1100 MPa grade alloying forging high manganese steel frog and preparation process thereof

Abstract

The invention provides a 1100MPa-grade alloyed forged high manganese steel frog and a preparation process thereof. The alloyed forged high manganese steel frog comprises the following chemical components in percentage by weight: 1.0 to 1.3 percent of C, 12.0 to 14.0 percent of Mn, 0.5 to 6.0 percent of Cr, 0.4 to 3.0 percent of Mo, 0.15 to 0.50 percent of V, 0.3 to 0.8 percent of Si, 0.5 to 4.0 percent of Ni, 0.02 to 0.05 percent of Al, 0.008 to 0.035 percent of N, less than or equal to 0.045 percent of P, less than or equal to 0.03 percent of S and the balance of Fe. The stacking fault energy of the material is regulated and controlled through alloying, so that the strain hardening behavior of the alloy in the deformation process is regulated and controlled, and the strong plasticity of the material is improved; and meanwhile, grain refinement is realized by utilizing an Al + N microalloying thought and controlling a forging process. According to the alloying forging high manganese steel frog, the grain size can be refined to 3-6 grades, the yield strength is 450 MPa or above, the tensile strength is 1100 MPa or above, the ductility is 70% or above, the impact energy (Aku) is 320 J or above, the service life is remarkably prolonged, and the use requirements of high-speed and heavy haul railways are met.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical metallurgy, and in particular relates to a 1100MPa grade alloyed forged high manganese steel frog and a preparation process thereof. Background Art

[0002] ZGMn13 has been widely used in the field of railway frog technology, but with the development of modern high-speed and heavy-load railways, traditional high-manganese steel frogs can no longer meet the actual use requirements due to their low strength, which leads to deformation and crushing during use. Therefore, using alloying to improve the mechanical properties of high-manganese steel frogs and thus increase the service life of frogs is an important direction for the development of high-manganese steel for railway frogs.

[0003] Under the existing technology, the United States has invented a Ni, V, Ti microalloyed high manganese steel that uses fine carbon and nitrogen compounds to improve the mechanical properties of frogs, which significantly improves the service life of frogs. The composition (wt%) of this microalloyed high manganese steel is: Mn11.0-24.0, C1.0-1.4, Si≥1, Cr≥1.9, Ni≥0.25, Mo≥1.0, Al≥0.2, Cu≥0.25, impurities P≤0.07, S≤0.06, the addition amount of microalloy Ti, Nb, V is about 0.020-0.070 respectively, N is about 0.001-0.01, and the sum of microalloying elements Ti+Nb+V+N is not less than 0.05% and not more than 0.22%.

[0004] Canada improves the mechanical properties of high manganese steel by adding V to it. The hardness of high manganese steel increases with the increase of V content. The wear resistance is best when the V content is 2%, and its wear resistance is 5 times that of ordinary high manganese steel.

[0005] The composition (wt%) of high manganese steel for frogs according to European standards is: C0.95-1.3, Si≤0.65, Mn11.5-14, Ni≤1.75, Mo≤0.75, Cr≤0.5, Cu≤0.3, Al≤0.045, P≤0.05, S≤0.03, which actually also includes the design concept of alloying.

[0006] Although the increase of alloying elements can significantly improve the yield strength of high manganese steel, the addition of alloying elements will aggravate segregation. More Cr is likely to lead to the formation of network carbides, and carbide-forming elements such as V, Cr, and Mo are also likely to lead to the formation of overheated carbides and undissolved carbides. Therefore, the content of alloying elements must be optimized and controlled.

[0007] Moreover, the existing high manganese steel frogs still have casting defects such as shrinkage cavities and shrinkage porosity, as well as coarse grains. These defects and coarse grains will also have an adverse effect on the service life of the frogs, damage the frog performance, and reduce their service life. Therefore, the use of forging technology to manufacture high manganese steel frogs has become an inevitable choice. However, the forging process window of traditional high manganese steel is relatively small, which makes the process implementation difficult in the actual production process. Therefore, it is of great significance to develop a forged high manganese steel alloy system and its forging process for frogs with a wide process window based on the technical ideas of alloying and microalloying refined organization. In this regard, the following technical scheme is proposed. Summary of the invention

[0008] The technical problem solved by the present invention is to provide a 1100MPa grade alloyed forged high manganese steel frog and a preparation process thereof, and to realize how to develop a forged high manganese steel alloy system for frogs with a wide process window and a forging process thereof based on the technical idea of ​​alloying and microalloying refined organization.

