High-hydrogen-embrittlement-resistant high-manganese steel with gradient ti c hydrogen trap barrier and method of manufacturing the same

Abstract

The application provides a high-hydrogen-embrittlement-resistant high-manganese steel with a gradient TiC hydrogen trap barrier and a preparation method thereof, and belongs to the technical field of metal materials and hydrogen embrittlement protection, wherein the mass percentage of each element is as follows: C 0.45-0.5, Mn 23.90-24.10, Cr 3.25-3.5, Si 0.15-0.20, N 0.01-0.015, O 0.001-0.002, Ti 0.04-0.08, P≤0.004, S≤0.0001, and the balance is iron. The application induces a continuous and controllable gradient distribution of TiC precipitated phases along the thickness direction by high-temperature homogenization treatment on the specific component high-manganese steel, then introduces an asymmetric rolling process in the low-temperature stage of the hot rolling process, fixes the organization through a quenching process, and eliminates residual dislocations and shear strain by combining with low-temperature tempering. The high-manganese steel is suitable for key load-bearing components sensitive to hydrogen embrittlement such as hydrogen energy equipment and hydrogen storage systems, and has important engineering application prospects.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials and hydrogen embrittlement protection technology, specifically relating to a high-manganese steel with a gradient TiC hydrogen trap barrier and its preparation method. Background Technology

[0002] High-manganese steel, due to its excellent combination of strength and plasticity, shows great promise in clean energy and advanced manufacturing fields such as hydrogen energy storage and transportation equipment, structural components for new energy vehicles, and deep-sea energy development. However, the hydrogen embrittlement sensitivity of this type of steel in hydrogen-containing environments has become a core bottleneck restricting its safe service life. After hydrogen atoms diffuse into the steel, they readily accumulate at grain boundaries, twin boundaries, dislocations, and other crystal defects and microstructural stress concentrations, significantly reducing grain boundary bonding and crack propagation resistance. This leads to a transformation from ductile fracture to brittle cleavage or intergranular fracture, seriously threatening the long-term reliability and structural integrity of critical components.

[0003] Currently, the mainstream strategy for improving the hydrogen embrittlement resistance of high-manganese steel mainly relies on microalloying technology, which involves introducing strong carbide-forming elements such as Ti and Nb to precipitate dispersed nanoscale carbides such as TiC and NbC in the matrix as hydrogen traps. The basic principle of this method is to "anchor" hydrogen atoms using the strong binding energy between hydrogen atoms and the second phase interface, thereby inhibiting their diffusion into high-stress areas. However, this uniformly distributed hydrogen trap design has inherent limitations: its trapping efficiency exhibits spatial uniformity, making it difficult to construct a dissipation barrier with a steep concentration gradient at the "front line" of hydrogen intrusion, namely the material surface and near-surface region. As a result, once hydrogen atoms break through the surface trap network, they can continuously penetrate into the interior of the material driven by the concentration gradient. More critically, existing designs lack a systematic planning and active guidance mechanism for hydrogen diffusion paths. The random movement of hydrogen atoms within the austenitic matrix is ​​not effectively intervened, allowing some hydrogen to bypass trap sites and penetrate deep into stress concentration regions at the core of the material (such as grain boundary junctions and inclusion interfaces), inducing delayed cracking. This "passive defense" design philosophy is no longer sufficient to meet the stringent requirements for the long-term service safety of materials under extreme hydrogen environments.

[0004] Therefore, the key to breaking through the existing technological bottlenecks lies in developing an innovative microstructure with a synergistic effect of "active guidance-gradient capture". By constructing a hydrogen trap array with spatial gradient distribution and directional hydrogen diffusion channels, the full-scale, progressive capture and harmless control of hydrogen atoms from the surface to the core can be achieved, thereby systematically improving the material's resistance to hydrogen embrittlement and damage tolerance. Summary of the Invention

[0005] The purpose of this invention is to address the problem of insufficient hydrogen embrittlement resistance and singular hydrogen trap distribution in existing high-manganese steels by proposing a high-manganese steel with a gradient TiC hydrogen trap barrier and its preparation method. The core of this invention lies in the precise control of hot rolling, asymmetric hot rolling, and heat treatment processes to construct a TiC precipitate phase distribution with a continuous spatial gradient within the material. This forms a multi-level interception and barrier system against invading hydrogen atoms, thereby significantly improving the high-manganese steel's resistance to embrittlement and its service reliability in hydrogen environments.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The purpose of this invention is to provide a high-manganese steel with a gradient TiC hydrogen trap barrier, wherein the mass percentage of each element is: C 0.45~0.5, Mn 23.90~24.10, Cr 3.25~3.5, Si 0.15~0.20, N 0.01~0.015, O 0.001~0.002, Ti 0.04~0.08, P≤0.004, S≤0.0001, and the balance is iron.

