High-toughness alloy for high-speed rail and preparation method of high-toughness alloy

Abstract

The invention relates to the technical field of metal materials, in particular to a high-toughness alloy for a high-speed rail and a preparation method of the high-toughness alloy. The alloy comprises 0.06%-0.12% of carbon, 0.05%-0.12% of cerium, 0.012%-0.032% of yttrium, 1.0%-1.5% of tantalum, 10.0%-15.0% of nickel, 12.0%-14.0% of chromium, 3.5%-5.0% of cobalt, 1.5%-2.5% of molybdenum, less than or equal to 0.005% of sulfur and the balance of iron. A preparation method of the modified carburant used in the preparation comprises the following steps: S1, pickling petroleum coke; s2, preparing cerium oxide sol; s3, preparing a cerium oxide coating layer; and 4, depositing a layer. The strength of the alloy is remarkably improved, meanwhile, the alloy has excellent toughness, wear resistance and hardness, and the service life of high-speed rail parts is prolonged. The preparation method is convenient to operate and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal materials for high-speed rail, and in particular to a high-toughness alloy for high-speed rail and a preparation method thereof. BACKGROUND

[0002] With the rapid development of high-speed rail technology, the performance requirements for high-speed rail components are becoming higher and higher. High-speed rail runs at extremely high speed, and components need to withstand huge mechanical stress, thermal stress and complex dynamic load. For example, key components such as high-speed rail wheels and axles need not only to have high strength to withstand the huge weight of the train and the centrifugal force generated by high-speed running, but also to have high toughness to prevent brittle fracture under impact load. In addition, high-speed rail components are affected by environmental factors such as friction, wear and corrosion during long-term operation, so the alloy material also needs to have good wear resistance and corrosion resistance.

[0003] At present, the alloy materials commonly used in the field of high-speed rail mainly include some high-strength steels and stainless steels. Although high-strength steels have relatively high strength, their toughness is relatively poor and they are prone to brittle fracture when impacted, which makes it difficult to meet the requirements of high-speed rail components for toughness during high-speed operation. Although stainless steels have good corrosion resistance, their strength and toughness cannot meet the high standards of high-speed rail for component performance. In addition, these traditional alloy materials are prone to performance degradation, such as strength reduction and toughness reduction, in high-temperature environments, which further limits their application in the field of high-speed rail. At the same time, the preparation process of existing alloy materials also has some problems, such as the introduction of impurities during smelting, which affects the performance of the alloy; complex processing process, high cost, which is not conducive to large-scale production and application.

[0004] Therefore, it is urgent to develop a high-toughness alloy with optimized composition and coordinated process to realize the unity of high strength and high toughness. SUMMARY

[0005] In order to solve the above problems, the present application provides a high-toughness alloy for high-speed rail and a preparation method thereof. The high-toughness alloy for high-speed rail of the present application is prepared by reasonably matching nickel (Ni), chromium (Cr), cobalt (Co) and molybdenum (Mo) and rare earth elements, and the strength of the alloy matrix is significantly improved, while the alloy has excellent toughness, wear resistance and hardness, prolonging the service life of high-speed rail components. The preparation method of the present application significantly improves the comprehensive performance of the alloy by precise composition control, efficient refining process, optimized heat treatment process and innovative material application, which can effectively meet the requirements of high-speed rail field for high-performance alloy materials.

[0006] The technical scheme adopted by the present application to achieve the above-mentioned purpose is as follows:

[0007] A high-tenacity alloy for high-speed rail, comprising the following ingredients in percentage by weight: carbon (C): 0.06%-0.12%, cerium (Ce): 0.05%-0.12%, yttrium (Y): 0.012%-0.032%, tantalum (Ta): 1.0%-1.5%, nickel (Ni): 10.0%-15.0%, chromium (Cr): 12.0%-14.0%, cobalt (Co): 3.5%-5.0%, molybdenum (Mo): 1.5%-2.5%, sulfur (S): ≤0.005%, and the balance being iron and other unavoidable impurities.

[0008] The preparation method of the high-tenacity alloy for high-speed rail, comprising the following steps:

[0009] Step 1, weighing the raw materials according to the weight percentage of each element in the alloy, and placing the raw materials in a vacuum furnace under a vacuum degree of ≤5×10 -2 Pa, melting at 1480-1520℃, and increasing the temperature to 1580-1620℃, adding a modified carbonizer and a rare earth metal compound to obtain an alloy liquid, and refining the alloy liquid for 30-40min;

[0010] Step 2, pouring the refined alloy liquid into a gradient preheated mold, and cooling to room temperature to obtain a cast ingot;

[0011] Step 3, annealing the cast ingot at 1150-1250℃ for 1.5-2.5h, then decreasing the temperature to 1150℃, starting multi-directional forging, and gradually decreasing the temperature until 900℃, and cooling to obtain the alloy;

[0012] The modified carbonizer is prepared by the following method:

[0013] Step S1, mixing petroleum coke with acid, and stirring at 58-63℃ for 1.5-2.5h for pickling, and then washing with water until neutral;

[0014] Step S2, adding cerium nitrate into water to prepare a cerium nitrate solution, adding polyethylene glycol, and adjusting the pH to 4.5 by dropwise adding ammonia water to form a cerium oxide sol;

[0015] Step S3, immersing the petroleum coke washed with water in step S1 into the cerium oxide sol, ultrasonic treatment, pre-drying, and then passing water vapor into the fluidized bed, and keeping the temperature at 180-220℃ for 25-35min to form a cerium oxide coated carbonizer; The precursor, and then calcining at 580-600℃ under a nitrogen atmosphere for 0.8-1.2h to obtain a cerium oxide coated carbonizer;

[0016] Step S4, depositing an ALD layer on the cerium oxide coated carbonizer obtained in step S3 , and then calcining at 550-650℃ under a nitrogen atmosphere for 50-70min to obtain a modified carbonizer.

[0017] Preferably, in step S1, the acid is hydrochloric acid with a concentration of 3 mol / L, and the weight-volume ratio of petroleum coke to hydrochloric acid is 1 g / 5-8 ml.

[0018] Preferably, in step S2, the concentration of cerium nitrate in the cerium nitrate solution is 0.08-0.12 M, and the concentration of polyethylene glycol in the cerium nitrate solution is 0.4-0.6 wt%.

[0019] Preferably, in step S3, the solid-liquid ratio of petroleum coke to ceria sol is 1 g / 90-110 ml, and the water vapor flow rate is 0.8-1.0 m³ / h.

[0020] Preferably, in step S4, the The deposition method of the layer is as follows: trimethylaluminum is used, the pulse time is 0.1 s, the amount used is 0.5 mg, argon is purged for 5 s, then deionized water is pulsed, the time is 0.05 s, the vapor pressure is 3 Torr, argon is purged for 5 s, the argon purge flow is 5 L / min, and the purge pressure is 50 Pa; the above is one cycle, and a total of 8-12 cycles are performed.

[0021] Preferably, the rare earth metal composite is a yttria@ceria composite, and the preparation method is as follows:

[0022] In step a, yttrium nitrate is added to water to prepare a yttrium nitrate solution, then cetyltrimethylammonium bromide is added, the solution is stirred until it becomes a translucent colloid, then urea is added, then the temperature is raised to 175-185°C, and the reaction is carried out for 7-9 h to form precipitation, separation and purification, then calcination at 480-510°C in air for 1.5-2.5 h to obtain yttria;

[0023] In step b, part of the cerium nitrate is dissolved in water to prepare a cerium nitrate solution, then sodium citrate and yttria are added, hydrothermal reaction is carried out at 180-210°C for 1.5-2.5 h, then the remaining cerium nitrate is added, the reaction is continued for 9-11 h, then the temperature is cooled to 55-65°C, oleylamine is added and mixed uniformly, and then dried to obtain a yttria@ceria composite.

[0024] Preferably, in step a, the concentration of the yttrium nitrate aqueous solution is 0.1 M, the concentration of cetyltrimethylammonium bromide in the yttrium nitrate aqueous solution is 0.1 wt%, and the molar ratio of yttrium nitrate to urea is 1:3.

[0025] Preferably, in step b, the mass concentrations of sodium citrate and oleylamine in the cerium nitrate solution are 0.26% and 0.5%, respectively, and the molar ratio of yttria to the total amount of cerium nitrate is 1:2-3.

[0026] Preferably, the amounts of the modified carbon raiser and the rare earth metal composite are 0.08-0.15% and 0.12-0.3% of the total amount of alloy liquid, respectively.

[0027] The present invention has the following beneficial effects:

[0028] The high-toughness alloy for high-speed rail of this invention significantly improves the matrix strength of the alloy through a rationally proportioned blend of alloying elements such as nickel (Ni), chromium (Cr), cobalt (Co), and molybdenum (Mo). Simultaneously, the rare earth elements cerium (Ce) and yttrium (Y) refine the grain structure, giving the alloy excellent toughness on top of high strength, effectively preventing brittle fracture under impact loads. This is particularly suitable for the dual requirements of high strength and high toughness in high-speed rail components during high-speed operation. The addition of tantalum (Ta) significantly enhances the alloy's high-temperature strength and creep resistance, enabling it to maintain stable mechanical properties even at high temperatures, extending the service life of high-speed rail components, and reducing the frequency of maintenance and replacement due to performance degradation caused by high temperatures. The synergistic effect of elements such as molybdenum (Mo) and tantalum (Ta) in the alloy improves its hardness and wear resistance. During the frictional contact process of high-speed rail components, the alloy effectively resists wear, maintains the dimensional accuracy and performance stability of the components, and extends their service life.

[0029] The preparation method of this invention, through precise composition control, efficient refining process, optimized heat treatment process and innovative material application, significantly improves the comprehensive performance of the alloy and can effectively meet the requirements of high-speed rail for high-performance alloy materials.

