A high-speed shaft-mounted cast steel brake disc material and its preparation method and application

Abstract

The invention discloses a high-speed shaft-mounted cast steel brake disc material and its preparation method and application, and belongs to the field of metallurgical technology. A high-speed shaft-mounted cast steel brake disc material comprises the following components in percentage by mass: C: 0.31-0.39%; Si: 0.36-0.42%; Ti: 0.87-1.56%; Cr: 0.90-1.75%; Ni: 1.66-2.54%; Ta: 1.03-1.57%; Al: 0.006-0.009%; N: 0.009-0.016%; P: ≤0.01%; S: ≤0.01%; the balance is Fe. The high-speed shaft-mounted cast steel brake disc material obtained by the invention has the characteristics of good heat dissipation performance, excellent high-temperature mechanical properties and wear resistance.

Description

Technical Field

[0001] The invention relates to a high-speed shaft-mounted cast steel brake disc material and a preparation method and application thereof, belonging to the technical field of metallurgy. Background Art

[0002] As the speed of high-speed trains continues to increase, the requirements for the braking system are also increasing. As a key component to ensure the safe operation of trains, the performance of the braking system is directly related to the safety of passengers. When running at high speed, the heat generated by the train during braking is extremely large, which puts higher requirements on the heat dissipation capacity and heat resistance of the braking system. Traditional braking technology has been unable to meet the braking needs of high-speed trains in emergency situations. For example, during high-speed driving, the train needs to slow down and stop in a short time, which requires the braking system to absorb and dissipate a large amount of heat in a short time to avoid brake failure due to excessive temperature. In addition to heat dissipation and strength requirements, the wear resistance of the braking system is equally important. In the case of high-speed continuous braking, the friction between the brake disc and the brake pad will aggravate the wear of the brake disc. Therefore, the brake disc material must have good wear resistance to extend its service life. In addition, the reliability of the braking system is also a factor that cannot be ignored. The braking system of a high-speed train needs to maintain stable operation under various harsh conditions, and any small fault may lead to serious consequences.

[0003] At present, the common brake discs on the market are mainly cast iron brake discs, forged steel brake discs and cast steel brake discs. Among them, cast iron brake discs are widely used in ordinary trains due to their low cost and mature processing technology; forged steel brake discs are used in some special application scenarios due to their high strength and toughness. However, in the braking system of high-speed trains, cast steel brake discs have occupied a dominant position due to their unique performance advantages. Although new materials such as ceramic-based composites and carbon / carbon composites have better performance in theory, they are not as good as cast steel brake discs in terms of cost and technical maturity. Therefore, at the current stage, cast steel brake discs are still the preferred material for high-speed train braking systems.

[0004] However, with the continuous advancement of high-speed rail technology, existing cast steel brake discs have gradually exposed some shortcomings. Under high-speed operating conditions, brake discs must have higher heat dissipation performance, more stable high-temperature mechanical properties, and better wear resistance. Especially during continuous braking, the brake disc needs to dissipate heat quickly and effectively to prevent excessive temperature from causing material performance degradation; at the same time, the brake disc must maintain good mechanical strength at high temperatures to ensure that the braking effect is not affected; in addition, frequent braking operations will aggravate the wear on the brake disc surface, so the brake disc material must have excellent wear resistance to extend its service life.

[0005] Therefore, those skilled in the art are in urgent need of developing a high-speed shaft-mounted cast steel brake disc material and a preparation method thereof to solve the above-mentioned problems. Summary of the invention

[0006] The invention provides a high-speed shaft-mounted cast steel brake disc material, which has the characteristics of good heat dissipation performance, excellent high-temperature mechanical properties and wear resistance.

[0007] At the same time, the present invention provides a method for preparing a high-speed shaft-mounted cast steel brake disc material, which enables the cast steel brake disc material to have a specific organizational morphology with a TaC@Ta(CN) composite strengthening phase distribution in its microstructure, so that it has good heat dissipation performance, high temperature performance and strong wear resistance.

[0008] At the same time, the present invention provides an application of a high-speed shaft-mounted cast steel brake disc material in a shaft-mounted cast steel brake disc.

[0009] At the same time, the invention provides a shaft-mounted cast steel brake disc.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0011] A high-speed shaft-mounted cast steel brake disc material comprises the following components in percentage by mass: C: 0.31-0.39%; Si: 0.36-0.42%; Ti: 0.87-1.56%; Cr: 0.90-1.75%; Ni: 1.66-2.54%; Ta: 1.03-1.57%; Al: 0.006-0.009%; N: 0.009-0.016%; P: ≤0.01%; S: ≤0.01%; the remainder is Fe.

[0012] Preferably, the microstructure of the cast steel brake disc material has a core-shell TaC@Ta(CN) composite strengthening phase distribution in which a Ta(CN) surface layer envelops a TaC core.