[0008] Preferably, the mass percentage of each element in the high-manganese steel is: C 0.46~0.49, Mn 23.95~24.05, Cr 3.25~3.35, Si 0.15~0.19, N 0.01~0.013, O 0.001~0.0015, Ti 0.04~0.07, P≤0.001, S≤0.0001.

[0009] This invention also provides a method for preparing the high-manganese steel with a gradient TiC hydrogen trapping barrier, comprising the following steps:

[0010] Step 1: Prepare high-manganese steel billets using a casting process, wherein the mass percentage of each element in the high-manganese steel billets is as described above;

[0011] Step 2: After homogenizing the high-manganese steel billet obtained in Step 1, it is hot rolled in five passes to obtain the steel plate. In the third to fifth passes of rolling, asymmetric rolling is adopted, and the ratio of the upper and lower roll linear speeds of asymmetric rolling is controlled between 1.1 and 1.3.

[0012] Step 3: After hot rolling, the steel plate obtained in Step 2 is air-cooled and then quenched.

[0013] Step 4: Temper the steel plate obtained in Step 3 to obtain the high manganese steel.

[0014] Preferably, in step two, the homogenization treatment is carried out at a temperature of 1250-1200℃, more preferably 1230-1220℃, for a time of 1-2 hours.

[0015] Preferably, in step two, the five-pass hot rolling of the steel billet includes: starting hot rolling at 1150~1100℃, wherein the temperature of the third pass is controlled at 920~890℃, and the final rolling temperature is 820~800℃. More preferably, the homogenized steel billet starts hot rolling at 1100℃, and asymmetric rolling is used in the third to fifth passes, with a roll diameter of 500mm, an upper roll speed of 24rpm, and a lower roll speed of 20rpm, so that the linear speed ratio of the upper and lower rolls is controlled at 1.2, the temperature of the third pass is controlled at 900℃, and the final rolling temperature is 800℃.

[0016] Preferably, in step two, the steel billet is hot rolled in five passes, with a total rolling deformation ranging from 50 mm to 10 mm, and the reduction rates for each pass are 24%, 26.3%, 28.6%, 30%, and 28.6%, respectively.

[0017] Preferably, in step three, the air cooling temperature is 780℃~760℃, more preferably 770℃, and the quenching treatment continues until the steel plate temperature drops to room temperature.

[0018] Preferably, in step four, the tempering temperature is 480-520℃, more preferably 490-500℃, and the holding time is 15-30 minutes, more preferably 20 minutes.

[0019] The high-manganese steel has a hydrogen embrittlement sensitivity of less than 20% and can be used in hydrogen energy equipment and hydrogen storage systems.

[0020] The design concept of this invention is as follows:

[0021] 1. Composition design: Ensure that the Ti content in the steel is higher than the N content, so that Ti preferentially combines with C to form TiC, avoiding the complete consumption of Ti elements in the formation of TiN, thereby ensuring a sufficient Ti source for the subsequent precipitation of gradient TiC.

[0022] 2. Homogenization treatment: Sufficient heat preservation in the high temperature range of 1250-1200℃ is carried out to achieve homogenization of the composition of the austenitic structure, laying the foundation for subsequent controlled phase transformation and precipitation.