[0009] The technical solution adopted by the present invention is: a 1100MPa grade alloyed forged high manganese steel frog, 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 rest is Fe.

[0010] In the above technical scheme, as a preferred technical scheme: 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, and the rest is Fe.

[0011] In the above technical scheme, as a preferred technical scheme: 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, and the rest 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: 1.29, Mn: 13.8, Cr: 0.52, Mo:

[0013] 2.93, V: 0.25, Si: 0.52, Ni: 3.96, Al: 0.035, N: 0.0028, P: ≦0.045, S: ≦0.03, and the rest is 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: 1.17, Mn: 12.9, Cr: 3.24, Mo:

[0015] 1.46, V: 0.17, Si: 0.37, Ni: 1.53, Al: 0.026, N: 0.0135, P: ≦0.045, S: ≦0.03, and the rest is Fe.

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

[0017] The present invention also requests protection for a preparation process of a 1100MPa grade alloyed forged high manganese steel frog: by controlling the contents of Cr, Mo, V and Ni in high manganese steel, the adverse factors of microalloying are avoided; by regulating 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; at the same time, based on Al+N microalloying combined with forging preparation technology, the grains are refined to improve the yield strength of the material.

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

[0019] Step 1, alloy smelting and ingot quality control steps;

[0020] Step 2, frog forging process step;

[0021] Step 3, a heat treatment step of the frog;

[0022] Step 4: Machining step of frog.

[0023] In the above technical scheme, in step 1: steelmaking is carried out in an electric furnace 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 20 ppm; the Al2O3 inclusion content is reduced by controlling O, and Al and N are promoted to combine to form dispersed AlN particles to refine the grains by increasing N; then, mold casting or continuous casting is used to cast the ingot of the required size, and the ingot is slowly cooled to room temperature (cooling rate ≤ 100°C / hour) to prevent the ingot from cracking.

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

[0025] Among them, the ingot is heated to 1100-1200°C at a heating rate of ≤200°C / hour and kept warm for 1-3 hours to ensure that AlN in the ingot is fully dissolved while avoiding overburning; the forging ratio is controlled to ensure material densification and microstructure refinement; within the temperature range of 900-1000°C, the forging ratio ≥1.5 is used to promote deformation-induced AlN dispersion and precipitation, thereby achieving microstructure refinement.

[0026] In the above technical scheme, in step 3: the forging blank obtained in step 2 is heated to 600°C at a heating rate of ≤100°C / hour and kept warm for 1 hour, and then heated to 950-1100°C at a heating rate of ≤200°C / hour and kept warm for 1.5-10 hours, and then water toughening treatment is performed, the workpiece entering water temperature is ≥900°C, and when the workpiece temperature is ≤400°C, the water is removed and the workpiece is 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 water during water toughening to 900°C, and at the same time increasing the water outlet temperature to 400°C, which is used to reduce the operational difficulty of the process implementation process.

[0028] In the above technical solution, in step 4: the frog blank after the heat treatment in step 3 is machined into a desired shape and size.

[0029] The advantages of the present invention compared with the prior art are:

[0030] 1. The grain size of the alloyed forged high manganese steel frog of the present invention is significantly finer than that of the ordinary high manganese steel frog, and can be refined to level 3 to 6, which can reduce the crack growth rate and increase the service life.

[0031] 2. The toughness of the alloyed forged high manganese steel frog of the present invention can be significantly improved after water toughening treatment: yield strength ≥ 450MPa, tensile strength ≥ 1100MPa, elongation ≥ 70%, impact value (A KU )≥320J, meeting the use requirements of high-speed and heavy-load railways. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The figure is an engineering stress-strain curve diagram related to the frog of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the attached embodiment of the present invention Figure 1 , the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0034] The invention discloses a 1100MPa grade alloyed forged high manganese steel frog. 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 rest is Fe.

