1100-mpa-grade alloyed-forged high-manganese steel frog and preparation process therefor

Abstract

Provided are a 1100-MPa-grade alloyed-forged high-manganese steel frog and a preparation process therefor. The chemical components of the alloyed-forged high-manganese steel frog are (wt%): C: 1.0-1.3, Mn: 12.0-14.0, Cr: 0.5-6.0, Mo: 0.4-3.0, V: 0.15-0.50, Si: 0.3-0.8, Ni: 0.5-4.0, Al: 0.02-0.05, N: 0.008-0.035, P: ≤0.045, S: ≤0.03, and the balance of Fe. In the present invention, the stacking fault energy of a material is regulated by means of alloying, and therefore the strain hardening behavior of an alloy during deformation can be regulated and the strength and plasticity of the material can be improved. Furthermore, the concept of Al+N microalloying is used and a forging process is controlled to realize grain refinement. The grain size of the alloyed-forged high-manganese steel frog of the present invention can be refined to Grade 3-6, the yield strength is 450 MPa or more, the tensile strength is 1100 MPa or more, the elongation is 70% or more, and the impact energy (Aku) is 320 J or more; therefore, the service life thereof is significantly prolonged, and the usage requirements of high-speed and heavy-haul railways are met.

Description

A 1100MPa grade alloyed forged high-manganese steel fork and its manufacturing process

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application filed on December 3, 2024, application number 202411758709.8, entitled "A 1100MPa grade alloyed forged high manganese steel fork and its preparation process", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention belongs to the field of chemical metallurgy technology, specifically relating to a 1100MPa grade alloyed forged high manganese steel fork and its preparation process. Background Technology

[0004] ZGMn13 has been widely used in the field of railway frog technology. However, with the development of modern high-speed and heavy-haul railways, traditional high-manganese steel frogs, due to their low strength, are prone to deformation and crushing during use, and can no longer meet the requirements of actual use. Therefore, improving the mechanical properties of high-manganese steel frogs through alloying, thereby increasing their service life, is an important direction for the development of high-manganese steel for railway frogs.

[0005] In the existing technology, the United States has invented a Ni, V, Ti microalloyed high-manganese steel that utilizes fine carbonitridium compounds to improve the mechanical properties of frogs, significantly extending their service life. The composition (wt%) of this microalloyed high-manganese steel is: Mn 11.0-24.0, C 1.0-1.4, Si ≥ 1, Cr ≥ 1.9, Ni ≥ 0.25, Mo ≥ 1.0, Al ≥ 0.2, Cu ≥ 0.25, impurities P ≤ 0.07, S ≤ 0.06, and the addition amounts of microalloyed Ti, Nb, and V are approximately 0.020-0.070, N is approximately 0.001-0.01, and the total sum of the microalloying elements Ti + Nb + V + N is not less than 0.05% and does not exceed 0.22%.

[0006] Canada improves the mechanical properties of high-manganese steel by adding v (V). The hardness of high-manganese steel increases with the increase of v content, and its wear resistance is optimal when the v content is 2%, reaching 5 times that of ordinary high-manganese steel.

[0007] The European standard for high-manganese steel used in turnouts has the following composition (wt%): C 0.95-1.3, Si ≤ 0.65, Mn 11.5-14, Ni ≤ 1.75, Mo ≤ 0.75, Cr ≤ 0.5, Cu ≤ 0.3, Al ≤ 0.045, P ≤ 0.05, S ≤ 0.03, which actually incorporates the design concept of alloying.

[0008] Although the addition of alloying elements can significantly improve the yield strength of high manganese steel, the addition of alloying elements will aggravate segregation. More Cr can easily lead to the formation of network carbides. Carbide-forming elements such as V, Cr, and Mo can also easily lead to the formation of overheated carbides and undissolved carbides. Therefore, the content of alloying elements must be optimized and controlled.