[0030] Furthermore, the modified carbon raiser of this invention removes impurities (such as ash and metal oxides) by acid washing of petroleum coke, improving carbon purity and ensuring uniform distribution of carbon in the alloy. Cerium oxide coating: As a rare earth oxide, cerium oxide can refine grains, inhibit grain boundary migration at high temperatures, and improve the strength and toughness of the alloy. Formed by sol-gel method combined with steam activation. The precursor, after calcination, generates highly dispersed cerium oxide, which enhances the interfacial bonding force with the iron matrix. The layer prevents cerium oxide from agglomerating during high-temperature smelting, maintaining its nanoscale dispersion, while also avoiding premature oxidation and loss of the carburizing agent. After calcination It forms a stable composite structure with cerium oxide, further optimizing the carbon release kinetics. The modified carbon raiser gradually releases carbon atoms during high-temperature smelting, avoiding excessively high local carbon concentrations and reducing the risk of segregation.

[0031] Yttrium oxide's high melting point and thermal stability allow it to maintain structural integrity as an inert core during high-temperature smelting. It can inhibit recrystallization grain growth and improve the high-temperature creep resistance of the alloy. Cerium oxide has high reactivity and readily reacts with impurities such as oxygen and sulfur in the melt (e.g., (Generation), purifying grain boundaries and reducing brittle phases. Forming a coherent interface with yttrium oxide enhances the compatibility of nanoparticles in the iron matrix. The core-shell structure provides more heterogeneous nucleation sites, refining the as-cast microstructure (e.g., reducing dendrite spacing) and improving the alloy's ductility and toughness. Yttrium oxide@cerium oxide hinders dislocation movement during hot working (multi-directional forging), promotes dynamic recrystallization, forms fine equiaxed grains, and optimizes the strength-toughness match. The cerium oxide shell can consume free oxygen in the alloy, forming a dense oxide film ( This enhances the corrosion resistance of high-speed rail in its service environment. Yttrium oxide nuclei slow down the growth rate of the oxide film, improving the stability of the alloy in high-temperature and humid environments. The modified carburizer... The layer slows down the carbon release rate, avoids carbon segregation, and promotes the uniform nucleation of fine carbides. Cerium oxide nanoparticles, as heterogeneous nucleation cores, refine the primary austenite grains, further enhancing strength and toughness. Detailed Implementation

[0032] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] Industrial pure iron, 99% purity, Tianjin Hejifeng Metal Materials Co., Ltd.; Electrolytic nickel plate, 99.9% high purity, Shandong Kunliyuan Steel Co., Ltd.; Ferrochrome alloy, micro-carbon ferrochrome. Qinghe County Chaotai Metal Materials Co., Ltd.; Electrolytic cobalt, purity ≥ 99.96%, Tianjin Haoyuan Metal Materials Co., Ltd.; Ferromolybdenum alloy. Particle size 10-100mm, Tianjin Hejifeng Metal Materials Co., Ltd.; Nickel-tantalum alloy, The following raw materials were used in the following examples: Shanghai Yanbei New Material Technology Co., Ltd.; petroleum coke, particle size 20-40 mesh, carbon 98.5%, Shijiazhuang Mayue Building Materials Co., Ltd.; cerium nitrate, purity 99%, Shandong Jinhe Chemical Co., Ltd.; polyethylene glycol 2000, Jinan Yiliuba Chemical Co., Ltd.; yttrium nitrate (yttrium nitrate hexahydrate); hexadecyltrimethylammonium bromide, Wuhan Smike Biotechnology Co., Ltd.; urea, purity 99%, brand: Kelunduo; sodium citrate, 99% purity, white crystals, Langfang Qianyao Technology Co., Ltd.; oleylamine, purity 99%, Jinan Zhiheng Zhiyuan Chemical Technology Co., Ltd. All raw materials used in the following examples are commercially available products.

[0034] Example 1

[0035] A high-toughness alloy for high-speed rail comprises the following components by weight percentage: carbon (C): 0.10%, cerium (Ce): 0.08%, yttrium (Y): 0.018%, tantalum (Ta): 1.2%, nickel (Ni): 12%, chromium (Cr): 13%, cobalt (Co): 4.2%, molybdenum (Mo): 2%, sulfur (S): ≤0.005%, with the balance being iron and other unavoidable impurities.

[0036] A method for preparing a high-toughness alloy for high-speed rail includes the following steps:

[0037] Step 1: Weigh the raw materials according to the weight percentage of each element in the alloy. Melt the raw materials (industrial pure iron, electrolytic nickel plate, ferrochrome alloy, electrolytic cobalt, ferromolybdenum alloy, and nickel-tantalum alloy) at 1500℃ under a vacuum degree ≤5×10⁻⁶. -2 To prevent oxidation, the temperature was raised to 1600℃, and a modified carbon refining agent and a rare earth metal composite were injected to obtain an alloy liquid. Argon was used as the carrier gas at a flow rate of 1.2 m³ / h, and the mixture was refined for 35 min. The amounts of the modified carbon refining agent and the rare earth metal composite were 0.13% and 0.20% of the total alloy liquid, respectively. The rare earth metal composite and the modified carbon refining agent were mixed and injected, with a carrier gas flow rate of 1.2 m³ / h and a temperature of 1580 ± 10℃.