[0035] Embodiment 1:

[0036] That is, as a preferred embodiment of a 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, and the rest is Fe.

[0037] Embodiment 2:

[0038] That is, as a preferred embodiment of a 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, and the rest is Fe.

[0039] Embodiment 3:

[0040] That is, as a preferred embodiment of a 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, and the rest is Fe.

[0041] Embodiment 4:

[0042] That is, as a preferred embodiment of a 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, and the rest is Fe.

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

[0044] The present invention also requests protection for a preparation process of a 1100MPa grade alloyed forged high manganese steel frog: the preparation process avoids the adverse factors of microalloying by controlling the contents of Cr, Mo, V and Ni in high manganese steel; regulates 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 at the same time, based on the Al+N microalloying design concept combined with the subsequent forging preparation process to refine the grains, thereby improving the yield strength of the material.

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

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

[0047] In step 1: steel is smelted in an electric furnace and subjected to LF refining and VD degassing treatment, 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 20 ppm; the Al2O3 inclusion content is reduced by controlling O, and Al and N are promoted to combine to form dispersed AlN particles to refine the grains by increasing N; then, a billet of the required size is cast by die casting or continuous casting, and the billet is slowly cooled to room temperature (cooling rate ≤ 100°C / hour) to prevent the billet from cracking.

[0048] Step 2: Forging process of frog.

[0049] In step 2: the ingot is heated to 600°C at a heating rate of ≤50°C / hour and kept warm for 2-5 hours, and then heated to 1100-1200°C at a heating rate of ≤200°C / hour and kept warm for 1-3 hours; then the heated ingot is taken out of the furnace and forged into a frog blank, the forging ratio is ≥3.5, the final forging temperature is ≥900°C, and the forging ratio is ≥1.5 in the temperature range of 900-1000°C, and then the forging blank is slowly cooled (cooling rate ≤100°C / hour) to room temperature.

[0050] Among them: It should be noted that the ingot is heated to 1100-1200°C at a heating rate of ≤200°C / hour and kept warm for 1-3 hours to ensure that AlN in the ingot is fully dissolved while avoiding overburning; the forging ratio is controlled to ensure material densification and microstructure refinement; within the temperature range of 900-1000°C, the forging ratio ≥1.5 is used to promote deformation-induced AlN dispersion and precipitation, thereby achieving microstructure refinement.

[0051] Step 3: Heat treatment step of frog.

[0052] In step 3: the forging blank obtained in step 2 is heated to 600°C at a heating rate of ≤100°C / hour and kept warm for 1 hour, and then heated to 950-1100°C at a heating rate of ≤200°C / hour and kept warm for 1.5-10 hours, and then water toughening is performed, and the workpiece entering water temperature is ≥900°C, and the workpiece is removed from the water when the temperature is ≤400°C and naturally cooled to room temperature; wherein, the alloying design increases the heat treatment process window, reduces the minimum temperature of the workpiece entering water during water toughening to 900°C, and at the same time increases the water outlet temperature to 400°C, so as to reduce the operational difficulty of the process implementation process.

[0053] Step 4: Machining step of frog.

[0054] In step 4, the frog blank after the heat treatment in step 3 is machined to a desired shape and size.

[0055] The specific preferred embodiment of the forging preparation process of the present invention is as follows:

[0056] For the 1100MPa grade alloyed forged high manganese steel frog of the aforementioned embodiment 1, 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, and the rest is Fe.

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

[0058] Step 1: Alloy smelting and ingot quality control step.

[0059] The steel is smelted in an electric furnace and subjected to LF refining and VD degassing treatment. The O content in the molten steel is controlled at about 15 ppm. The steel is cast into ingots by die casting, and the ingots are slowly cooled to room temperature (cooling rate ≤ 100°C / hour).

[0060] Step 2: Forging process of frog.