[0009] Furthermore, existing cast high-manganese steel frogs suffer from casting defects such as shrinkage cavities and porosity, as well as coarse grains. These defects and coarse grains negatively impact the service life of the frogs, impairing their performance and reducing their service life. Therefore, manufacturing high-manganese steel frogs using forging becomes an inevitable choice. However, the forging process window for traditional high-manganese steel is relatively small, leading to significant challenges in actual production. Therefore, developing a forged high-manganese steel alloy system for frogs with a wide process window and its forging process based on alloying and microalloying techniques to refine the microstructure is of great significance. The following technical solution is proposed to address this issue. Summary of the Invention

[0010] The technical problem solved by this invention is to provide a 1100MPa grade alloyed forged high manganese steel frog and its preparation process, realizing how to develop a forged high manganese steel alloy system for frogs with a wide process window and its forging process based on the technical idea of ​​alloying and micro-alloying to refine the microstructure.

[0011] The technical solution adopted in this invention is: a 1100MPa grade alloyed forged high-manganese steel frog, wherein the chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.0-1.3, Mn: 12.0-14.0, Cr: 0.5-6.0, Mo: 0.4-3.0, V: 0.15-0.50, Si: 0.3-0.8, Ni: 0.5-4.0, Al: 0.02-0.05, N: 0.008-0.035, P: ≤0.045, S: ≤0.03, and the remainder is Fe.

[0012] In the above technical solution, as a preferred technical solution: the chemical composition (wt%) of the alloyed forged high manganese steel frog is C: 1.13, Mn: 12.1, Cr: 0.52, Mo: 0.4, V: 0.35, Si: 0.35, Ni: 0.53, Al: 0.022, N: 0.0085, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0013] In the above technical solution, as a preferred technical solution: the chemical composition (wt%) of the alloyed forged high manganese steel frog is C: 1.01, Mn: 13.6, Cr: 5.5, Mo: 2.4, V: 0.48, Si: 0.75, Ni: 3.93, Al: 0.042, N: 0.035, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0014] In the above technical solution, as a preferred technical solution: the chemical composition (wt%) of the alloyed forged high manganese steel frog is C: 1.29, Mn: 13.8, Cr: 0.52, Mo: 2.93, V: 0.25, Si: 0.52, Ni: 3.96, Al: 0.035, N: 0.0028, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0015] In the above technical solution, as a preferred technical solution: the chemical composition (wt%) of the alloyed forged high manganese steel frog is C: 1.17, Mn: 12.9, Cr: 3.24, Mo: 1.46, V: 0.17, Si: 0.37, Ni: 1.53, Al: 0.026, N: 0.0135, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0016] In the above technical solution, the alloyed forged high-manganese steel frog has a yield strength ≥450MPa, tensile strength ≥1100MPa, elongation ≥70%, and impact value (A) KU ≥320J.

[0017] This invention also claims protection for a manufacturing process of 1100MPa grade alloyed forged high-manganese steel frogs: by controlling the content of Cr, Mo, V and Ni in high-manganese steel to avoid the adverse factors of microalloying; by controlling the stacking fault energy of the material through alloy coupling design to improve the strain hardening ability of the alloy, thereby improving the tensile strength and elongation of the material; and by refining the grains based on Al+N microalloying combined with forging manufacturing process to improve the yield strength of the material.

[0018] In the above technical solution, the forging process includes the following steps:

[0019] Step 1: Alloy smelting and billet quality control steps;

[0020] Step 2: Forging process of the turnout;

[0021] Step 3: Heat treatment of the turnout;

[0022] Step 4: Machining steps for the frog.

[0023] In the above technical solution, in step 1: electric furnace steelmaking is adopted and LF refining and VD degassing treatment are carried out. Nitrogen-containing Cr iron is used to increase the N content in the molten steel, and the O content in the molten steel is controlled below 20ppm; the Al2O3 inclusion content is reduced by controlling O, and the formation of dispersed AlN particles is promoted by increasing N to refine the grains; then, the billet is cast into the required size and specifications by ingot casting or continuous casting, and the billet is slowly cooled to room temperature (cooling rate ≤100℃ / hour) to prevent the billet from cracking.

[0024] In the above technical solution, in step 2: the billet is heated to 600℃ at a heating rate of ≤50℃ / hour and held for 2-5 hours, then heated to 1100-1200℃ at a heating rate of ≤200℃ / hour and held for 1-3 hours; then the heated billet is taken out of the furnace and forged into a turnout billet with a forging ratio ≥3.5, a final forging temperature ≥900℃, and a forging ratio ≥1.5 within the temperature range of 900-1000℃; then the forged billet is slowly cooled (cooling rate ≤100℃ / hour) to room temperature.

