Preparation method of high-strength multi-level heterostructure high-manganese light steel

Abstract

The invention discloses a preparation method of high-strength multi-level heterostructure high-manganese light steel, relates to the technical field of high-performance alloy preparation, and aims to solve the technical problems that the strength of existing high-manganese light steel is low, plasticity is seriously sacrificed while the strength is improved, and high strength and high plasticity cannot be met at the same time. The preparation method of the high-strength multi-level heterostructure high-manganese light steel comprises the steps that high-manganese steel is obtained; the high manganese steel is subjected to first heat preservation treatment; the temperature of the first heat preservation treatment is 800-1000 DEG C, and the time is 10-90 minutes; the high manganese steel is quenched to the room temperature; the high manganese steel is quenched to the room temperature after being subjected to second heat preservation treatment; the temperature of the second heat preservation treatment is 450-650 DEG C, and the time is 10-90 minutes; wherein after the second heat preservation treatment, the high manganese steel at least has a first heterostructure, a second heterostructure and a third heterostructure. The invention is used for providing the preparation method of the high-strength multi-level heterostructure high-manganese light steel and the prepared high-manganese light steel.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance alloy preparation, and more specifically, to a method for preparing high-strength multi-level heterogeneous structure high-manganese lightweight steel. Background Art

[0002] With the rapid development of the manufacturing industry, the research on alloy materials with high strength and high plasticity has received great attention. High manganese lightweight steel has shown a wide range of application prospects in the fields of aircraft landing gear, missile shells, automobile anti-collision beams and new energy (such as liquefied petroleum gas, liquid hydrogen) storage tanks due to its high strength, high wear resistance, excellent corrosion resistance and good low-temperature impact toughness.

[0003] The strengthening of existing high-manganese lightweight steel mainly relies on the coherent precipitation of nano-scale κ'-carbides, which can improve the yield strength of the material; however, the strengthening contribution provided by κ'-carbides is limited, usually less than 500MPa, which is difficult to meet the use requirements in harsh environments; in addition, the aging time required for the precipitation of κ'-carbides is relatively long (about 24 hours), and long-term aging will cause additional brittle phases to form at the grain boundaries, such as D03 and β-Mn phases, which seriously sacrifice the plasticity of the steel. It can be seen that the existing high-manganese lightweight steel has low strength, and while improving strength, it will seriously sacrifice plasticity, and cannot meet the performance of high strength and high plasticity at the same time. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a high-strength multi-level heterogeneous structure high manganese light steel, which is used to solve the technical problems that the existing high manganese light steel has low strength, and seriously sacrifices plasticity while improving strength, and cannot meet the requirements of high strength and high plasticity at the same time. In view of this, the present invention is implemented through the following scheme.

[0005] In a first aspect, the present invention provides a method for preparing a high-strength multi-level heterogeneous structure high manganese lightweight steel, comprising: Obtain high manganese steel; Performing a first heat preservation treatment on the high manganese steel; the temperature of the first heat preservation treatment is 800-1000° C. and the time is 10-90 minutes; Quenching the high manganese steel to room temperature; After the high manganese steel is subjected to a second heat preservation treatment, it is quenched to room temperature; the temperature of the second heat preservation treatment is 450-650° C. and the time is 10-90 minutes; Among them, after the second insulation treatment, the high manganese steel has at least a first heterostructure, a second heterostructure and a third heterostructure; the first heterostructure contains L'12 particles of different sizes or volume fractions, the second heterostructure contains recrystallized austenite regions and non-recrystallized austenite regions, and the third heterostructure contains ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions.

