Machining method of large-specification axle steel billet for high-speed rail with speed of 400 km / h and above

Abstract

The invention discloses a processing method of a large-specification axle steel billet for a high-speed rail with the speed of 400 kilometers and above per hour, which comprises the steps of continuous casting billet preparation, continuous casting billet heating, continuous casting billet forging and post-forging heat treatment, and adopts a continuous casting billet four-section heating process, a continuous casting billet two-upsetting two-drawing forging process and a post-forging heat treatment process of waste heat normalizing and annealing. The problems of structure uniformity, density, banded structure and transverse and longitudinal impact toughness of the large-specification axle steel billet for the high-speed rail with the speed of 400 kilometers and above per hour are solved, the banded structure of the produced large-specification axle steel billet is smaller than or equal to the first level, the macrostructure center porosity is smaller than or equal to the first level, the transverse and longitudinal impact value ratio is larger than or equal to 0.9, and the production cost is low. And the application requirements of axles of high-speed rails with the speed of 400 kilometers or above per hour are completely met.

Description

Technical Field

[0001] The present invention belongs to the technical field of forging and heat treatment, and more specifically relates to a method for processing large-size axle steel billets for high-speed railways with a speed of 400 kilometers per hour or more. Background Art

[0002] Axles are important running parts for the safe operation of high-speed trains. As the speed of high-speed trains increases, the dynamic loads on axles also increase, making fatigue failure more likely. The research and development of axles for high-speed trains with a speed of 400 km / h and above has been put on the agenda. Compared with axle billets for high-speed trains with speed levels of 250 km / h and 350 km / h, large-sized axle billets for high-speed trains with a speed of 400 km / h and above have larger specifications. In order to ensure the safety of high-speed trains with a speed of 400 km / h and above, the requirements for the uniformity and density of large-sized axle billets are more stringent, requiring the looseness and segregation of axle billets to be ≤1 level, and especially the requirements for banded structure ≤1 level and the ratio of transverse and longitudinal impact values ​​≥0.9. The internal quality of axle steel billets has very strict requirements on the forging process. Axle steel billets produced by traditional forging and heat treatment processes using existing technologies generally have serious looseness and component segregation, and their transverse and longitudinal impact toughness and strength are low, and the banded structure is only level 2-3, which cannot meet the above-mentioned density, banded structure and transverse and longitudinal impact toughness requirements of large-size axle steel billets for high-speed railways with a speed of 400km / h and above. Summary of the invention

[0003] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a method for processing a large-sized axle billet for high-speed railways with a speed of 400 kilometers per hour or above, comprising the following steps:

[0004] (I) Continuous casting slab preparation

[0005] Through electric furnace smelting → LF furnace refining → VD degassing treatment → continuous casting, a continuous casting round billet with a cross section of Φ690mm is prepared;

[0006] (2) Continuous casting billet heating

[0007] A four-stage heating process is adopted to heat the continuous casting billet: (1) in the first stage of heating, the continuous casting billet is kept at 500°C for 2 hours after entering the furnace; (2) in the second stage of heating, the billet is heated to 850±10°C at a heating rate of ≤100°C / h and kept at this temperature for 2 hours; (3) in the third stage of heating, the billet is heated to 1150±10°C at a heating rate of ≤120°C / h and kept at this temperature for 3 hours; (4) in the fourth stage of heating, the billet is heated to 1270±10°C at a heating rate of ≤100°C / h and kept at this temperature for 4-5 hours before being taken out of the furnace;

[0008] (2) Continuous casting forging

[0009] The continuous casting round billet with a cross section of Φ690mm is forged into an axle billet with a cross section of 300mm×300mm, including:

[0010] (1) First fire forging: The billet is subjected to first fire upsetting, and the continuous casting billet is upset to 1 / 2 of the original continuous casting billet height using a wide plate, and then the billet is subjected to first fire drawing, and the billet is drawn to the original continuous casting billet height. The forging temperature during the first fire forging process is controlled at 1200-850°C;

[0011] (2) Second fire forging: The billet is returned to the furnace and heated to 1240±30°C, kept at this temperature for 2 hours, and then subjected to second fire upsetting. The billet is upset to 1 / 2 of the original continuous casting billet height, and then subjected to second fire drawing. The billet is drawn to a 300mm×300mm axle billet. The forging temperature during the second fire forging process is controlled at 1200-900°C.