[0013] Preferably, the cast steel brake disc material has a tensile strength of ≥1403Mpa, a yield strength of ≥1265Mpa, an elongation after fracture of ≥22.1%, and a wear of ≤4.6mm. 3 , no cracks in thermal fatigue test.

[0014] A method for preparing a high-speed shaft-mounted cast steel brake disc material comprises the following steps:

[0015] S1. Electric furnace smelting: The raw materials are smelted into molten iron, followed by oxygen blowing and adding quicklime for slag making, slag blocking and steel tapping to obtain molten steel;

[0016] The smelting molten steel includes the following element components in percentage by mass: C: 0.87-1.12%; Si: 0.36-0.42%; Ti: 0.87-1.56%; Cr: 0.90-1.75%; Ni: 0.63-0.97%; Al: ≤0.004%; P: ≤0.03%; S: ≤0.03%; the balance is Fe;

[0017] S2. Double furnace refining: LF refining and VD refining of the molten steel obtained by S1 electric furnace smelting;

[0018] S21.LF refining: the molten steel obtained in S1 is transferred to the LF refining furnace, the temperature is increased, tantalum-nickel master alloy is added, the composition is adjusted, argon gas is blown in, aluminum wire is fed in for precipitation deoxidation and diffusion deoxidation, quicklime and fluorite are added for slag formation, and refined molten steel is obtained;

[0019] S22. VD refining: the refined molten steel obtained in S21 is transferred to a VD vacuum furnace, vacuumed, and subjected to vacuum degassing treatment on the refined molten steel. Subsequently, nitrogen is blown from the bottom to break the vacuum and add nitrogen to the molten steel. Calcium wire is fed, and slag is removed to obtain high-nitrogen casting molten steel.

[0020] S3 pressure casting: The high nitrogen casting molten steel obtained by S22 was poured into the casting mold by pressure, and the molten steel was cooled to room temperature after solidification to obtain a cast steel brake disc;

[0021] S4. Post-processing: The cast steel brake disc obtained in S3 is subjected to three-stage performance heat treatment to finally obtain a high-speed shaft-mounted cast steel brake disc.

[0022] Preferably, in S21, the composition of the refined molten steel and its mass percentage include C: 0.47~0.75%; Si: 0.36~0.42%; Ti: 0.87~1.56%; Cr: 0.90~1.75%; Ni: 1.66~2.54%; Ta: 1.03~1.57%; Al: 0.006~0.009%; P: ≤0.01%; S: ≤0.01%; the balance is Fe.

[0023] Preferably, in S22, the components and their mass percentages in the high nitrogen casting molten steel include C: 0.31-0.39%; Si: 0.36-0.42%; Ti: 0.87-1.56%; Cr: 0.90-1.75%; Ni: 1.66-2.54%; Ta: 1.03-1.57%; Al: 0.006-0.009%; N: 0.009-0.016%; P: ≤0.01%; S: ≤0.01%; and the balance is Fe.

[0024] Preferably, in S1, the smelting temperature is 1600-1650°C, and the smelting time is based on the C content reaching the standard.

[0025] Preferably, in S21, the LF refining temperature is 1800-1850°C, the argon flow rate is 100-230NL / min, the feeding amount of aluminum wire is 2-4kg / ton, and the refining time is calculated as 17min / ton.

[0026] Preferably, in S22, the VD refining vacuum is 45-54 Pa, the refining temperature is 1850-1900°C, the nitrogen flow rate is 255-270NL / min, 0.07-0.09kg / ton of calcium wire is fed, and the refining time is calculated as 12min / ton.

[0027] Preferably, in S3, the pouring temperature of the pressure pouring is 1800-1820° C., the pressure is 88-96 MPa, and the filling speed is 40-45 m / s.

[0028] Preferably, in S3, controlled cooling treatment is performed during the solidification process, and the cooling rate control is divided into 4 stages, including a cooling rate of 80 to 90°C / s within -1 / 6T after pouring, a cooling rate of 50 to 55°C / s within 1 / 6T to 1 / 3T, a cooling rate of 20 to 30°C / s within 1 / 3T to 2 / 3T, and a cooling rate of 10 to 15°C / s within the last 1 / 3T.

[0029] Preferably, T represents the total pouring time in seconds, T=KM, M is the total pouring mass in kg, K is the pouring coefficient, and K is 0.13-0.26.

[0030] Preferably, in S4, the three-stage performance heat treatment includes: a first-stage heat treatment: heating the cast steel brake disc to 1020-1050°C at 35-45°C / min and keeping it warm for 10-15h, then heating it to 1230-1260°C at 5-8°C / min and keeping it warm for 20-24h for a second-stage heat treatment, then cooling it to 540-570°C at 15-20°C / min and keeping it warm for 30-36h for a third-stage heat treatment, and finally opening the furnace door to cool it to room temperature.

[0031] A high-speed shaft-mounted cast steel brake disc material is used in a shaft-mounted cast steel brake disc, with a high speed of ≥400 km / h.