[0006] Compared with the prior art, in the preparation method of the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the first heat preservation treatment of the high manganese steel can improve its recrystallization degree and phase composition, obtain recrystallized austenite region and non-recrystallized austenite region, and form ferrite-κ-carbide composite particles with different shapes, sizes and volume fractions; specifically, the temperature of the first heat preservation treatment is controlled to be the above-mentioned 800~1000℃, and the heat preservation time is controlled within the above-mentioned range. During the first heat preservation treatment, the recrystallized austenite region and the non-recrystallized austenite region are first obtained, and further, the ferrite nucleates at the recrystallized grain boundary, the recrystallized grain, and the non-recrystallized region respectively; as the heat preservation process continues, the recrystallized grain boundary and the recrystallized grain are , and the ferrite in the non-recrystallized region is partially transformed into κ-carbide to form ferrite-κ-carbide composite particles, and ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions can form the above-mentioned third heterostructure; after the high manganese steel is quenched to room temperature, a second insulation treatment is performed, and the temperature of the second insulation treatment is controlled within the above-mentioned 450~650℃, and the insulation time is controlled within the above-mentioned range, nano-scale L'12 ordered particles can be obtained in the recrystallized austenite region and the non-recrystallized austenite region, and the nano-scale L'12 ordered particles with different sizes and volume fractions in these two regions can form the above-mentioned first heterostructure; the second heterostructure can be composed of recrystallized austenite regions and non-recrystallized austenite regions. By means of the technical solution of the present invention, a multi-level heterogeneous structure (such as the first heterogeneous structure, the second heterogeneous structure and the third heterogeneous structure) can be obtained in the high manganese steel. The existence of the multi-level heterogeneous structure can significantly improve the strength of the high manganese steel without sacrificing the plasticity of the high manganese steel, or in other words, the plasticity of the high manganese steel is sacrificed very little and does not affect its performance. The technical solution solves the technical problem that the existing high manganese light steel has low strength and seriously sacrifices plasticity while improving strength, and cannot meet the requirements of high strength and high plasticity at the same time. For example, after the high manganese light steel is prepared by the technical solution, the strength and plasticity tests are performed on the high manganese light steel. The yield strength of the high manganese light steel is 1000-1300MPa, the tensile strength is 1250-1400MPa, and the elongation after fracture is 14-35%.

[0007] Furthermore, in the preparation method of the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the composition of the high manganese steel is, by weight percentage: Manganese is 20~24wt%, aluminum is 5~7wt%, carbon is 0.8~1.2wt%, silicon is 3~4wt%, and the balance is iron and inevitable impurity elements.

[0008] Furthermore, in the method for preparing the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the high manganese steel is a coarse-grained austenitic high manganese steel.

[0009] Furthermore, in the method for preparing the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, before the first heat preservation treatment is performed on the high manganese steel, the method further comprises: The high manganese steel is subjected to high pressure torsion.

[0010] Furthermore, in the method for preparing the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the high-pressure torsion is carried out at room temperature.

[0011] Furthermore, in the preparation method of the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the pressure of the high-pressure torsion is 2~10GPa, the rotation speed is 0.5~3 rpm, and the number of torsion turns is 5~15 turns.

[0012] Furthermore, in the method for preparing the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, during the quenching to room temperature, the quenching liquid includes water.

[0013] Furthermore, in the preparation method of the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the first heterogeneous structure is composed of L'12 particles of different sizes or volume fractions, the second heterogeneous structure is composed of recrystallized austenite regions and non-recrystallized austenite regions, and the third heterogeneous structure is composed of ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions.

[0014] In a second aspect, the present invention provides a high manganese lightweight steel, which is prepared using the above-mentioned method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel; the high manganese lightweight steel has a yield strength of 1000~1300MPa, a tensile strength of 1250~1400MPa, and an elongation after fracture of 14~35%.