[0012] (3) Heat treatment after forging

[0013] (1) Residual heat normalizing: The axle billet is normalized using the residual heat from forging. After each axle billet is forged, it is placed on a cooling rack and cooled to below 200°C by a fan.

[0014] (2) Annealing: The axle billet after air cooling is placed in an annealing furnace for annealing to eliminate thermal stress. The billet is heated to 670±10℃ at a heating rate of 100℃ / h, kept at this temperature for 6 to 8 hours, and then cooled to below 200℃ before being taken out of the furnace.

[0015] Furthermore, in the above-mentioned processing method of large-size axle steel billets for high-speed railways with a speed of 400 kilometers per hour or above, in the continuous casting billet preparation step, the chemical composition of the continuous casting billet is controlled by mass percentage as follows: C: 0.24-0.32%, Si: 0.20-0.40%, Mn: 0.60-0.90%, P≤0.010%, S≤0.010%, Cr: 0.90-1.20%, Mo: 0.20-0.30%, Ni: 0.50-1.50%, V≤0.06%, Al: 0.010-0.040%, Cu≤0.20%, and the rest are Fe and unavoidable impurities.

[0016] Furthermore, in the above-mentioned processing method of large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or above, in the continuous casting billet heating step, a chamber heating furnace is used to heat the continuous casting billet, the chamber heating furnace is 3.5 meters long and is heated by natural gas.

[0017] Furthermore, in the above-mentioned processing method of large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or above, in the continuous casting billet forging step, the number of passes with a single-side reduction of ≥80 mm during the second fire drawing is controlled to be no less than two passes.

[0018] Furthermore, in the above-mentioned processing method of large-sized axle billets for high-speed railways with a speed of 400 kilometers per hour or above, in the continuous casting billet forging step, the forging equipment used is a 5,000-ton fast forging press.

[0019] The processing method of the large-size axle steel billet for high-speed railways with a speed of 400 kilometers per hour or above of the present invention has the following advantages and beneficial effects: the present invention solves the problems of organizational uniformity, density, banded structure and transverse and longitudinal impact toughness of the large-size axle steel billet for high-speed railways with a speed of 400 kilometers per hour or above by adopting a four-stage heating process for continuous casting billets, a two-upsetting and two-drawing forging process for continuous casting billets, and a post-forging heat treatment process of waste heat normalizing + annealing. The banded structure of the large-size axle steel billet produced and prepared is ≤ grade 1, the low-multiple organizational center porosity is ≤ grade 1, and the transverse and longitudinal impact value ratio is ≥0.9, which fully meets the application requirements of axles for high-speed railways with a speed of 400 kilometers per hour or above, and is of great significance for promoting the development of my country's high-speed trains to higher speeds and promoting the implementation of my country's railway high-end equipment technology leading strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0021] Figure 1 This is a curve diagram of the continuous casting billet heating process in the method for processing large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or more of the present invention;

[0022] Figure 2 It is a schematic diagram of the process of forging a continuous casting billet in the method for processing a large-size axle billet for high-speed railways with a speed of 400 kilometers per hour or more of the present invention;

[0023] Figure 3 This is a steel billet annealing process curve diagram in the processing method of large-size axle steel billets for high-speed railways with a speed of 400 kilometers per hour or more of the present invention;

[0024] Figure 4 A banded structure diagram of an axle steel billet manufactured by the processing method of the present invention for a large-size axle steel billet for high-speed railways with a speed of 400 kilometers per hour or more;

[0025] Figure 5 A macrostructure diagram of an axle steel billet manufactured by the processing method of the present invention for a large-size axle steel billet for high-speed railways with a speed of 400 kilometers per hour or more;