[0032] A shaft-mounted cast steel brake disc is prepared from the high-speed shaft-mounted cast steel brake disc material of the invention.

[0033] The present invention discloses a high-speed shaft-mounted cast steel brake disc material and a preparation method thereof. Through the control of C, N and Ta elements during the smelting and casting process, combined with a subsequent heat treatment process, the cast steel brake disc material is finally formed with a Ta (CN) strengthening phase distribution in the microstructure. The formation principle is as follows: (1) The formation of the brake disc material of the present invention requires specific composition requirements, that is, the composition contains specific contents of C, N and Ta elements, wherein C: 0.31-0.39%, N: 0.009-0.016%, Ta: 1.03-1.57% by mass, the content of carbon element is regulated by a double furnace refining method, the nitrogen element is regulated by nitrogen addition to the material in the form of bottom blowing nitrogen, and the tantalum element is regulated by a tantalum-nickel intermediate alloy method. (2) After meeting the specific composition requirements, high temperature pressure casting is carried out at a temperature of 1800-1820℃, a pressure of 88-96MPa, and a filling speed of 40-45m / s. On the one hand, rapid defect-free forming is achieved, and on the other hand, the N and Ta elements in the material are dissolved into the matrix at high temperature. (3) A step-by-step three-stage heat treatment is adopted: the first stage heat treatment: the casting sample is heated to 1020-1050℃ at 35-45℃ / min and kept at this temperature for 10-15h, then heated to 1230-1260℃ at 5-8℃ / min and kept at this temperature for 20-24h for the second stage heat treatment, then cooled to 540-570℃ at 15-20℃ / min and kept at this temperature for 30-36h for the third stage heat treatment, and finally the furnace door is opened to control the cooling to room temperature, so that continuous reaction and phase transformation occur in the cast material, and finally the cast steel brake disc material forms a specific organizational morphology with Ta (CN) strengthening phase distribution in the microstructure. (The formation principle: 1. One-stage heat treatment: When the casting sample is heated to 1020-1050℃ at 35-45℃ / min and kept warm for 10-15h, tantalum in solid solution is precipitated and reacts with carbon to form tantalum carbide intermediate phase. The reaction formula is: Ta+C→TaC(1020-1050℃); 2. When the temperature is raised to 1230-1260℃ at 5-8℃ / min and kept warm for 20-24h for the second-stage heat treatment, the diffusion of nitrogen in the material is accelerated, so that N and TaC intermediate phases react with each other under high temperature conditions. Contact and react to form a Ta(CN) strengthening phase on the TaC surface, and the reaction formula is: TaC+N→Ta(CN)(1230~1260℃)), and finally a core-shell TaC@Ta(CN) composite strengthening phase is formed in which the Ta(CN) surface layer wraps the TaC core; 3. When the temperature is reduced to 540~570℃ at 15~20℃ / min and kept for 30-36h for three-stage heat treatment, the residual stress is released and the carbide (TaC@Ta(CN) composite strengthening phase) is more evenly distributed in the matrix.

[0034] The S3 of the present invention performs controlled cooling during the solidification process, and the cooling rate control is divided into 4 stages. The 4-stage controlled cooling has the following technical effects: 1. ensuring a high degree of solid solution of the Ta element, so that the subsequent precipitation forms a strengthening phase and provides a composition basis; 2. reducing composition segregation; 3. reducing casting defects and residual stress.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. Good heat dissipation performance: The microstructure of the cast steel brake disc material has a specific organizational morphology with TaC@Ta(CN) composite strengthening phase distribution, which makes it have good heat dissipation performance. The reason is that TaC and Ta(CN) strengthening phases have good thermal conductivity, which significantly improves the overall thermal conductivity of the material and solves the problem of heat accumulation during friction.

[0037] 2. Excellent high-temperature performance: The microstructure of the cast steel brake disc material has a specific organizational morphology with the distribution of TaC@Ta(CN) composite strengthening phase, which makes it have excellent high-temperature performance. The reason is that TaC and Ta(CN) strengthening phases themselves have excellent high-temperature stability and high-temperature mechanical properties, which significantly improves the overall high-temperature performance of the material.

[0038] 3. Strong wear resistance: TaC@Ta(CN) composite strengthening phase has strong wear resistance. It is distributed in the cast steel brake disc material as a strengthening phase, which significantly improves the overall wear resistance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a microstructure diagram of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0041] Example 1

[0042] A method for preparing a high-speed shaft-mounted cast steel brake disc material, comprising four steps of electric furnace smelting-double furnace refining-casting-post-processing;

[0043] S1. Electric furnace smelting: The raw materials are smelted into molten iron at a smelting temperature of 1600°C. The smelting time is based on the C content reaching the standard. Subsequently, oxygen is blown and quicklime is added for slag formation. The slag is blocked and steel is tapped to obtain molten steel.

