.015%, T.O: ≤ 7 ppm, [H]: ≤ 1.5 ppm, N: 60 - 100 ppm, and the rest is Fe and inevitable impurity elements.

[0010] The composition of the high wear-resistant and crack-resistant wheel steel also meets the following requirements: carbon equivalent Ceq=[C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15]×100%, Ceq=0.82-0.92.

[0011] The composition of the high wear-resistant and crack-resistant wheel steel also meets the following requirements: DI: ≥3.0.in; combined with the effective cross-sectional thickness of the wheel rim being 65mm (2.55.in) and performance requirements, the critical quenching diameter of the steel is set to DI: ≥3.0.in, DI = (0.54×C)×(1.00+3.3333×Mn)×(1.00+0.7×Si)×(1.00+2.16×Cr)×(1.00+1.73×V);

[0012] The composition of the high wear-resistant and crack-resistant wheel steel also meets the following requirement: TS≥1200;

[0013] TS = 833 + 1063 × (C - 0.55) + 140 × Si + 151 × Mn + 132 × Cr + 294 × V; Further in-depth research on the effect of each alloying element on strength, assuming that the contribution of each of the above elements to the strength of wheel steel is linear, after multiple linear regression analysis, we obtain: TS = 833 + 1063 × (C - 0.55) + 140 × Si + 151 × Mn + 132 × Cr + 294 × V ≥ 1200.

[0014] When calculating the above formula, the index value of each element is the content of the corresponding element of the above high wear-resistant and crack-resistant wheel steel × 100.

[0015] The present invention provides a wheel manufacturing method using the aforementioned high wear-resistant and crack-resistant wheel steel.

[0016] The wheel production method includes the following process flow: sawing-heating-rolling-heat treatment-processing.

[0017] The heating process involves controlling the temperature of the steel billet in the heating section of the heating furnace at 1220-1260℃, the homogenization temperature at 1260-1310℃, and the total time for preheating, heating, and homogenization at 3-4 hours.

[0018] The rolling process is described below: the wheel rolling temperature is 1150-1200℃, which is the high plasticity temperature range. Below 1150℃, the deformation resistance is high, which is not conducive to metal distribution. Above 1200℃, dynamic recrystallization is not conducive, resulting in coarse grains. The pressing rate is 20-30mm / s. Below 20mm / s, the deformation is slow, and it is impossible to guarantee that deformation will be completed in the high plasticity temperature range. Above 30mm / s, the mill pressure is too high, which is not good for the equipment.

[0019] The heat treatment involves heating at 850-890℃ in the heating section and at 850-870℃ in the soaking section for a total heating time of 2-2.5 hours, with the soaking section lasting 0.5 hours. Then, a weak water cooling process is applied to cool the near-surface metal of the rim tread at a rate of 0.1℃ / s-0.2℃ / s, ensuring cooling within 10mm of the tread surface while maintaining the internal temperature of the rim at point Ac3. Next, a strong water cooling process is performed, with a rim cooling rate of 4-7℃ / s. Simultaneously, air cooling is applied to the wheel spokes and the hub arc transition at a rate of 1-1.5℃ / s, cooling the hub to 780℃ below the phase transformation point temperature. Finally, a tempering treatment is performed at 480-520℃ for 3-4 hours.

[0020] The heat treatment process for the wheel of this invention includes three stages: heating, rim strengthening and cooling, and tempering. During the heat treatment process, due to the combined effects of thermal stress and structural stress, localized plastic deformation occurs in the wheel, manifesting as wheel hub settlement during production. Inaccurate estimation of heat treatment settlement in the process design often leads to significant metal waste during machining, increased machining load, and even unmachined areas of the wheel, resulting in scrap. During the rim strengthening and cooling process, the wheel deforms due to the effects of thermal stress, structural stress, and phase transformation plasticity. Wheel deformation is mainly manifested as outer diameter shrinkage and hub settlement, as described above. Figure 5 (The deformation amount in the figure is magnified by 2 times). The deformation amount during the rim strengthening and cooling process needs to be compensated for by allowing for allowances during the forming design stage. In other words, the accurate prediction of the deformation amount during the rim strengthening and cooling process has a significant impact on the billet design during the rolling forming stage. The deformation during the rim strengthening and cooling process is mainly due to the further bending of the spokes. As the tread and rim continue to cool, the temperature in the vicinity of the tread decreases, and after the austenite transformation occurs, the thermal conductivity increases, the temperature drop accelerates further, and the yield stress increases, preventing further plastic deformation. The shrinkage stress of the rim will be transmitted to the spokes. However, due to the slow temperature drop and high temperature of the spokes, the yield stress generated at the curved ends of the spokes causes the curved ends to bend. During the subsequent isothermal process, due to the further increase in thermal stress, the curved deformation at both ends of the spokes further increases. Throughout the entire heat treatment process, there is basically no plastic deformation in the rim center and hub.