[0026] Figure 6The banded structure diagram of the axle steel billet manufactured by using the embodiment 1 of the present invention;

[0027] Figure 7 This is a macrostructure diagram of an axle steel billet manufactured by using Example 1 of the present invention;

[0028] Figure 8 The banded structure diagram of the axle steel billet manufactured by using the second embodiment of the present invention;

[0029] Fig. 9 This is a low-magnification microstructure diagram of an axle steel billet manufactured using Example 2 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] The basic process route of the processing method of the large-sized axle steel billet for high-speed railway with a speed of 400 kilometers per hour or more of the present invention is: continuous casting billet preparation → continuous casting billet heating → continuous casting billet forging → post-forging heat treatment. Specifically, the processing method of the large-sized axle steel billet for high-speed railway with a speed of 400 kilometers per hour or more of the present invention comprises the following steps:

[0032] (I) Continuous casting slab preparation

[0033] The method comprises the following steps: smelting in an electric furnace → refining in an LF furnace → VD degassing → continuous casting, a continuous casting round billet with a cross section of Φ690 mm is prepared, wherein the chemical composition of the continuous casting billet is controlled as follows by mass percentage: C: 0.24-0.32%, Si: 0.20-0.40%, Mn: 0.60-0.90%, P≤0.010%, S≤0.010%, Cr: 0.90-1.20%, Mo: 0.20-0.30%, Ni: 0.50-1.50%, V≤0.06%, Al: 0.010-0.040%, Cu≤0.20%, and the rest is Fe and unavoidable impurities.

[0034] (2) Continuous casting billet heating

[0035] The continuous casting billet is heated by a chamber heating furnace to ensure uniform heating temperature of the billet. Figure 1As shown, the continuous casting billet heating step adopts a four-stage heating process: (1) the first stage of heating, after the continuous casting billet is put into the furnace, it is first kept at 500℃ for 2 hours, (2) the second stage of heating, heating to 850±10℃ at a heating rate of ≤100℃ / h, and keeping it warm for 2 hours, (3) the third stage of heating, heating to 1150±10℃ at a heating rate of ≤120℃ / h, and keeping it warm for 3 hours, (4) the fourth stage of heating, heating to 1270±10℃ at a heating rate of ≤100℃ / h, and taking it out of the furnace after keeping it warm for 4-5 hours.

[0036] (2) Continuous casting forging

[0037] The continuous casting round billet with a cross section of Φ690mm is forged into an axle billet with a cross section of 300mm×300mm. Figure 2 As shown, the continuous casting billet forging steps include:

[0038] (1) First fire forging: The billet is subjected to first fire upsetting, and the continuous casting billet is upset to 1 / 2 of the original continuous casting billet height using a wide plate, and then the billet is subjected to first fire drawing, and the billet is drawn to the original continuous casting billet height. The forging temperature during the first fire forging process is controlled at 1200-850°C;

[0039] (2) Second fire forging: The billet is returned to the furnace and heated to 1240±30℃, kept warm for 2 hours, and then subjected to second fire upsetting. The billet is upset to 1 / 2 of the original continuous casting billet height, and then subjected to second fire drawing. The billet is squared to an axle billet of 300mm×300mm. During the second fire drawing, the number of passes with a single-side reduction of ≥80mm is not less than two. The forging temperature during the second fire forging process is controlled at 1200~900℃.

[0040] (3) Heat treatment after forging

[0041] In order to improve the banded structure of the axle steel billet and eliminate thermal stress, the axle steel billet is subjected to post-forging heat treatment, which includes:

[0042] (1) Residual heat normalizing: The axle billet is normalized using the residual heat from forging. After each axle billet is forged, it is placed on a cooling rack and cooled to below 200°C by a fan.

[0043] (2) Annealing: The axle billet after air cooling is placed in an annealing furnace for annealing treatment to eliminate thermal stress. Figure 3 As shown, heat to 670±10℃ at a heating rate of 100℃ / h, keep warm for 6 to 8 hours, and then cool the furnace to below 200℃ before taking out of the furnace.