[0044] The molten steel includes the following element components by mass percentage: C: 0.98%; Si: 0.40%; Ti: 1.25%; Cr: 1.50%; Ni: 0.80%; Al: 0.004%; P: 0.03%; S: 0.03%; the balance is Fe;

[0045] S2. Double furnace refining: LF refining and VD refining of the molten steel obtained by S1 electric furnace smelting;

[0046] S21.LF refining: the molten steel obtained in S1 is transferred to the LF refining furnace, the temperature is raised, the LF refining temperature is 1850°C, tantalum-nickel master alloy is added, the composition is adjusted, argon gas is blown in, the argon gas flow rate is 150NL / min, aluminum wire is fed for precipitation deoxidation and diffusion deoxidation, the amount of aluminum wire fed is 3kg / ton of raw materials, quicklime and fluorite are added for slag making, the refining time is calculated as 17min / ton of raw materials, and refined molten steel is obtained;

[0047] The components and contents of the refined molten steel include C: 0.55%; Si: 0.40%; Ti: 1.25%; Cr: 1.50%; Ni: 2.15%; Ta: 1.30%; Al: 0.008%; P: 0.01%; S: 0.01%; the balance is Fe;

[0048] S22. VD refining: the refined molten steel obtained in S21 is transferred to a VD vacuum furnace for vacuuming, and the refined molten steel is subjected to vacuum degassing treatment. The VD refining vacuum degree is 50Pa, and the refining temperature is 1850°C. Subsequently, nitrogen is blown from the bottom to break the vacuum and add nitrogen to the molten steel. The nitrogen flow rate is 260NL / min. Calcium wire is fed. The amount of calcium wire fed is 0.08kg / ton of raw material. The refining time is calculated as 12min / ton of raw material. Slag is removed to obtain high-nitrogen casting molten steel.

[0049] The components and their contents in high nitrogen casting molten steel include C: 0.35%; Si: 0.40%; Ti: 1.25%; Cr: 1.50%; Ni: 2.15%; Ta: 1.30%; Al: 0.008%; N: 0.012%; P: 0.01%; S: 0.01%; the balance is Fe;

[0050] The CaO in the calcium wire reacts with oxygen in the molten steel at high temperatures to form Ca(OH)2, while releasing calcium, which then reacts to form stable compounds such as Ca3(PO4)2, which are removed after forming slag;

[0051] S3 pressure casting: The molten steel obtained by S22 is poured into the casting mold by pressure, the pouring temperature of the pressure pouring is 1800 ℃, the pressure is 90MPa, the filling speed is 42m / s; after the molten steel solidifies and is cooled to room temperature, the cast steel brake disc is removed;

[0052] Controlled cooling is carried out during the solidification process, and the cooling speed control is divided into 4 sections, namely, the cooling speed is 85℃ / s within -1 / 6T time after pouring, the cooling speed is 52℃ / s within 1 / 6T-1 / 3T time, the cooling speed is 25℃ / s within 1 / 3T-2 / 3T time, and the cooling speed is 13℃ / s within the last 1 / 3T time; T represents the total pouring time, the unit is s, T=KM, M is the total pouring mass, the unit is kg, K is the pouring coefficient, and its value is 0.20.

[0053] S4. Post-treatment: The cast steel brake disc obtained in S3 is subjected to a three-stage performance heat treatment, which includes a first-stage heat treatment: the casting sample is heated to 1030°C at 40°C / min and kept warm for 12.5h, then heated to 1250°C at 6°C / min and kept warm for 22h for a second-stage heat treatment, then cooled to 550°C at 18°C / min and kept warm for 32h for a third-stage heat treatment, and finally the furnace door is opened to cool to room temperature, and finally a high-speed shaft-mounted cast steel brake disc is obtained.

[0054] A high-speed shaft-mounted cast steel brake disc material comprises the following components in percentage by mass: C: 0.35%; Si: 0.40%; Ti: 1.25%; Cr: 1.50%; Ni: 2.15%; Ta: 1.30%; Al: 0.008%; N: 0.012%; P: 0.01%; S: 0.01%; and the balance is Fe.

[0055] The high-speed shaft-mounted cast steel brake disc material obtained in this embodiment has the characteristics of good heat dissipation performance, excellent high-temperature mechanical properties and wear resistance.

[0056] The microstructure of the high-speed shaft-mounted cast steel brake disc material obtained in this embodiment has a core-shell TaC@Ta(CN) composite strengthening phase distribution in which a Ta(CN) surface layer encloses a TaC core.

[0057] A high-speed shaft-mounted cast steel brake disc material is used in a shaft-mounted cast steel brake disc, with a high speed of ≥400 km / h.

[0058] A shaft-mounted cast steel brake disc is prepared from the high-speed shaft-mounted cast steel brake disc material obtained in this embodiment.

[0059] Example 2

[0060] A method for preparing a high-speed shaft-mounted cast steel brake disc material, comprising four steps of electric furnace smelting-double furnace refining-casting-post-processing;

[0061] S1. Electric furnace smelting: The raw materials are smelted into molten iron at a smelting temperature of 1650°C. The smelting time is based on the C content reaching the standard. Subsequently, oxygen is blown and quicklime is added for slag formation. The slag is blocked and steel is tapped to obtain molten steel.

