A rare earth modified cast steel material for high-speed rail brake disc and a preparation method thereof

Abstract

The application relates to the technical field of metal materials, in particular to a rare earth modified cast steel material for high-speed rail brake discs and a preparation method thereof. The rare earth modified cast steel material is composed of carbon, manganese, aluminum, nickel, chromium, molybdenum, titanium, vanadium, lanthanum, scandium and other elements, wherein the rare earth elements lanthanum and scandium are introduced in the form of being loaded on porous carbon microspheres, the porous carbon microspheres have a large specific surface area and abundant pore structures, the rare earth elements are more uniformly distributed, the grains are further refined, the microstructure is optimized, and therefore the tensile strength, impact toughness and high-temperature friction resistance of the material are significantly improved. The rare earth modified cast steel material prepared by the application meets the requirements of high strength, high toughness and high-temperature stability of high-speed rail brake discs, and has important application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal materials, and particularly relates to a rare earth modified cast steel material for high-speed rail brake discs and a preparation method thereof. BACKGROUND

[0002] The high-speed rail brake disc is a key component in the braking system of high-speed trains, and its performance is directly related to the safety and reliability of train operation. During high-speed operation and frequent braking, the brake disc needs to withstand high stress, impact load and high-temperature friction environment, so high requirements are put forward for the mechanical properties and high-temperature friction resistance of the material thereof. Although the traditional cast steel material has certain strength and toughness, it is prone to problems such as fluctuation of friction coefficient, accelerated wear and insufficient oxidation resistance under high-temperature conditions, and it is difficult to meet the severe working condition requirements of high-speed rail brake discs.

[0003] In recent years, rare earth elements have been widely used in the modification research of steel materials due to their unique modification and strengthening effects. Rare earth elements lanthanum and scandium can refine grains, optimize microstructure and form stable oxide films under high-temperature conditions, thereby significantly improving the strength, toughness and high-temperature friction resistance of the material. However, the uniformity of the distribution of rare earth elements in the steel matrix has an important influence on the modification effect. The traditional rare earth element addition method has the problems of uneven distribution and low utilization rate, which limits the further improvement of its performance.

[0004] In summary, it is of important engineering application value and promotion prospect to develop a rare earth modified cast steel material and a preparation method thereof to significantly improve the mechanical properties and high-temperature friction resistance of high-speed rail brake disc materials. SUMMARY

[0005] Therefore, the present application aims to provide a rare earth modified cast steel material for high-speed rail brake discs and a preparation method thereof to solve the problems of uneven distribution and low utilization rate of the traditional rare earth element addition method.

[0006] To achieve the above purpose, the present application provides a rare earth modified cast steel material for high-speed rail brake discs, which comprises the following chemical component raw materials in percentage by weight: carbon 0.64%-0.85%, manganese 14.2%-16.8%, aluminum 7.1%-8.2%, nickel 4.5%-5.6%, chromium 0.49%-0.58%, molybdenum 0.51%-0.59%, titanium 0.045%-0.055%, vanadium 0.035%-0.045%, lanthanum 0.005%-0.007%, scandium 0.001%-0.003%, sulfur ≤0.01%, phosphorus ≤0.01%, and the rest is iron and unavoidable impurities.

[0007] Further, the carbon component, lanthanum component and scandium component are provided by porous carbon microspheres loaded with lanthanum and scandium.

[0008] Preferably, the content of lanthanum in the lanthanum and scandium loaded porous carbon microspheres is 0.78wt%-0.82wt%, and the content of scandium is 0.16wt%-0.35wt%.

[0009] Further, the preparation steps of the lanthanum and scandium loaded porous carbon microspheres are as follows:

[0010] S1: grinding and mixing chitosan and ammonium chloride, and then calcining in Ar gas, the calcining temperature is 750-850℃, and the temperature is kept for 2.5-3.5h, and then the temperature is lowered to room temperature to obtain porous carbon microspheres;

[0011] S2: immersing the porous carbon microspheres in a mixed aqueous solution of lanthanum nitrate and scandium nitrate, immersing for 8-12h, and then washing, and then calcining in Ar / H2 mixed gas, the calcining temperature is 650-750℃, and the temperature is kept for 1.5-2.5h, and then the temperature is lowered to room temperature to obtain lanthanum and scandium loaded porous carbon microspheres;

[0012] Preferably, the weight ratio of chitosan and ammonium chloride in step S1 is 10:5-15.