[0015] Compared with the prior art, the beneficial effects of the high manganese lightweight steel of the present invention are the same as the beneficial effects of the method for preparing the high-strength multi-level heterogeneous structure high manganese lightweight steel described in the above technical solution, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1A transmission electron microscope (TEM) schematic diagram of the high manganese lightweight steel of Example 1 of the present invention; Figure 2 A transmission electron microscope (TEM) schematic diagram of the high manganese lightweight steel of Example 2 of the present invention; Figure 3 Schematic diagram of X-ray diffraction (XRD) of high manganese lightweight steel prepared in Example 1 and Example 2 of the present invention; Figure 4 Schematic diagram of the uniaxial tensile engineering stress-strain curve of the high manganese lightweight steel of Examples 1 and 2 of the present invention. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0020] The strengthening of existing high-manganese lightweight steel mainly relies on the coherent precipitation of nano-scale κ'-carbides, which can significantly improve the yield strength of the material; however, the strengthening contribution provided by κ'-carbides is limited, usually less than 500MPa, which is difficult to meet the use requirements in harsh environments; in addition, the aging time required for the precipitation of κ'-carbides is relatively long (about 24 hours), and long-term aging will cause additional brittle phases to form at the grain boundaries, such as D03 and β-Mn phases, which seriously sacrifice the plasticity of the steel. It can be seen that the existing high-manganese lightweight steel has low strength, and while improving strength, it will seriously sacrifice plasticity, and cannot meet the performance of high strength and high plasticity at the same time.

[0021] In order to solve the above technical solution, in a first aspect, the present invention provides a method for preparing a high-strength multi-level heterogeneous structure high manganese lightweight steel, comprising: Obtain high manganese steel; Performing a first heat preservation treatment on the high manganese steel; the temperature of the first heat preservation treatment is 800-1000° C. and the time is 10-90 minutes; Quenching the high manganese steel to room temperature; After the high manganese steel is subjected to a second heat preservation treatment, it is quenched to room temperature; the temperature of the second heat preservation treatment is 450-650° C. and the time is 10-90 minutes; Among them, after the second insulation treatment, the high manganese steel has at least a first heterostructure, a second heterostructure and a third heterostructure; the first heterostructure contains L'12 particles of different sizes or volume fractions, the second heterostructure contains recrystallized austenite regions and non-recrystallized austenite regions, and the third heterostructure contains ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions.

[0022] Under the condition of adopting the above technical scheme, in the preparation method of high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the first heat preservation treatment of the high manganese steel can improve its recrystallization degree and phase composition, obtain recrystallized austenite region and non-recrystallized austenite region, and form ferrite-κ-carbide composite particles with different shapes, sizes and volume fractions; specifically, the temperature of the first heat preservation treatment is controlled to be the above-mentioned 800~1000℃, and the heat preservation time is controlled within the above-mentioned range. During the first heat preservation treatment, the recrystallized austenite region and the non-recrystallized austenite region are first obtained, and further, the ferrite nucleates at the recrystallized grain boundary, the recrystallized grain, and the non-recrystallized region respectively; as the heat preservation process continues, the recrystallized grain boundary, the recrystallized grain, and the non-recrystallized region are formed. The ferrite in the crystal and the non-recrystallized region is partially transformed into κ-carbide to form ferrite-κ-carbide composite particles, and ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions can form the above-mentioned third heterostructure; after the high manganese steel is quenched to room temperature, a second insulation treatment is performed, and the temperature of the second insulation treatment is controlled within the above-mentioned 450~650℃, and the insulation time is controlled within the above-mentioned range, nano-scale L'12 ordered particles can be obtained in the recrystallized austenite region and the non-recrystallized austenite region, and the nano-scale L'12 ordered particles with different sizes and volume fractions in these two regions can form the above-mentioned first heterostructure; the second heterostructure can be composed of recrystallized austenite regions and non-recrystallized austenite regions. Through the above technical solution of the present invention, a multi-level heterogeneous structure (such as the above-mentioned first heterogeneous structure, the second heterogeneous structure and the third heterogeneous structure) can be obtained in the high manganese steel. The existence of the multi-level heterogeneous structure can significantly improve the strength of the high manganese steel without basically sacrificing the plasticity of the high manganese steel, or in other words, the plasticity of the high manganese steel is sacrificed very little and does not affect its performance. The technical solution solves the technical problem that the existing high manganese lightweight steel has low strength, and seriously sacrifices plasticity while improving strength, and cannot meet the requirements of high strength and high plasticity at the same time; for example, the above technical solution After the high manganese lightweight steel is prepared by the scheme, strength and plasticity tests are performed on it. The yield strength of the high manganese lightweight steel is 1000-1300MPa, the tensile strength is 1250-1400MPa, and the elongation after break is 14-35%; for example, the temperature of the first insulation treatment can be 800°C, 900°C or 1000°C, and the time can be 10 minutes, 50 minutes or 90 minutes, and the temperature of the second insulation treatment can be 450°C, 550°C or 650°C, and the time can be 10 minutes, 50 minutes or 90 minutes.

