High-cold-resistant steel plate for railway bogie and production method of high-cold-resistant steel plate

Abstract

The invention discloses a high-cold-resistance steel plate for a railway bogie and a production method of the high-cold-resistance steel plate, and belongs to the technical field of metallurgy, the steel plate comprises the following chemical components in percentage by mass: 0.06-0.08% of C, 1.20-1.35% of Mn, 0.45-0.55% of Cr, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.015-0.035% of Nb, 0.03-0.05% of V, 0.15-0.30% of Ni, 0.25-0.35% of Cu and the balance of Fe and inevitable impurities, and the sum of the components is 100%. According to the production method, the component design with the low C content is adopted, and excellent internal quality, good-55 DEG C low-temperature toughness and excellent atmospheric corrosion resistance, welding performance and fatigue performance are obtained in the mode of compositely adding Nb, V, Cr, Ni and Cu alloy, a special smelting method and a special rolling and cooling control mode.

Description

Technical Field

[0001] The invention relates to a method for producing steel, in particular to a method for producing steel for a highly cold-resistant railway bogie, and belongs to the technical field of metallurgy. Background Art

[0002] As the speed of passenger cars continues to increase, the reliability and safety of railway vehicles are particularly important. Bogies are key components to ensure the safe operation of trains, especially high-speed trains. They mainly have the functions of load-bearing, guiding, shock absorption, traction, braking, etc. High-speed EMUs cannot run fast and steadily without the bogies. The steel used for bogies requires sufficient strength and rigidity, as well as appropriate elasticity, good impact resistance and fatigue resistance, so as to meet the safety and operation quality of passenger cars, EMUs and high-speed railways.

[0003] Currently, only a few steel companies in Europe and Japan are able to mass-produce high-speed train bogies. The prices are extremely high and the order cycle is long, which seriously restricts the development of my country's rail manufacturing industry.

[0004] With the advancement of my country's high-speed rail policy, the operating climate environment of high-speed trains will inevitably become complex and diverse, including operation in harsh environments in high-altitude cold regions such as Northern Europe. However, in low-temperature environments, the plasticity of materials decreases sharply and brittle fractures are prone to occur, causing sudden safety accidents and economic losses. In order to achieve safe, reliable and high-speed operation of trains and realize my country's development strategy of high-speed railway vehicles, it is of great significance to develop high-cold-resistant railway bogie steel.

[0005] At present, the domestic manufacturers with certain production experience of bogies are mainly Baosteel, Ansteel and Wuhan Iron and Steel. The international standard of 355MPa grade weathering steel for railway bogies is usually only for low temperature impact of -20℃, while the domestic standard minimum temperature is -40℃. The technical requirement of -55℃ low temperature impact weathering steel has not been developed at home and abroad.

[0006] Patent CN110592478B discloses a weathering steel for railway bogies and a manufacturing method thereof. The weathering steel for railway bogies optimizes the addition amount of C, Mn, P, and S elements through a reasonable chemical composition ratio, and reasonably adds other alloy elements according to the upper limit of the carbon equivalent, so as to ensure the corrosion resistance of the steel plate while ensuring excellent welding performance and high strength and toughness. The advanced rolling control technology is adopted to refine the grain size of austenite and ferrite, and obtain a uniform internal structure. The descaling equipment is reasonably arranged, and the descaling process in the rolling descaling process is optimized. The descaling system of rough rolling descaling 4 times and finishing rolling descaling 1st time is adopted, and the descaling system of finishing rolling descaling and rough rolling descaling is separated to ensure the cleanliness of the steel plate surface. The surface quality of the steel is excellent and the internal quality purity is high; however, it can only achieve -40℃ low temperature impact, and cannot meet the low temperature impact of lower temperature.

[0007] Therefore, developing and producing a high cold-resistant railway bogie steel that can overcome the above defects has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0008] The technical problem to be solved by the present invention is to propose a production method for highly cold-resistant railway bogie steel in view of the shortcomings of the above-mentioned prior art. The production method adopts a composition design with low C content, and obtains excellent internal quality, good -55°C low-temperature toughness, and excellent atmospheric corrosion resistance, welding performance and fatigue performance by compositely adding Nb, V, Cr, Ni, and Cu alloys, a special smelting method, a special rolling controlled cooling mode and a tempering process.