[0025] Specifically, heating the billet to 1100-1200℃ at a heating rate of ≤200℃ / hour and holding it for 1-3 hours is used to ensure that AlN in the billet is fully dissolved while avoiding overheating; controlling the forging ratio is used to ensure material densification and microstructure refinement; and a forging ratio ≥1.5 in the temperature range of 900-1000℃ is used to promote deformation-induced AlN dispersion precipitation, thereby achieving microstructure refinement.

[0026] In the above technical solution, in step 3: the forging billet obtained in step 2 is heated to 600°C at a heating rate of ≤100°C / hour and held for 1 hour, then heated to 950~1100°C at a heating rate of ≤200°C / hour and held for 1.5~10 hours before water toughening treatment. The workpiece is immersed in water at a temperature ≥900°C, and when the workpiece temperature is ≤400°C, it is removed from the water and naturally cooled to room temperature.

[0027] Among them, the alloying design increases the heat treatment process window, reducing the minimum temperature of the workpiece entering the water during water toughening to 900℃, while increasing the water outlet temperature to 400℃, thereby reducing the operational difficulty of the process.

[0028] In the above technical solution, step 4 involves machining the heat-treated frog blank from step 3 to the required shape and size.

[0029] Advantages of this invention compared to existing technologies:

[0030] 1. The alloyed forged high-manganese steel frog of this invention has a significantly finer grain size than that of ordinary high-manganese steel frog, which can be refined to level 3 to 6, thereby reducing the crack propagation rate and improving service life.

[0031] 2. The alloyed forged high-manganese steel turnout of this invention exhibits significantly improved strength and toughness after water quenching treatment: yield strength ≥ 450 MPa, tensile strength ≥ 1100 MPa, elongation ≥ 70%, and impact value (A... KU ≥320J, meeting the usage requirements of high-speed and heavy-haul railways. Attached Figure Description

[0032] Figure 1 is a diagram of the engineering stress-strain curves related to the frog of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to Figure 1. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] A 1100MPa grade alloyed forged high-manganese steel frog, wherein the chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.0-1.3, Mn: 12.0-14.0, Cr: 0.5-6.0, Mo: 0.4-3.0, V: 0.15-0.50, Si: 0.3-0.8, Ni: 0.5-4.0, Al: 0.02-0.05, N: 0.008-0.035, P: ≤0.045, S: ≤0.03, with the remainder being Fe.

[0035] Example 1:

[0036] As a preferred embodiment of an 1100MPa grade alloyed forged high-manganese steel frog, the chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.13, Mn: 12.1, Cr: 0.52, Mo: 0.4, V: 0.35, Si: 0.35, Ni: 0.53, Al: 0.022, N: 0.0085, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0037] Example 2:

[0038] This is a preferred embodiment of an 1100MPa grade alloyed forged high-manganese steel frog: the chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.01, Mn: 13.6, Cr: 5.5, Mo: 2.4, V: 0.48, Si: 0.75, Ni: 3.93, Al: 0.042, N: 0.035, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0039] Example 3:

[0040] This is a preferred embodiment of an 1100MPa grade alloyed forged high-manganese steel frog: the chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.29, Mn: 13.8, Cr: 0.52, Mo: 2.93, V: 0.25, Si: 0.52, Ni: 3.96, Al: 0.035, N: 0.0028, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0041] Example 4:

[0042] This is a preferred embodiment of an 1100MPa grade alloyed forged high-manganese steel frog: the chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.17, Mn: 12.9, Cr: 3.24, Mo: 1.46, V: 0.17, Si: 0.37, Ni: 1.53, Al: 0.026, N: 0.0135, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0043] In any of the above embodiments, the alloyed forged high-manganese steel frog has a yield strength ≥450MPa, tensile strength ≥1100MPa, elongation ≥70%, and impact value (A) KU ≥320J.