[0021] To suppress wheel hub settlement, after rolling, the wheel of this invention enters a heat treatment furnace. It is heated at 850-890℃ in the heating section and at 850-870℃ in the soaking section for a total heating time of 2-2.5 hours, including 0.5 hours in the soaking section, ensuring uniform austenitization of the wheel's internal structure. Based on the phase transformation characteristics of wheel steel, a weak water cooling is initially used, allowing the near-surface metal of the rim tread to cool at a rate of 0.1℃ / s-0.2℃ / s, ensuring cooling within 10mm of the tread surface. Simultaneously, the internal temperature of the rim is maintained at the Ac3 point (approximately above 560℃), allowing FP transformation to occur at a certain depth near the surface of the wheel tread, while the interior of the rim remains austenitic. After the weak spraying, a strong spray nozzle begins spraying the wheel tread, with a rim cooling rate of 4-7℃ / s. The internal metal of the rim rapidly passes through the Ar3-Ar1 temperature range, suppressing the precipitation of proeutectoid ferrite and preventing the internal structure from transforming into bainite. Simultaneously, the wheel spokes and hub arc transition are air-cooled at a cooling rate of 1-1.5℃ / s, with the hub cooled to 780℃ below the phase transition temperature. When the spoke cooling rate is <1℃ / s, the effect of suppressing sinking is not significant; when the cooling rate is greater than 1.5℃ / s, the spokes lack sufficient toughness. Finally, a tempering treatment is performed at 480-520℃ for 3-4 hours. The wheels produced by this invention have a sinking amount ≤1.0mm.

[0022] The present invention provides a wheel produced by the above method. The wheel has a ferrite-pearlite microstructure with a grain size finer than grade 9 and a pearlite interparticle spacing ≤0.11μm.

[0023] The wheel's rim impact performance is as follows: -60℃ impact energy KV≥6.0J, -40℃ impact energy KV≥9.0J, -20℃ impact energy KV≥13.0J, 0℃ impact energy KV≥15.0J, 20℃ impact energy KV≥24.0J; spoke impact performance is as follows: -60℃ impact energy KV≥5.5J, -40℃ impact energy KV≥7.0J, -20℃ impact energy KV≥11.0J, 0℃ impact energy KV≥14.0J, 20℃ impact energy KV≥22.0J; rim tensile strength R... m ≥1200MPa, yield strength ≥800MPa, rim fracture elongation ≥20%, reduction of area ≥40%; rim wear limit Brinell hardness ≥321HBW, rim microstructure requires pearlite and a small amount of ferrite; possesses good crack resistance.

[0024] The design concept of this invention is as follows:

[0025] Carbon (C): Carbon is essential for steel to achieve high strength and hardness. Steel with a carbon content greater than 0.75% wt exhibits excellent wear resistance and contact fatigue resistance, but poor toughness, and its resistance to thermal damage (primarily thermal fatigue resistance) is also poor. Steel with a carbon content less than 0.58% wt has good toughness and excellent thermal fatigue resistance, but poor wear resistance and contact fatigue resistance. C readily combines with Cr and V to form carbides, which offer good wear resistance and scratch resistance. Considering all factors, for heavy-duty wheels, to balance mechanical and thermal damage, the C content should be controlled between 0.58% and 0.75%.