[0062] The molten steel includes the following element components by mass percentage: C: 0.87%; Si: 0.36%; Ti: 0.87%; Cr: 0.90%; Ni: 0.63%; Al: 0.003%; P: 0.03%; S: 0.02%; the balance is Fe;

[0063] S2. Double furnace refining: LF refining and VD refining of the molten steel obtained by S1 electric furnace smelting;

[0064] S21.LF refining: the molten steel obtained in S1 is transferred to the LF refining furnace, the temperature is raised, the LF refining temperature is 1800°C, tantalum-nickel master alloy is added, the composition is adjusted, argon gas is blown in, the argon gas flow rate is 100NL / min, aluminum wire is fed for precipitation deoxidation and diffusion deoxidation, the amount of aluminum wire fed is 2kg / ton of raw materials, quicklime and fluorite are added for slag making, the refining time is calculated as 17min / ton of raw materials, and refined molten steel is obtained;

[0065] The components and contents of the refined molten steel include C: 0.47%; Si: 0.36%; Ti: 0.87%; Cr: 0.90%; Ni: 1.66%; Ta: 1.03%; Al: 0.006%; P: 0.007%; S: 0.006%; the balance is Fe;

[0066] S22. VD refining: the refined molten steel obtained in S21 is transferred to a VD vacuum furnace for vacuuming, and the refined molten steel is subjected to vacuum degassing treatment. The VD refining vacuum degree is 45Pa, and the refining temperature is 1900°C. Subsequently, nitrogen is blown from the bottom to break the vacuum and add nitrogen to the molten steel. The nitrogen flow rate is 255NL / min. Calcium wire is fed, and the amount of calcium wire fed is 0.07kg / ton of raw material. The refining time is calculated as 12min / ton of raw material. Slag is removed to obtain high-nitrogen casting molten steel.

[0067] The components and their contents in high nitrogen casting molten steel include C: 0.31%; Si: 0.36%; Ti: 0.87%; Cr: 0.90%; Ni: 1.66%; Ta: 1.03%; Al: 0.006%; N: 0.009%; P: 0.007%; S: 0.006%; the balance is Fe;

[0068] The CaO in the calcium wire reacts with oxygen in the molten steel at high temperatures to form Ca(OH)2, while releasing calcium, which then reacts to form stable compounds such as Ca3(PO4)2, which are removed after forming slag;

[0069] S3 pressure casting: The molten steel obtained by S22 was poured into the casting mold by pressure, the pouring temperature of the pressure pouring was 1820 ° C, the pressure was 88MPa, the filling speed was 40m / s; after the molten steel solidified and cooled to room temperature, the cast steel brake disc was removed;

[0070] Controlled cooling is carried out during the solidification process, and the cooling speed control is divided into 4 sections, namely, the cooling speed is 80℃ / s within -1 / 6T time after pouring, the cooling speed is 50℃ / s within 1 / 6T-1 / 3T time, the cooling speed is 20℃ / s within 1 / 3T-2 / 3T time, and the cooling speed is 10℃ / s within the last 1 / 3T time; T represents the total pouring time, in s, T=KM, M is the total pouring mass, in kg, K is the pouring coefficient, and its value is 0.13.

[0071] S4. Post-treatment: The cast steel brake disc obtained in S3 is subjected to a three-stage performance heat treatment, which includes a first-stage heat treatment: the casting sample is heated to 1020°C at 35°C / min and kept warm for 10 hours, then heated to 1230°C at 5°C / min and kept warm for 20 hours for a second-stage heat treatment, then cooled to 540°C at 15°C / min and kept warm for 30 hours for a third-stage heat treatment, and finally the furnace door is opened to cool to room temperature to finally obtain a high-speed shaft-mounted cast steel brake disc.

[0072] A high-speed shaft-mounted cast steel brake disc material comprises the following components in percentage by mass: C: 0.31%; Si: 0.36%; Ti: 0.87%; Cr: 0.90%; Ni: 1.66%; Ta: 1.03%; Al: 0.006%; N: 0.009%; P: 0.007%; S: 0.006%; the remainder is Fe.

[0073] The high-speed shaft-mounted cast steel brake disc material obtained in this embodiment has the characteristics of good heat dissipation performance, excellent high-temperature mechanical properties and wear resistance.

[0074] The microstructure of the high-speed shaft-mounted cast steel brake disc material obtained in this embodiment has a core-shell TaC@Ta(CN) composite strengthening phase distribution in which a Ta(CN) surface layer encloses a TaC core.

[0075] A high-speed shaft-mounted cast steel brake disc material is used in a shaft-mounted cast steel brake disc, with a high speed of ≥400 km / h.

[0076] A shaft-mounted cast steel brake disc is prepared from the high-speed shaft-mounted cast steel brake disc material obtained in this embodiment.