[0023] Furthermore, in the preparation method of the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, for example, the first heterogeneous structure is composed of L'12 particles of different sizes or volume fractions, the second heterogeneous structure is composed of recrystallized austenite regions and non-recrystallized austenite regions, and the third heterogeneous structure is composed of ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions.

[0024] It should be understood that in order to further improve the strength of the high manganese steel without sacrificing plasticity, it can also be said that in order to make the preparation method of the high-strength multi-level heterogeneous structure high manganese lightweight steel more suitable for high manganese steel of a specific component, the composition of the high manganese steel should also be controlled within a reasonable range; for example, in terms of weight percentage, the composition of the high manganese steel is: manganese is 20-24wt%, aluminum is 5-7wt%, carbon is 0.8-1.2wt%, silicon is 3-4wt%, and the balance is iron and unavoidable impurity elements; for another example, in terms of weight percentage, the composition of the high manganese steel is The composition of the high manganese steel is: 20wt% manganese, 5wt% aluminum, 0.8wt% carbon, 3wt% silicon, and the balance is iron and inevitable impurity elements; as another example, in terms of weight percentage, the composition of the high manganese steel is: 24wt% manganese, 7wt% aluminum, 1.2wt% carbon, 4wt% silicon, and the balance is iron and inevitable impurity elements; as another example, in terms of weight percentage, the composition of the high manganese steel is: 22wt% manganese, 6wt% aluminum, 1wt% carbon, 3.5wt% silicon, and the balance is iron and inevitable impurity elements.

[0025] As a possible implementation manner, in the method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, the high manganese steel is coarse-grained austenite high manganese steel; before the high manganese steel is subjected to the first heat preservation treatment, the method further comprises: The high manganese steel is subjected to high pressure torsion.

[0026] Under the condition of adopting the above technical scheme, in the preparation method of high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, by subjecting the high manganese steel to high-pressure torsion, under the condition of strong shear deformation, the coarse austenite grains of the coarse-grained austenitic high manganese steel can be subjected to strong shear deformation and refined into smaller grains. Since the fine grains can more effectively hinder the expansion of cracks, the strength and plasticity of the high manganese steel can be improved after high-pressure torsion; exemplarily, the high-pressure torsion is carried out at room temperature, the pressure of the high-pressure torsion is 2~10GPa, the rotation speed is 0.5~3 rpm, and the number of twisting turns is 5~15 turns; as another example, the temperature of the high-pressure torsion can be 25°C, the pressure of the high-pressure torsion can be 2GPa, 6GPa or 10GPa, the rotation speed of the high-pressure torsion can be 0.5 rpm, 2 rpm or 3 rpm, and the number of high-pressure torsion turns can be 5 turns, 10 turns or 15 turns.

[0027] Furthermore, in the preparation method of the high-strength multi-level heterogeneous structure high manganese lightweight steel of the present invention, after the first heat preservation treatment and the second heat preservation treatment, the high manganese steel is quenched respectively, and a high manganese steel with a stable structure at a corresponding high temperature can be obtained through the quenching treatment; illustratively, the quenching liquid of the quenching treatment can be water; illustratively, the quenching to room temperature can be immersing the high manganese steel in water to rapidly cool it to 15-25°C; in another example, the high manganese steel can be immersed in water to rapidly cool it to 15°C, 20°C or 25°C.