[0023] 3. Introduction of dislocation and strain and TiC-controlled precipitation: Hot rolling is performed at 1150-1100℃, with asymmetric rolling applied in the third to fifth passes. By controlling the ratio of the upper and lower roll linear speeds between 1.1 and 1.3, a controllable dislocation density gradient and shear strain gradient are introduced in the thickness direction of the sheet. If asymmetric rolling is performed in the first or second pass, firstly, the hot rolling temperature is too high, and the resulting dislocations and shear strain are easily annihilated at high temperatures, resulting in a smaller rolling effect; secondly, the initial sheet thickness is large, and during asymmetric rolling, the strain penetration in the thickness direction is uneven, easily leading to severe deformation defects such as warping and camber, compromising sheet shape accuracy; furthermore, the large sheet thickness results in significant equipment wear. Therefore, asymmetric rolling is performed in the third pass. The temperature of the third pass is precisely controlled at 920-890℃, and the final rolling temperature is set at 820-800℃. This temperature range matches the precipitation window of TiC. The high dislocation density region provides abundant nucleation sites for TiC, while the strain field further induces and promotes the nucleation and early growth of TiC.

[0024] 4. Cooling and Precipitation Control: After rolling, air cooling is used, and the final cooling temperature is controlled at 780-760℃, which is below the TiC precipitation temperature range. This process allows sufficient growth time for the nucleated TiC while avoiding excessive coarsening of TiC particles due to excessive heat preservation or slow cooling.

[0025] 5. Stress relief and microstructure stabilization: Finally, tempering is carried out at 480-520℃ and held for 15-30 minutes to eliminate residual dislocations and internal stresses introduced by asymmetric rolling and stabilize the gradient microstructure.

[0026] Through the aforementioned synergistic process, the TiC precipitated phase of the prepared material exhibits a continuous gradient characteristic from the surface to the core, with the number density decreasing from high to low. This gradient TiC structure constructs a highly efficient "tiered hydrogen capture and barrier system".

[0027] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0028] By employing asymmetric rolling as a physical processing method, controllable dislocations and shear strain gradients are introduced. Dislocations provide nucleation sites for TiC, while shear strain induces TiC nucleation and precipitation. This achieves precise design from macroscopic mechanical field control to nanoscale second-phase distribution, forming a continuously varying TiC hydrogen trap gradient from the surface inwards. Furthermore, the constructed gradient TiC structure constitutes an efficient "tiered hydrogen capture and barrier system." The high-density, fine TiC on the surface acts as the "first barrier," maximizing the capture of initially invading hydrogen atoms; the internally gradient-reduced TiC acts as a "subsequent defense line," continuously capturing hydrogen that bypasses the surface. This design systematically extends the hydrogen capture path, reduces the concentration of diffusible hydrogen, and fundamentally inhibits the initiation and propagation of hydrogen-induced cracks.

[0029] Furthermore, the entire process is based entirely on traditional hot rolling and heat treatment procedures. High-performance gradient materials can be prepared simply by adjusting the rolling method (i.e., using asymmetric rolling) and optimizing the process window. This eliminates the need for complex and expensive surface modification or powder metallurgy equipment, making it easy to achieve industrial production. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flow chart of the heat treatment, cooling, and tempering process of the present invention.

[0032] Figure 2 The images show the gradient TiC precipitates in the high-manganese steel obtained in Example 1 (TEM), where (a) is 0.5 mm from the outer surface; (b) is 2.5 mm from the outer surface; (c) is 5 mm from the outer surface; (d) is 7.5 mm from the outer surface; (e) is the TiC precipitate (extraction); and (f) is the TiC energy spectrum.

[0033] Figure 3 The bar chart shows the hydrogen embrittlement sensitivity of the high-manganese steels obtained in Examples 1-7 and Comparative Examples 1-3.

[0034] Figure 4 SEM images of the fracture edge morphology of high manganese steel in Example 1 and Comparative Example 1. Detailed Implementation

[0035] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0036] Figure 1 This is a flow chart of the heat treatment, cooling, and tempering process of this invention. The invention involves hot rolling the billet at 1150-1100℃, followed by asymmetric rolling in the third to fifth passes to introduce a controllable dislocation density gradient and shear strain gradient along the thickness of the sheet. The temperature of the third pass is precisely controlled between 920-890℃, and the final rolling temperature is set at 820-800℃. This temperature range matches the precipitation window of TiC, providing abundant nucleation sites for TiC, while the strain field further induces and promotes the nucleation and early growth of TiC. After rolling, air cooling is used, with the final cooling temperature controlled at 760-780℃ to allow the nucleated TiC particles to grow. Finally, tempering is performed at 480-520℃ to eliminate residual dislocations and internal stresses introduced by asymmetric rolling, stabilizing the gradient microstructure.