[0038] Step 2: Pour the refined alloy liquid into a gradient-preheated mold. The temperature of the lower part of the mold is 400±10℃, and the temperature of the upper part is 150±10℃. Then cool it to room temperature to obtain an ingot. The cooling process is carried out in stages. The first stage is 1600℃→1300℃, with the cooling rate controlled at ≤1.5℃ / s and the duration is 15-22min, so that Cr atoms can diffuse fully. The second stage is 1300℃→1100℃, with the cooling rate increased by 2.0-3.0℃ / s and the duration is 8-10min, to prevent chromium precipitation.

[0039] Step 3: The above ingot is homogenized and annealed at 1200℃ for 2 hours to eliminate dendrite segregation. Then, it is cooled to 1150℃ and multi-directional forging begins. During the process, the temperature is gradually reduced until the final forging at 900℃, with a cumulative deformation of 75% in 6 passes. Under an argon atmosphere, it is held at 1050℃ for 1 hour, and then oil quenched. The alloy after holding is quickly transferred to 100℃ quenching oil (such as mineral oil), completely immersed, and the oil is stirred to ensure uniform cooling. After removal, it is cooled to ≤50℃ and subjected to liquid nitrogen cryogenic treatment. Specifically, it is cooled to -196℃ at a rate of ≤5°C / min, held for 6 hours, and then heated to room temperature at a rate of ≤2°C / min.

[0040] The modified carbon raiser is prepared by the following method:

[0041] Step 1, pickling petroleum coke with hydrochloric acid at a concentration of 3 mol / L: mix petroleum coke and hydrochloric acid, stir at 60°C for 2 hours for pickling, and then wash with water until neutral. The weight-volume ratio of petroleum coke to hydrochloric acid is 1 g / 6 ml.

[0042] Step S2: Cerium nitrate is added to water to prepare a cerium nitrate solution, then polyethylene glycol is added, and ammonia is added dropwise to adjust the pH to 4.5, forming a cerium oxide sol; the concentration of cerium nitrate in the cerium nitrate solution is 0.10M, the concentration of polyethylene glycol in the cerium nitrate solution is 0.5wt%, and the concentration of ammonia is 25%;

[0043] Step S3: Immerse the petroleum coke washed in step S1 into cerium oxide sol, with a solid-liquid ratio of petroleum coke to cerium oxide sol of 1 g / 100 ml. Sonicate at 40 kHz for 30 min, centrifuge, pre-dry at 120 °C for 2 h, then introduce steam into a fluidized bed at a flow rate of 0.9 m³ / h and hold at 200 °C for 30 min to form… The precursor was calcined at 590°C under a nitrogen atmosphere for 1 hour to obtain cerium oxide-coated carbon raiser.

[0044] Step S4: The cerium oxide-coated carburizer obtained in step S3 is deposited by ALD. The process involves a layer of trimethylaluminum pulsed for 0.1 s at a dosage of 0.5 mg, followed by argon purging for 5 s. Deionized water pulsed for 0.05 s at a vapor pressure of 3 Torr, and argon purging for 5 s. The argon purging flow rate is 5 L / min, and the purging pressure is 50 Pa. This constitutes one cycle, and a total of 8-12 cycles are performed. The mixture is then calcined at 600 °C under a nitrogen atmosphere for 60 min to obtain the modified carbon raiser.

[0045] The rare earth metal composite is a yttrium oxide@cerium oxide composite, and its preparation method is as follows:

[0046] Step a: Yttrium nitrate is added to water to prepare a 0.1M solution. Then, 0.1 wt% hexadecyltrimethylammonium bromide is added to the yttrium nitrate solution, and the mixture is magnetically stirred at 45°C for 30 minutes until the solution becomes a translucent colloid. Urea is then added to the solution, and stirring continues for 10 minutes. The molar ratio of urea to urea is 1:3, then the temperature is raised to 175-185℃ and the reaction is carried out for 7-9 hours to form... After precipitation and separation, the hexadecyltrimethylammonium bromide was removed by Soxhlet extraction with ethanol, and then calcined at 480℃ in air for 2.5 h to obtain yttrium oxide;

[0047] Step b: Dissolve half of the cerium nitrate in water to prepare a 0.025M solution. Add sodium citrate and yttrium oxide, and perform a hydrothermal reaction at 190°C for 2 hours. Then add the remaining cerium nitrate and continue the reaction for 10 hours. Cool to 60°C, add oleylamine, and stir magnetically at 500 rpm for 45 minutes. Dry under vacuum at 60°C to obtain the yttrium oxide@cerium oxide complex. The mass concentrations of sodium citrate and oleylamine in the cerium nitrate solution are 0.26% and 0.5%, respectively, and the molar ratio of yttrium oxide to the total amount of cerium nitrate is 1:3.

