An ods steel and a method of making the same

Abstract

The present application relates to the technical field of steel metallurgy, and particularly relates to an ODS steel and a preparation method thereof, the preparation raw material of the ODS steel provided by the present application comprises a steel alloy and a yttrium salt, the amount of the yttrium salt is 0.4%-1.1% of the mass of the steel alloy; the yttrium salt is selected from one or both of yttrium acetate and yttrium carbonate. The ODS steel provided by the present application solves the defects that the oxide reinforcing phase particles are prone to agglomeration, uneven in size and uneven in distribution when the ODS steel is prepared by directly adding oxide powder (such as yttrium oxide) in the prior art, realizes the uniform and dispersed distribution of the nanoscale oxide reinforcing phase in the steel matrix, and thus significantly improves the comprehensive mechanical properties of the ODS steel, such as the strength, plasticity, toughness and high-temperature creep resistance.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to an ODS steel and its preparation method. Background Technology

[0002] 9%-12%Cr martensitic heat-resistant steel has become the preferred structural material for lead-cooled fast reactors due to its excellent thermal conductivity, outstanding resistance to radiation swelling, and low coefficient of thermal expansion. However, with the maturation and commercial application of lead-cooled fast reactor technology, its economic issues are becoming increasingly prominent. Future core design temperatures will gradually increase to 650℃ or higher, and 9%-12%Cr martensitic heat-resistant steel will no longer be able to meet the structural material requirements of future lead-cooled fast reactors, necessitating the development of new structural materials.

[0003] The formation of oxide dispersion strengthened (ODS) steel, which involves uniformly dispersing nanoscale, thermally stable oxide particles (such as Y₂O₃ and Al₂O₃) in 9%-12% Cr martensitic heat-resistant steel, is one of the most promising development directions for lead-cooled fast reactor structural materials. The large number of uniformly distributed nanoscale oxide particles in ODS steel not only inhibit grain growth and significantly improve the high-temperature creep strength of the material, but also pin dislocations, further enhancing the mechanical properties of the alloy. Under irradiation, the nanoparticles in ODS steel can effectively adsorb point defects and transmutated helium caused by irradiation, significantly inhibiting irradiation swelling and hardening, and improving radiation resistance. Simultaneously, ODS steel exhibits excellent anti-swelling and corrosion resistance, demonstrating extremely high stability in high-temperature and high-radiation environments. The numerous phase interfaces between ODS steel and the steel matrix effectively inhibit the diffusion of alloying elements and reduce the corrosion rate of liquid metal. Therefore, compared with traditional 9%-12% Cr martensitic heat-resistant steel, ODS steel exhibits superior performance in high-temperature mechanics, irradiation, and corrosion.

[0004] Despite the excellent properties of ODS steel, its complex manufacturing process and low efficiency remain major bottlenecks for large-scale engineering applications. Mechanical alloying is a common method for preparing ODS steel, typically involving ball milling of elemental powders of Y₂O₃, Fe, and other alloying elements. This allows Y₂O₃ to dissolve into the matrix during alloying. However, for hard alloying elements, this method requires a long milling time and is prone to uneven distribution. Another method involves ball milling iron-based pre-alloyed powder with Y₂O₃ powder. These methods involve directly adding Y₂O₃ powder for milling, but achieving supersaturated solution of Y₂O₃ requires a long milling time, typically exceeding 40 hours. This significantly reduces manufacturing efficiency and increases the risk of powder contamination. Summary of the Invention

[0005] This invention provides an ODS steel and its preparation method, which solves the defects in the prior art when preparing ODS steel by directly adding oxide powder (such as yttrium oxide), where the oxide reinforcing phase particles are prone to agglomeration, uneven size and distribution. This invention achieves uniform dispersion of nano-scale oxide reinforcing phase in the steel matrix, thereby significantly improving the comprehensive mechanical properties of ODS steel.

[0006] According to a first aspect of the present invention, the present invention provides an ODS steel, the raw materials for which are prepared include a steel alloy and a yttrium salt, wherein the amount of the yttrium salt is 0.4%-1.1% of the mass of the steel alloy; wherein the yttrium salt is selected from one or two of yttrium acetate and yttrium carbonate.

[0007] The ODS steel provided by this invention uses a specific type of yttrium salt as the yttrium source precursor, replacing the existing method of directly adding yttrium oxide powder. This fundamentally solves the technical problem of easy agglomeration and uneven distribution of oxide reinforcing phases. This method enables the in-situ formation of smaller, more uniformly distributed nanoscale oxide dispersion reinforcing phases during the ODS steel preparation process. Due to the obtained ideal dispersion-reinforced microstructure, the ODS steel prepared by this invention exhibits significantly improved comprehensive mechanical properties, particularly the ability to simultaneously improve the material's strength (e.g., tensile strength) and ductility (e.g., elongation), effectively addressing the difficulty in achieving both simultaneously in traditional ODS steels.