[0028] In a second aspect, the present invention provides a high manganese lightweight steel, which is prepared using the above-mentioned method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel; the high manganese lightweight steel has a yield strength of 1000~1300MPa, a tensile strength of 1250~1400MPa, and an elongation after fracture of 14~35%.

[0029] Under the condition of adopting the above technical scheme, the high manganese lightweight steel of the present invention is prepared by utilizing the above method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel. In the method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel, subjecting the high manganese steel to a first heat preservation treatment can improve its recrystallization degree and phase composition, obtain a recrystallized austenite region and a non-recrystallized austenite region, and form ferrite-κ-carbide composite particles with different shapes, sizes and volume fractions; specifically, the temperature of the first heat preservation treatment is controlled to be the above 800~1000°C, and the heat preservation time is controlled to be within the above range. During the first heat preservation treatment, a recrystallized austenite region and a non-recrystallized austenite region are first obtained, and further, ferrite nucleates at the recrystallized grain boundary, in the recrystallized grain, and in the non-recrystallized region, respectively; as the heat preservation time increases, the recrystallized austenite region and the non-recrystallized austenite region are nucleated. As the temperature process continues, the ferrite at the recrystallized grain boundary, the recrystallized grain, and the non-recrystallized region is partially transformed into κ-carbide to form ferrite-κ-carbide composite particles, and ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions can form the above-mentioned third heterostructure; after the high manganese steel is quenched to room temperature, a second heat preservation treatment is performed, and by controlling the temperature of the second heat preservation treatment within the above-mentioned 450~650℃ and the heat preservation time within the above-mentioned range, nano-scale L'12 ordered particles can be obtained in the recrystallized austenite region and the non-recrystallized austenite region, and the nano-scale L'12 ordered particles with different sizes and volume fractions in these two regions can form the above-mentioned first heterostructure; the second heterostructure can be composed of recrystallized austenite regions and non-recrystallized austenite regions. By means of the technical solution of the present invention, a multi-level heterogeneous structure (such as the first heterogeneous structure, the second heterogeneous structure and the third heterogeneous structure) can be obtained in the high manganese steel. The existence of the multi-level heterogeneous structure can significantly improve the strength of the high manganese steel without sacrificing the plasticity of the high manganese steel, or in other words, the plasticity of the high manganese steel is sacrificed very little and does not affect its performance. The technical solution solves the technical problem that the existing high manganese light steel has low strength and seriously sacrifices plasticity while improving strength, and cannot meet the requirements of high strength and high plasticity at the same time. For example, after the high manganese light steel is prepared by the technical solution, the strength and plasticity tests are performed on the high manganese light steel. The yield strength of the high manganese light steel is 1000-1300MPa, the tensile strength is 1250-1400MPa, and the elongation after fracture is 14-35%.

[0030] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0031] Unless otherwise specified, the raw materials used in the following examples are commercially available. Example 1

[0032] This embodiment provides a method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel, comprising: Step 1, obtaining high manganese steel, wherein the coarse-grained austenitic high manganese steel has the following composition by weight percentage: iron (Fe) is 67.803wt%, manganese (Mn) is 21.25wt%, aluminum (Al) is 5.89wt%, carbon (C) is 1.10wt%, silicon (Si) is 3.95wt%, and sulfur (S) is 0.007wt%; Step 2, cutting the high manganese steel into discs with a diameter of 6 mm and a thickness of 2 mm; Step 3, placing the disc under a high-pressure twisting machine for high-pressure twisting, wherein the high-pressure twisting is performed at room temperature (25° C.), which is conducive to the loading device applying a pressure of 6 GPa, so that the disc rotates along its central axis. During the high-pressure twisting process, the rotation speed of the disc is 0.5 rpm, and the number of twisting turns is 6 turns; Step 4, placing the high manganese steel after high pressure twisting in step 3 in a box furnace, controlling the furnace temperature to 900° C., and keeping the temperature for 10 minutes, and then quenching with water to room temperature (25° C.); Step 5, placing the high manganese steel after water quenching in step 4 in the box furnace again, controlling the furnace temperature to 550° C., and keeping it warm for 30 minutes, and then water quenching it to room temperature (25° C.); obtaining a high-strength multi-level heterogeneous structure high manganese lightweight steel. Example 2