[0009] The technical solution of the present invention to solve the above technical problems is: A highly cold-resistant steel plate for railway bogies, characterized in that the chemical composition and mass percentage of the steel plate are: C: 0.06-0.08%, Mn: 1.20-1.35%, Cr: 0.45-0.55%, P≤0.012%, S≤0.003%, Nb: 0.015-0.035%, V: 0.03-0.05%, Ni: 0.15-0.30%, Cu: 0.25-0.35%, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%.

[0010] The technical solution further defined in the present invention is: Furthermore, in the aforementioned cold-resistant railway bogie steel plate, the chemical composition and its mass percentage are: C: 0.073%, Mn: 1.28%, Cr: 0.47%, P: 0.012%, S: 0.002%, Nb: 0.020%, V: 0.031%, Ni: 0.20%, Cu: 0.25%, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%.

[0011] In the aforementioned cold-resistant railway bogie steel plate, the chemical composition and its mass percentage are: C: 0.0652%, Mn: 1.22%, Cr: 0.48%, P: 0.010%, S: 0.003%, Nb: 0.018%, V: 0.036%, Ni: 0.27%, Cu: 0.26%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

[0012] In the aforementioned cold-resistant railway bogie steel plate, the chemical composition and its mass percentage are: C: 0.073%, Mn: 1.23%, Cr: 0.52%, P: 0.009%, S: 0.001%, Nb: 0.017%, V: 0.035%, Ni: 0.30%, Cu: 0.25%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

[0013] In the aforementioned cold-resistant railway bogie steel plate, the chemical composition and its mass percentage are: C: 0.074%, Mn: 1.25%, Cr: 0.48%, P: 0.010%, S: 0.001%, Nb: 0.022%, V: 0.033%, Ni: 0.25%, Cu: 0.28%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

[0014] In the aforementioned cold-resistant railway bogie steel plate, the chemical composition and its mass percentage are: C: 0.063%, Mn: 1.27%, Cr: 0.47%, P: 0.011%, S: 0.002%, Nb: 0.020%, V: 0.031%, Ni: 0.26%, Cu: 0.26%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

[0015] Among the aforementioned cold-resistant railway bogie steel plates, the thickness of the highly cold-resistant railway bogie steel plates is 8-50 mm.

[0016] The present invention also provides a production method for a high cold-resistant railway bogie steel plate, comprising the following process: raw material preparation → molten iron pretreatment → converter smelting → LF refining → RH refining → continuous casting → billet inspection → billet stack cooling → billet furnace acceptance → billet heating → billet descaling → rolling → controlled cooling → tempering → sampling, wherein: (1) The steel plate is refined by LF and RH to ensure that the gas H content of the steel plate is ≤2ppm, the N content is ≤50ppm, the RH vacuum time is controlled to be ≥30 minutes, and the static stirring time is controlled to be ≥20 minutes; (2) During the rolling process, the steel plate rolling temperature is controlled to be 830-900°C; (3) During the controlled cooling process, the steel plate's red-return temperature is controlled at 640-700°C; (4) During the heat treatment process, a temperature of 500-600°C is used for rapid tempering.

[0017] The technical solution further defined in the present invention is: Furthermore, in the aforementioned production method of high cold-resistant railway bogie steel plates, when the steel plates are refined by LF and RH, the levels of various types of inclusions are ≤1.5 according to the GB / T10561 A method assessment criteria. Inclusions can be divided into five categories: A, B, C, D and DS according to their shape and distribution, among which the total of A+B+C+D inclusions is ≤4.5.

[0018] In the above-mentioned production method of high cold-resistant railway bogie steel plate, the steel plate has a yield strength ≥355Mpa, a tensile strength of 490-630Mpa, an elongation ≥22%, an -55°C impact ≥100J, and a Z-direction performance ≥35%.

[0019] The beneficial effects of the present invention are: The present invention adopts the LF+RH refining method outside the furnace, controls the RH vacuum time to be ≥30 minutes, controls the static stirring time to be ≥20 minutes, and fully removes the oxygen in the molten steel and the inclusions are aggregated and floated to obtain high-purity internal quality.

[0020] The steel plate of the present invention has a rolling start temperature of 830-900°C. By rolling in the non-recrystallized zone, the deformed austenite grains are elongated and flattened, and the deformation energy storage accumulation is increased. During the subsequent austenite-ferrite phase transformation, a very fine ferrite grain size structure is obtained to improve the strength and toughness of the steel plate.