[0008] In the ODS steel according to the present invention, the amount of yttrium salt used is 0.5%-0.85% of the mass of the steel alloy.

[0009] According to the ODS steel of the present invention, the yttrium salt has a particle size of 80 nm-120 nm. This particle size range ensures that the yttrium salt can achieve a higher degree of uniform mixing with the steel alloy powder, laying a microscopic and uniform foundation for subsequent reactions; particles of this size have a huge specific surface area and high reactivity, which can promote more complete and uniform in-situ decomposition and oxidation of the yttrium salt during the preparation process.

[0010] According to the ODS steel of the present invention, the particle size of the steel alloy is ≤25µm (preferably 6µm-25µm). This particle size range provides more and more uniform adhesion sites for the nanoscale yttrium salt precursor, thereby ensuring uniform microscale distribution during the mechanical mixing stage.

[0011] According to the ODS steel of the present invention, the composition of the steel alloy, by mass percentage, includes: 0.1%-0.3%C, 0.5%-2.0%Si, 9%-12%Cr, 1.0%-2.0%W, 0.2%-0.3%V, 0.08%-0.15%Ta, 0.4%-0.5%Mn, 0.07%-0.08%Ni, with the balance being Fe.

[0012] In this invention, 9%-12% Cr imparts excellent high-temperature oxidation and corrosion resistance to the steel matrix, while the combined addition of strong carbide-forming elements such as W, V, and Ta enables the formation of fine and stable carbide precipitates in the steel matrix, achieving both solid solution strengthening and precipitation strengthening. The careful formulation of the matrix alloy composition in this invention results in ODS steel with excellent room-temperature strength and ductility.

[0013] According to the ODS steel of the present invention, the ultimate tensile strength of the ODS steel is 750MPa-950MPa and the elongation is 18%-25%.

[0014] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-described ODS steel, comprising the following steps: Steel alloy powder was prepared by gas atomization. The steel alloy powder was mixed with yttrium salt powder and then ball-milled to obtain precursor powder. The precursor powder was sintered using spark plasma technology. The sintered alloy is then subjected to heat treatment.

[0015] The method for preparing ODS steel provided by this invention first uses gas atomization to prepare steel alloy powder with uniform particle size and good sphericity, providing a high-quality matrix raw material for subsequent uniform mixing. Subsequently, mechanical alloying is performed through high-energy ball milling, where the yttrium salt precursor is forcibly broken down at the nanoscale and embedded and coated within the steel alloy powder particles under high-energy impact, thereby obtaining an extremely uniform composite precursor powder at the microscopic level. Utilizing the extremely fast heating rate and short sintering time of spark plasma sintering technology, the in-situ decomposition and oxidation of yttrium salt can be instantly triggered while rapidly densifying the powder, forming dispersed nano-oxides. This effectively inhibits the growth and agglomeration of these newly formed oxide particles and significantly suppresses the growth of steel matrix grains, thereby obtaining an ultrafine-grained matrix structure and achieving fine-grain strengthening. The final heat treatment step can regulate the phase structure of the steel matrix (such as forming tempered martensite) and promote the precipitation of second-phase carbides by alloying elements (W, V, Ta, etc.), thereby fully tapping the strengthening potential of the high-performance matrix itself and forming a perfect match with the already formed oxide dispersion strengthening mechanism.

[0016] According to the method for preparing ODS steel of the present invention, the diameter of the grinding balls in the ball mill is 3mm-5mm, the mass ratio of the balls to the powder is (4-6):1, the ball milling time is 15h-24h, and the ball milling speed is 250rpm-350rpm.

[0017] This invention synergistically optimizes the ball milling process parameters (milling ball size, ball-to-powder ratio, time, and rotation speed) to prepare micro-uniform composite precursor powder from the source, thereby ensuring the subsequent in-situ generation of finer and more dispersed nano-oxides, which can further and more stably improve the final comprehensive mechanical properties of ODS steel.

[0018] According to the method for preparing ODS steel of the present invention, the initial sintering pressure is 8MPa-12MPa, the sintering temperature is 950℃-1100℃, the heating rate is 80℃ / min-120℃ / min, the holding time is 3min-10min, and the sintering pressure is 40MPa-50MPa; the sintering atmosphere is a vacuum environment.