[0061] The ingot is heated to 600°C at a heating rate of 30°C / hour and kept at this temperature for 5 hours, and then heated to 1100°C at a heating rate of 100°C / hour and kept at this temperature for 3 hours; the heated ingot is then taken out of the furnace for upsetting, the total forging ratio is greater than 5, the final forging temperature is 920°C, the forging ratio is 1.5 within the temperature range of 920-1000°C, and then the ingot is slowly cooled (cooling rate ≤100°C / hour) to room temperature.

[0062] Step 3: Heat treatment step of frog.

[0063] The forging blank was heated to 600°C at a heating rate of 100°C / hour and kept warm for 1 hour, and then heated to 1000°C at a heating rate of 200°C / hour and kept warm for 3 hours, and then water toughening was performed. The workpiece entering water temperature was 950°C, and the workpiece exiting water temperature was 400°C.

[0064] The heat-treated frog 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 step of the frog, machining the frog blank after the heat treatment in step 3 to the required shape and size.

[0066] For a 1100MPa grade alloyed forged high manganese steel frog of the aforementioned embodiment 2, 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, and the rest is Fe.

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

[0068] Step 1: Alloy smelting and ingot quality control step.

[0069] The steel is smelted in an electric furnace and subjected to LF refining and VD degassing treatment. The O content in the molten steel is controlled at about 12ppm. The molten steel is cast into ingots by a continuous casting process, and the ingots are slowly cooled to room temperature (cooling rate ≤ 100°C / hour).

[0070] Step 2: Forging process of frog.

[0071] The ingot is heated to 600°C at a heating rate of 50°C / hour and kept warm for 2 hours, and then heated to 1200°C at a heating rate of 80°C / hour and kept warm for 1 hour; the heated ingot is then taken out of the furnace for upsetting, the total forging ratio is greater than 3.5, the final forging temperature is 900°C, the forging ratio is 1.9 in the temperature range of 900°C to 1000°C, and then the ingot is slowly cooled (cooling rate ≤100°C / hour) to room temperature.

[0072] Step 3: Heat treatment step of frog.

[0073] The forging blank was heated to 600°C at a heating rate of 100°C / hour and kept warm for 1 hour, and then heated to 950°C at a heating rate of 150°C / hour and kept warm for 10 hours, and then water toughening was performed. The workpiece entering water temperature was 921°C, and the workpiece exiting water temperature was 334°C.

[0074] The heat-treated frog 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 step of the frog, machining the frog blank after the heat treatment in step 3 to the required shape and size.

[0076] For the 1100MPa grade alloyed forged high manganese steel frog of the aforementioned embodiment 3, 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, and the rest is Fe.

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

[0078] Step 1: Alloy smelting and ingot quality control step.

[0079] The steel is smelted in an electric furnace and subjected to LF refining and VD degassing treatment. The O content in the molten steel is controlled at about 10 ppm. The steel is cast into ingots by die casting, and the ingots are slowly cooled to room temperature (cooling rate ≤ 100°C / hour).

[0080] Step 2: Forging process of frog.

[0081] The ingot is heated to 600°C at a heating rate of 30°C / hour and kept at this temperature for 4 hours, and then heated to 1170°C at a heating rate of 200°C / hour and kept at this temperature for 2 hours; the heated ingot is then taken out of the furnace for upsetting, the total forging ratio is greater than 5, the final forging temperature is 912°C, the forging ratio is 2.1 within the temperature range of 912-1000°C, and then the ingot is slowly cooled (cooling rate ≤100°C / hour) to room temperature.

[0082] Step 3: Heat treatment step of frog.

[0083] The forging blank was heated to 600°C at a heating rate of 80°C / hour and kept warm for 1 hour, and then heated to 1070°C at a heating rate of 100°C / hour and kept warm for 2 hours, and then water toughening was performed. The workpiece entering water temperature was 917°C, and the workpiece exiting water temperature was 273°C.

[0084] The heat-treated frog 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 step of the frog, machining the frog blank after the heat treatment in step 3 to the required shape and size.

[0086] For the 1100MPa grade alloyed forged high manganese steel frog of the aforementioned embodiment 4, 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, and the rest is Fe.

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

[0088] Step 1: Alloy smelting and ingot quality control step.