[0026] Si (Si): Si is the main deoxidizing element in steel, possessing strong solid solution strengthening properties. It also improves the hardenability of wheel steel, particularly enabling a more uniform strength and hardness distribution over a wider cooling rate range, thus enhancing the operability of heat treatment processes. Increasing the Si content increases the Ac1 and Ac3 of the steel, reducing the probability of phase transformation due to braking heat and effectively mitigating thermal delamination and preventing thermal damage defects such as hot cracking. With increasing Si content, the ductile-brittle transition temperature of steel not only does not increase but actually decreases. 20℃ is precisely the sensitive temperature for the ductile-brittle transition; as the ductile-brittle transition temperature decreases, the impact energy at 20℃ also increases and becomes more stable. However, with increasing Si content, the impact plateau energy of the steel decreases. Based on the above observations, it can be concluded that as long as the Si content in wheel steel does not exceed 1.00%wt, the impact toughness of the steel will not be significantly compromised. Therefore, the Si content should be controlled between 0.55-1.0%.

[0027] Mn (Mn) can alter the properties and shape of oxides formed during steel solidification. It also has a strong affinity for sulfur (S), preventing the formation of low-melting-point sulfides (FeS) at grain boundaries and instead allowing it to exist as MnS with a certain degree of plasticity, thus eliminating the harmful effects of sulfur and improving the hot workability of steel. Mn has a solid solution strengthening effect, thereby increasing the strength and hardness of ferrite and austenite. Although its solid solution strengthening effect is not as strong as that of carbon, phosphorus, and silicon, it has almost no effect on the ductility of steel. In ferrite-pearlite steels, Mn is the only alloying element that can increase yield strength while minimizing changes in the brittle-cold transition temperature. A high Mn / S ratio can improve the plasticity and toughness of wheel steel, but it increases overheat sensitivity and temper brittleness. Therefore, this invention defines the Mn content range as 0.70-1.0% and the S content range as 0.006-0.015%.

[0028] Cr: Cr can improve the hardenability and strength of steel. Cr can also reduce the activity of carbon (C), thus reducing the tendency for surface decarburization during heating, rolling, and heat treatment, which is beneficial for obtaining high fatigue resistance. In addition, Cr exhibits a characteristic where the ductile-brittle transition temperature of steel initially decreases and then increases with increasing Cr content. When the Cr content in wheel steel exceeds 0.20%wt, reaching approximately 0.35%wt, the ductile-brittle transition temperature of the steel may increase, reducing the impact energy at 20℃. The Cr content should be controlled between 0.15-0.35%.

[0029] Vanadium (V) is an important strong carbonitride-forming element in wheel steel. Through heating and dissolution followed by cooling and precipitation, it can form interstitial VC, V4C3, and nitrogen-rich V(C,N) second-phase particles in the steel, resulting in strong precipitation strengthening and grain refinement, significantly improving yield strength. Furthermore, the formation of vanadium-containing second-phase particles, due to carbon depletion and a small lattice mismatch with ferrite in the surrounding micro-regions, promotes the formation of proeutectoid ferrite, moderately increasing the wear rate. This achieves a balance between contact fatigue and wear competition, improving the wheel's resistance to surface contact fatigue. This invention sets the vanadium content range at 0.03%-0.06% for the following reasons: Firstly, exceeding this value requires higher heating temperatures to produce a significant strengthening effect; otherwise, the low solid solution V content and low matrix carbon content will severely limit the strength-enhancing effect of V microalloying, even producing negative effects. Secondly, excessively low vanadium content fails to provide significant precipitation strengthening, and improper heat treatment can even lead to a decrease in strength due to vanadium capturing carbon from the matrix.

[0030] Sulfur readily combines with manganese in steel to form MnS inclusions, causing hot brittleness. However, adding a small amount of sulfur can significantly improve the machinability of wheel steel without affecting product performance. MnS also has the effect of refining grain size. The uniform and dispersed precipitation of MnS during solidification requires an appropriate amount of sulfur in the steel. Wheel customers have strict requirements for the rating of MnS inclusions in their standards. Therefore, both aspects must be considered in the process design. Through comparison and analysis of previous data, the optimal value of [S] in the molten steel for the inclusion plasticization process is determined to be controlled between 0.006% and 0.015%.