[0013] More preferably, the rare earth modified cast steel material for high-iron brake disc comprises the following chemical components: carbon 0.72%, manganese 15.3%, aluminum 7.7%, nickel 5.1%, chromium 0.53%, molybdenum 0.56%, titanium 0.050%, vanadium 0.032%, lanthanum 0.006%, scandium 0.002%, sulfur ≤0.008%, phosphorus ≤0.005%, and the rest is iron and inevitable impurities.

[0014] Preferably, the volume ratio of Ar / H2 mixed gas in step S2 is 10:1.

[0015] Preferably, the concentration of lanthanum nitrate in step S2 is 17.8-19.1g / L, and the concentration of scandium nitrate is 7.5-16.5g / L.

[0016] Further, the present application also provides a preparation method of a rare earth modified cast steel material for high-iron brake disc, comprising the following steps:

[0017] (1) batching: according to the chemical component raw material ratio, the pure iron, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, sponge titanium, vanadium iron, lanthanum and scandium loaded porous carbon microspheres are weighed respectively;

[0018] (2) Melting: now pure iron is added into a vacuum melting furnace, the vacuum degree is 0.3-0.6 Pa, the temperature is raised to 1450-1550 DEG C, the porous carbon microspheres loaded with lanthanum and scandium are added, Ar gas is passed to 800-1200 Pa, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge and vanadium iron are added, the temperature is raised to 1630-1680 DEG C again, and the molten steel is obtained after refining for 15-20 min, deoxidizing and degassing;

[0019] (3) Pouring: the molten steel is poured into a sand mold, and the casting is obtained after air cooling and placing at room temperature;

[0020] (4) Heat treatment: the casting is quenched and tempered to obtain the rare earth modified cast steel material for high-speed rail brake disc.

[0021] Preferably, the quenching in step (4) is raised to 900-1100 DEG C at a temperature rising rate of 40-60 DEG C / min, and then oil-quenched to room temperature after holding for 0.5-1.5 h.

[0022] Preferably, the tempering in step (4) is raised to 600-700 DEG C at a temperature rising rate of 40-60 DEG C / min, and then air-cooled to room temperature after holding for 0.5-1.5 h.

[0023] The beneficial effects of the present application are:

[0024] The rare earth modified cast steel material for high-speed rail brake disc provided by the present application has high tensile strength and impact toughness, and can withstand high stress and impact load during high-speed operation and frequent braking, meeting the strict requirements of high-speed rail brake disc on strength and toughness. This is due to the addition of rare earth elements lanthanum and scandium, which optimizes the grain structure of the material and refines the grain, thereby significantly improving the strength and toughness of the material.

[0025] The rare earth modified cast steel material for high-speed rail brake disc exhibits excellent wear resistance and high temperature stability under high temperature conditions. The addition of rare earth elements lanthanum and scandium optimizes the microstructure of the material and forms a stable oxide film at high temperature, reducing friction and wear, and improving the oxidation resistance, so that the material can maintain stable performance under high temperature and complex working conditions.

[0026] The present application loads rare earth elements lanthanum and scandium on porous carbon microspheres, which makes the particle size of rare earth metals smaller and more uniform, further refines the grain, and optimizes the microstructure of the material, thereby significantly improving the mechanical properties and high temperature friction resistance of the material.

[0027] The porous carbon microspheres provided by the application have a large specific surface area and abundant pore structures, can more uniformly load rare earth elements, and play a solid solution strengthening and grain boundary strengthening role in a steel matrix as a reinforcing phase. The synergistic effect of the porous carbon microspheres and the rare earth elements effectively improves the grain boundary characteristics of the material, reduces grain boundary defects, and further improves the strength and wear resistance of the material.