[0021] In the heat treatment process, the present invention adopts a temperature of 500-600° C. for rapid tempering, utilizes the precipitation of carbides of Nb, V and Ti, significantly improves the yield strength performance of the steel plate, eliminates the internal stress of the steel plate, and prevents the steel plate from being deformed during cutting.

[0022] The steel plate of the present invention has the characteristics of small number of internal inclusions and long fatigue life; the steel plate has a yield strength of ≥355MPa, a tensile strength of 490-630MPa, an impact of -55°C ≥100J, and a Z-direction performance of ≥35%, and these indicators can meet the use requirements in different low-temperature environments; a low-carbon and nickel-chromium-copper composite design is adopted to improve atmospheric corrosion resistance (I≥6.0). DETAILED DESCRIPTION

[0023] The present invention will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0024] This embodiment provides a high cold-resistant railway bogie steel plate with a thickness of 8 mm, and its chemical composition and mass percentage are shown in Table 1.

[0025] The production method of the above-mentioned high cold-resistant railway bogie steel plate includes the following process: raw material preparation → molten iron pretreatment → converter smelting → LF refining → RH refining → continuous casting → billet inspection → billet stack cooling → billet furnace acceptance → billet heating → billet descaling → rolling → controlled cooling → tempering → sampling, wherein: (1) The steel plate is refined by LF and RH to ensure that the gas H content of the steel plate is 1.2ppm, the N content is 32ppm, the RH vacuum time is controlled to be ≥30 minutes, the static stirring time is controlled to be ≥20 minutes, and the level of all kinds of inclusions is below level 1.0 according to the GB / T10561 A method assessment criteria, and the total level of inclusions is 3.5; (2) During the rolling process, the steel plate rolling temperature is controlled to be 900°C; (3) During the controlled cooling process, the red-return temperature of the steel plate is controlled at 670°C; (4) During the heat treatment process, a temperature of 530°C is used for rapid tempering, and alloy carbides are precipitated to increase the yield strength of the steel plate and eliminate the internal stress of the steel plate.

[0026] The mechanical properties of the highly cold-resistant steel plate for railway bogies obtained in this embodiment are shown in Table 2. Example

[0027] This embodiment provides a high cold-resistant railway bogie steel plate with a thickness of 16 mm, and its chemical composition and mass percentage are shown in Table 1.

[0028] The production method of the above-mentioned high cold-resistant railway bogie steel plate includes the following process: raw material preparation → molten iron pretreatment → converter smelting → LF refining → RH refining → continuous casting → billet inspection → billet stack cooling → billet furnace acceptance → billet heating → billet descaling → rolling → controlled cooling → tempering → sampling, wherein: (1) The steel plate is refined by LF and RH to ensure that the gas H content of the steel plate is 1.5ppm, the N content is 35ppm, the RH vacuum time is controlled to be ≥30 minutes, and the static stirring time is controlled to be ≥20 minutes; according to the GB / T10561 A method assessment criteria, the level of various inclusions is below level 1.0, and the total level of inclusions is 3.0; (2) During the rolling process, the steel plate rolling temperature is controlled to be 890°C; (3) During the controlled cooling process, the steel plate's red-return temperature is controlled at 700°C; (4) During the heat treatment process, a temperature of 500°C is used for rapid tempering to utilize the precipitation of alloy carbides to increase the yield strength of the steel plate and eliminate the internal stress of the steel plate.

[0029] The mechanical properties of the highly cold-resistant steel plate for railway bogies obtained in this embodiment are shown in Table 2. Example

[0030] This embodiment provides a high cold-resistant railway bogie steel plate with a thickness of 30 mm, and its chemical composition and mass percentage are shown in Table 1.

[0031] The production method of the above-mentioned high cold-resistant railway bogie steel plate includes the following process: raw material preparation → molten iron pretreatment → converter smelting → LF refining → RH refining → continuous casting → billet inspection → billet stack cooling → billet furnace acceptance → billet heating → billet descaling → rolling → controlled cooling → tempering → sampling, wherein: (1) The steel plate is refined by LF and RH to ensure that the gas H content of the steel plate is 1.1ppm, the N content is 36ppm, the RH vacuum time is controlled to be ≥30 minutes, and the static stirring time is controlled to be ≥20 minutes; according to the GB / T10561 A method assessment criteria, the level of various inclusions is below 0.5 level, and the total level of inclusions is 2.5; (2) During the rolling process, the steel plate rolling temperature is controlled to be 870°C; (3) During the controlled cooling process, the red-return temperature of the steel plate is controlled at 640°C; (4) During the heat treatment process, a temperature of 550°C is used for rapid tempering, and alloy carbides are precipitated to increase the yield strength of the steel plate and eliminate the internal stress of the steel plate.

