A hot-rolled medium manganese steel with excellent high-temperature mechanical properties and its preparation method

Abstract

The present invention belongs to the technical field of heat treatment of metal materials and relates to a hot-rolled medium manganese steel with excellent high-temperature mechanical properties and a preparation method thereof. The hot-rolled medium manganese steel with excellent high-temperature mechanical properties is prepared by adopting a homogenization annealing, rough hot rolling, fine hot rolling and ferrite phase transformation coupling process. The yield strength of the hot-rolled medium manganese steel at 500°C is 430-670 MPa, the tensile strength is 590-750 MPa, and the elongation after fracture is 25-28%. This overcomes the problem of "insufficient high-temperature strength" of medium manganese steel, achieves a good match between strength and plasticity of medium manganese steel for high-temperature environments, and broadens its application field.

Description

Technical Field

[0001] The present invention relates to the technical field of heat treatment of metal materials, in particular to a hot-rolled medium manganese steel with excellent high-temperature mechanical properties and a preparation method thereof. Background Art

[0002] Medium-manganese steel, with its low price and excellent room-temperature mechanical properties, is highly anticipated in the aviation, navigation, energy, and transportation sectors. However, its poor high-temperature mechanical properties make it difficult to meet the demands of some components used in high-temperature environments. Microstructure control is a crucial scientific foundation for the development of advanced metal materials. To this end, methods such as grain boundary engineering, gradient microstructure, dislocation engineering, complex phase transformation, heterogeneous structure, multiphase microstructure, and precipitation phase control have been widely applied to microstructure control of medium-manganese steel. However, high temperatures can cause grain growth, coarsening of precipitation particles, and reduced austenite stability, thereby deteriorating its high-temperature mechanical properties. These factors have led to the production of high-strength medium-manganese steel using a multi-step microstructure control strategy, such as hot / cold / warm rolling combined with quenching-partitioning, quenching-partitioning-tempering, and quenching-partitioning-annealing-tempering. These complex and lengthy thermomechanical coupling processes make it difficult to significantly increase strength and are unsuitable for industrial production. Therefore, optimizing existing hot working processes for medium-manganese steel to address these microstructure control challenges is urgent. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a hot-rolled medium manganese steel with excellent high-temperature mechanical properties and a preparation method thereof.

[0004] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0005] A method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties comprises the following steps:

[0006] S1. Homogenization annealing: The medium manganese steel ingot is subjected to homogenization annealing to obtain an annealed ingot;

[0007] S2. Rough hot rolling: The annealed ingot is subjected to rough hot rolling, and then water-cooled to room temperature to obtain a rough hot-rolled plate;

[0008] S3, finishing hot rolling: the rough hot rolled plate is put into the furnace after reaching the temperature and kept warm, and then subjected to finishing hot rolling and air cooling to room temperature to obtain the finishing hot rolled plate;

[0009] S4. Ferrite phase transformation process: The hot-rolled plate is put into the furnace at the required temperature and then kept warm. After the ferrite phase transformation process, it is air-cooled to room temperature to obtain hot-rolled medium manganese steel with excellent high-temperature mechanical properties.

[0010] As a preferred embodiment of the method for preparing a hot-rolled medium manganese steel with excellent high-temperature mechanical properties described in the present invention, the hot-rolled medium manganese steel with excellent high-temperature mechanical properties comprises, by mass percentage, C: 0.35-0.50%, Mn: 9.5-11.0%, Al: 2.0-3.0%, V: 0.5-0.7%, and the balance being Fe and unavoidable impurities.

[0011] As a preferred embodiment of the method for preparing a hot-rolled medium manganese steel with excellent high-temperature mechanical properties according to the present invention, the method further comprises, before step S1, S0, melting the medium manganese steel ingot: preparing ingredients according to the composition of the medium manganese steel, and adding the ingredients to the furnace cavity of a vacuum induction melting furnace in the order of the melting points of the elements from low to high, at a melting temperature of 1400-1500°C. After the melting is completed, the ingot is cast in a mold and air-cooled to room temperature.