[0089] The steel is smelted in an electric furnace and subjected to LF refining and VD degassing treatment. The O content in the molten steel is controlled at about 19 ppm. The steel is cast into ingots by die casting, and the ingots are slowly cooled to room temperature (cooling rate ≤ 100°C / hour).

[0090] Step 2: Forging process of frog.

[0091] The ingot is heated to 600°C at a heating rate of 40°C / hour and kept at this temperature for 3 hours, and then heated to 1180°C at a heating rate of 150°C / hour and kept at this temperature for 3 hours; the heated ingot is then taken out of the furnace for upsetting, the total forging ratio is greater than 5.5, the final forging temperature is 906°C, the forging ratio is 1.7 within the temperature range of 906-1000°C, and then the ingot is slowly cooled (cooling rate ≤100°C / hour) to room temperature.

[0092] Step 3: Heat treatment step of frog.

[0093] The forging blank was heated to 600°C at a heating rate of 80°C / hour and kept warm for 1 hour, and then heated to 1100°C at a heating rate of 150°C / hour and kept warm for 1.5 hours, and then water toughening was performed. The workpiece entering water temperature was 943°C, and the workpiece exiting water temperature was 322°C.

[0094] The heat-treated frog 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 step of the frog, machining the frog blank after the heat treatment in step 3 to the required shape and size.

[0096] The design principle of the present invention is as follows: the effects of Cr, Mo, V and Ni in high manganese steel are fully considered in the alloying design. First, their contents are controlled to avoid the adverse effects of alloying, and the stacking fault energy of the material is regulated through alloy coupling design to improve the strain hardening ability of the alloy, thereby improving 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 the alloy smelting and ingot quality control step of step 1, electric furnace steelmaking is used and LF refining and VD degassing are performed, nitrogen-containing Cr iron is used to increase the N content in the molten steel, the O content in the molten steel is controlled below 20ppm, and the content of other elements meets the required alloy range; mold casting or continuous casting is used to cast the ingot of the required size, and the ingot is slowly cooled to room temperature (cooling rate ≤ 100°C / hour) to prevent the ingot from cracking. O, N and Al are strictly controlled during the smelting process, and the O content is mainly controlled to reduce the Al2O3 inclusion content, and the N increase is mainly to promote the combination of Al and N to form dispersed AlN particles to refine the grains.

[0098] In the forging process of the frog in step 2, the temperature is controlled at 1100-1200°C during the forging heating process, on the one hand, to ensure the full dissolution of AlN (aluminum nitride) in the ingot, while avoiding overburning; the forging ratio is controlled to ensure material densification and microstructure refinement, and the forging ratio is controlled to be ≥1.5 in the temperature range of 900-1000°C to promote the dispersion and precipitation of deformation-induced AlN to achieve microstructure refinement.

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

[0100] Through experiments, it is found that the grain size of the alloyed forged high manganese steel frog of the present invention is significantly finer than that of the ordinary high manganese steel frog, and the grain size can be refined to level 3 to 6, thereby reducing the crack growth rate and increasing the service life of the frog.

[0101] The alloyed forged high manganese steel frog of the present invention can significantly improve its toughness after water toughening treatment: yield strength ≥450MPa, tensile strength ≥1100MPa, elongation ≥70%, impact value (A KU )≥320J, meeting the use requirements of high-speed and heavy-load railways.

[0102] In conjunction with the instruction manual Figure 1 , which 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 way to distinguish the performance differences between them. The horizontal axis in the figure represents the engineering strain percentage and the vertical axis represents the stress value. The lines of different colors represent the stress-strain relationship of different alloys. By observing the shape and position of these curves, we can have a basic understanding of the mechanical properties of the alloy.

[0103] Combination Figure 1 According to the information, 1100MPa grade alloyed forged high manganese steel frog has the following characteristics:

[0104] High strength properties: Figure 1 The alloys shown in the figure can still maintain a certain strain under higher stress, which shows that they have higher 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, so high strength is one of their essential characteristics.