[0044] As a specific implementation, the chamber heating furnace used in the continuous casting billet heating step has a length of 3.5 m and is heated by natural gas.

[0045] As a specific implementation, the forging equipment used in the continuous casting billet forging step is a 5000-ton fast forging press.

[0046] The banded structure diagram and macrostructure diagram of the axle steel billet manufactured by the processing method of the present invention for large-size axle steel billet for high-speed railway with a speed of 400 kilometers per hour or more are respectively shown in Figure 4 and Figure 5 After testing, the large-size axle billet processed and manufactured by the present invention has a banded structure of ≤1 level, a low-multiple structure center looseness of ≤1 level, and a transverse and longitudinal impact value ratio of ≥0.9, which fully meets the application requirements of high-speed rail axles with a speed of 400 kilometers per hour and above.

[0047] The following is a detailed description of the processing method of the large-sized axle billet for high-speed railways with a speed of 400 kilometers per hour or above of the present invention in conjunction with the embodiments. The implementation methods of the following embodiments without specifying specific conditions are carried out according to conventional methods and conditions, and the present invention does not make specific limitations on this.

[0048] Example 1

[0049] The processing method of the large-sized axle steel billet for high-speed railway with a speed of 400 kilometers per hour or more according to the first embodiment of the present invention is specifically implemented as follows:

[0050] (I) Continuous casting slab preparation

[0051] Through electric furnace smelting → LF furnace refining → VD degassing treatment → continuous casting, a continuous casting round billet with a cross-section of Φ690mm is prepared, wherein the chemical composition of the continuous casting billet is as follows by mass percentage: C: 0.27%, Si: 0.25%, Mn: 0.70%, P: 0.007%, S: 0.001%, Cr: 1.00%, Mo: 0.26%, Ni: 1.13%, V: 0.04%, Al: 0.021%, and the rest is Fe and unavoidable impurities.

[0052] (2) Continuous casting billet heating

[0053] Four Φ690mm×1500mm continuous casting billets were loaded into a chamber heating furnace for four-stage heating. After entering the furnace, the continuous casting billets were first kept at 500℃ for 2 hours, then heated to 850℃ at a heating rate of 100℃ / h and kept for 2 hours, then heated to 1150℃ at a heating rate of 120℃ / h and kept for 3 hours, then heated to 1270℃ at a heating rate of 100℃ / h and kept for 4 hours before being taken out of the furnace for forging.

[0054] (2) Continuous casting forging

[0055] (1) First fire forging: The blank is subjected to first fire upsetting, and a wide plate is used to upset the blank to a height of 750 mm. After upsetting, the blank is subjected to first fire drawing, and is directly drawn to 1500 mm. The forging temperature during the first fire forging process is 1200-850°C;

[0056] (2) Second fire forging: The billet is returned to the furnace and heated to 1270℃ for 2 hours, and then subjected to second fire upsetting to a height of 750mm. The billet is then subjected to second fire drawing to a square shape of 300mm×300mm for an axle steel billet. During the second fire drawing, the single-side reduction of the third and fourth passes, a total of two passes, is 80mm. The forging temperature during the second fire forging process is controlled at 1200-900℃.

[0057] (3) Heat treatment after forging

[0058] (1) Residual heat normalizing: The final forging temperatures of the four axle billets are 910°C, 915°C, 900°C, and 910°C, respectively. After forging each axle billet, the axle billet is placed on a cooling rack and cooled to below 200°C by a fan;

[0059] (2) Annealing: The axle billet after air cooling is placed in an annealing furnace for annealing to eliminate thermal stress. The billet is heated to 670°C at a heating rate of 100°C / h, kept at this temperature for 7 hours, and then cooled to below 200°C before being taken out of the furnace.