[0037] Example 1

[0038] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤0.001%, S ≤0.0001%, all by mass) was subjected to high-temperature homogenization treatment at 1230℃ for 2 hours. Subsequently, it underwent five passes of hot rolling starting at 1100℃, with the third pass temperature controlled at 900℃ and the final rolling temperature at 800℃. Asymmetric rolling technology was used in the third to fifth passes, with each roll having a diameter of 500 mm, and the upper roll speed set at 24 rpm and the lower roll speed at 20 rpm. The rolling speed was rpm, with an upper and lower roll linear speed ratio of 1.2; the total rolling deformation ranged from 50 mm to 10 mm, and the reduction rates for each pass were 24%, 26.3%, 28.6%, 30%, and 28.6%, respectively. After hot rolling, the steel plate was air-cooled to 770℃, followed by quenching; finally, it was tempered at 480℃ for 20 min.

[0039] Figure 2 The images show the gradient TiC precipitates in the high-manganese steel obtained in Example 1. (a) shows the precipitates at a distance of 0.5 mm from the outer surface; (b) shows them at a distance of 2.5 mm from the outer surface; (c) shows them at a distance of 5 mm from the outer surface; (d) shows them at a distance of 7.5 mm from the outer surface; and (e) shows the TiC precipitates (extracted). Figures (a) to (e) are TEM images. Combined with the TiC energy dispersive spectroscopy (EDS) in (f), it can be seen that the precipitates in figures (a) to (e) are TiC, and the density of the precipitates decreases with increasing distance from the outer surface. This indicates that the high-manganese steel prepared in this example uses appropriate elemental content and hot-rolling process, resulting in an ideal microstructure.

[0040] Example 2

[0041] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.02%, P ≤0.001%, S ≤0.0001% (all by mass fraction)) was subjected to high-temperature homogenization treatment at 1230℃ and held for 2 hours. Subsequently, five passes of hot rolling were started at 1100℃, with the third pass temperature controlled at 900℃ and the final rolling temperature at 800℃. Asymmetric rolling process was used in the third to fifth passes, with roll diameters of 500 mm, upper roll speed of 24 rpm, lower roll speed of 20 rpm, and upper and lower roll linear speed ratio of 1.2. The total rolling deformation and reduction rate of each pass were the same as in Example 1. After hot rolling, the steel plate is air-cooled to 770℃ and then quenched; finally, it is tempered at 480℃ and held for 20 minutes.

[0042] Example 3

[0043] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤0.001%, S ≤0.0001% (all by mass fraction)) was subjected to high-temperature homogenization treatment at 1150℃ and held for 1 h. Subsequently, five passes of hot rolling were started at 1100℃, with the third pass rolling temperature controlled at 900℃ and the final rolling temperature at 800℃. Asymmetric rolling process was used in the third to fifth passes, with roll diameters of 500 mm, upper roll speed of 24 rpm, lower roll speed of 20 rpm, and upper and lower roll linear speed ratio of 1.2. The total rolling deformation and reduction rate of each pass were the same as in Example 1. After hot rolling, the steel plate is air-cooled to 770℃ and then quenched; finally, it is tempered at 480℃ and held for 20 minutes.

[0044] Example 4

[0045] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤0.001%, S ≤0.0001% (all by mass fraction)) was subjected to high-temperature homogenization treatment at 1230℃ and held for 2 hours. Subsequently, it was hot-rolled in five passes starting at 1100℃, with the third pass temperature controlled at 950℃ and the final rolling temperature at 850℃. Asymmetric rolling process was used in the third to fifth passes, with roll diameters of 500 mm, upper roll speed of 24 rpm, lower roll speed of 20 rpm, and upper and lower roll linear speed ratio of 1.2. The total rolling deformation and reduction rate of each pass were the same as in Example 1. After hot rolling, the steel plate is air-cooled to 770℃ and then quenched; finally, it is tempered at 480℃ and held for 20 minutes.

[0046] Example 5

[0047] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤0.001%, S ≤0.0001% (all by mass fraction)) was subjected to high-temperature homogenization treatment at 1230℃ and held for 2 hours. Subsequently, it was hot rolled in five passes starting at 1100℃, with the third pass temperature controlled at 900℃ and the final rolling temperature at 800℃. Asymmetric rolling process was used in the third to fifth passes, with roll diameters of 500 mm, upper roll speed of 24 rpm, lower roll speed of 15 rpm, and upper and lower roll linear speed ratio of 1.6. The total rolling deformation and reduction rate of each pass were the same as in Example 1. After hot rolling, the steel plate is air-cooled to 770℃ and then quenched; finally, it is tempered at 480℃ and held for 20 minutes.