[0033] This embodiment provides a method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel, comprising: Step 1, obtaining high manganese steel, wherein the coarse-grained austenitic high manganese steel has the following composition by weight percentage: iron (Fe) is 67.803wt%, manganese (Mn) is 21.25wt%, aluminum (Al) is 5.89wt%, carbon (C) is 1.10wt%, silicon (Si) is 3.95wt%, and sulfur (S) is 0.007wt%; Step 2, cutting the high manganese steel into discs with a diameter of 6 mm and a thickness of 2 mm; Step 3, placing the disc under a high-pressure twisting machine for high-pressure twisting, wherein the high-pressure twisting is performed at room temperature (25° C.), which is conducive to the loading device applying a pressure of 6 GPa, so that the disc rotates along its central axis. During the high-pressure twisting process, the rotation speed of the disc is 0.5 rpm, and the number of twisting turns is 6 turns; Step 4, placing the high manganese steel after high pressure twisting in step 3 in a box furnace, controlling the furnace temperature to 900° C., and keeping the temperature for 10 minutes, and then quenching with water to room temperature (25° C.); Step 5, placing the high manganese steel after water quenching in step 4 in the box furnace again, controlling the furnace temperature to 550° C., and keeping it warm for 1 hour, and then water quenching it to room temperature (25° C.); obtaining a high-strength multi-level heterogeneous structure high manganese lightweight steel. Example 3

[0034] This embodiment provides a method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel, comprising: Step 1, obtaining high manganese steel, wherein the coarse-grained austenitic high manganese steel has the following composition by weight percentage: iron (Fe) is 67.803wt%, manganese (Mn) is 21.25wt%, aluminum (Al) is 5.89wt%, carbon (C) is 1.10wt%, silicon (Si) is 3.95wt%, and sulfur (S) is 0.007wt%; Step 2, cutting the high manganese steel into discs with a diameter of 6 mm and a thickness of 2 mm; Step 3, placing the disc in a high-pressure torsion machine for high-pressure torsion, wherein the high-pressure torsion is performed at room temperature (25° C.), so that the loading device applies a pressure of 10 GPa, causing the disc to rotate along its central axis. During the high-pressure torsion process, the disc rotates at 2 revolutions per minute, and the number of twists is 10 turns; Step 4, placing the high manganese steel after high pressure twisting in step 3 in a box furnace, controlling the furnace temperature to 800° C., and keeping the temperature for 80 minutes, and then quenching with water to room temperature (25° C.); Step 5, placing the high manganese steel after water quenching in step 4 in the box furnace again, controlling the furnace temperature to 450°C, and keeping it warm for 90 minutes, and then water quenching it to room temperature (25°C); obtaining a high-strength multi-level heterogeneous structure high manganese lightweight steel. Example 4

[0035] This embodiment provides a method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel, comprising: Step 1, obtaining high manganese steel, wherein the coarse-grained austenitic high manganese steel has the following composition by weight percentage: iron (Fe) is 67.803wt%, manganese (Mn) is 21.25wt%, aluminum (Al) is 5.89wt%, carbon (C) is 1.10wt%, silicon (Si) is 3.95wt%, and sulfur (S) is 0.007wt%; Step 2, cutting the high manganese steel into discs with a diameter of 6 mm and a thickness of 2 mm; Step 3, placing the disc in a high-pressure torsion machine for high-pressure torsion, wherein the high-pressure torsion is performed at room temperature (25° C.), which is conducive to the loading device applying a pressure of 3 GPa to make the disc rotate along its central axis. During the high-pressure torsion process, the rotation speed of the disc is 3 revolutions per minute, and the number of twisting turns is 15 turns; Step 4, placing the high manganese steel after high pressure twisting in step 3 in a box furnace, controlling the furnace temperature to 1000° C., and keeping the temperature for 10 minutes, and then quenching with water to room temperature (25° C.); Step 5, placing the high manganese steel after water quenching in step 4 in the box furnace again, controlling the furnace temperature to 650° C., and keeping it warm for 10 minutes, and then water quenching it to room temperature (25° C.); obtaining a high-strength multi-level heterogeneous structure high manganese lightweight steel.