[0060] The banded structure diagram and macrostructure diagram of the axle steel billet manufactured by using Example 1 of the present invention are respectively shown in Figure 6 and Figure 7 After testing, the axle steel billet manufactured by using Example 1 of the present invention has a banded structure of 0.5 level, a macrostructure center looseness of 1 level, and as shown in Table 1 below, a transverse to longitudinal impact value ratio of 0.95.

[0061] Table 1 Ratio of transverse and longitudinal impact values ​​of axle steel billets of Example 1

[0062]

[0063] Example 2

[0064] The processing method of the large-sized axle steel billet for high-speed railway with a speed of 400 kilometers per hour or more according to the second embodiment of the present invention is specifically implemented as follows:

[0065] (I) Continuous casting slab preparation

[0066] Through electric furnace smelting → LF furnace refining → VD degassing treatment → continuous casting, a continuous casting round billet with a cross-section of Φ690mm is prepared, wherein the chemical composition of the continuous casting billet is as follows by mass percentage: C: 0.28%, Si: 0.26%, Mn: 0.71%, P: 0.007%, S: 0.001%, Cr: 1.01%, Mo: 0.26%, Ni: 1.14%, V: 0.05%, Al: 0.022%, and the rest is Fe and unavoidable impurities.

[0067] (2) Continuous casting billet heating

[0068] Six Φ690mm×1520mm continuous casting billets were loaded into a chamber heating furnace for four-stage heating. After entering the furnace, the continuous casting billets were first kept at 500℃ for 2 hours, then heated to 850℃ at a heating rate of 100℃ / h and kept for 2 hours, then heated to 1150℃ at a heating rate of 120℃ / h and kept for 3 hours, then heated to 1270℃ at a heating rate of 100℃ / h and kept for 5 hours before being taken out of the furnace for forging.

[0069] (2) Continuous casting forging

[0070] (1) First fire forging: The blank is subjected to first fire upsetting, and a wide plate is used to upset the blank to a height of 760 mm. After upsetting, the blank is subjected to first fire drawing, and is directly drawn to a round length of 1520 mm. The forging temperature during the first fire forging process is 1200-850°C;

[0071] (2) Second fire forging: The billet is returned to the furnace and heated to 1270℃ for 2 hours, and then subjected to second fire upsetting to a height of 760mm. The billet is then subjected to second fire drawing to a square shape of 300mm×300mm for an axle steel billet. During the second fire drawing, the single-side reduction of the third and fourth passes, a total of two passes, is 80mm. The forging temperature during the second fire forging process is controlled at 1200-900℃.

[0072] (3) Heat treatment after forging

[0073] (1) Residual heat normalizing: The final forging temperatures of the six axle billets are 905°C, 910°C, 915°C, 905°C, 900°C, and 910°C, respectively. After forging each axle billet, the axle billet is placed on a cooling rack and cooled to below 200°C by a fan;

[0074] (2) Annealing: The axle billet after air cooling is placed in an annealing furnace for annealing to eliminate thermal stress. The billet is heated to 680°C at a heating rate of 100°C / h, kept at this temperature for 8 hours, and then cooled to below 200°C before being taken out of the furnace.

[0075] The banded structure diagram and macrostructure diagram of the axle steel billet manufactured by using Example 2 of the present invention are respectively shown in Figure 8 and Fig. 9 After testing, the axle steel billet manufactured by using Example 2 of the present invention has a banded structure of 0.5 level, a macrostructure center looseness of 0.5 level, and as shown in Table 2 below, a transverse to longitudinal impact value ratio of 0.92.

[0076] Table 2 Ratio of transverse and longitudinal impact values ​​of axle steel billets of Example 2

[0077]

[0078] To sum up, the processing method of large-size axle steel billets for high-speed railways with a speed of 400 kilometers per hour and above of the present invention solves the problems of organizational uniformity, density, banded structure and transverse and longitudinal impact toughness of large-size axle steel billets for high-speed railways with a speed of 400 kilometers per hour and above by adopting a four-stage heating process for continuous casting billets, a two-upsetting and two-drawing forging process for continuous casting billets, and a post-forging heat treatment process of waste heat normalizing + annealing. The banded structure of the large-size axle steel billets produced and prepared is ≤ grade 1, the low-magnification central porosity is ≤ grade 1, and the transverse and longitudinal impact value ratio is ≥0.9, which fully meets the application requirements of axles for high-speed railways with a speed of 400 kilometers per hour and above, and is of great significance for promoting the development of my country's high-speed trains to higher speeds and promoting the implementation of my country's railway high-end equipment technology leading strategy.