[0044] This invention also claims protection for a manufacturing process of 1100MPa grade alloyed forged high-manganese steel frog: the manufacturing process avoids the adverse factors of microalloying by controlling the content of Cr, Mo, V and Ni in high-manganese steel; it improves the strain hardening ability of the alloy by regulating the stacking fault energy of the material through alloy coupling design, thereby improving the tensile strength and elongation of the material; at the same time, it refines the grains based on the Al+N microalloying design concept combined with the subsequent forging manufacturing process, thereby improving the yield strength of the material.

[0045] In the above embodiments, the forging process includes the following steps:

[0046] Step 1: Alloy smelting and billet quality control steps.

[0047] In step 1: steelmaking is carried out in an electric furnace, followed by LF refining and VD degassing. Nitrogen-containing Cr iron is used to increase the N content in the molten steel, while the O content in the molten steel is controlled below 20 ppm. By controlling O, the content of Al2O3 inclusions is reduced, and by increasing N, Al and N are combined to form dispersed AlN particles to refine the grains. Then, the billet is cast into the required size and specifications by ingot casting or continuous casting, and the billet is slowly cooled to room temperature (cooling rate ≤100℃ / hour) to prevent the billet from cracking.

[0048] Step 2: Forging process of the turnout.

[0049] In step 2: the billet is heated to 600℃ at a heating rate of ≤50℃ / hour and held for 2-5 hours, then heated to 1100-1200℃ at a heating rate of ≤200℃ / hour and held for 1-3 hours; the heated billet is then removed from the furnace and forged into a turnout billet with a forging ratio ≥3.5, a final forging temperature ≥900℃, and a forging ratio ≥1.5 within the temperature range of 900-1000℃; the forged billet is then slowly cooled (cooling rate ≤100℃ / hour) to room temperature.

[0050] It should be noted that heating the billet to 1100~1200℃ at a heating rate of ≤200℃ / hour and holding it for 1~3 hours is to ensure that AlN in the billet is fully dissolved, while avoiding overheating; controlling the forging ratio is to ensure material densification and microstructure refinement; and a forging ratio ≥1.5 in the temperature range of 900~1000℃ is to promote deformation-induced AlN dispersion precipitation, thereby achieving microstructure refinement.

[0051] Step 3: Heat treatment of the turnout.

[0052] In step 3: the forging billet obtained in step 2 is heated to 600℃ at a heating rate of ≤100℃ / hour and held for 1 hour, then heated to 950~1100℃ at a heating rate of ≤200℃ / hour and held for 1.5~10 hours before water toughening treatment. The workpiece immersion temperature is ≥900℃, and when the workpiece temperature is ≤400℃, it is removed from the water and naturally cooled to room temperature. The alloying design increases the heat treatment process window, reducing the minimum immersion temperature of the workpiece in the water toughening treatment to 900℃, while increasing the immersion temperature to 400℃, thereby reducing the operational difficulty of the process.

[0053] Step 4: Machining steps for the frog.

[0054] In step 4: the fork blank after heat treatment in step 3 is machined to the required shape and size.

[0055] Preferred embodiments of the forging preparation process of this invention are as follows:

[0056] For the 1100MPa grade alloyed forged high manganese steel frog of Example 1 above, its chemical composition (wt%) is: C: 1.13, Mn: 12.1, Cr: 0.52, Mo: 0.4, V: 0.35, Si: 0.35, Ni: 0.53, Al: 0.022, N: 0.0085, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0057] Preferred embodiment 1 of its forging preparation process:

[0058] Step 1: Alloy smelting and billet quality control steps.

[0059] The steel is produced by electric arc furnace refining and LF refining and VD degassing. The O content in the molten steel is controlled at about 15ppm. The steel is cast into billets by ingot casting and then slowly cooled to room temperature (cooling rate ≤100℃ / hour).

[0060] Step 2: Forging process of the turnout.

[0061] The billet is heated to 600°C at a heating rate of 30°C / hour and held for 5 hours, then heated to 1100°C at a heating rate of 100°C / hour and held for 3 hours. The heated billet is then removed from the furnace and upset, with a total forging ratio greater than 5 and a final forging temperature of 920°C. The forging ratio is 1.5 within the temperature range of 920 to 1000°C. The billet is then slowly cooled (cooling rate ≤ 100°C / hour) to room temperature.