[0019] This invention optimizes the spark plasma sintering process, enabling control over the transformation of precursor powder into a dense alloy state, and stably obtaining an ideal microstructure with uniformly dispersed ultrafine-grained matrix and nano-oxides. Specifically, a non-equilibrium rapid sintering strategy employing rapid heating (80℃ / min-120℃ / min) and short-time holding (3min-10min) effectively suppresses the growth and agglomeration of steel matrix grains and in-situ generated nano-oxides from a kinetic perspective, successfully solidifying and preserving the uniform microstructure obtained in the preceding process into the final material. Simultaneously, a two-stage pressurization strategy—low-pressure pre-pressurization followed by high-pressure sintering—combined with a vacuum environment, ensures that the material achieves increased densification while eliminating internal defects and avoiding high-temperature oxidation.

[0020] According to the method for preparing ODS steel of the present invention, the heat treatment involves heating the sintered alloy to 1000℃-1100℃ at a heating rate of 3℃ / min-10℃ / min and holding it at that temperature for 20min-40min; then cooling it to room temperature and then heating the alloy to 700℃-800℃ and holding it at that temperature for 50min-70min; the heat treatment is carried out under an argon atmosphere.

[0021] This invention employs an optimized two-stage heat treatment process to finely control the microstructure of the sintered alloy matrix, thereby fully activating the material's intrinsic performance potential and forming a perfect synergistic effect with existing oxide dispersion strengthening, thus obtaining ODS steel with a perfect match between strength and toughness and excellent high-temperature performance.

[0022] According to the method for preparing ODS steel of the present invention, the gas atomization method is carried out under inert gas protection and the atomization gas pressure is 0.5MPa-2.0MPa.

[0023] This invention involves melting various metallic elements and then breaking down and dispersing the high-temperature alloy melt into numerous micron-sized droplets using a gas atomization method. These droplets achieve extremely high supercooling due to a dramatic increase in specific surface area, causing them to solidify instantaneously during flight, forming alloy powder with high sphericity and uniform composition. This promotes the homogeneous distribution of alloying elements, resulting in a more uniform distribution during subsequent forming. This avoids the difficulties in alloying hard elements and uneven element distribution encountered in mechanical alloying for steel powder preparation.

[0024] The beneficial effects of this invention are: The ODS steel provided by this invention uses a specific type of nano-sized yttrium salt as a precursor and precisely controls the particle size of the steel alloy matrix powder. Combined with an optimized low-energy, long-term ball milling process, a micro-mixed, highly uniform composite precursor powder is prepared from the source. Then, a rapid heating and short-time holding discharge plasma sintering process is employed to achieve rapid material densification while successfully realizing the in-situ generation of nano-oxides and effectively suppressing the growth of matrix grains and reinforcing phase particles. Finally, combined with high-performance alloy composition design and a two-stage fine heat treatment process, dispersed nano-carbides are further precipitated in the ultrafine-grained steel matrix. This invention fundamentally solves the technical problem of easy agglomeration and uneven distribution of the reinforcing phase in traditional ODS steel, leading to unstable performance, and achieves excellent comprehensive mechanical properties with synergistic improvements in strength, ductility, toughness, and high-temperature creep resistance. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a process flow diagram of an ODS steel preparation method provided in Embodiment 1 of the present invention.

[0027] Figure 2 This is a tensile property curve of ODS steel at room temperature provided in the embodiments and comparative examples of the present invention.

[0028] Figure 3 These are the fracture SEM and EDS images of ODS steel provided in Embodiments 1, 2, 2, and 3 of the present invention; wherein, (a) is the fracture SEM and EDS image of ODS steel provided in Embodiment 1; (b) is the fracture SEM and EDS image of ODS steel provided in Embodiment 2; (c) is the fracture SEM and EDS image of ODS steel provided in Comparative Example 3; and (d) is the fracture SEM and EDS image of ODS steel provided in Comparative Example 2. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] Example 1 This embodiment provides an ODS steel, the raw materials for which include steel alloy and yttrium salt, wherein the amount of yttrium salt is 0.82% of the mass of the steel alloy; wherein the yttrium salt is selected from yttrium acetate.

[0031] This embodiment also provides a method for preparing the ODS steel, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps: (1) Preparation of steel alloy powder by gas atomization: High-purity raw materials such as Fe, Cr, W, Si, Mn, C, V, Ta, and Ni were accurately weighed according to their mass percentages. The alloy melt was obtained by vacuum induction, and then gas atomized under atomizing pressure of 1.5 MPa and protection of high-purity argon to obtain spherical powder. The particle size distribution of the obtained powder was 6 μm-25 μm, and its specific composition was: 0.204% C, 0.71% Si, 11% Cr, 1.47% W, 0.2% V, 0.083% Ta, 0.42% Mn, 0.079% Ni, with the balance being Fe.