[0028] The pressurization process in the smelting process of the application promotes the molten steel to fully enter the pores of the porous carbon microspheres, significantly increases the contact area of the molten steel and the porous carbon microspheres, enables the rare earth elements to be more uniformly dispersed in the steel matrix, further enhances the solid solution strengthening and grain boundary strengthening effect of the porous carbon microspheres, and thus comprehensively improves the comprehensive performance of the material. DETAILED DESCRIPTION

[0029] To make the purpose, technical scheme and advantages of the application clearer, the application is further described in detail below with reference to specific examples.

[0030] Example 1

[0031] (1) chitosan and ammonium chloride were ground and mixed at a weight ratio of 2:1, and then calcined in Ar gas, the calcination temperature was 750 DEG C, the holding time was 2.5 h, and the temperature was lowered to room temperature to obtain porous carbon microspheres;

[0032] (2) the porous carbon microspheres were immersed in a mixed aqueous solution of lanthanum nitrate and scandium nitrate (the concentration of lanthanum nitrate was 17.8 g / L, and the concentration of scandium nitrate was 7.5 g / L), the immersion time was 8 h, then the porous carbon microspheres were washed and calcined in Ar / H2 (the volume ratio was 10:1), the calcination temperature was 650 DEG C, the holding time was 1.5 h, and the temperature was lowered to room temperature to obtain lanthanum and scandium loaded porous carbon microspheres with a lanthanum content of 0.78 wt% and a scandium content of 0.16 wt%;

[0033] (3) ingredients: pure iron, electrolytic manganese, aluminum particles, nickel plate, metallic chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum and scandium loaded porous carbon microspheres were weighed according to the chemical composition of the raw materials in Table 1;

[0034] (4) smelting: the pure iron was added to a vacuum smelting furnace, the vacuum degree was 0.3 Pa, the temperature was raised to 1450 DEG C, the lanthanum and scandium loaded porous carbon microspheres were added, Ar gas was passed to 800 Pa, the electrolytic manganese, aluminum particles, nickel plate, metallic chromium, molybdenum iron, titanium sponge and vanadium iron were added, the temperature was raised to 1630 DEG C, and the refining time was 15 min, and then the molten steel was obtained after deoxidation and degassing;

[0035] (5) pouring: the molten steel was poured into a sand mold, and the castings were obtained after air cooling and standing at room temperature;

[0036] (6) heat treatment: the castings are quenched and tempered, the quenching is heated to 900℃ at a heating rate of 40℃ / min, and then the castings are kept for 0.5h, and then oil quenched to room temperature, the tempering is heated to 600℃ at a heating rate of 40℃ / min, and then kept for 0.5h, and then air cooled to room temperature, to obtain the rare earth modified cast steel material for high-iron brake disc.

[0037] Example 2

[0038] (1) chitosan and ammonium chloride are mixed by grinding at a weight ratio of 1:1, and then calcined in Ar gas, the calcination temperature is 800℃, and the temperature is kept for 3h, and then cooled to room temperature, to obtain porous carbon microspheres;

[0039] (2) the porous carbon microspheres are immersed in a mixed aqueous solution of lanthanum nitrate and scandium nitrate (the concentration of lanthanum nitrate is 18.4g / L, and the concentration of scandium nitrate is 12g / L), and then immersed for 10h, and then washed, and then calcined in Ar / H2 (volume ratio is 10:1) mixed gas, the calcination temperature is 700℃, and the temperature is kept for 2h, and then cooled to room temperature, to obtain lanthanum and scandium loaded porous carbon microspheres with the content of lanthanum being 0.79wt% and the content of scandium being 0.26wt%;

[0040] (3) batching: pure iron, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, and lanthanum and scandium loaded porous carbon microspheres are weighed according to the chemical composition of the raw materials in Table 1;

[0041] (4) smelting: the pure iron is added into a vacuum smelting furnace, the vacuum degree is 0.5Pa, and the temperature is raised to 1500℃, the lanthanum and scandium loaded porous carbon microspheres are added, Ar gas is introduced to 1000Pa, the electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, and vanadium iron are added, and then the temperature is raised to 1660℃, and then refined for 18min, to obtain molten steel after deoxidation and degassing;