[0062] Step 3: Heat treatment of the turnout.

[0063] The forging billet was heated to 600°C at a heating rate of 100°C / hour and held for 1 hour. Then it was heated to 1000°C at a heating rate of 200°C / hour and held for 3 hours before water toughening treatment. The workpiece was immersed in water at 950°C and exited water at 400°C.

[0064] The heat-treated turnout has a yield strength of 455 MPa, a tensile strength of 1100 MPa, an elongation of 91%, and an impact value (A). KU )331J.

[0065] Step 4: Machining steps for the frog. The frog blank after heat treatment in Step 3 is machined to the required shape and size.

[0066] For the 1100MPa grade alloyed forged high manganese steel frog of Example 2 above, its chemical composition (wt%) is: C: 1.01, Mn: 13.6, Cr: 5.5, Mo: 2.4, V: 0.48, Si: 0.75, Ni: 3.93, Al: 0.042, N: 0.035, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0067] Preferred embodiment 2 of its forging preparation process:

[0068] Step 1: Alloy smelting and billet quality control steps.

[0069] The steel is produced by electric arc furnace refining and LF refining and VD degassing. The O content in the molten steel is controlled at about 12ppm. The steel is cast into billets using continuous casting and then slowly cooled to room temperature (cooling rate ≤100℃ / hour).

[0070] Step 2: Forging process of the turnout.

[0071] The billet is heated to 600°C at a heating rate of 50°C / hour and held for 2 hours, then heated to 1200°C at a heating rate of 80°C / hour and held for 1 hour. The heated billet is then removed from the furnace and upset, with a total forging ratio greater than 3.5 and a final forging temperature of 900°C. The forging ratio is 1.9 within the temperature range of 900°C to 1000°C. The billet is then slowly cooled (cooling rate ≤ 100°C / hour) to room temperature.

[0072] Step 3: Heat treatment of the turnout.

[0073] The forging billet was heated to 600°C at a heating rate of 100°C / hour and held for 1 hour. Then it was heated to 950°C at a heating rate of 150°C / hour and held for 10 hours before water toughening treatment. The workpiece was immersed in water at 921°C and exited water at 334°C.

[0074] The heat-treated turnout has a yield strength of 464 MPa, a tensile strength of 1161 MPa, an elongation of 88%, and an impact value (A). KU )355J.

[0075] Step 4: Machining steps for the frog. The frog blank after heat treatment in Step 3 is machined to the required shape and size.

[0076] For the 1100MPa grade alloyed forged high manganese steel frog of Example 3 above, its chemical composition (wt%) is: C: 1.29, Mn: 13.8, Cr: 0.52, Mo: 2.93, V: 0.25, Si: 0.52, Ni: 3.96, Al: 0.035, N: 0.0028, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0077] Preferred embodiment 3 of its forging preparation process:

[0078] Step 1: Alloy smelting and billet quality control steps.

[0079] Electric furnace steelmaking is adopted, followed by LF refining and VD degassing treatment. The O content in the molten steel is controlled at around 10ppm. The steel is cast into billets by ingot casting and then slowly cooled to room temperature (cooling rate ≤100℃ / hour).

[0080] Step 2: Forging process of the turnout.

[0081] The billet is heated to 600°C at a heating rate of 30°C / hour and held for 4 hours, then heated to 1170°C at a heating rate of 200°C / hour and held for 2 hours. The heated billet is then removed from the furnace and upset. The total forging ratio is greater than 5, the final forging temperature is 912°C, and the forging ratio is 2.1 in the temperature range of 912 to 1000°C. The billet is then slowly cooled (cooling rate ≤ 100°C / hour) to room temperature.

[0082] Step 3: Heat treatment of the turnout.

[0083] The forging billet was heated to 600°C at a heating rate of 80°C / hour and held for 1 hour. Then it was heated to 1070°C at a heating rate of 100°C / hour and held for 2 hours before water toughening treatment. The workpiece was immersed in water at 917°C and exited water at 273°C.