[0032] (2) Preparation of precursor powder: According to the mass fraction of yttrium acetate in steel alloy powder being 0.82%, steel alloy powder and yttrium acetate powder with a particle size of 100 nm were weighed and placed in a cemented carbide ball milling jar. Cemented carbide grinding balls with a diameter of 4 mm and a ball-to-powder mass ratio of 5:1 were added. The ball milling jar was sealed in an argon atmosphere vacuum glove box and then placed in a high-energy ball mill at a speed of 300 rpm for 15 h.

[0033] (3) Sintering: The ball-milled precursor powder is loaded into a graphite sintering mold, and the mold wall is isolated from the powder with carbon paper. The mold is placed in a discharge plasma sintering furnace and the furnace is evacuated. The initial pressure is set to 10 MPa, the sintering temperature to 1050℃, the heating rate to 100℃ / min, the holding time to 10 min, and the sintering pressure to 50 MPa. The pressure is manually increased to the sintering pressure during the heating process. After the holding time is completed, the product is cooled in the furnace under vacuum conditions, and the carbon paper on the surface is polished with a grinding wheel.

[0034] (4) Annealing treatment: The sintered sample is placed in a heat treatment furnace and heated to 1050°C at a heating rate of 5°C / min under an argon atmosphere. The temperature is held for 30 min. After cooling to room temperature, the sample is heated to 750°C and held for 60 min. After cooling, the sample is taken out.

[0035] Example 2 This embodiment provides an ODS steel, the raw materials for which include steel alloy and yttrium salt, wherein the amount of yttrium salt is 0.55% of the mass of the steel alloy; wherein the yttrium salt is selected from yttrium carbonate.

[0036] This embodiment also provides a method for preparing the ODS steel, including the following steps: (1) Preparation of steel alloy powder by gas atomization: High-purity raw materials such as Fe, Cr, W, Si, Mn, C, V, Ta, and Ni were accurately weighed according to their mass percentages. The alloy melt was obtained by vacuum induction, and then gas atomized under atomizing pressure of 1.5 MPa and protection of high-purity argon to obtain spherical powder. The particle size distribution of the obtained powder was 6 μm-25 μm, and its specific composition was: 0.204% C, 0.71% Si, 11% Cr, 1.47% W, 0.2% V, 0.083% Ta, 0.42% Mn, 0.079% Ni, with the balance being Fe.

[0037] (2) Preparation of precursor powder: According to the mass fraction of yttrium carbonate in steel alloy powder being 0.55%, steel alloy powder and yttrium carbonate powder with a particle size of 100 nm were weighed and placed in a cemented carbide ball milling jar. Cemented carbide grinding balls with a diameter of 4 mm and a ball-to-powder mass ratio of 5:1 were added. The ball milling jar was sealed in an argon atmosphere vacuum glove box and then placed in a high-energy ball mill at a speed of 300 rpm for 15 h.

[0038] (3) Sintering: The ball-milled precursor powder is loaded into a graphite sintering mold, and the mold wall is isolated from the powder with carbon paper. The mold is placed in a discharge plasma sintering furnace and the furnace is evacuated. The initial pressure is set to 10 MPa, the sintering temperature to 1050℃, the heating rate to 100℃ / min, the holding time to 10 min, and the sintering pressure to 50 MPa. The pressure is manually increased to the sintering pressure during the heating process. After the holding time is completed, the product is cooled in the furnace under vacuum conditions, and the carbon paper on the surface is polished with a grinding wheel.

[0039] (4) Annealing treatment: The sintered sample is placed in a heat treatment furnace and heated to 1050°C at a heating rate of 5°C / min under an argon atmosphere. The temperature is held for 30 min. After cooling to room temperature, the sample is heated to 750°C and held for 60 min. After cooling, the sample is taken out.

[0040] Comparative Example 1 This comparative example provides a method for preparing steel, the specific preparation method being as follows: (1) Preparation of steel alloy powder by gas atomization: High-purity raw materials such as Fe, Cr, W, Si, Mn, C, V, Ta, and Ni were accurately weighed according to their mass percentages. The alloy melt was obtained by vacuum induction, and then gas atomized under atomizing pressure of 1.5 MPa and protection of high-purity argon to obtain spherical powder. The particle size distribution of the obtained powder was 6 μm-25 μm, and its specific composition was: 0.204% C, 0.71% Si, 11% Cr, 1.47% W, 0.2% V, 0.083% Ta, 0.42% Mn, 0.079% Ni, with the balance being Fe.