[0042] (5) pouring: the molten steel is poured into a sand mold, and then the castings are obtained after air cooling and standing at room temperature;

[0043] (6) heat treatment: the castings are quenched and tempered, the quenching is heated to 1000℃ at a heating rate of 50℃ / min, and then kept for 1h, and then oil quenched to room temperature, the tempering is heated to 650℃ at a heating rate of 50℃ / min, and then kept for 1h, and then air cooled to room temperature, to obtain the rare earth modified cast steel material for high-iron brake disc.

[0044] Example 3

[0045] (1) chitosan and ammonium chloride are mixed by grinding at a weight ratio of 2:3, and then calcined in Ar gas, the calcination temperature is 850℃, and the temperature is kept for 3.5h, and then cooled to room temperature, to obtain porous carbon microspheres;

[0046] (2) The porous carbon microspheres are immersed in a mixed aqueous solution of lanthanum nitrate and scandium nitrate (the concentration of lanthanum nitrate is 19.1 g / L, and the concentration of scandium nitrate is 16.5 g / L) for 12 h, then washed, and calcined in Ar / H2 (volume ratio of 10:1) mixed gas, the calcination temperature is 750℃, and the holding time is 2.5 h, and then the temperature is reduced to room temperature, to obtain lanthanum and scandium loaded porous carbon microspheres with the content of lanthanum of 0.82 wt% and the content of scandium of 0.35 wt%;

[0047] (3) Ingredients: pure iron, electrolytic manganese, aluminum particles, nickel plate, metallic chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum and scandium loaded porous carbon microspheres are weighed according to the chemical composition of the raw materials in Table 1;

[0048] (4) Melting: the pure iron is added into a vacuum melting furnace, the vacuum degree is 0.6 Pa, the temperature is raised to 1550℃, the lanthanum and scandium loaded porous carbon microspheres are added, Ar gas is introduced to 1200 Pa, the electrolytic manganese, aluminum particles, nickel plate, metallic chromium, molybdenum iron, titanium sponge and vanadium iron are added, and then the temperature is raised to 1680℃, the refining is performed for 20 min, and the deoxidation and degassing are performed, to obtain molten steel;

[0049] (5) Pouring: the molten steel is poured into a sand mold, and the casting is obtained after air cooling and standing at room temperature;

[0050] (6) Heat treatment: the casting is quenched and tempered, the quenching is performed at a temperature rising rate of 60℃ / min to 1100℃, oil quenching is performed to room temperature after holding for 1.5 h, the tempering is performed at a temperature rising rate of 60℃ / min to 700℃, and air cooling is performed to room temperature after holding for 1.5 h, to obtain a rare earth modified cast steel material for high-iron brake disc.

[0051] Comparative Example 1:

[0052] The difference between Comparative Example 1 and Example 2 is that the lanthanum is not loaded on the porous carbon microspheres, and the lanthanum is introduced through lanthanum-iron alloy;

[0053] The specific steps are as follows:

[0054] (1) The chitosan and ammonium chloride are ground and mixed according to a weight ratio of 1:1, and then calcined in Ar gas, the calcination temperature is 800℃, and the holding time is 3 h, and then the temperature is reduced to room temperature, to obtain porous carbon microspheres;

[0055] (2) The porous carbon microspheres are immersed in an aqueous solution of scandium nitrate (the concentration of scandium nitrate is 12 g / L) for 10 h, then washed, and calcined in Ar / H2 (volume ratio of 10:1) mixed gas, the calcination temperature is 700℃, and the holding time is 2 h, and then the temperature is reduced to room temperature, to obtain scandium loaded porous carbon microspheres with the content of scandium of 0.28 wt%;

[0056] (3) batching: pure iron, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum iron, and scandium-loaded porous carbon microspheres were weighed according to the chemical composition of the raw materials in Table 1;

[0057] (4) Melting: pure iron was added to a vacuum melting furnace, the vacuum degree was 0.5 Pa, the temperature was raised to 1500℃, and the lanthanum-loaded porous carbon microspheres were added. Ar gas was introduced to 1000 Pa, and electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, and lanthanum iron were added. The temperature was raised to 1660℃, and the steel was refined for 18 min to obtain molten steel.