[0084] The heat-treated turnout has a yield strength of 475 MPa, a tensile strength of 1183 MPa, an elongation of 84%, and an impact value (A). KU )329J.

[0085] Step 4: Machining steps for the frog. The frog blank after heat treatment in Step 3 is machined to the required shape and size.

[0086] For the 1100MPa grade alloyed forged high manganese steel frog of Example 4 above, its chemical composition (wt%) is: C: 1.17, Mn: 12.9, Cr: 3.24, Mo: 1.46, V: 0.17, Si: 0.37, Ni: 1.53, Al: 0.026, N: 0.0135, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

[0087] Preferred embodiment 4 of its forging preparation process:

[0088] Step 1: Alloy smelting and billet quality control steps.

[0089] The steel is produced by electric arc furnace refining and LF refining and VD degassing. The O content in the molten steel is controlled at about 19ppm. The steel is cast into billets by ingot casting and then slowly cooled to room temperature (cooling rate ≤100℃ / hour).

[0090] Step 2: Forging process of the turnout.

[0091] The billet is heated to 600°C at a heating rate of 40°C / hour and held for 3 hours, then heated to 1180°C at a heating rate of 150°C / hour and held for 3 hours. The heated billet is then removed from the furnace and upset, with a total forging ratio greater than 5.5 and a final forging temperature of 906°C. The forging ratio is 1.7 within the temperature range of 906°C to 1000°C. The billet is then slowly cooled (cooling rate ≤ 100°C / hour) to room temperature.

[0092] Step 3: Heat treatment of the turnout.

[0093] The forging billet was heated to 600°C at a heating rate of 80°C / hour and held for 1 hour. Then it was heated to 1100°C at a heating rate of 150°C / hour and held for 1.5 hours before water toughening treatment. The workpiece was immersed in water at 943°C and exited water at 322°C.

[0094] The heat-treated turnout has a yield strength of 462 MPa, a tensile strength of 1152 MPa, an elongation of 86%, and an impact value (A). KU )371J.

[0095] Step 4: Machining steps for the frog. The frog blank after heat treatment in Step 3 is machined to the required shape and size.

[0096] The design principle of this invention is as follows: In the alloying design, the roles of Cr, Mo, V and Ni in high manganese steel are fully considered. First, their contents are controlled to avoid the adverse effects of alloying. Then, the stacking fault energy of the material is controlled through alloy coupling design to improve the strain hardening ability of the alloy and enhance the tensile strength and elongation of the material. At the same time, based on the Al+N microalloying design concept and combined with the subsequent controlled forging process, the grains are refined to improve the yield strength of the material.

[0097] In step 1, the alloy smelting and billet quality control process involves electric furnace steelmaking followed by LF refining and VD degassing. Nitrogen-containing Cr iron is used to increase the N content in the molten steel, while the O content is controlled below 20 ppm. The contents of other elements meet the required alloy range. Billets of the required dimensions are cast using ingot casting or continuous casting, and the billets are slowly cooled to room temperature (cooling rate ≤ 100℃ / hour) to prevent cracking. During the smelting process, O, N, and Al are strictly controlled. Controlling O content primarily reduces Al2O3 inclusions, while increasing N content promotes the combination of Al and N to form dispersed AlN particles, thus refining the grain size.

[0098] In the forging process of the turnout in step 2, the temperature is controlled at 1100-1200℃ during the forging heating process. This is to ensure the full dissolution of AlN (aluminum nitride) in the billet while avoiding overheating. Controlling the forging ratio is to ensure material densification and microstructure refinement. Controlling the forging ratio to ≥1.5 within the temperature range of 900-1000℃ is to promote the dispersion precipitation of AlN induced by deformation, thereby achieving microstructure refinement.

[0099] In step 3, the turnout heat treatment process, the alloying design increases the heat treatment process window, reducing the minimum temperature of the workpiece entering the water during water quenching to 900℃, while the water outlet temperature can be increased to 400℃, thus reducing the difficulty of the process implementation.

[0100] Experiments have shown that the grain size of the alloyed forged high-manganese steel frog of this invention is significantly finer than that of ordinary high-manganese steel frogs, with the grain size being refined to level 3-6, thereby reducing the crack propagation rate and improving the service life of the frog.