[0048] Example 6

[0049] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤0.001%, S ≤0.0001% (all by mass fraction)) was subjected to high-temperature homogenization treatment at 1230℃ and held for 2 hours. Subsequently, five passes of hot rolling were started at 1100℃, with the third pass temperature controlled at 900℃ and the final rolling temperature at 800℃. Asymmetric rolling process was used in the third to fifth passes, with roll diameters of 500 mm, upper roll speed of 24 rpm, lower roll speed of 20 rpm, and upper and lower roll linear speed ratio of 1.2. The total rolling deformation and reduction rate of each pass were the same as in Example 1. After hot rolling, the steel plate is air-cooled to 740℃ and then quenched; finally, it is tempered at 480℃ and held for 20 minutes.

[0050] Example 7

[0051] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤0.001%, S ≤0.0001% (all by mass fraction) was subjected to high-temperature homogenization treatment at 1230℃ and held for 2 hours. Subsequently, it was hot rolled in five passes starting at 1100℃, with the third pass temperature controlled at 900℃ and the final rolling temperature at 800℃. In the third to fifth passes, an asymmetric rolling process was used, with roll diameters of 500 mm, upper roll speed of 24 rpm, lower roll speed of 20 rpm, and upper and lower roll linear speed ratio of 1.2. The total rolling deformation and reduction rate of each pass were the same as in Example 1. After hot rolling, the steel plate is air-cooled to 770℃ and then quenched; finally, it is tempered at 550℃ and held for 20 minutes.

[0052] Comparative Example 1

[0053] The chemical composition (mass fraction) of the high-manganese steel used is: C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, P ≤ 0.001%, S ≤ 0.0001%. The steel billet was subjected to high-temperature homogenization treatment at 1230℃ and held for 2 hours; subsequently, it was hot-rolled at 1100℃, with the third rolling pass temperature controlled at 900℃ and the final rolling temperature at 800℃; the total rolling deformation ranged from 50mm to 10mm, and the reduction rates for each pass were 24%, 26.3%, 28.6%, 30%, and 28.6% respectively; after rolling, it was immediately quenched to room temperature.

[0054] Comparative Example 2

[0055] The chemical composition (mass fraction) of the high-manganese steel used is as follows: C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤ 0.001%, S ≤ 0.0001%. The steel billet was subjected to high-temperature homogenization treatment at 1230℃ for 2 hours; subsequently, it was hot-rolled at 1100℃, with the third rolling pass temperature controlled at 900℃ and the final rolling temperature at 800℃; the total rolling deformation and reduction rate of each pass were the same as in Comparative Example 1; after rolling, it was immediately quenched to room temperature.

[0056] Comparative Example 3

[0057] The high-manganese steel was processed using the following process: First, a steel billet with the following composition (C 0.46%, Mn 24.01%, Cr 3.25%, Si 0.15%, N 0.01%, O 0.001%, Ti 0.05%, P ≤0.001%, S ≤0.0001% (all by mass fraction)) was subjected to high-temperature homogenization treatment at 1230℃ and held for 2 hours. Subsequently, it was hot-rolled in five passes at 1100℃, with the third pass temperature controlled at 900℃ and the final rolling temperature at 800℃. The total rolling deformation and reduction rate of each pass were the same as in Comparative Example 1. After hot rolling, the steel plate was air-cooled to 770℃ and then quenched. Finally, it was tempered at 480℃ and held for 20 minutes.

[0058] The plates processed according to the above examples and comparative examples were processed into standard tensile specimens and placed in a mixed electrolyte composed of 3% mol / L NaOH and 0.3 g / L thiourea, using 50 A / m 2 The sample was subjected to electrochemical hydrogen charging for 72 h at a current density of [value missing]. Following hydrogen charging, a tensile treatment was performed at a slow tensile strain rate of 2.5 × 10 [value missing]. -4 s -1 The mechanical properties are shown in Table 1.