[0077] Example 3

[0078] A method for preparing a high-speed shaft-mounted cast steel brake disc material, comprising four steps of electric furnace smelting-double furnace refining-casting-post-processing;

[0079] S1. Electric furnace smelting: The raw materials are smelted into molten iron at a smelting temperature of 1620°C. The smelting time is based on the C content reaching the standard. Subsequently, oxygen is blown and quicklime is added for slag formation. The slag is blocked and steel is tapped to obtain molten steel.

[0080] The molten steel includes the following element components by mass percentage: C: 1.12%; Si: 0.42%; Ti: 1.56%; Cr: 1.75%; Ni: 0.97%; Al: 0.003%; P: 0.02%; S: 0.02%; the balance is Fe;

[0081] S2. Double furnace refining: LF refining and VD refining of the molten steel obtained by S1 electric furnace smelting;

[0082] S21.LF refining: the molten steel obtained in S1 is transferred to the LF refining furnace, the temperature is raised, the LF refining temperature is 1825°C, tantalum-nickel master alloy is added, the composition is adjusted, argon gas is blown in, the argon gas flow rate is 230NL / min, aluminum wire is fed for precipitation deoxidation and diffusion deoxidation, the amount of aluminum wire fed is 4kg / ton of raw materials, quicklime and fluorite are added for slag making, the refining time is calculated as 17min / ton of raw materials, and refined molten steel is obtained;

[0083] The components and contents of the refined molten steel include C: 0.75%; Si: 0.42%; Ti: 1.56%; Cr: 1.75%; Ni: 2.54%; Ta: 1.57%; Al: 0.009%; P: 0.004%; S: 0.003%; the balance is Fe;

[0084] S22. VD refining: the refined molten steel obtained in S21 is transferred to a VD vacuum furnace for vacuuming, and the refined molten steel is subjected to vacuum degassing treatment. The VD refining vacuum degree is 54Pa, and the refining temperature is 1870°C. Subsequently, nitrogen is blown from the bottom to break the vacuum and add nitrogen to the molten steel. The nitrogen flow rate is 270NL / min. Calcium wire is fed. The amount of calcium wire fed is 0.09kg / ton of raw material. The refining time is calculated as 12min / ton of raw material. Slag is removed to obtain high-nitrogen casting molten steel.

[0085] The components and their contents in high nitrogen casting molten steel include C: 0.39%; Si: 0.42%; Ti: 1.56%; Cr: 1.75%; Ni: 2.54%; Ta: 1.57%; Al: 0.009%; N: 0.016%; P: 0.004%; S: 0.003%; the balance is Fe;

[0086] The CaO in the calcium wire reacts with oxygen in the molten steel at high temperatures to form Ca(OH)2, while releasing calcium, which then reacts to form stable compounds such as Ca3(PO4)2, which are removed after forming slag;

[0087] S3 pressure casting: The molten steel obtained by S22 was poured into the casting mold by pressure, the pouring temperature of the pressure pouring was 1810 ° C, the pressure was 96MPa, the filling speed was 45m / s; after the molten steel solidified and cooled to room temperature, the cast steel brake disc was removed;

[0088] Controlled cooling is carried out during the solidification process, and the cooling speed control is divided into 4 sections, namely, the cooling speed is 90℃ / s within -1 / 6T time after pouring, the cooling speed is 55℃ / s within 1 / 6T-1 / 3T time, the cooling speed is 30℃ / s within 1 / 3T-2 / 3T time, and the cooling speed is 15℃ / s within the last 1 / 3T time; T represents the total pouring time, in s, T=KM, M is the total pouring mass, in kg, K is the pouring coefficient, and its value is 0.26.

[0089] S4. Post-treatment: The cast steel brake disc obtained in S3 is subjected to a three-stage performance heat treatment, which includes a first-stage heat treatment: the casting sample is heated to 1050°C at 45°C / min and kept warm for 15 hours, then heated to 1260°C at 8°C / min and kept warm for 24 hours for a second-stage heat treatment, then cooled to 570°C at 20°C / min and kept warm for 36 hours for a third-stage heat treatment, and finally the furnace door is opened to cool to room temperature, and finally a high-speed shaft-mounted cast steel brake disc is obtained.

[0090] A high-speed shaft-mounted cast steel brake disc material comprises the following components in percentage by mass: C: 0.39%; Si: 0.42%; Ti: 1.56%; Cr: 1.75%; Ni: 2.54%; Ta: 1.57%; Al: 0.009%; N: 0.016%; P: 0.004%; S: 0.003%; the remainder is Fe.

[0091] The high-speed shaft-mounted cast steel brake disc material obtained in this embodiment has the characteristics of good heat dissipation performance, excellent high-temperature mechanical properties and wear resistance.

[0092] The microstructure of the high-speed shaft-mounted cast steel brake disc material obtained in this embodiment has a core-shell TaC@Ta(CN) composite strengthening phase distribution in which a Ta(CN) surface layer encloses a TaC core.