[0031] P: P is an element with a strong tendency to segregate, increasing the cold brittleness of steel, reducing plasticity, and being detrimental to the uniformity of product microstructure and properties. P should be controlled to ≤0.010%. However, excessively reducing the P content would lead to excessively high refining costs. Therefore, considering typical industrial production conditions, the preferred lower limit for P content is 0.005%.

[0032] TO and [H]: TO forms oxide inclusions in steel, so TO should be controlled to ≤7ppm; [H] forms white spots in steel, which seriously affects product performance, so [H] should be controlled to ≤1.5ppm.

[0033] Nitrogen (N): Nitrogen atoms in steel mainly occupy octahedral interstitial positions in the austenite lattice as interstitial atoms, playing a significant solid solution strengthening role. Simultaneously, N increases the concentration of free electrons in austenite, leading to increased electron energy in the face-centered cubic lattice and enhancing the interatomic metallic bond strength, thereby improving the stability of the microstructure and the strength of the material. However, excessively high N content is detrimental to the ductility and toughness of wheel steel; therefore, this invention sets the N content to 60-100 ppm.

[0034] Based on the strengthening effects of each element in wheel steel, the coefficients are matched according to the different strengthening effects of each element to obtain the Ceq formula. When Ceq is less than 0.82, the wear resistance and rotational fatigue resistance are almost no better than when using "CL60" railway wheel steel of TB / T2817 as raw material, and sometimes even lower. Therefore, it is difficult to use it as raw material for railway wheels used in extremely harsh environments with increased travel distance and load. On the other hand, if Ceq exceeds 0.92, it is difficult to obtain a pearlitic microstructure, resulting in reduced wear resistance. Consequently, the hardness is too high, thus reducing toughness.

[0035] Heavy-duty wheels are subjected to high mechanical loads and large braking thermal loads. To take into account these usage characteristics, it is necessary to start by optimizing the properties of wheel materials. Based on CL60 grade wheel materials, appropriate alloying can be used to improve the hardness of wheel materials to enhance contact fatigue performance and wear resistance. At the same time, the austenite transformation critical temperature of wheel materials can be increased to reduce the probability of thermal damage, thereby improving the performance of heavy-duty wheels.

[0036] Increasing the austenitization phase transformation temperature of wheel steel is the most effective way to improve its anti-peeling properties. Reducing the carbon content can significantly increase the austenitization temperature, but it will also reduce the hardness and wear resistance. Therefore, it is necessary to consider changing other alloying elements of wheel steel to improve its crack resistance.

[0037] Compared with the prior art, the present invention, through component design and the design of matching wheel production and heat treatment processes, produces heavy-duty wheels with rim tensile strength (Rm) ≥1200MPa, yield strength ≥800MPa, and rim wear limit Brinell hardness ≥321HBW. These wheels possess excellent high wear resistance and crack resistance. Attached Figure Description

[0038] Figure 1The stress test of the wheel tread in Example 1 is as follows: The stress of the wheel tread in Example 1 is -139.98 MPa, and the zero stress point is 45 mm below the tread.

[0039] Figure 2 In Example 2, the wheel tread stress is -141.57 MPa, and the zero stress point is 47.54 mm below the tread.

[0040] Figure 3 In Example 3, the stress on the wheel tread is -128.93 MPa, and the zero stress point is 39.51 mm below the tread.

[0041] Figure 4 For comparative example 1, the stress on the wheel tread is -110.75 MPa, and the zero stress point is 35.7 mm below the tread.

[0042] Figure 5 This image shows the deformation of the rim of a heavy-duty HESA wheel after it has been reinforced and cooled. Detailed Implementation

[0043] The present application will be further described below with reference to embodiments and comparative examples.

[0044] Examples 1-3

[0045] A high wear-resistant and crack-resistant wheel steel comprises the following components by mass percentage as shown in Table 1. The balance not shown in Table 1 is Fe and unavoidable impurities.