[0101] The alloyed forged high-manganese steel frog of this invention exhibits significantly improved strength and toughness after water quenching: yield strength ≥ 450 MPa, tensile strength ≥ 1100 MPa, elongation ≥ 70%, and impact value (A... KU ≥320J, meeting the usage requirements of high-speed and heavy-haul railways.

[0102] Referring to Figure 1 in the instruction manual, this figure shows the strain curves of different alloys (Mn13, TWIP-1, TWIP-2, TWIP-3, and TWIP-4) under engineering stress. The curves for each alloy are presented in a different manner to facilitate differentiation of their performance characteristics. The horizontal axis represents the percentage of engineering strain, and the vertical axis represents the stress value. Different colored lines represent the stress-strain relationships of different alloys. By observing the shape and position of these curves, a basic understanding of the mechanical properties of the alloys can be obtained.

[0103] Based on the information in Figure 1, the 1100MPa grade alloyed forged high-manganese steel frog has the following characteristics:

[0104] High strength characteristics: The alloys shown in Figure 1 can maintain a certain strain even under high stress, indicating that they have high strength. As a key component of railway tracks, 1100MPa grade alloyed forged high-manganese steel frogs need to withstand train loads and complex stress environments; therefore, high strength is one of their essential characteristics.

[0105] Good plastic deformation capacity: As shown in Figure 1, the alloy exhibits a certain plastic deformation capacity during strain, meaning that as stress increases, strain gradually increases without immediate material fracture. During service, 1100MPa grade alloyed forged high-manganese steel frogs may be subjected to impacts and compression from train loads. Good plastic deformation capacity helps them absorb energy, alleviate stress concentration, and thus improve service life.

[0106] Excellent wear resistance and impact resistance: Although the data on wear resistance and impact resistance are not directly shown in Figure 1, high manganese steel is renowned for its excellent wear resistance and impact resistance. The 1100MPa grade alloyed forged high manganese steel frogs, through optimization of alloying and forging processes, can further improve their wear resistance and impact resistance, thus making them more suitable for the harsh working environment of railway tracks.

[0107] Possible work hardening effect: During service, high manganese steel may undergo work hardening due to the continuous action of train loads, meaning the material's hardness and strength gradually increase. While the figure does not explicitly show data on the work hardening effect, based on the general characteristics of high manganese steel, 1100MPa grade alloyed forged high manganese steel frogs may exhibit a work hardening effect during long-term use, thereby improving their service life and safety.

[0108] In summary, this invention regulates the stacking fault energy of materials through alloying, thereby controlling the strain hardening behavior of the alloy during deformation and improving the strength and plasticity of the material; at the same time, it utilizes the Al+N microalloying approach and controls the forging process to achieve grain refinement, significantly improving the service life of turnouts.

[0109] Each embodiment in this specification focuses on its differences from other embodiments. Any modifications and equivalent substitutions made within the spirit and principles of this invention are included within the scope of protection of this invention.

Claims

1. A 1100MPa grade alloyed forged high-manganese steel frog is provided, characterized in that: The chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.0-1.3, Mn: 12.0-14.0, Cr: 0.5-6.0, Mo: 0.4-3.0, V: 0.15-0.50, Si: 0.3-0.8, Ni: 0.5-4.0, Al: 0.02-0.05, N: 0.008-0.035, P: ≤0.045, S: ≤0.03, with the remainder being Fe.

2. The 1100MPa grade alloyed forged high-manganese steel fork according to claim 1, characterized in that: The chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.13, Mn: 12.1, Cr: 0.52, Mo: 0.4, V: 0.35, Si: 0.35, Ni: 0.53, Al: 0.022, N: 0.0085, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

3. The 1100MPa grade alloyed forged high-manganese steel frog according to claim 1, characterized in that: The chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.01, Mn: 13.6, Cr: 5.5, Mo: 2.4, V: 0.48, Si: 0.75, Ni: 3.93, Al: 0.042, N: 0.035, P: ≤0.045, S: ≤0.03, with the remainder being Fe.