[0036] After the high-strength multi-level heterogeneous structure high manganese light steel (hereinafter referred to as high manganese light steel) in the above-mentioned embodiments 1 to 4 was prepared, it was characterized and its performance tested respectively; the following will take the high manganese light steel in embodiments 1 and 2 as an example for detailed description. Figure 3 ,from Figure 3 It can be seen that the high manganese light steel prepared in the above-mentioned Example 1 and Example 2 is composed of austenite, ferrite, L'12 ordered particles / κ-carbide particles. Figure 1 ,from Figure 1 (a) It can be seen that the high manganese lightweight steel prepared in Example 1 includes micron-sized recrystallized austenite regions and non-recrystallized austenite regions. Figure 1 (b) and Figure 1 (c) It can be seen that submicron ferrite-κ-carbide composite particles of different shapes, sizes and volume fractions are formed in the recrystallized austenite region and the non-recrystallized austenite region, respectively. Specifically, in the recrystallized austenite region, the ferrite-κ-carbide composite particles are blocky, with an average diameter of 0.38μm and a volume fraction of 7.61%; in the non-recrystallized austenite region, the ferrite-κ-carbide composite particles are layered, with an average major axis of 0.25μm, a minor axis of 0.075μm and a volume fraction of 3.00%. Figure 1 (d) and Figure 1 (e) It can be seen that nanometer-scale L'12 ordered particles of different sizes and volume fractions are obtained in the recrystallized austenite region and the non-recrystallized austenite region, respectively; specifically, in the recrystallized austenite region, the average size of the L'12 particles is 1.32nm, and the volume fraction is 10%; in the non-recrystallized austenite region, the average size of the L'12 particles is 1.72nm, and the volume fraction is 11%. Further, the mechanical properties of the high manganese lightweight steel prepared in Example 1 were measured according to GB / T228.1-2010 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method", please refer to Figure 4 The yield strength of the high manganese lightweight steel in Example 1 is 1054MPa, the tensile strength is 1287MPa, and the elongation after fracture still reaches 31%; compared with the coarse-grained austenitic high manganese steel (yield strength of 289MPa, tensile strength of 641MPa), the yield strength of the high manganese lightweight steel prepared in Example 1 is increased by 2.6 times, and the tensile strength is increased by 1 times.

[0037] For further information, see Figure 2 ,from Figure 2(a) It can be seen that the high manganese light steel prepared in Example 2 also includes a recrystallized austenite region and a non-recrystallized austenite region. Figure 2 (b) and Figure 2 (c) It can be seen that submicron ferrite-κ-carbide composite particles of different shapes, sizes and volume fractions are formed in the recrystallized austenite region and the non-recrystallized austenite region, respectively. Specifically, in the recrystallized austenite region, the ferrite-κ-carbide composite particles are blocky, with an average diameter of 0.41μm and a volume fraction of 7.02%. In the non-recrystallized austenite region, the ferrite-κ-carbide composite particles are layered, with an average major axis of 0.27μm, a minor axis of 0.13μm and a volume fraction of 4.20%. Figure 2 (d) and Figure 2 (e) It can be seen that nanometer-scale L'12 ordered particles of different sizes and volume fractions are obtained in the recrystallized austenite region and the non-recrystallized austenite region, respectively; specifically, in the recrystallized austenite region, the average size of the L'12 particles is 1.45nm, and the volume fraction is 22.4%, and in the non-recrystallized austenite region, the average size of the L'12 particles is 1.75nm, and the volume fraction is 27.8%. Further, similarly, the mechanical properties of the high manganese lightweight steel prepared in Example 2 were measured according to GB / T228.1-2010 "Metallic Materials Tensile Test Part 1: Room Temperature Test Method", please refer to Figure 4 The yield strength of the high manganese lightweight steel prepared in Example 2 is 1210MPa, the tensile strength is 1367MPa, and the elongation after fracture still reaches 14%. Compared with the coarse-grained austenitic high manganese steel (yield strength of 289MPa, tensile strength of 641MPa), the yield strength of the high manganese lightweight steel prepared in Example 2 is increased by 3.2 times, and the tensile strength is increased by 1.1 times.