[0032] The mechanical properties of the highly cold-resistant steel plate for railway bogies obtained in this embodiment are shown in Table 2. Example

[0033] This embodiment provides a high cold-resistant railway bogie steel plate with a thickness of 40 mm, and its chemical composition and mass percentage are shown in Table 1.

[0034] The production method of the above-mentioned high cold-resistant railway bogie steel plate includes the following process: raw material preparation → molten iron pretreatment → converter smelting → LF refining → RH refining → continuous casting → billet inspection → billet stack cooling → billet furnace acceptance → billet heating → billet descaling → rolling → controlled cooling → tempering → sampling, wherein: (1) The steel plate is refined by LF and RH to ensure that the gas H content of the steel plate is 1.5ppm, the N content is 33ppm, the RH vacuum time is controlled to be ≥30 minutes, and the static stirring time is controlled to be ≥20 minutes; according to the GB / T10561 A method assessment criteria, the level of various inclusions is below 0.5 level, and the total inclusion level is 2.0; (2) During the rolling process, the steel plate rolling temperature is controlled to be 830°C; (3) During the controlled cooling process, the steel plate's red-return temperature is controlled at 650°C; (4) During the heat treatment process, a temperature of 590°C is used for rapid tempering, and alloy carbides are precipitated to increase the yield strength of the steel plate and eliminate the internal stress of the steel plate.

[0035] The mechanical properties of the highly cold-resistant steel plate for railway bogies obtained in this embodiment are shown in Table 2. Example

[0036] This embodiment provides a high cold-resistant railway bogie steel plate with a thickness of 50 mm, and its chemical composition and mass percentage are shown in Table 1.

[0037] The production method of the above-mentioned high cold-resistant railway bogie steel plate includes the following process: raw material preparation → molten iron pretreatment → converter smelting → LF refining → RH refining → continuous casting → billet inspection → billet stack cooling → billet furnace acceptance → billet heating → billet descaling → rolling → controlled cooling → tempering → sampling, wherein: (1) The steel plate is refined by LF and RH to ensure that the gas H content of the steel plate is 1.8ppm, the N content is 35ppm, the RH vacuum time is controlled to be ≥30 minutes, and the static stirring time is controlled to be ≥20 minutes; according to the GB / T10561 A method assessment criteria, the level of various inclusions is below level 1.0, and the total level of inclusions is 2.5; (2) During the rolling process, the steel plate rolling temperature is controlled to be 838°C (3) During the controlled cooling process, the red-return temperature of the steel plate is controlled at 640°C; (4) During the heat treatment process, a temperature of 600°C is used for rapid tempering, and alloy carbides are precipitated to increase the yield strength of the steel plate and eliminate the internal stress of the steel plate.

[0038] The mechanical properties of the highly cold-resistant steel plate for railway bogies obtained in this embodiment are shown in Table 2.

[0039] Table 1 Chemical composition of steel plates of Examples 1-5 Example No. C Mn P S Cr Nb V Ni Cu Atmospheric corrosion resistance coefficient I 1 0.073 1.28 0.012 0.002 0.47 0.020 0.031 0.20 0.25 6.2 2 0.0652 1.22 0.010 0.003 0.48 0.018 0.036 0.27 0.26 6.3 3 0.073 1.23 0.009 0.001 0.52 0.017 0.035 0.30 0.25 6.2 4 0.074 1.25 0.010 0.001 0.48 0.022 0.033 0.25 0.28 6.4 5 0.063 1.27 0.011 0.002 0.47 0.020 0.031 0.26 0.26 6.3 The balance of each example in Table 1 is Fe and unavoidable impurities, and the sum of the above components is 100%.