[0046] Comparative Examples 1-5

[0047] A high wear-resistant and crack-resistant wheel steel comprises the following components by mass percentage as shown in Table 1. The balance not shown in Table 1 is Fe and unavoidable impurities.

[0048] Table 1. Mass of chemical composition of smelting in the examples and comparative examples

[0049]

[0050] The chemical compositions of the embodiments and comparative examples of this invention are shown in Table 1. The production method of producing wheels using the above-mentioned high wear-resistant and crack-resistant wheel steel includes the following process flow:

[0051] The process involves electric arc furnace smelting, LF refining, RH vacuum treatment, continuous casting, sawing, heating, rolling, heat treatment, machining, and flaw detection.

[0052] 1) Heating: The temperature of the billet in the heating section of the heating furnace is controlled between 1220-1260℃, the soaking temperature is controlled between 1260-1310℃, and the total time for preheating, heating and soaking is controlled between 3h and 4h.

[0053] 2) Rolling: The rolling temperature of the wheel is 1150-1200℃, which is the high plasticity temperature range, and the pressing speed is 20-30mm / s.

[0054] 3) Heat Treatment Process for Wheel Steel: To suppress wheel hub settlement, after rolling, the wheel enters a heat treatment furnace. Heating is carried out at 850-890℃ in the heating section and 850-870℃ in the soaking section, with a total heating time of 2-2.5 hours, including 0.5 hours in the soaking section, ensuring uniform austenitization of the wheel's internal structure. Based on the phase transformation characteristics of wheel steel, a relatively weak water cooling is initially used, allowing the near-surface metal of the rim tread to cool at a rate of 0.1℃ / s-0.2℃ / s, ensuring cooling within 10mm of the tread surface. Simultaneously, the internal temperature of the rim is maintained at point Ac3 (approximately above 560℃), allowing the FP transformation to occur first within a certain depth near the surface of the wheel tread, while the interior of the rim remains austenitic. After the weak spraying is completed, the strong spray nozzles begin spraying the wheel tread surface, with a rim cooling rate of 4-7℃ / s. The metal inside the rim rapidly passes through the Ar3-Ar1 temperature range, suppressing the precipitation of proeutectoid ferrite and preventing the internal structure from transforming into bainite. Simultaneously, the wheel spokes and the wheel hub arc transition are air-cooled at a cooling rate of 1-1.5℃ / s, with the wheel hub cooled to 780℃ below the phase transformation point temperature; finally, a tempering treatment is performed at 480-520℃ for 3-4 hours.

[0055] Tables 2 and 3 below show the specific embodiments and comparative examples of the production process parameters of the present invention.

[0056] Table 2. Steel rolling production process parameters for each embodiment and comparative example

[0057]

[0058] Table 3. Heat treatment production process parameters for each embodiment and comparative example

[0059]

[0060] The performance of the wheels produced in the above embodiments and comparative examples is shown in Table 4.

[0061] Table 4. Performance of wheels manufactured in Examples 1-3 and Comparative Examples 1-5

[0062]

[0063] Continued from Table 4

[0064]

[0065] Continued from Table 4

[0066]

[0067] The underlined data above does not meet the requirements of this application.

[0068] The fatigue crack propagation threshold value test for wheel steel profiles is as follows:

[0069] Type I fatigue crack propagation test:

[0070] Fatigue crack propagation specimens were cut from wheel rims at 10mm and 35mm thicknesses. The specimens were 7mm thick and 70mm wide and high. A 25mm long and 0.2mm wide notch was machined on one side of the specimen's axis of symmetry using wire cutting. Fatigue cracks were then pre-induced using a type I loading method on a high-frequency fatigue testing machine (HFP5000). The pre-crack test was conducted at room temperature with a loading frequency of approximately 80 Hz. The force ratio R (the ratio of minimum load to maximum load) at the time of pre-crack induction was the same as the force ratio R used to measure the fatigue crack propagation threshold. During the test, an optical microscope mounted on a micrometer was used to track the crack tip position and measure the crack propagation rate. The crack length on each side of the specimen was denoted as *a*, and the crack propagation rate was denoted as Δa. The crack length was taken as the average of the results from both sides. When the pre-induced type I fatigue crack length was approximately 8mm, a step-down loading method was used to bring the crack propagation rate close to 0.1 mm / 10⁻¹⁰. 6 cyc, and obtained the type I fatigue crack propagation threshold value ΔK. Ⅰth Then, at the same force ratio, the type II fatigue crack propagation threshold ΔK of the specimen was measured. Ⅱth At least two valid samples should be taken under each condition.