[0048] Example 2

[0049] A high-toughness alloy for high-speed rail comprises the following components by weight percentage: carbon (C): 0.06%, cerium (Ce): 0.05%, yttrium (Y): 0.012%, tantalum (Ta): 1.5%, nickel (Ni): 15.0%, chromium (Cr): 14%, cobalt (Co): 3.5%, molybdenum (Mo): 1.5%, sulfur (S): ≤0.005%, with the balance being iron and other unavoidable impurities.

[0050] A method for preparing a high-toughness alloy for high-speed rail includes the following steps:

[0051] Step 1: Weigh the raw materials according to the weight percentage of each element in the alloy. Melt the raw materials (industrial pure iron, electrolytic nickel plate, ferrochrome alloy, electrolytic cobalt, ferromolybdenum alloy, and nickel-tantalum alloy) at 1480℃ under a vacuum degree ≤5×10⁻⁶. -2 To prevent oxidation, the temperature was raised to 1580℃, and a modified carbon refining agent and a rare earth metal composite were injected to obtain an alloy liquid. Argon was used as the carrier gas at a flow rate of 1.0 m³ / h, and the mixture was refined for 40 min. The amounts of the modified carbon refining agent and the rare earth metal composite were 0.08% and 0.12% of the total amount of the alloy liquid, respectively. The rare earth metal composite and the modified carbon refining agent were mixed and injected, with a carrier gas flow rate of 1.2 m³ / h and a temperature of 1580±10℃.

[0052] Step 2 is the same as in Example 1;

[0053] Step 3: The above ingot is homogenized and annealed at 1150℃ for 2.5h to eliminate dendrite segregation, and then multi-directional forging is started. During the process, the temperature is gradually reduced to 900℃ for final forging, with a cumulative deformation of 75% in 6 passes. Under an argon atmosphere, it is held at 1050℃ for 1h, and then oil quenched. The alloy after holding is quickly transferred to 80℃ quenching oil (such as mineral oil), completely immersed and stirred to ensure uniform cooling. After removal, it is cooled to ≤50℃ and subjected to liquid nitrogen cryogenic treatment. Specifically, it is cooled to -196℃ at a rate of ≤5°C / min, held for 4 hours, and then heated to room temperature at a rate of ≤2°C / min.

[0054] The modified carbon raiser is prepared by the following method:

[0055] Step 1: Pickling petroleum coke with hydrochloric acid at a concentration of 3 mol / L: mix petroleum coke and hydrochloric acid, stir at 58°C for 2.5 h for pickling, and then wash with water until neutral. The weight-volume ratio of petroleum coke to hydrochloric acid is 1 g / 5 ml.

[0056] Step S2: Cerium nitrate is added to water to prepare a cerium nitrate solution, then polyethylene glycol is added, and ammonia is added dropwise to adjust the pH to 4.5, forming a cerium oxide sol; the concentration of cerium nitrate in the cerium nitrate solution is 0.08M, the concentration of polyethylene glycol in the cerium nitrate solution is 0.4wt%, and the concentration of ammonia is 25%;

[0057] Step S3: Immerse the petroleum coke washed in step S1 into cerium oxide sol, with a solid-liquid ratio of petroleum coke to cerium oxide sol of 1 g / 90 ml. Sonicate at 40 kHz for 25 min, centrifuge, pre-dry at 110℃ for 2.5 h, then introduce steam into a fluidized bed at a flow rate of 0.8 m³ / h and hold at 180℃ for 35 min to form… The precursor was calcined at 600°C under a nitrogen atmosphere for 0.8 h to obtain cerium oxide-coated carbon raiser;

[0058] Step S4: The cerium oxide-coated carburizer obtained in step S3 is deposited by ALD. The modified carbon raiser was prepared by pulsed trimethylaluminum for 0.1 s at a dose of 0.5 mg, followed by argon purging for 5 s, and then purging deionized water for 0.05 s at a vapor pressure of 3 Torr for 5 s. The argon purging flow rate was 5 L / min and the purging pressure was 50 Pa. This constituted one cycle, and a total of 8 cycles were performed. The mixture was then calcined at 650 °C under a nitrogen atmosphere for 50 min to obtain the modified carbon raiser.

[0059] The rare earth metal composite is a yttrium oxide@cerium oxide composite, and its preparation method is as follows:

[0060] Step a: Yttrium nitrate is added to water to prepare a 0.1M solution. Then, 0.1 wt% hexadecyltrimethylammonium bromide is added to the yttrium nitrate solution, and the mixture is magnetically stirred at 45°C for 30 minutes until the solution becomes a translucent colloid. Urea is then added to the solution, and stirring continues for 10 minutes. The molar ratio of urea to urea is 1:3, then the temperature is raised to 185℃ and the reaction is carried out for 7 hours to form... After precipitation and separation, the hexadecyltrimethylammonium bromide was removed by Soxhlet extraction with ethanol, and then calcined at 500℃ in air for 2 hours to obtain yttrium oxide.