[0058] (5) Pouring: the molten steel was poured into a sand mold, and the castings were obtained after air cooling and standing at room temperature;

[0059] (6) Heat treatment: the castings were quenched and tempered. The quenching temperature was raised to 1000℃ at a rate of 50℃ / min, and the steel was oil quenched to room temperature after holding for 1h. The tempering temperature was raised to 650℃ at a rate of 50℃ / min, and the steel was air cooled to room temperature after holding for 1h to obtain the cast steel material.

[0060] Comparative Example 2:

[0061] The difference between Comparative Example 2 and Example 2 is that the porous carbon microspheres are not loaded with scandium, and scandium is introduced through scandium iron alloy;

[0062] The specific steps are as follows:

[0063] (1) Cystine and ammonium chloride were ground and mixed at a weight ratio of 1:1, and then calcined in Ar gas. The calcination temperature was 800℃, the holding time was 3h, and the temperature was lowered to room temperature to obtain porous carbon microspheres;

[0064] (2) The porous carbon microspheres were immersed in a lanthanum nitrate aqueous solution (the concentration of lanthanum nitrate was 18.4g / L) for 10h, and then washed and calcined in Ar / H2(mixed gas with a volume ratio of 10:1). The calcination temperature was 700℃, the holding time was 2h, and the temperature was lowered to room temperature to obtain lanthanum-loaded porous carbon microspheres with a lanthanum content of 0.82wt%;

[0065] (3) Batching: pure iron, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, scandium iron, and lanthanum-loaded porous carbon microspheres were weighed according to the chemical composition of the raw materials in Table 1;

[0066] (4) Melting: pure iron was added to a vacuum melting furnace, the vacuum degree was 0.5 Pa, the temperature was raised to 1500℃, and the lanthanum-loaded porous carbon microspheres were added. Ar gas was introduced to 1000 Pa, and electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, and scandium iron were added. The temperature was raised to 1660℃, and the steel was refined for 18 min to obtain molten steel.

[0067] (5) Pouring: pouring the molten steel into a sand mold, and obtaining a casting after air cooling and standing to room temperature;

[0068] (6) Heat treatment: quenching and tempering the casting, quenching at a temperature rising rate of 50 ℃ / min to 1000 ℃, holding for 1 h, and then oil quenching to room temperature, tempering at a temperature rising rate of 50 ℃ / min, tempering at a temperature of 650 ℃, holding for 1 h, and then air cooling to room temperature, to obtain a cast steel material.

[0069] Comparative Example 3:

[0070] The difference between Comparative Example 3 and Example 2 is that lanthanum and scandium are not loaded on the porous carbon microspheres, and the lanthanum and scandium are introduced through lanthanum-iron alloy and scandium-iron alloy, respectively;

[0071] The specific steps are as follows:

[0072] (1) Grinding and mixing chitosan and ammonium chloride at a weight ratio of 1:1, and then calcining in Ar gas, the calcining temperature is 800 ℃, holding for 3 h, and cooling to room temperature to obtain porous carbon microspheres;

[0073] (2) Proportioning: proportioning pure iron, electrolytic manganese, aluminum particles, nickel plate, metallic chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum iron, scandium iron, and porous carbon microspheres according to the chemical composition of Table 1, and weighing them respectively;

[0074] (3) Melting: adding pure iron into a vacuum melting furnace, vacuumizing to 0.5 Pa, heating to 1500 ℃, adding porous carbon microspheres, passing Ar gas to 1000 Pa, adding electrolytic manganese, aluminum particles, nickel plate, metallic chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum iron, and scandium iron, and then heating to 1660 ℃, refining for 18 min, and deoxidizing and degassing to obtain molten steel;

[0075] (4) Pouring: pouring the molten steel into a sand mold, and obtaining a casting after air cooling and standing to room temperature;

[0076] (5) Heat treatment: quenching and tempering the casting, quenching at a temperature rising rate of 50 ℃ / min to 1000 ℃, holding for 1 h, and then oil quenching to room temperature, tempering at a temperature rising rate of 50 ℃ / min, tempering at a temperature of 650 ℃, holding for 1 h, and then air cooling to room temperature, to obtain a cast steel material.