[0012] As a preferred embodiment of the method for preparing a hot-rolled medium manganese steel with excellent high-temperature mechanical properties according to the present invention, in step S1, the homogenization annealing temperature is 1100-1150°C, the annealing time is 2-4 hours, and the cooling method is air cooling.

[0013] As a preferred embodiment of the method for preparing a hot-rolled medium manganese steel with excellent high-temperature mechanical properties described in the present invention, in which: in the step S2, the rough hot rolling is divided into 3 to 4 passes, the total deformation of the rough hot rolling is 65 to 75%, the starting rolling temperature is 1000 to 1050°C, and the finishing rolling temperature is 950 to 1000°C.

[0014] As a preferred embodiment of the method for preparing a hot-rolled medium manganese steel with excellent high-temperature mechanical properties described in the present invention, wherein: in the step S3, the holding temperature is 640-660°C, and the holding time is 10-60 minutes; the finishing hot rolling is divided into 1-3 passes, and the total deformation of the finishing hot rolling is 40-50%; and the final rolling temperature is 580-600°C.

[0015] As a preferred embodiment of the method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties according to the present invention, in step S4, the holding temperature is 490-510° C. and the holding time is 10-30 min.

[0016] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0017] A hot-rolled medium manganese steel with excellent high-temperature mechanical properties is prepared by adopting the above-mentioned preparation method of the hot-rolled medium manganese steel with excellent high-temperature mechanical properties.

[0018] As a preferred embodiment of the hot-rolled medium manganese steel with excellent high-temperature mechanical properties described in the present invention, the hot-rolled medium manganese steel has a yield strength of 430-670 MPa, a tensile strength of 590-750 MPa, and an elongation after fracture of 25-28% under high-temperature deformation conditions of 500°C.

[0019] As a preferred embodiment of the hot-rolled medium manganese steel with excellent high-temperature mechanical properties described in the present invention, the matrix structure of the hot-rolled medium manganese steel with excellent high-temperature mechanical properties includes 45-56 vol% austenite and 44-55 vol% ferrite / martensite, and the precipitated phase includes nano-cementite and vanadium carbide particles.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention proposes a hot-rolled medium-manganese steel with excellent high-temperature mechanical properties and a preparation method thereof. The hot-rolled medium-manganese steel with excellent high-temperature mechanical properties is prepared by adopting a homogenization annealing, rough hot rolling, fine hot rolling, and ferrite phase transformation coupling process. The yield strength of the hot-rolled medium-manganese steel at 500°C is 430-670 MPa, the tensile strength is 590-750 MPa, and the elongation after fracture is 25-28%. This overcomes the problem of "insufficient high-temperature strength" of medium-manganese steel, achieves a good match between strength and plasticity of medium-manganese steel for high-temperature environments, and broadens its application field. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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 ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 These are the SEM and TEM images of the hot-rolled medium manganese steel according to Example 1 of the present invention.

[0024] Figure 2 These are the SEM and TEM images of the hot-rolled medium manganese steel according to Example 2 of the present invention.

[0025] Figure 3 These are the SEM and TEM images of the hot-rolled medium manganese steel according to Example 3 of the present invention.

[0026] Figure 4 This is the SEM image of the hot-rolled medium manganese steel of Comparative Example 1 of the present invention.

[0027] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0028] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described 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 making any creative efforts are within the scope of protection of the present invention.

[0029] Given the complex multiphase microstructure of medium-manganese steel, this invention replaces the traditional rolling and annealing process with dual-phase rolling, refining the microstructure while producing a sufficient volume fraction of austenite. Subsequently, a ferrite transformation process replaces the traditional tempering process. This accelerates the decomposition of unstable austenite to form fine-grained ferrite and nano-cementite particles. Simultaneously, the lower ferrite phase temperature promotes the precipitation of nano-vanadium carbides while retaining a high density of dislocations, resulting in a stable austenite, fine-grained ferrite, and a high-density nano-sized dual-precipitate (cementite and vanadium carbide) particles. This simplified multiphase microstructure can effectively control grain growth, precipitate coarsening, and reduced austenite stability, potentially overcoming the bottleneck of medium-manganese steel's "inadequate high-temperature strength" and holding significant significance for its future development.