[0061] Step b: Dissolve half of the cerium nitrate in water to prepare a 0.025M solution. Add sodium citrate and yttrium oxide, and perform a hydrothermal reaction at 180°C for 2.5 hours. Then add the remaining cerium nitrate and continue the reaction for 9.5 hours. Cool to 60°C, add oleylamine, and stir magnetically at 500 rpm for 45 minutes. Dry under vacuum at 60°C to obtain the yttrium oxide@cerium oxide complex. The mass concentrations of sodium citrate and oleylamine in the cerium nitrate solution are 0.26% and 0.5%, respectively, and the molar ratio of yttrium oxide to the total amount of cerium nitrate is 1:2.

[0062] Example 3

[0063] A high-toughness alloy for high-speed rail comprises the following components by weight percentage: carbon (C): 0.12%, cerium (Ce): 0.12%, yttrium (Y): 0.032%, tantalum (Ta): 1%, nickel (Ni): 10%, chromium (Cr): 12%, cobalt (Co): 5%, molybdenum (Mo): 2.5%, sulfur (S): ≤0.005%, with the balance being iron and other unavoidable impurities.

[0064] A method for preparing a high-toughness alloy for high-speed rail includes the following steps:

[0065] Step 1: Weigh the raw materials according to the weight percentage of each element in the alloy. Melt the raw materials (industrial pure iron, electrolytic nickel plate, ferrochrome alloy, electrolytic cobalt, ferromolybdenum alloy, and nickel-tantalum alloy) at 1520℃ under a vacuum degree ≤5×10⁻⁶. -2 To prevent oxidation, the temperature was raised to 1620℃, and a modified carbon refining agent and a rare earth metal composite were injected to obtain an alloy liquid. Argon was used as the carrier gas at a flow rate of 1.3 m³ / h, and the mixture was refined for 30 min. The amounts of the modified carbon refining agent and the rare earth metal composite were 0.15% and 0.30% of the total alloy liquid, respectively. The rare earth metal composite and the modified carbon refining agent were mixed and injected, with a carrier gas flow rate of 1.2 m³ / h and a temperature of 1580±10℃.

[0066] Step 2 is the same as in Example 1;

[0067] Step 3: The above ingot is homogenized and annealed at 1250℃ for 1.5h to eliminate dendrite segregation, and then cooled to 1150℃ to begin multi-directional forging. During the process, the temperature is gradually reduced to 900℃ for final forging, with a cumulative deformation of 75% in 6 passes. Under an argon atmosphere, it is held at 1050℃ for 1h, and then oil quenched. The alloy after holding is quickly transferred to 120℃ quenching oil (such as mineral oil), completely immersed and stirred to ensure uniform cooling. After removal, it is cooled to ≤50℃ and subjected to liquid nitrogen cryogenic treatment, specifically cooling to -196℃ at a rate of ≤5°C / min, holding for 8 hours, and then heating to room temperature at a rate of ≤2°C / min.

[0068] The modified carbon raiser is prepared by the following method:

[0069] Step 1: Pickling petroleum coke with hydrochloric acid at a concentration of 3 mol / L: mix petroleum coke and hydrochloric acid, stir at 63°C for 1.5 h for pickling, and then wash with water until neutral. The weight-volume ratio of petroleum coke to hydrochloric acid is 1 g / 8 ml.

[0070] Step S2: Cerium nitrate is added to water to prepare a cerium nitrate solution, then polyethylene glycol is added, and ammonia is added dropwise to adjust the pH to 4.5, forming a cerium oxide sol; the concentration of cerium nitrate in the cerium nitrate solution is 0.12M, the concentration of polyethylene glycol in the cerium nitrate solution is 0.6wt%, and the concentration of ammonia is 25%;

[0071] Step S3: Immerse the petroleum coke washed in step S1 into cerium oxide sol, with a solid-liquid ratio of petroleum coke to cerium oxide sol of 1 g / 110 ml. Sonicate at 40 kHz for 35 min, centrifuge, pre-dry at 130 °C for 1.5 h, then introduce steam into a fluidized bed at a flow rate of 1.0 m³ / h and maintain at 220 °C for 25 min to form… The precursor was calcined at 580°C under a nitrogen atmosphere for 1.2 h to obtain cerium oxide-coated carbon raiser;

[0072] Step S4: The cerium oxide-coated carburizer obtained in step S3 is deposited by ALD. The modified carbon raiser was prepared by pulsed trimethylaluminum for 0.1 s at a dose of 0.5 mg, followed by argon purging for 5 s, deionized water pulsed for 0.05 s at a vapor pressure of 3 Torr, and argon purging for 5 s at a flow rate of 5 L / min and a purging pressure of 50 Pa. This constituted one cycle, and a total of 12 cycles were performed. The mixture was then calcined at 550 °C under a nitrogen atmosphere for 70 min to obtain the modified carbon raiser.