[0105] Good plastic deformation ability: from Figure 1It can be seen that the alloy exhibits a certain plastic deformation ability during the strain process, that is, as the stress increases, the strain gradually increases, but the material does not break immediately. During the service process, the 1100MPa grade alloyed forged high manganese steel frog may be impacted and squeezed by train loads. Good plastic deformation ability helps it absorb energy and relieve stress concentration, thereby increasing its service life.

[0106] Excellent wear and impact resistance: Although Figure 1 The data on wear resistance and impact resistance are not directly shown in the report, but high manganese steel is famous for its excellent wear resistance and impact resistance. The wear resistance and impact resistance of 1100MPa grade alloyed forged high manganese steel frog can be further improved through the optimization of alloying and forging processes, making it more suitable for the harsh working environment of railway tracks.

[0107] Possible work hardening effect: During the service life of high manganese steel, work hardening may occur due to the continuous action of train loads, that is, the hardness and strength of the material gradually increase. The data of work hardening effect is not clearly shown in the figure, but according to the general characteristics of high manganese steel, 1100MPa grade alloyed forged high manganese steel frogs may show work hardening effect during long-term use, thereby improving their service life and safety.

[0108] In summary, the present invention regulates the stacking fault energy of the material through alloying, thereby regulating the strain hardening behavior of the alloy during deformation and improving the strength and plasticity of the material; at the same time, the Al+N microalloying idea is used and the forging process is controlled to achieve grain refinement, thereby significantly improving the service life of the frog.

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

Claims

1. A 1100MPa grade alloyed forged high manganese steel frog, 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, and the rest is Fe.

2. 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: 1.13, 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, and the rest is 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, and the rest is 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, and the rest is 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, and the rest is Fe.

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

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

8. The preparation process according to claim 6, characterized in that: The forging preparation process comprises the following steps: Step 1, alloy smelting and ingot quality control step; Step 2, frog forging process step; Step 3, a heat treatment step of the frog; Step 4: Machining step of frog.

9. The preparation process according to claim 8, characterized in that: In step 1: steel is smelted in an electric furnace and subjected to LF refining and VD degassing treatment, 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 20 ppm; the Al2O3 inclusion content is reduced by controlling O, and Al and N are promoted to combine to form dispersed AlN particles to refine the grains by increasing N; then, a billet of the required size is cast by die casting or continuous casting, and the billet is slowly cooled to room temperature (cooling rate ≤ 100°C / hour) to prevent the billet from cracking.

10. The preparation process according to claim 8, characterized in that: In step 2: the ingot is heated to 600° C. at a heating rate of ≤50° C. / hour and kept at this temperature for 2 to 5 hours, and then heated to 1100 to 1200° C. at a heating rate of ≤200° C. / hour and kept at this temperature for 1 to 3 hours; then the heated ingot is taken out of the furnace and forged into a frog blank, the forging ratio is ≥3.5, the final forging temperature is ≥900° C., and the forging ratio is ≥1.5 within the temperature range of 900 to 1000° C., and then the forging blank is slowly cooled (cooling rate ≤100° C. / hour) to room temperature; Among them, the ingot is heated to 1100-1200°C at a heating rate of ≤200°C / hour and kept warm for 1-3 hours to ensure that AlN in the ingot is fully dissolved while avoiding overburning; the forging ratio is controlled to ensure material densification and microstructure refinement; within the temperature range of 900-1000°C, the forging ratio ≥1.5 is used to promote deformation-induced AlN dispersion and precipitation, thereby achieving microstructure refinement.

11. The preparation process according to claim 8, characterized in that: In step 3: the forging blank obtained in step 2 is heated to 600°C at a heating rate of ≤100°C / hour and kept at that temperature for 1 hour, and then heated to 950-1100°C at a heating rate of ≤200°C / hour and kept at that temperature for 1.5-10 hours, and then subjected to water toughening treatment, the workpiece entering water temperature is ≥900°C, and when the workpiece temperature is ≤400°C, the water is removed and the workpiece is naturally cooled to room temperature; Among them, the alloying design increases the heat treatment process window, reducing the minimum temperature of the workpiece entering water during water toughening to 900°C, and at the same time increasing the water outlet temperature to 400°C, which is used to reduce the operational difficulty of the process implementation process.

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

Images