[0093] A high-speed shaft-mounted cast steel brake disc material is used in a shaft-mounted cast steel brake disc, with a high speed of ≥400 km / h.

[0094] A shaft-mounted cast steel brake disc is prepared from the high-speed shaft-mounted cast steel brake disc material obtained in this embodiment.

[0095] Comparative Example 1

[0096] The difference between this comparative example and Example 1 is only that:

[0097] In the post-treatment step of S4, only one heat treatment was performed, that is, the cast sample was heated to 1030°C at 40°C / min and kept at that temperature for 12.5h, and then the furnace door was opened and cooled to room temperature. Only a single strengthening phase was obtained in this comparative example.

[0098] Comparative Example 2

[0099] The difference between this comparative example and Example 1 is only that:

[0100] In the post-treatment step of S4, only two heat treatments were performed, that is, the cast sample was heated to 1030°C at 40°C / min and kept at this temperature for 12.5h, then heated to 1250°C at 6°C / min and kept at this temperature for 22h for the second heat treatment, and then the furnace door was opened and cooled to room temperature. This comparative example only obtained a single strengthening phase.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 1 is only that:

[0103] In S3, a controlled cooling treatment is performed during the solidification process, and the cooling rate is controlled to be 85°C / s to room temperature.

[0104] Comparative Example 4

[0105] The difference between this comparative example and Example 1 is only that:

[0106] In S3, controlled cooling is carried out during the solidification process, and the cooling speed control is divided into two stages, with a cooling speed of 85°C / s within -1 / 6T time after pouring and a cooling speed of 13°C / s within the last 5 / 6T time.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 1 is only that:

[0109] In S3, controlled cooling is carried out during the solidification process, and the cooling speed control is divided into three stages, namely, the cooling speed is 85℃ / s within -1 / 6T time after pouring, the cooling speed is 52℃ / s within 1 / 6T-1 / 3T time, and the cooling speed is 13℃ / s within the last 2 / 3T time.

[0110] The mechanical property data of the embodiments of the present invention are shown in Table 1 below.

[0111] Table 1 shows the performance comparison data

[0112] sample Tensile strength MPa Yield strength MPa Elongation after break % <![CDATA[Wear mm 3 > Heat fatigue Example 1 1479 1338 22.1 3.7 No cracks Example 2 1410 1271 25.9 4.2 No cracks Example 3 1403 1265 26.3 4.6 No cracks Comparative Example 1 1014 836 19.8 63.7 Level 4 Comparative Example 2 1126 907 18.3 51.9 Level 3 Comparative Example 3 1213 1015 16.9 48.7 Level 2 Comparative Example 4 1209 998 17.2 41.2 Level 2 Comparative Example 5 1234 1024 16.6 39.5 Level 2

[0113] Tensile test: adopt national standard GB / T 228.1-2021;

[0114] Wear test: adopt national standard GB / T 12444-2006;

[0115] Thermal fatigue test: Adopt national standard GB / T 15824-2008.

[0116] like Figure 1As shown, the structure of the material obtained in Example 1 of the present invention contains TaC and Ta(CN) composite strengthening phases in the range of 100 to 160 nm, wherein the Ta(CN) strengthening phase wraps the TaC strengthening phase to form a typical core-shell composite structure strengthening phase.

[0117] Table 2 provides a composition analysis of the precipitated phase (i.e., TaC@Ta(CN) composite strengthening phase) of the cast steel brake disc material.

[0118] Table 2 Analysis of precipitated phase composition

[0119]