[0079] It should be noted that, in this article, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for processing large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or more, characterized in that: The steps include: (I) Continuous casting slab preparation Through electric furnace smelting → LF furnace refining → VD degassing treatment → continuous casting, a continuous casting round billet with a cross section of Φ690mm is prepared; (II) Continuous Casting Billet Heating A four-stage heating process is adopted to heat the continuous casting billet: (1) in the first stage of heating, the continuous casting billet is kept at 500°C for 2 hours after entering the furnace; (2) in the second stage of heating, the billet is heated to 850±10°C at a heating rate of ≤100°C / h and kept at this temperature for 2 hours; (3) in the third stage of heating, the billet is heated to 1150±10°C at a heating rate of ≤120°C / h and kept at this temperature for 3 hours; (4) in the fourth stage of heating, the billet is heated to 1270±10°C at a heating rate of ≤100°C / h and kept at this temperature for 4-5 hours before being taken out of the furnace; (2) Continuous casting forging The continuous casting round billet with a cross section of Φ690mm is forged into an axle billet with a cross section of 300mm×300mm, including: (1) First fire forging: The billet is subjected to first fire upsetting, and the continuous casting billet is upset to 1 / 2 of the original continuous casting billet height using a wide plate, and then the billet is subjected to first fire drawing, and the billet is drawn to the original continuous casting billet height. The forging temperature during the first fire forging process is controlled at 1200-850°C; (2) Second fire forging: The billet is returned to the furnace and heated to 1240±30°C, kept at this temperature for 2 hours, and then subjected to second fire upsetting. The billet is upset to 1 / 2 of the original continuous casting billet height, and then subjected to second fire drawing. The billet is drawn to a 300mm×300mm axle billet. The forging temperature during the second fire forging process is controlled at 1200-900°C. (3) Heat treatment after forging (1) Residual heat normalizing: The axle billet is normalized using the residual heat from forging. After each axle billet is forged, it is placed on a cooling rack and cooled to below 200°C by a fan. (2) Annealing: The axle billet after air cooling is placed in an annealing furnace for annealing to eliminate thermal stress. The billet is heated to 670±10℃ at a heating rate of 100℃ / h, kept at this temperature for 6 to 8 hours, and then cooled to below 200℃ before being taken out of the furnace.

2. The method for processing large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or more according to claim 1, characterized in that: In the continuous casting billet preparation step, the chemical composition of the continuous casting billet is controlled by mass percentage as follows: C: 0.24-0.32%, Si: 0.20-0.40%, Mn: 0.60-0.90%, P≤0.010%, S≤0.010%, Cr: 0.90-1.20%, Mo: 0.20-0.30%, Ni: 0.50-1.50%, V≤0.06%, Al: 0.010-0.040%, Cu≤0.20%, and the rest is Fe and unavoidable impurities.

3. The method for processing large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or more according to claim 1, characterized in that: In the continuous casting billet heating step, a chamber type heating furnace is used to heat the continuous casting billet. The chamber type heating furnace has a length of 3.5 m and is heated by natural gas.

4. The method for processing large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or more according to claim 1, characterized in that: In the continuous casting billet forging step, the number of passes with a single-side reduction of ≥80 mm during the second fire drawing is controlled to be no less than two passes.

5. The method for processing large-size axle billets for high-speed railways with a speed of 400 kilometers per hour or more according to claim 1, characterized in that: In the continuous casting billet forging step, the forging equipment used is a 5000-ton fast forging press.

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