[0038] In summary, the high manganese lightweight steel prepared by the above embodiments of the present invention has excellent mechanical properties, and has the characteristics of high strength and plasticity. From the perspective of the microscopic composition of the high manganese lightweight steel, this is mainly due to the combined effect of the recrystallization zone and the non-recrystallization zone in the prepared high manganese lightweight steel; specifically, the austenite in the recrystallization zone provides grain boundary strengthening, and the austenite in the non-recrystallization zone provides dislocation strengthening. In the two regions, ferrite-κ-carbide composite particles and L'12 ordered particles of different sizes, shapes and volume fractions provide different Orowan strengthening and ordered strengthening, respectively; in addition, the difference in mechanical properties of the two regions provides back stress strengthening; thus, a multi-level heterogeneous structure high manganese lightweight steel with high strength is successfully obtained.

[0039] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0040] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel, characterized in that: include: Obtain high manganese steel; Performing a first heat preservation treatment on the high manganese steel; The temperature of the first heat preservation treatment is 800-1000° C. and the time is 10-90 minutes; Quenching the high manganese steel to room temperature; After the high manganese steel is subjected to a second heat preservation treatment, it is quenched to room temperature; the temperature of the second heat preservation treatment is 450-650° C. and the time is 10-90 minutes; Among them, after the second insulation treatment, the high manganese steel has at least a first heterostructure, a second heterostructure and a third heterostructure; the first heterostructure contains L'12 particles of different sizes or volume fractions, the second heterostructure contains recrystallized austenite regions and non-recrystallized austenite regions, and the third heterostructure contains ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions.

2. The method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel according to claim 1, characterized in that: In terms of weight percentage, the composition of the high manganese steel is: Manganese is 20~24wt%, aluminum is 5~7wt%, carbon is 0.8~1.2wt%, silicon is 3~4wt%, and the balance is iron and inevitable impurity elements.

3. The method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel according to claim 2, characterized in that: The high manganese steel is coarse-grained austenitic high manganese steel.

4. The method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel according to claim 3, characterized in that: Before the high manganese steel is subjected to the first heat preservation treatment, the method further comprises: The high manganese steel is subjected to high pressure torsion.

5. The method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel according to claim 4, characterized in that: The high pressure twisting is performed at room temperature.

6. The method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel according to claim 5, characterized in that: The high-pressure twisting pressure is 2-10 GPa, the rotation speed is 0.5-3 rpm, and the number of twisting turns is 5-15 turns.

7. The method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel according to claim 6, characterized in that: During the quenching to room temperature, the quenching liquid includes water.

8. The method for preparing high-strength multi-level heterogeneous structure high manganese lightweight steel according to claim 7, characterized in that: The first heterostructure consists of L'12 particles of different sizes or volume fractions, the second heterostructure consists of recrystallized austenite regions and non-recrystallized austenite regions, and the third heterostructure consists of ferrite-κ-carbide composite particles of different shapes, sizes or volume fractions.

9. A high manganese lightweight steel, characterized in that: The high-strength multi-level heterogeneous structure high manganese lightweight steel is prepared by the preparation method of any one of claims 1 to 8; the high manganese lightweight steel has a yield strength of 1000~1300MPa, a tensile strength of 1250~1400MPa, and an elongation after fracture of 14~35%.

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