[0059] Table 1. Mechanical property test results of Examples 1-7 and Comparative Examples 1-2

[0060]

[0061] According to the data in Table 1, in Example 1, after austenite homogenization treatment at 1230℃, rolling deformation was performed, with an asymmetric rolling process used in the third pass. This process introduced a high dislocation density and a significant strain gradient into the material. Dislocations, acting as effective nucleation sites, promoted the precipitation and nucleation of TiC particles; simultaneously, the gradient distribution of shear strain further guided TiC to exhibit gradient nucleation. Subsequently, air cooling to 770℃ allowed the TiC particles to initially grow, followed by immediate quenching to suppress further coarsening of TiC. Finally, tempering was performed at 480℃ to eliminate residual dislocations and strain, stabilizing the material's microstructure and properties.

[0062] Compared to Example 1, Example 2 shows a reduced Ti content, resulting in fewer TiC particles formed in the matrix and increased hydrogen embrittlement sensitivity. Example 3, compared to Example 1, has a shorter high-temperature homogenization holding time, leading to incomplete austenite homogenization and reduced mechanical properties, further affecting hydrogen embrittlement sensitivity. Example 4, compared to Example 1, features higher asymmetric rolling temperatures in the third to fifth passes, partially eliminating dislocation density and strain gradient, thus reducing the number of TiC nuclei and increasing hydrogen embrittlement sensitivity. Example 5, compared to Example 1, significantly increased the ratio of upper and lower roll linear speeds, promoting increased TiC nucleation density. However, despite the increased TiC density, higher dislocation density and shear strain lead to decreased mechanical properties and increased hydrogen embrittlement sensitivity. Example 6, compared to Example 1, has a lower hot-rolled air-cooling temperature, promoting TiC particle growth and reducing mechanical properties, but also resulting in lower hydrogen embrittlement sensitivity. Compared to Example 1, Example 7 shows a higher tempering temperature, resulting in more significant elimination of residual stress. This is manifested in a more thorough elimination of residual dislocations and shear strain, leading to improved mechanical properties without affecting the TiC gradient distribution and minimal impact on hydrogen embrittlement sensitivity. In Examples 1-7 above, TiC particles are all distributed in a gradient within the matrix.

[0063] Compared to Example 1, Comparative Example 1 did not undergo asymmetric rolling or the addition of Ti, resulting in a carbide without TiC, leading to higher hydrogen embrittlement sensitivity. Comparative Example 2, compared to Example 1, did not undergo asymmetric rolling or tempering, resulting in TiC uniformly distributed in the matrix without a gradient distribution, also leading to higher hydrogen embrittlement sensitivity. Comparative Example 3, compared to Example 1, did not undergo asymmetric rolling, resulting in TiC uniformly distributed in the matrix without a gradient distribution, also leading to higher hydrogen embrittlement sensitivity.

[0064] Figure 3 The table shows bar charts illustrating the hydrogen embrittlement susceptibility of high-manganese steels obtained in Examples 1-7 and Comparative Examples 1-3. The comparison reveals that the Ti-containing high-manganese steel exhibits better hydrogen embrittlement susceptibility. Table 1 indicates that Example 1 demonstrates the best overall performance and also exhibits good hydrogen embrittlement susceptibility. Comparative Example 1, using a conventional process and lacking Ti, exhibits higher hydrogen embrittlement susceptibility.

[0065] Figure 4 SEM images show the fracture edge morphology of the high-manganese steel in Example 1 and Comparative Example 1. The high-manganese steel in Example 1 exhibits gradient TiC precipitates and numerous dimples at the fracture edge, indicating good plasticity. The high-manganese steel in Comparative Example 1 lacks gradient TiC precipitates, and its fracture surface shows almost no dimples.

[0066] As can be seen from the above embodiments and comparative examples, this invention involves high-temperature homogenization treatment of high-manganese steel with a specific composition, followed by the introduction of an asymmetric rolling process during the low-temperature stage of hot rolling. The resulting dislocation density gradient and shear strain gradient induce a continuous and controllable gradient distribution of TiC precipitates along the thickness direction. Subsequently, the microstructure is fixed through quenching, and residual dislocations and shear strain are eliminated by low-temperature tempering. This method synergistically regulates the second-phase precipitation behavior through the dislocation field and strain field, and the process is simple.