[0077] Comparative Example 4:

[0078] The difference between Comparative Example 4 and Example 2 is that the lanthanum and scandium loaded porous carbon microspheres are replaced by graphite, scandium, and lanthanum scandium is introduced through lanthanum-iron alloy and scandium-iron alloy, respectively;

[0079] The specific steps are as follows:

[0080] (1)Batching: pure iron, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum iron, scandium iron, graphite were weighed according to the chemical composition of the raw material ratio in Table 1;

[0081] (2) Melting: pure iron was added to the vacuum melting furnace, the vacuum degree was 0.5 Pa, the temperature was raised to 1500℃, graphite was added, Ar gas was passed to 1000 Pa, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum iron, scandium iron were added, and the temperature was raised to 1660℃, and the refining time was 18 min, and the deoxidizing and degassing were carried out to obtain molten steel;

[0082] (3) Pouring: the molten steel was poured into a sand mold, and the castings were obtained after air cooling and placing at room temperature;

[0083] (4) Heat treatment: the castings were quenched and tempered, the quenching was at a temperature rising rate of 50℃ / min to 1000℃, oil quenching to room temperature after 1h of holding, the tempering was at a temperature rising rate of 50℃ / min to 650℃, and air cooling to room temperature after 1h of holding to obtain cast steel material.

[0084] Comparative Example 5:

[0085] The difference between Comparative Example 5 and Example 2 is that in step (4), Ar gas is not passed to 1000 Pa, but electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge and vanadium iron are directly added;

[0086] The specific steps are as follows:

[0087] (1) Chitosan and ammonium chloride were ground and mixed at a weight ratio of 1:1, then calcined in Ar gas, the calcination temperature was 800℃, the holding time was 3h, and the temperature was lowered to room temperature to obtain porous carbon microspheres;

[0088] (2) The porous carbon microspheres were immersed in a mixed aqueous solution of lanthanum nitrate and scandium nitrate (the concentration of lanthanum nitrate was 18.4g / L, and the concentration of scandium nitrate was 12g / L) for 10h, then washed and calcined in Ar / H2(mixed gas with a volume ratio of 10:1), the calcination temperature was 700℃, the holding time was 2h, and the temperature was lowered to room temperature to obtain lanthanum and scandium loaded porous carbon microspheres with a lanthanum content of 0.79wt% and a scandium content of 0.26wt%;

[0089] (3)Batching: pure iron, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge, vanadium iron, lanthanum and scandium loaded porous carbon microspheres were weighed according to the chemical composition of the raw material ratio in Table 1;

[0090] (4) Melting: now pure iron is added into the vacuum melting furnace, the vacuum degree is 0.5 Pa, the temperature is raised to 1500℃, lanthanum and scandium loaded porous carbon microspheres, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, titanium sponge and vanadium iron are added, the temperature is raised to 1660℃, refining is carried out for 18 min, deoxidation and degassing are carried out, and the molten steel is obtained;

[0091] (5) Pouring: the molten steel is poured into a sand mold, and the casting is obtained after air cooling and standing at room temperature;

[0092] (6) Heat treatment: the casting is quenched and tempered, the quenching is raised to 1000℃ at a temperature rising rate of 50℃ / min, oil quenched to room temperature after holding for 1h, the tempering is raised to 650℃ at a temperature rising rate of 50℃ / min, air cooled to room temperature after holding for 1h, and the cast steel material is obtained.