[0120] It should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the previously disclosed embodiments. Therefore, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0121] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and teaching purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative, not restrictive, with respect to the scope of the present invention, which is defined by the appended claims.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a high-speed shaft-mounted cast steel brake disc material, characterized in that: The high-speed shaft-mounted cast steel brake disc material includes the following components in percentage by mass: C: 0.31~0.39%; Si: 0.36~0.42%; Ti: 0.87~1.56%; Cr: 0.90~1.75%; Ni: 1.66~2.54%; Ta: 1.03~1.57%; Al: 0.006~0.009%; N: 0.009~0.016%; P: ≤0.01%; S: ≤0.01%; the balance is Fe; The preparation method comprises the following steps: S1. Electric furnace smelting: The raw materials are smelted into molten iron, followed by oxygen blowing and adding quicklime for slag making, slag blocking and steel tapping to obtain molten steel; The smelting molten steel includes the following element components in percentage by mass: C: 0.87~1.12%; Si: 0.36~0.42%; Ti: 0.87~1.56%; Cr: 0.90~1.75%; Ni: 0.63~0.97%; Al: ≤0.004%; P: ≤0.03%; S: ≤0.03%; the balance is Fe; S2. Double furnace refining: LF refining and VD refining of the molten steel obtained by S1 electric furnace smelting; S21.LF refining: the molten steel obtained in S1 is transferred to the LF refining furnace, the temperature is increased, tantalum-nickel master alloy is added, the composition is adjusted, argon gas is blown in, aluminum wire is fed in for precipitation deoxidation and diffusion deoxidation, quicklime and fluorite are added for slag formation, and refined molten steel is obtained; S22. VD refining: the refined molten steel obtained in S21 is transferred to a VD vacuum furnace, vacuumed, and subjected to vacuum degassing treatment on the refined molten steel. Subsequently, nitrogen is blown from the bottom to break the vacuum and add nitrogen to the molten steel. Calcium wire is fed, and slag is removed to obtain high-nitrogen casting molten steel. S3 pressure casting: The high nitrogen casting molten steel obtained in S22 is poured into the casting mold by pressure, and the molten steel is cooled to room temperature after solidification to obtain a cast steel brake disc; S4. Post-processing: The cast steel brake disc obtained in S3 is subjected to three-stage performance heat treatment to finally obtain a high-speed shaft-mounted cast steel brake disc; In S4, the three-stage performance heat treatment includes: the first stage heat treatment: the cast steel brake disc is heated to 1020~1050℃ at 35~45℃ / min and kept warm for 10-15h, then heated to 1230~1260℃ at 5~8℃ / min and kept warm for 20-24h for the second stage heat treatment, then cooled to 540~570℃ at 15~20℃ / min and kept warm for 30-36h for the third stage heat treatment, and finally the furnace door is opened to cool to room temperature.

2. The method for preparing a high-speed shaft-mounted cast steel brake disc material according to claim 1, characterized in that: The microstructure of the cast steel brake disc material has a core-shell TaC@Ta(CN) composite strengthening phase distribution with a Ta(CN) surface layer encapsulating a TaC core.

3. The method for preparing a high-speed shaft-mounted cast steel brake disc material according to claim 1, characterized in that: The tensile strength of cast steel brake disc material is ≥1403Mpa, the yield strength is ≥1265Mpa, the elongation after fracture is ≥22.1%, and the wear is ≤4.6mm 3 , no cracks in thermal fatigue test.

4. The preparation method according to claim 1, characterized in that: In S21, the composition and mass percentage of the refined steel include C: 0.47~0.75%; Si: 0.36~0.42%; Ti: 0.87~1.56%; Cr: 0.90~1.75%; Ni: 1.66~2.54%; Ta: 1.03~1.57%; Al: 0.006~0.009%; P: ≤0.01%; S: ≤0.01%; the balance is Fe.

5. The preparation method according to claim 1, characterized in that: In S22, the components and their mass percentages in high nitrogen casting steel include C: 0.31~0.39%; Si: 0.36~0.42%; Ti: 0.87~1.56%; Cr: 0.90~1.75%; Ni: 1.66~2.54%; Ta: 1.03~1.57%; Al: 0.006~0.009%; N: 0.009~0.016%; P: ≤0.01%; S: ≤0.01%; the balance is Fe.

6. The preparation method according to claim 1, characterized in that: In S1, the smelting temperature is 1600~1650℃, and the smelting time is based on the C content reaching the standard.

7. The preparation method according to claim 1, characterized in that: In S21, the LF refining temperature is 1800~1850℃, the argon flow rate is 100~230NL / min, the feeding amount of aluminum wire is 2~4kg / ton, and the refining time is calculated as 17min / ton.

8. The preparation method according to claim 1, characterized in that: In S22, the VD refining vacuum degree is 45~54Pa, the refining temperature is 1850~1900℃, the nitrogen flow rate is 255~270NL / min, the calcium line is fed at 0.07~0.09kg / ton, and the refining time is calculated as 12min / ton.

9. The preparation method according to claim 1, characterized in that: In S3, the pouring temperature of pressure pouring is 1800~1820℃, the pressure is 88~96MPa, and the filling speed is 40~45m / s.

10. The preparation method according to claim 1, characterized in that: In S3, controlled cooling treatment is carried out during the solidification process, and the cooling rate control is divided into 4 stages, including a cooling rate of 80~90℃ / s within -1 / 6T after pouring, a cooling rate of 50~55℃ / s within 1 / 6T-1 / 3T, a cooling rate of 20~30℃ / s within 1 / 3T-2 / 3T, and a cooling rate of 10~15℃ / s within the last 1 / 3T.

11. The preparation method according to claim 10, characterized in that: T represents the total pouring time in seconds, T=KM, M is the total pouring mass in kg, K is the pouring coefficient, and the value of K is 0.13-0.

26.

12. Application of a high-speed shaft-mounted cast steel brake disc material obtained by the preparation method according to any one of claims 1 to 11 on shaft-mounted cast steel brake discs, characterized in that: High speed is ≥400 km / h.

13. A shaft-mounted cast steel brake disc, characterized in that: A high-speed shaft-mounted cast steel brake disc material is prepared by the preparation method according to any one of claims 1 to 11.

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