[0030] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0031] A method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties comprises the following steps:

[0032] S1. Homogenization annealing: The medium manganese steel ingot is subjected to homogenization annealing to obtain an annealed ingot;

[0033] S2. Rough hot rolling: The annealed ingot is subjected to rough hot rolling, and then water-cooled to room temperature to obtain a rough hot-rolled plate;

[0034] S3, finishing hot rolling: the rough hot rolled plate is put into the furnace after reaching the temperature and kept warm, and then subjected to finishing hot rolling and air cooling to room temperature to obtain the finishing hot rolled plate;

[0035] S4. Ferrite phase transformation process: The hot-rolled plate is put into the furnace at the required temperature and then kept warm. After the ferrite phase transformation process, it is air-cooled to room temperature to obtain hot-rolled medium manganese steel with excellent high-temperature mechanical properties.

[0036] Preferably, the hot-rolled medium manganese steel with excellent high-temperature mechanical properties comprises, by mass percentage, the following: C: 0.35-0.50%, Mn: 9.5-11.0%, Al: 2.0-3.0%, V: 0.5-0.7%, and the balance being Fe and unavoidable impurities.

[0037] Preferably, before step S1, the step further includes: S0, melting a medium manganese steel ingot: preparing ingredients according to the composition of the medium manganese steel, adding the ingredients to the vacuum induction melting furnace in ascending order of melting point, at a melting temperature of 1400-1500°C. After melting, the ingot is cast into a mold and air-cooled to room temperature. Specifically, the melting temperature can be, for example, any one of 1400°C, 1420°C, 1440°C, 1460°C, 1480°C, and 1500°C, or a range between any two of them.

[0038] Preferably, in step S1, the homogenization annealing temperature is 1100-1150°C, the annealing time is 2-4 hours, and the cooling method is air cooling. Specifically, the homogenization annealing temperature can be, for example, any one of 1100°C, 1110°C, 1120°C, 1130°C, 1140°C, and 1150°C, or a range between any two thereof; and the annealing time can be, for example, any one of 2 hours, 3 hours, and 4 hours, or a range between any two thereof.

[0039] Preferably, in step S2, the rough hot rolling is divided into 3 to 4 passes, the total deformation of the rough hot rolling is 65 to 75%, the starting rolling temperature is 1000 to 1050°C, and the finishing rolling temperature is 950 to 1000°C. Specifically, the total deformation of the hot rolling can be, for example, any one of 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, or a range between any two of them; the starting rolling temperature can be, for example, any one of 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, or a range between any two of them; and the finishing rolling temperature can be, for example, any one of 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, or a range between any two of them.

[0040] Preferably, in step S3, the holding temperature is 640-660°C, the holding time is 10-60 minutes, the finishing hot rolling is divided into 1-3 passes, the total deformation of the finishing hot rolling is 40-50%, and the final rolling temperature is 580-600°C. Specifically, the finishing hot rolling holding temperature can be, for example, any one of 640°C, 645°C, 650°C, 655°C, and 660°C, or a range between any two thereof; the finishing hot rolling holding time can be, for example, any one of 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, and 60 minutes, or a range between any two thereof; the total deformation of the finishing hot rolling can be, for example, any one of 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, and 50%, or a range between any two thereof; and the final rolling temperature can be, for example, any one of 580°C, 585°C, 590°C, 595°C, and 600°C, or a range between any two thereof.

[0041] Preferably, in step S4, the holding temperature is 490-510°C, and the holding time is 10-30 minutes. Specifically, the holding temperature can be, for example, any one of 490°C, 495°C, 500°C, 505°C, and 510°C, or a range between any two thereof; and the holding time can be, for example, any one of 10 minutes, 15 minutes, 20 minutes, 25 minutes, and 30 minutes, or a range between any two thereof.