[0073] The rare earth metal composite is a yttrium oxide@cerium oxide composite, and its preparation method is as follows:

[0074] Step a: Yttrium nitrate is added to water to prepare a 0.1M solution. Then, 0.1 wt% hexadecyltrimethylammonium bromide is added to the yttrium nitrate solution, and the mixture is magnetically stirred at 45°C for 30 minutes until the solution becomes a translucent colloid. Urea is then added to the solution, and stirring continues for 10 minutes. The molar ratio of urea to urea is 1:3, then the temperature is raised to 175℃ and the reaction is carried out for 9 hours to form... After precipitation and separation, the hexadecyltrimethylammonium bromide was removed by Soxhlet extraction with ethanol, and then calcined at 510℃ in air for 1.5 h to obtain yttrium oxide;

[0075] Step b: Dissolve half of the cerium nitrate in water to prepare a 0.025M solution. Add sodium citrate and yttrium oxide, and react hydrothermally at 210°C for 1.5 hours. Then add the remaining cerium nitrate and continue the reaction for 10.5 hours. Cool to 55°C, add oleylamine, and stir magnetically at 500 rpm for 45 minutes. Dry under vacuum at 60°C to obtain the yttrium oxide@cerium oxide complex. The mass concentrations of sodium citrate and oleylamine in the cerium nitrate solution are 0.26% and 0.5%, respectively, and the molar ratio of yttrium oxide to the total amount of cerium nitrate is 1:3.

[0076] Comparative Example 1

[0077] A method for preparing an alloy for high-speed rail, wherein unmodified petroleum coke is used as a carbon raiser, and the rest is the same as in Example 1.

[0078] Comparative Example 2

[0079] A method for preparing an alloy for high-speed rail, wherein a mixture of yttrium oxide and cerium oxide is used to replace the yttrium oxide@cerium oxide composite, wherein the molar ratio of yttrium oxide to the total amount of cerium nitrate is 1:3, and the rest is the same as in Example 1.

[0080] Comparative Example 3

[0081] A method for preparing an alloy for high-speed rail, wherein unmodified petroleum coke is used as a carbon raiser, and a mixture of yttrium oxide and cerium oxide is used to replace the yttrium oxide@cerium oxide composite, wherein the molar ratio of yttrium oxide to the total amount of cerium nitrate is 1:3, and the rest is the same as in Example 1.

[0082] 1. Impact Toughness: The impact test was performed in accordance with the national standards GB / T229-2020 "Metallic Materials Charpy Pendulum Impact Test Method" and GB / T19748-2019 "Metallic Materials Charpy V-Notch Pendulum Impact Test Instrumented Test Method". The specimen size was a standard specimen of 55×10×10mm, with a V-notch, a notch depth of 2mm, and a root radius of 0.25mm. The radius of curvature of the pendulum hammer edge was 2mm.

[0083] 2. Wear Resistance Test: The dry friction and wear performance of the coated material was studied using a UMT-2 tribometer with a "ball-on-disc" design. A ceramic ball with a diameter of 10 mm was used as the upper body. A load of 50 N, a linear velocity of 10 mm / s, and a wear cycle of 60 mm were set. The mass loss after the experiment was recorded to evaluate the wear resistance of the alloy material.

[0084] 3. Tensile testing shall be conducted in accordance with GB / T228-2010 Tensile Testing of Metallic Materials; hardness testing shall be conducted in accordance with GB / T230.1—2018 Rockwell Hardness Test of Metallic Materials.

[0085] Table 1. Test Results

[0086]

[0087] As shown in Table 1, Examples 1-3, due to the use of modified carbon raisers and yttrium oxide@cerium oxide core-shell structures, significantly refined the grains and improved toughness, resulting in impact values ​​higher than Comparative Examples 1-3. Furthermore, their wear resistance and tensile properties were also superior to Comparative Examples 1-3. Comparative Example 3 (unmodified carbon raiser + mixed rare earth elements) exhibited the worst performance, indicating that the synergistic modification using the modified carbon raiser and yttrium oxide@cerium oxide core-shell particles of this invention is crucial for improving toughness and overall performance.

[0088] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0089] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-toughness alloy for high-speed rail, characterized in that, It contains the following components by weight percentage: carbon 0.06%-0.12%, cerium 0.05%-0.12%, yttrium 0.012%-0.032%, tantalum 1.0%-1.5%, nickel 10.0%-15.0%, chromium 12.0%-14.0%, cobalt 3.5%-5.0%, molybdenum 1.5%-2.5%, sulfur ≤0.005%, and the balance being iron.