[0071] Type II fatigue crack propagation test:

[0072] For pre-cracked specimens (specimens with a Type I fatigue crack propagation threshold), under Type II crack fatigue loading conditions, a lower load amplitude, i.e., a lower Type II stress intensity factor amplitude, is initially applied for 2*10. 6 If the crack does not propagate or the crack propagation is less than 0.1 mm, increase the load amplitude by 10% each time. When the specimen is subjected to the new load amplitude for 2 × 10⁻⁶ cycles... 6 When a crack propagates under cyc loading but the extent of propagation is no greater than 0.2 mm, it is considered a valid specimen, and the load amplitude under this condition is denoted as ΔP. Ⅱ If the crack propagation exceeds 0.2 mm, the specimen is considered invalid. For valid specimens that meet the specified conditions, the average of the load amplitude when crack propagation occurs and the maximum load amplitude when crack propagation does not occur is taken. This average value is used to calculate the stress intensity factor at the tip of the type II crack, i.e., the fatigue crack propagation threshold value ΔK, using the finite element method. Ⅱth The test results are shown in Table 5.

[0073] Table 5 Fatigue crack propagation threshold values ​​for each embodiment and comparative example

[0074]

[0075] Wear performance and contact fatigue performance were compared and tested on an MMS-2A microcomputer-controlled testing machine according to GB 10622 "Metallic Materials Rolling Contact Fatigue Test Method". The test results are shown in Tables 9 and 10. During the tests, the main specimens were wheel specimens prepared according to the embodiments or comparative examples of this invention, and the auxiliary specimens were all U71Mn steel rail specimens of the same hardness. The diameter of both the main specimen and the auxiliary specimen was 60 mm. Wear test: One set of 3 specimens, main specimen rotation speed 360 rpm, auxiliary specimen rotation speed 400 rpm, corresponding to a rotational slip rate of 0.75%, contact stress of 1100 MPa, and 500,000 cycles. Contact fatigue test: One set of 6 specimens, rotation speed 2000 rpm, corresponding to a rotational slip rate of 0.3%, contact stress of 1100-1500 MPa, lubricated with 20# machine oil.

[0076] Table 6 Comparison of wheel wear performance between Examples 1-3 and Comparative Examples 1-5

[0077]

[0078] Table 6 Comparison of wheel contact fatigue performance between Examples 1-3 and Comparative Examples 1-5

[0079]

[0080] The method used in this test is the one recommended in Annex C of EN 13262:2016(C) Railway Applications – Wheelsets and Bogies – Wheels – Product Requirements. This method continuously releases the residual stress in the wheel flange through several cutting processes, while strain gauges are used to monitor the local surface deformation during each cutting process, and finally the residual stress on the wheel surface is calculated.

[0081] Comparison of wheel residual stress in Examples 1-3 and Comparative Examples 1-5 Figures 1-4 Example 1: The wheel tread stress is -139.98 MPa, and the zero-stress point is 45 mm below the tread. Example 2: The wheel tread stress is -141.57 MPa, and the zero-stress point is 47.54 mm below the tread. Example 3: The wheel tread stress is -128.93 MPa, and the zero-stress point is 39.51 mm below the tread. Comparative Example 1: The wheel tread stress is -110.75 MPa, and the zero-stress point is 35.7 mm below the tread.