[0042] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0043] A hot-rolled medium manganese steel with excellent high-temperature mechanical properties is prepared using the above-mentioned method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties. The hot-rolled medium manganese steel with excellent high-temperature mechanical properties has a yield strength of 430-670 MPa, a tensile strength of 590-750 MPa, and an elongation after fracture of 25-28% under high-temperature deformation conditions of 500°C.

[0044] Preferably, the matrix structure of the hot-rolled medium manganese steel with excellent high-temperature mechanical properties includes 45-56 vol% austenite and 44-55 vol% ferrite / martensite, and the precipitated phase includes nano-cementite and vanadium carbide particles.

[0045] The technical solution of the present invention is further described below with reference to specific embodiments.

[0046] The medium manganese steel used in the comparative examples of each embodiment was prepared by the following method: the ingredients were prepared according to the composition of the medium manganese steel, and the ingredients were added to the vacuum induction melting furnace cavity in the order of the melting points of the elements from low to high. The melting temperature was 1400~1500℃. After the melting was completed, the ingot was cast in a mold and air-cooled to room temperature.

[0047] The chemical composition of medium manganese steel ingots is shown in Table 1.

[0048] Table 1 Chemical composition of medium manganese steel ingots in various examples (mass percentage)

[0049]

[0050] The high-temperature tensile test conditions of the medium manganese steel prepared in each embodiment and comparative example are as follows: the hot-rolled medium manganese steel is rapidly heated to the deformation temperature in an electronic universal tensile testing machine equipped with a heating device, and then subjected to high-temperature tensile deformation: the deformation temperature is 500°C, the holding time is 10 min, the heating rate is 20°C / s, and the deformation rate is 0.5 mm / min.

[0051] Example 1

[0052] A method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties comprises the following steps:

[0053] S1. Homogenization annealing: The medium manganese steel ingot is subjected to homogenization annealing to obtain an annealed ingot; the homogenization annealing temperature is 1130°C, the annealing time is 3 hours, and the cooling method is air cooling;

[0054] S2. Rough hot rolling: The annealed ingot is subjected to rough hot rolling, and then water-cooled to room temperature to obtain a rough hot rolled plate; the starting rolling temperature is 1020°C, and the finishing rolling temperature is 980°C; the rough hot rolling is divided into 4 passes, and the total deformation of the rough hot rolling is 70%;

[0055] S3, finishing hot rolling: the rough hot rolled plate is put into the furnace to be kept warm, and then the finishing hot rolled plate is air-cooled to room temperature after finishing hot rolling; the holding temperature is 650℃, and the holding time is 60min; the finishing hot rolling is divided into 2 passes, and the total deformation of the finishing hot rolling is 50%; the final rolling temperature is 590℃;

[0056] S4. Ferrite phase transformation process: The hot-rolled plate is kept warm by being put into the furnace after reaching the temperature. The holding temperature is 500℃ and the holding time is 30 minutes. The ferrite phase transformation process is then carried out and the plate is air-cooled to room temperature to obtain a hot-rolled medium manganese steel with excellent high-temperature mechanical properties.

[0057] The microstructure of the hot-rolled medium manganese steel prepared in this embodiment is as follows: Figure 1 As shown ( Figure 1 The middle left picture is the SEM picture. Figure 1 The middle right figure is a TEM image). Its matrix structure includes 56 vol% austenite and 44 vol% ferrite / martensite, as well as high-density nano-cementite and vanadium carbide particles. The hot-rolled medium-manganese steel prepared in this example has a yield strength of 670 MPa, a tensile strength of 736 MPa, and an elongation at break of 27% under high-temperature deformation conditions of 500°C.