[0093] Table 1 Chemical composition of raw materials in examples and comparative examples in percentage by weight

[0094]

[0095]

[0096] Performance test:

[0097] Tensile test: the tensile test is carried out on a universal testing machine according to national standard GB / T228.1-2010, the tensile rate is 1.5mm / min, the inlet force is 300N, and the results are shown in Table 2;

[0098] Impact test: V-shaped notch samples are used, the notch of the impact sample faces away from the pendulum direction, the pendulum energy is 300J, three impact tests are carried out for each group of samples, the average value is taken, and the results are shown in Table 2;

[0099] High temperature friction and wear: high temperature friction and wear test is carried out by high speed high temperature friction and wear testing machine, according to the equipment standard, the test temperature is 400±5℃, the rotating speed is 1850rpm, the braking load is 1.8MPa, the friction coefficient and wear amount are measured, three samples are used for each group of tests, and the average value is taken, and the results are shown in Table 2.

[0100] Table 2 Performance test results

[0101]

[0102] Data analysis:

[0103] As can be seen from the data of examples 1-3 in table 2, the rare earth modified cast steel material prepared for high-speed rail brake disc has higher tensile strength and impact toughness, which indicates that the material has excellent mechanical properties under high stress and impact load, and can meet the strict requirements of high-speed rail brake disc on strength and toughness during high-speed operation and frequent braking. This is because the addition of rare earth elements lanthanum and scandium optimizes the grain structure of the material, refines the grain, and improves the strength and toughness of the material.

[0104] As can be seen from the data of examples 1-3 in table 2, the rare earth modified cast steel material prepared for high-speed rail brake disc has excellent high-temperature friction resistance, which indicates that the material can exhibit excellent wear resistance and high-temperature stability under high-temperature conditions. This is because the addition of rare earth elements lanthanum and scandium optimizes the microstructure of the material and forms a stable oxide film at high temperature, reducing friction and wear, while improving the oxidation resistance.

[0105] As can be seen from the data of examples 2 and comparative examples 1-3 in table 2, the addition of lanthanum and scandium has a greater impact on the mechanical properties and high-temperature friction resistance of the cast steel material. The introduction of lanthanum and scandium by loading them on porous carbon microspheres can significantly improve the mechanical properties and high-temperature friction resistance of the cast steel material. This is mainly because the lanthanum and scandium loaded on the porous carbon microspheres have a smaller particle size. When the molten steel is immersed into the pores, the rare earth elements can be uniformly distributed and the grain can be refined, optimizing the microstructure of the material and thus improving the mechanical properties and high-temperature friction resistance.

[0106] As can be seen from the data of examples 2 and comparative examples 3-4 in table 2, compared with graphite, porous carbon microspheres can further improve the tensile strength and high-temperature friction resistance of the cast steel material. This is mainly because the porous carbon microspheres have a large specific surface area and abundant pore structure, which can more uniformly load the rare earth elements lanthanum and scandium, making them more uniformly distributed in the molten steel. On the other hand, as a reinforcing phase, the porous carbon microspheres play a solid solution strengthening role in the steel matrix, and the synergistic effect of the rare earth elements can effectively improve the grain boundary characteristics of the material, reduce grain boundary defects, and improve the strength and wear resistance of the material.

[0107] As can be seen from the data of examples 2 and comparative example 5 in table 2, the pressurization process during melting can further improve the mechanical properties and high-temperature friction resistance of the cast steel material. This may be due to the fact that the pressurization process can cause the molten steel to enter the pores of the porous carbon microspheres, thereby increasing the contact area between the molten steel and the porous carbon microspheres, allowing the rare earth elements lanthanum and scandium to be more uniformly dispersed in the steel matrix, and the solid solution strengthening and grain boundary strengthening effect of the porous carbon microspheres.

[0108] The above discussion of any of the embodiments is merely exemplary in nature and not intended to suggest limitation on the scope of the application: as it is being set forth in the claims below; combinations of the above embodiments, or variations: of individual: embodiments, can also be: possible under the teachings of the application: and steps can be implemented in any order, and are not limited to the order presented in the description above.