[0040] Table 2 Mechanical properties of steel plates of Examples 1-5 Example No. Yield StrengthMpa Tensile strengthMpa Elongation% -55℃ impact energy J Z-direction performance 1 425 550 25 270，267，280 / 2 410 555 26.5 301，290，299 55，58，60 3 442 562 24 279，291，288 65，68，59 4 432 570 26 292，289，298 67，70，68 5 440 565 23 299，290，287 70，71，66 As can be seen from Tables 1 and 2, the production method of the present invention adopts a composition design with a low C content, and obtains high-purity steel plate internal quality, good -55°C low-temperature toughness, and excellent atmospheric corrosion resistance, welding performance and fatigue performance by compositely adding Nb, V, Cr, Ni, and Cu alloys, a special smelting method, and a special rolling controlled cooling mode.

[0041] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A highly cold-resistant steel plate for railway bogies, characterized in that: The chemical composition of the steel plate and its mass percentage are: C: 0.06-0.08%, Mn: 1.20-1.35%, Cr: 0.45-0.55%, P≤0.012%, S≤0.003%, Nb: 0.015-0.035%, V: 0.03-0.05%, Ni: 0.15-0.30%, Cu: 0.25-0.35%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

2. The high cold-resistant railway bogie steel plate according to claim 1, characterized in that: The chemical composition of the steel plate and its mass percentage are: C: 0.073%, Mn: 1.28%, Cr: 0.47%, P: 0.012%, S: 0.002%, Nb: 0.020%, V: 0.031%, Ni: 0.20%, Cu: 0.25%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

3. The highly cold-resistant steel plate for railway bogie according to claim 1, characterized in that: The chemical composition of the steel plate and its mass percentage are: C: 0.0652%, Mn: 1.22%, Cr: 0.48%, P: 0.010%, S: 0.003%, Nb: 0.018%, V: 0.036%, Ni: 0.27%, Cu: 0.26%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

4. The high cold-resistant railway bogie steel plate according to claim 1, characterized in that: The chemical composition of the steel plate and its mass percentage are: C: 0.073%, Mn: 1.23%, Cr: 0.52%, P: 0.009%, S: 0.001%, Nb: 0.017%, V: 0.035%, Ni: 0.30%, Cu: 0.25%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

5. The highly cold-resistant steel plate for railway bogie according to claim 1, characterized in that: The chemical composition of the steel plate and its mass percentage are: C: 0.074%, Mn: 1.25%, Cr: 0.48%, P: 0.010%, S: 0.001%, Nb: 0.022%, V: 0.033%, Ni: 0.25%, Cu: 0.28%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

6. The high cold-resistant railway bogie steel plate according to claim 1, characterized in that: The chemical composition of the steel plate and its mass percentage are: C: 0.063%, Mn: 1.27%, Cr: 0.47%, P: 0.011%, S: 0.002%, Nb: 0.020%, V: 0.031%, Ni: 0.26%, Cu: 0.26%, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

7. The high cold-resistant railway bogie steel plate according to claim 1, characterized in that: The thickness of the steel plate for high cold-resistant railway bogies is 8-50mm.

8. A method for producing a highly cold-resistant railway bogie steel plate as claimed in any one of claims 1 to 7, characterized in that: It includes the following processes: raw material preparation → molten iron pretreatment → converter smelting → LF refining → RH refining → continuous casting → billet inspection → billet stack cooling → billet furnace acceptance → billet heating → billet descaling → rolling → controlled cooling → tempering → sampling, among which: (1) The steel plate is refined by LF and RH to ensure that the gas H content of the steel plate is ≤2ppm, the N content is ≤50ppm, the RH vacuum time is controlled to be ≥30 minutes, and the static stirring time is controlled to be ≥20 minutes; (2) During the rolling process, the steel plate rolling temperature is controlled to be 830-900°C; (3) During the controlled cooling process, the steel plate's red-return temperature is controlled at 640-700°C; (4) During the heat treatment process, a temperature of 500-600°C is used for rapid tempering.

9. The method for producing a highly cold-resistant railway bogie steel plate according to claim 1, characterized in that: When the steel plate is refined by LF and RH, according to the GB / T10561 A method assessment standard, the level of each type of inclusions is ≤1.5, and the sum of A+B+C+D inclusions is ≤4.

5.

10. The method for producing a highly cold-resistant railway bogie steel plate according to claim 1, characterized in that: The steel plate has a yield strength of ≥355Mpa, a tensile strength of 490-630Mpa, an elongation of ≥22%, an impact of -55℃ ≥100J, and Z-direction performance of ≥35%.