[0058] Example 2

[0059] A method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties comprises the following steps:

[0060] S1. Homogenization annealing: The medium manganese steel ingot is subjected to homogenization annealing to obtain an annealed ingot; the homogenization annealing temperature is 1130°C, the annealing time is 3 hours, and the cooling method is air cooling;

[0061] S2. Rough hot rolling: The annealed ingot is subjected to rough hot rolling, and then water-cooled to room temperature to obtain a rough hot rolled plate; the starting rolling temperature is 1020°C, and the finishing rolling temperature is 980°C; the rough hot rolling is divided into 4 passes, and the total deformation of the rough hot rolling is 70%;

[0062] S3, finishing hot rolling: the rough hot rolled plate is put into the furnace to be kept warm, and then the finishing hot rolled plate is air-cooled to room temperature after finishing hot rolling; the holding temperature is 650℃, and the holding time is 30min; the finishing hot rolling is divided into 2 passes, and the total deformation of the finishing hot rolling is 50%; the final rolling temperature is 590℃;

[0063] S4. Ferrite phase transformation process: The hot-rolled plate is kept warm by being put into the furnace after reaching the temperature. The holding temperature is 500℃ and the holding time is 30 minutes. The ferrite phase transformation process is then carried out and the plate is air-cooled to room temperature to obtain a hot-rolled medium manganese steel with excellent high-temperature mechanical properties.

[0064] The microstructure of the hot-rolled medium manganese steel prepared in this embodiment is as follows: Figure 2 As shown ( Figure 2 The middle left picture is the SEM picture. Figure 2 The middle right figure is a TEM image). Its matrix structure includes 52 vol% austenite and 48 vol% ferrite / martensite, as well as relatively high-density nano-cementite and vanadium carbide particles. The hot-rolled medium-manganese steel prepared in this example has a yield strength of 569 MPa, a tensile strength of 710 MPa, and an elongation at break of 25% under high-temperature deformation conditions of 500°C.

[0065] Example 3

[0066] A method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties comprises the following steps:

[0067] S1. Homogenization annealing: The medium manganese steel ingot is subjected to homogenization annealing to obtain an annealed ingot; the homogenization annealing temperature is 1130°C, the annealing time is 3 hours, and the cooling method is air cooling;

[0068] S2. Rough hot rolling: The annealed ingot is subjected to rough hot rolling, and then water-cooled to room temperature to obtain a rough hot rolled plate; the starting rolling temperature is 1020°C, and the finishing rolling temperature is 980°C; the rough hot rolling is divided into 4 passes, and the total deformation of the rough hot rolling is 70%;

[0069] S3, finishing hot rolling: the rough hot rolled plate is put into the furnace to be kept warm, and then subjected to finishing hot rolling and air cooling to room temperature to obtain the finishing hot rolled plate; the holding temperature is 650℃, and the holding time is 10min; the finishing hot rolling is divided into 2 passes, and the total deformation of the finishing hot rolling is 50%; the final rolling temperature is 590℃;

[0070] S4. Ferrite phase transformation process: The hot-rolled plate is kept warm by being put into the furnace after reaching the temperature. The holding temperature is 500℃ and the holding time is 30 minutes. The ferrite phase transformation process is then carried out and the plate is air-cooled to room temperature to obtain a hot-rolled medium manganese steel with excellent high-temperature mechanical properties.

[0071] The microstructure of the hot-rolled medium manganese steel prepared in this embodiment is as follows: Figure 3 As shown ( Figure 3 The middle left picture is the SEM picture. Figure 3 The middle right figure is a TEM image). Its matrix structure includes 45 vol% austenite and 55 vol% ferrite / martensite, as well as relatively high-density nano-cementite and vanadium carbide particles. The hot-rolled medium-manganese steel prepared in this example has a yield strength of 430 MPa, a tensile strength of 591 MPa, and an elongation at break of 28% under high-temperature deformation conditions of 500°C.

[0072] Comparative Example 1

[0073] The difference from Example 1 is that step S4 is not performed.