Claims

1. A rare earth-modified cast steel material for high-speed railway brake discs, characterized in that, The high-iron brake disc rare earth modified cast steel material comprises the following chemical components: carbon 0.64%-0.85%, manganese 14.2%-16.8%, aluminum 7.1%-8.2%, nickel 4.5%-5.6%, chromium 0.49%-0.58%, molybdenum 0.51%-0.59%, titanium 0.045%-0.055%, vanadium 0.035%-0.045%, lanthanum 0.005%-0.007%, scandium 0.001%-0.003%, sulfur ≤0.01%, phosphorus ≤0.01%, and the rest is iron and inevitable impurities. The carbon component, the lanthanum component and the scandium component are provided by the lanthanum and scandium loaded porous carbon microspheres; the content of lanthanum in the lanthanum and scandium loaded porous carbon microspheres is 0.78wt%-0.82wt%, and the content of scandium is 0.16wt%-0.35wt%. The preparation steps of the lanthanum and scandium loaded porous carbon microspheres are as follows: S1: chitosan and ammonium chloride are ground and mixed, and then calcined in Ar gas, the calcination temperature is 750-850℃, the temperature is kept for 2.5-3.5h, and then cooled to room temperature to obtain porous carbon microspheres; S2: the porous carbon microspheres are immersed in a mixed aqueous solution of lanthanum nitrate and scandium nitrate for 8-12h, and then washed and calcined in Ar / H2 mixed gas, the calcination temperature is 650-750℃, the temperature is kept for 1.5-2.5h, and then cooled to room temperature to obtain lanthanum and scandium loaded porous carbon microspheres; The weight ratio of chitosan to ammonium chloride in step S1 is 10:5-15.

2. The rare earth modified cast steel material for high speed railway brake disc according to claim 1, characterized in that, The high-iron brake disc rare earth modified cast steel material comprises the following chemical components: carbon 0.64%-0.85%, manganese 14.2%-16.8%, aluminum 7.1%-8.2%, nickel 4.5%-5.6%, chromium 0.49%-0.58%, molybdenum 0.51%-0.59%, titanium 0.045%-0.055%, vanadium 0.035%-0.045%, lanthanum 0.005%-0.007%, scandium 0.001%-0.003%, sulfur ≤0.01%, phosphorus ≤0.01%, and the rest is iron and inevitable impurities.

3. The rare earth modified cast steel material for high speed train brake disc according to claim 1, characterized in that, The volume ratio of Ar / H2 mixed gas in step S2 is 10:

1.

4. The rare earth modified cast steel material for high speed train brake disc according to claim 1, characterized in that, The concentration of lanthanum nitrate in step S2 is 17.8-19.1g / L, and the concentration of scandium nitrate is 7.5-16.5g / L.

5. A method for the production of a rare earth modified cast steel material for high-iron brake discs according to any one of claims 1 to 4, characterized in that, The steps include: (1) batching: pure iron, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, sponge titanium, vanadium iron, lanthanum and scandium loaded porous carbon microspheres are weighed according to the chemical component raw material ratio; (2) melting: the pure iron is added into a vacuum melting furnace, the vacuum degree is 0.3-0.6Pa, the temperature is raised to 1450-1550℃, the lanthanum and scandium loaded porous carbon microspheres are added, Ar gas is introduced to 800-1200Pa, electrolytic manganese, aluminum particles, nickel plate, metal chromium, molybdenum iron, sponge titanium and vanadium iron are added, the temperature is raised to 1630-1680℃, and then refined for 15-20min to obtain molten steel; (3) pouring: the molten steel is poured into a sand mold, and then cooled to room temperature to obtain a casting; (4) heat treatment: the casting is quenched and tempered to obtain the high-iron brake disc rare earth modified cast steel material.

6. The method of producing a rare earth-modified cast steel material for high-speed rail brake discs according to claim 5, characterized in that, In step (4), the quenching is raised to 900-1100℃ at a temperature rising rate of 40-60℃ / min, kept for 0.5-1.5h, and then oil quenched to room temperature.

7. The method of producing a rare earth modified cast steel material for high speed railway brake discs according to claim 5, characterized in that, The tempering in step (4) is performed at a temperature rising rate of 40-60 ℃ / min, the temperature is raised to 600-700 ℃, and then the temperature is kept for 0.5-1.5 h and then air-cooled to room temperature.

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