2. The method for preparing high-toughness alloy for high-speed rail as described in claim 1, characterized in that, Includes the following steps: Step 1: Weigh the raw materials according to the weight percentage of each element in the alloy. The raw materials include industrial pure iron, electrolytic nickel plate, ferrochrome alloy, electrolytic cobalt, ferromolybdenum alloy, and nickel-tantalum alloy. Place them under a vacuum of ≤5×10⁻⁶. -2 The alloy liquid is obtained by melting at 1480-1520℃, heating to 1580-1620℃, adding a modified carbon raiser and a rare earth metal composite, and refining the alloy liquid for 30-40 minutes. Step 2: Pour the refined alloy liquid into a gradient preheated mold and cool it to room temperature to obtain an ingot; Step 3: Anneal the above ingot at 1150-1250℃ for 1.5-2.5 hours, then cool it down to 1150℃ to start multi-directional forging, and gradually cool it down to 900℃ to finish. Cool it down to obtain the product. The modified carbon raiser is prepared by the following method: Step S1: Mix petroleum coke and acid, stir at 58-63℃ for 1.5-2.5h for acid washing, and then wash with water until neutral; Step S2: Add cerium nitrate to water to make a cerium nitrate solution, then add polyethylene glycol, and add ammonia to adjust the pH to 4.5 to form cerium oxide sol; Step S3: Immerse the petroleum coke washed in step S1 into cerium oxide sol, ultrasonically treat and pre-dry it, then pass steam through it in a fluidized bed and keep it at 180-220℃ for 25-35 minutes to form... The precursor is then calcined at 580-600℃ under a nitrogen atmosphere for 0.8-1.2 h to obtain cerium oxide-coated carbon raiser; Step S4: The cerium oxide-coated carburizer obtained in step S3 is deposited by ALD. The mixture is then calcined at 550-650℃ under a nitrogen atmosphere for 50-70 minutes to obtain the modified carbon raiser.

3. The method for preparing high-toughness alloy for high-speed rail as described in claim 2, characterized in that, In step S1, the acid is hydrochloric acid with a concentration of 3 mol / L, and the weight-to-volume ratio of petroleum coke to hydrochloric acid is 1 g / 5-8 ml.

4. The method for preparing high-toughness alloy for high-speed rail as described in claim 2, characterized in that, In step S2, the concentration of cerium nitrate in the cerium nitrate solution is 0.08-0.12M, and the concentration of polyethylene glycol in the cerium nitrate solution is 0.4-0.6wt%.

5. The method for preparing high-toughness alloy for high-speed rail as described in claim 2, characterized in that, In step S3, the solid-liquid ratio of petroleum coke to cerium oxide sol is 1 g / 90-110 ml, and the steam flow rate is 0.8-1.0 m³ / h.

6. The method for preparing high-toughness alloy for high-speed rail as described in claim 2, characterized in that, In step S4, the The deposition method of the layer is as follows: trimethylaluminum is used, the pulse time is 0.1s, the dosage is 0.5mg, argon gas is purged for 5s, then deionized water is pulsed for 0.05s, the vapor pressure is 3 Torr, and argon gas is purged for 5s. The argon gas purging flow rate is 5L / min and the purging pressure is 50Pa. The above is one cycle, and a total of 8-12 cycles are performed.

7. The method for preparing high-toughness alloy for high-speed rail as described in claim 2, characterized in that, The rare earth metal composite is a yttrium oxide@cerium oxide composite, and its preparation method is as follows: Step a: Yttrium nitrate is added to water to prepare a Yttrium nitrate solution. Then, hexadecyltrimethylammonium bromide is added and stirred until the solution becomes a semi-transparent colloid. Urea is then added, and the temperature is raised to 175-185℃ and reacted for 7-9 hours to form... The precipitate was separated and purified, and then calcined in air at 480-510℃ for 1.5-2.5 h to obtain yttrium oxide. Step b: Dissolve part of cerium nitrate in water to prepare cerium nitrate solution, then add sodium citrate and yttrium oxide, and perform a hydrothermal reaction at 180-210℃ for 1.5-2.5 hours. Then add the remaining cerium nitrate and continue the reaction for 9-11 hours. Then cool to 55-65℃, add oleylamine, mix well, and dry to obtain yttrium oxide@cerium oxide complex.

8. The method for preparing high-toughness alloy for high-speed rail as described in claim 7, characterized in that, In step a, the concentration of the aqueous solution of yttrium nitrate is 0.1M, the concentration of hexadecyltrimethylammonium bromide in the aqueous solution of yttrium nitrate is 0.1wt%, and the molar ratio of yttrium nitrate to urea is 1:

3.

9. The method for preparing high-toughness alloy for high-speed rail as described in claim 7, characterized in that, In step b, the mass concentrations of sodium citrate and oleylamine in the cerium nitrate solution are 0.26% and 0.5%, respectively, and the molar ratio of yttrium oxide to the total amount of cerium nitrate is 1:2-3.

10. The method for preparing high-toughness alloy for high-speed rail as described in claim 2, characterized in that, The modified carbon raiser and rare earth metal composite are used at amounts of 0.08-0.15% and 0.12-0.3% of the total alloy liquid, respectively.

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