[0067] The prepared high-manganese steel exhibits a continuous gradient distribution of TiC from the surface to the core, decreasing in density, thus constructing a highly efficient "tiered hydrogen capture and barrier system." This system significantly delays hydrogen atom penetration and reduces the concentration of diffusible hydrogen in the material. In this "tiered hydrogen capture and barrier system," the high-density, fine TiC on the surface acts as the "first line of defense," maximizing the capture and anchoring of initially invading hydrogen atoms. The TiC gradient decreasing with depth in the interior forms a "deep defense line," continuously capturing and slowing down hydrogen crossing the surface barrier. This systematically inhibits hydrogen diffusion and accumulation, significantly improving the material's resistance to hydrogen embrittlement.

[0068] Experiments show that this material exhibits significantly lower plasticity loss under harsh electrolytic hydrogen charging conditions compared to traditional homogeneous structural materials, demonstrating superior resistance to hydrogen embrittlement. This high-manganese steel is suitable for critical load-bearing components sensitive to hydrogen embrittlement, such as hydrogen energy equipment and hydrogen storage systems, and has significant engineering application prospects.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-manganese steel with a gradient TiC hydrogen trapping barrier, characterized in that, The mass percentages of each element are as follows: C 0.45~0.5, Mn 23.90~24.10, Cr 3.25~3.5, Si 0.15~0.20, N 0.01~0.015, O 0.001~0.002, Ti 0.04~0.08, P≤0.004, S≤0.0001, with the balance being iron.

2. The high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 1, characterized in that, The mass percentage of each element in the high-manganese steel is as follows: C 0.46~0.49, Mn 23.95~24.05, Cr 3.25~3.35, Si 0.15~0.19, N 0.01~0.013, O 0.001~0.0015, Ti 0.04~0.07, P≤0.001, S≤0.0001.

3. The method for preparing high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 1 or 2, characterized in that, The method includes the following steps: Step 1: Prepare high-manganese steel billets using a casting process; Step 2: After homogenizing the high-manganese steel billet obtained in Step 1, it is hot rolled in five passes to obtain the steel plate. In the third to fifth passes of rolling, asymmetric rolling is adopted, and the ratio of the upper and lower roll linear speeds of asymmetric rolling is controlled between 1.1 and 1.

3. Step 3: After hot rolling, the steel plate obtained in Step 2 is air-cooled and then quenched. Step 4: Temper the steel plate obtained in Step 3 to obtain the high manganese steel.

4. The method for preparing high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 3, characterized in that, In step two, the homogenization treatment is carried out at a temperature of 1250-1200℃, preferably 1230-1220℃, for a time of 1-2 hours.

5. The method for preparing high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 3, characterized in that, In step two, the steel billet undergoes five hot rolling passes, including starting hot rolling at 1150~1100℃, with the third pass temperature controlled at 920~890℃ and the final rolling temperature at 820~800℃.

6. The method for preparing high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 5, characterized in that, After homogenization, the steel billet is hot rolled at 1100℃. Asymmetric rolling is used in the third to fifth passes. The diameter of the rolls is 500mm, the upper roll speed is 24rpm, and the lower roll speed is 20rpm, so that the ratio of the upper and lower roll linear speeds is controlled at 1.

2. The temperature of the third pass is controlled at 900℃, and the final rolling temperature is 800℃.

7. The method for preparing high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 5 or 6, characterized in that, In step two, the steel billet is hot rolled in five passes, with a total rolling deformation ranging from 50 mm to 10 mm. The reduction rates for each pass are 24%, 26.3%, 28.6%, 30%, and 28.6%, respectively.

8. The method for preparing high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 3, characterized in that, In step three, the air cooling temperature is 780℃~760℃, preferably 770℃, and the quenching treatment continues until the steel plate temperature drops to room temperature.

9. The method for preparing high-manganese steel with a gradient TiC hydrogen trapping barrier according to claim 3, characterized in that, In step four, the tempering temperature is 480-520℃, preferably 490-500℃, and the holding time is 15-30 minutes, preferably 20 minutes.

10. The application of high-manganese steel prepared by the method according to any one of claims 3 to 9 in the field of hydrogen energy equipment and hydrogen storage systems, characterized in that, The hydrogen embrittlement sensitivity of the high-manganese steel is less than 20%.

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