4. The 1100MPa grade alloyed forged high-manganese steel frog according to claim 1, characterized in that: The chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.29, Mn: 13.8, Cr: 0.52, Mo: 2.93, V: 0.25, Si: 0.52, Ni: 3.96, Al: 0.035, N: 0.0028, P: ≦0.045, S: ≦0.03, with the remainder being Fe.

5. The 1100MPa grade alloyed forged high-manganese steel frog according to claim 1, characterized in that: The chemical composition (wt%) of the alloyed forged high-manganese steel frog is C: 1.17, Mn: 12.9, Cr: 3.24, Mo: 1.46, V: 0.17, Si: 0.37, Ni: 1.53, Al: 0.026, N: 0.0135, P: ≤0.045, S: ≤0.03, with the remainder being Fe.

6. The 1100MPa grade alloyed forged high-manganese steel frog according to claim 1, characterized in that: The alloyed forged high-manganese steel turnout has a yield strength ≥450MPa, tensile strength ≥1100MPa, elongation ≥70%, and impact value (A). KU ≥320J.

7. A manufacturing process for a 1100MPa grade alloyed forged high-manganese steel frog as described in any one of claims 1-6, characterized in that: By controlling the content of Cr, Mo, V and Ni in high manganese steel, the adverse effects of microalloying are avoided; by controlling the stacking fault energy of the material through alloy coupling design, the strain hardening ability of the alloy is improved, thereby enhancing the tensile strength and elongation of the material; at the same time, based on Al+N microalloying combined with forging preparation process, the grains are refined to improve the yield strength of the material.

8. The preparation process according to claim 7, characterized in that: The forging process includes the following steps: Step 1: Alloy smelting and billet quality control steps; Step 2: Forging process of the turnout; Step 3: Heat treatment of the turnout; Step 4: Machining steps for the frog.

9. The preparation process according to claim 8, characterized in that: In step 1: steelmaking is carried out in an electric furnace, followed by LF refining and VD degassing. Nitrogen-containing Cr iron is used to increase the N content in the molten steel, while the O content in the molten steel is controlled below 20 ppm. By controlling O, the content of Al2O3 inclusions is reduced, and by increasing N, Al and N are combined to form dispersed AlN particles to refine the grains. Then, the billet is cast into the required size and specifications by ingot casting or continuous casting, and the billet is slowly cooled to room temperature (cooling rate ≤100℃ / hour) to prevent the billet from cracking.

10. The preparation process according to claim 8, characterized in that: In step 2: the billet is heated to 600℃ at a heating rate of ≤50℃ / hour and held for 2-5 hours, then heated to 1100-1200℃ at a heating rate of ≤200℃ / hour and held for 1-3 hours; the heated billet is then removed from the furnace and forged into a turnout billet with a forging ratio ≥3.5, a final forging temperature ≥900℃, and a forging ratio ≥1.5 within the temperature range of 900-1000℃; the forged billet is then slowly cooled (cooling rate ≤100℃ / hour) to room temperature. Specifically, heating the billet to 1100-1200℃ at a heating rate of ≤200℃ / hour and holding it for 1-3 hours is used to ensure that AlN in the billet is fully dissolved while avoiding overheating; controlling the forging ratio is used to ensure material densification and microstructure refinement; and a forging ratio ≥1.5 in the temperature range of 900-1000℃ is used to promote deformation-induced AlN dispersion precipitation, thereby achieving microstructure refinement.

11. The preparation process according to claim 8, characterized in that: In step 3: the forging billet obtained in step 2 is heated to 600℃ at a heating rate of ≤100℃ / hour and held for 1 hour, then heated to 950~1100℃ at a heating rate of ≤200℃ / hour and held for 1.5~10 hours before water toughening treatment. The workpiece is immersed in water at a temperature ≥900℃, and is removed from the water and allowed to cool naturally to room temperature when the workpiece temperature is ≤400℃. Among them, the alloying design increases the heat treatment process window, reducing the minimum temperature of the workpiece entering the water during water toughening to 900℃, while increasing the water outlet temperature to 400℃, thereby reducing the operational difficulty of the process.

12. The preparation process according to claim 8, characterized in that: In step 4: the fork blank after heat treatment in step 3 is machined to the required shape and size.

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