Claims

1. A high wear and crack resistant wheel steel, characterized in that, The high wear-resisting and anti-crack wheel steel comprises the following components in percentage by mass: C: 0.58-0.75%, Si: 0.55-1.0%, Mn: 0.70-1.0%, Cr: 0.15-0.35%, V: 0.03-0.06%, P: 0.005-0.010%, S: 0.006-0.015%, T.O: ≤7ppm, [H]: ≤1.5ppm, N: 60-100ppm, and the rest is Fe and inevitable impurity elements; The components of the high wear-resisting and anti-crack wheel steel further satisfy: DI: ≥3.0.in; critical quenching diameter DI: ≥3.0.in, DI=(0.54xC)×(1.00+3.3333×Mn)×(1.00+0.7×Si)×(1.00+2.16×Cr)×(1.00+1.73×V); The components of the high wear-resisting and anti-crack wheel steel further satisfy: TS≥1200; TS=833+1063×(C-0.55)+140×Si+151×Mn+132×Cr+294×V; The wheel produced from the high wear-resisting and anti-crack wheel steel satisfies: sinking amount ≤1.0mm; The production method of the wheel produced from the high wear-resisting and anti-crack wheel steel comprises the following technological process: sawing-heating-rolling-heat treatment-processing; The heating: the temperature of the billet in the heating section of the heating furnace is controlled between 1220-1260℃, the soaking temperature is controlled between 1260-1310℃, and the total time of preheating, heating and soaking is controlled between 3h-4h; The rolling: the wheel rolling temperature is 1150-1200℃, and the pressing rate is 20-30mm / s; The heat treatment: heating at 850-890℃ in the heating section, and heating at 850-870℃ in the soaking section, and the total heating time is 2-2.5h, wherein the soaking time is 0.5h; then weak water cooling is firstly adopted, so that the near-surface layer metal of the rim tread is cooled at a cooling speed of 0.1℃ / s-0.2℃ / s, the cooling within 10mm of the tread is ensured, and the temperature inside the rim is ensured at the Ac3 point; then strong water cooling is adopted, the cooling rate of the rim is 4-7℃ / s; at the same time, the spoke and the hub arc transition of the wheel are air-cooled at a cooling speed of 1-1.5℃ / s; finally, tempering treatment is performed at 480-520℃ for 3-4 hours.

2. The high wear, crack resistant wheel steel of claim 1, wherein, The components of the high wear-resisting and anti-crack wheel steel further satisfy: carbon equivalent Ceq=[C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15]×100%, Ceq=0.82-0.

92.

3. A method of producing a vehicle wheel, characterized by, The production method of the high wear-resisting and anti-crack wheel steel comprises the following technological process: sawing-heating-rolling-heat treatment-processing; the heating: the temperature of the billet in the heating section of the heating furnace is controlled between 1220-1260℃, the soaking temperature is controlled between 1260-1310℃, and the total time of preheating, heating and soaking is controlled between 3h-4h; The rolling: the wheel rolling temperature is 1150-1200℃, and the pressing rate is 20-30mm / s; The heat treatment is as follows: heating at 850-890 DEG C in the heating section, at 850-870 DEG C in the soaking section, and for a total time of 2-2.5 h, wherein the soaking section time is 0.5 h; then first weak water cooling is adopted, so that the near surface layer metal of the tread of the rim is cooled at a cooling speed of 0.1 DEG C / s-0.2 DEG C / s, the cooling within 10 mm of the tread is ensured, and meanwhile the temperature inside the rim is ensured at the Ac3 point; then strong water cooling is adopted, the cooling speed of the rim is 4-7 DEG C / s; meanwhile, the spoke and the hub arc transition of the wheel are air cooled at a cooling speed of 1-1.5 DEG C / s; finally, tempering treatment is carried out at 480-520 DEG C for 3-4 h.

4. A wheel produced by the method of claim 3, wherein The structure of the wheel is ferrite-pearlite, the grain size is finer than 9 levels, and the pearlite interlattice distance is ≤0.11 μm.

5. The vehicle wheel of claim 4, wherein, The tensile strength R of the wheel rim of said wheel m ≥ 1200 MPa, yield strength ≥ 800 MPa, elongation at break of the rim ≥ 20%, reduction of area ≥ 40%; limit Brinell hardness of the rim wear ≥ 321 HBW.

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