[0074] The SEM image of the medium manganese steel prepared in this comparative example is as follows Figure 4 As shown in the figure, its matrix structure is 69 vol% austenite and 31 vol% ferrite / martensite, and the precipitated phases include low-density nano-cementite and vanadium carbide particles; under high-temperature deformation conditions of 500°C, the yield strength is 452 MPa, the tensile strength is 536 MPa, and the elongation after fracture is 30%.

[0075] Comparative Example 2

[0076] The difference from Example 1 is that the holding temperature in step S4 is 450°C.

[0077] The medium manganese steel matrix structure prepared in this comparative example includes 43 vol% austenite and 57 vol% ferrite / martensite, and the precipitated phase includes low-density nano-cementite and vanadium carbide particles. The yield strength under high-temperature deformation conditions of 500°C is 580 MPa, the tensile strength is 635 MPa, and the elongation after fracture is 19.5%.

[0078] It can be seen from the various embodiments and comparative examples of the present invention that the present invention adopts a homogenization annealing, rough hot rolling, finish hot rolling, and ferrite phase transformation coupling process to prepare a hot-rolled medium manganese steel with excellent high-temperature mechanical properties. The yield strength at 500°C is 430~670MPa, the tensile strength is 590~750MPa, and the elongation after fracture is 25~28%. It breaks through the problem of "insufficient high-temperature strength" of medium manganese steel, achieves a good match between strength and plasticity of medium manganese steel for high-temperature environments, and broadens its application field.

[0079] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties, characterized in that: The steps include: S1. Homogenization annealing: The medium manganese steel ingot is subjected to homogenization annealing to obtain an annealed ingot; S2. Rough hot rolling: The annealed ingot is subjected to rough hot rolling, and then water-cooled to room temperature to obtain a rough hot-rolled plate; S3, finishing hot rolling: the rough hot rolled plate is put into the furnace and kept warm at 650℃ for 10 minutes; then the finishing hot rolled plate is air cooled to room temperature to obtain the finishing hot rolled plate; the finishing hot rolling is divided into 2 passes, and the total deformation of the finishing hot rolling is 50%; the final rolling temperature is 590℃; S4, ferrite phase transformation process: the hot-rolled plate is put into the furnace and held at a temperature of 500°C for 30 minutes. After the ferrite phase transformation process, it is air-cooled to room temperature to obtain hot-rolled medium manganese steel with excellent high-temperature mechanical properties. The hot-rolled medium-manganese steel with excellent high-temperature mechanical properties comprises, by mass percentage, 0.41% C, 10.2% Mn, 2.2% Al, 0.6% V, with the remainder being Fe and unavoidable impurities. The hot-rolled medium-manganese steel has a yield strength of 430 MPa, a tensile strength of 591 MPa, and an elongation after fracture of 28% under high-temperature deformation conditions of 500°C. The matrix structure of the hot-rolled medium-manganese steel comprises 45 vol% austenite and 55 vol% ferrite / martensite, and the precipitated phases comprise nano-cementite and vanadium carbide particles.

2. The method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties according to claim 1, characterized in that: Before step S1, the method further includes: S0, smelting medium manganese steel ingots: preparing ingredients according to the composition of the medium manganese steel, adding the ingredients into the vacuum induction melting furnace cavity in the order of the melting points of the elements from low to high, at a melting temperature of 1400-1500° C., casting the ingots into molds after smelting, and air cooling the ingots to room temperature.

3. The method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties according to claim 1, characterized in that: In step S1, the homogenization annealing temperature is 1130° C., the annealing time is 3 hours, and the cooling method is air cooling.

4. The method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties according to claim 1, characterized in that: In step S2, the initial rolling temperature is 1020°C, and the final rolling temperature is 980°C; the rough hot rolling is divided into 4 passes, and the total deformation of the rough hot rolling is 70%.

5. A hot-rolled medium manganese steel with excellent high-temperature mechanical properties, characterized in that: The steel is prepared by the method for preparing hot-rolled medium manganese steel with excellent high-temperature mechanical properties according to any one of claims 1 to 4.

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