[0041] (2) Sintering and forming: The powder is loaded into the graphite sintering mold, and the mold wall is isolated from the powder with carbon paper. The mold is placed in the discharge plasma sintering furnace and the sintering furnace is evacuated. The initial pressure is set to 10 MPa, the sintering temperature is 1050℃, the heating rate is 100℃ / min, the holding time is 10 min, and the sintering pressure is 50 MPa. The pressure is manually increased to the sintering pressure during the heating process. After the holding time is completed, the product is cooled with the furnace under vacuum conditions, and the carbon paper on the surface is polished with a grinding wheel.

[0042] (3) Annealing treatment: The sintered sample is placed in a heat treatment furnace and heated to 1050°C at a heating rate of 5°C / min under an argon atmosphere. The temperature is held for 30 min. After cooling to room temperature, the sample is heated to 750°C and held for 60 min. After cooling, the sample is taken out.

[0043] Comparative Example 2 This comparative example provides an ODS steel and its preparation method, wherein the preparation method is specifically as follows: (1) Preparation of steel alloy powder by gas atomization: High-purity raw materials such as Fe, Cr, W, Si, Mn, C, V, Ta, and Ni were accurately weighed according to their mass percentages. The alloy melt was obtained by vacuum induction, and then gas atomized under atomizing pressure of 1.5 MPa and protection of high-purity argon to obtain spherical powder. The particle size distribution of the obtained powder was 6 μm-25 μm, and the specific composition was: 0.204% C, 0.71% Si, 11% Cr, 1.47% W, 0.2% V, 0.083% Ta, 0.42% Mn, 0.079% Ni, with the balance being Fe.

[0044] (2) Preparation of precursor powder: According to the mass fraction of yttrium oxide in steel alloy powder being 0.35%, steel alloy powder and yttrium oxide powder with a particle size of 100 nm were weighed and placed in a cemented carbide ball milling jar. Cemented carbide grinding balls with a diameter of 4 mm and a ball-to-powder mass ratio of 5:1 were added. The ball milling jar was sealed in an argon atmosphere vacuum glove box and then placed in a high-energy ball mill at a speed of 300 rpm for 15 h.

[0045] (3) Sintering: The ball-milled precursor powder is loaded into a graphite sintering mold, and the mold wall is isolated from the powder with carbon paper. The mold is placed in a discharge plasma sintering furnace and the furnace is evacuated. The initial pressure is set to 10 MPa, the sintering temperature to 1050℃, the heating rate to 100℃ / min, the holding time to 10 min, and the sintering pressure to 50 MPa. The pressure is manually increased to the sintering pressure during the heating process. After the holding time is completed, the product is cooled in the furnace under vacuum conditions, and the carbon paper on the surface is polished with a grinding wheel.

[0046] (4) Annealing treatment: The sintered sample is placed in a heat treatment furnace and heated to 1050°C at a heating rate of 5°C / min under an argon atmosphere. The temperature is held for 30 min. After cooling to room temperature, the sample is heated to 750°C and held for 60 min. After cooling, the sample is taken out.

[0047] Comparative Example 3 This comparative example provides an ODS steel and its preparation method, wherein the preparation method is specifically as follows: (1) Preparation of steel alloy powder by gas atomization: High-purity raw materials such as Fe, Cr, W, Si, Mn, C, V, Ta, and Ni were accurately weighed according to their mass percentages. The alloy melt was obtained by vacuum induction, and then gas atomized under atomizing pressure of 1.5 MPa and protection of high-purity argon to obtain spherical powder. The particle size distribution of the obtained powder was 6 μm-25 μm, and the specific composition was: 0.204% C, 0.71% Si, 11% Cr, 1.47% W, 0.2% V, 0.083% Ta, 0.42% Mn, 0.079% Ni, with the balance being Fe.

[0048] (2) Preparation of precursor powder: According to the mass fraction of yttrium oxide in steel alloy powder being 0.35%, steel alloy powder and yttrium oxide powder with a particle size of 100 nm were weighed and placed in a cemented carbide ball milling jar. Cemented carbide grinding balls with a diameter of 4 mm and a ball-to-powder mass ratio of 5:1 were added. The ball milling jar was sealed in an argon atmosphere vacuum glove box and then placed in a high-energy ball mill at a speed of 300 rpm for 24 h.

[0049] (3) Sintering: The ball-milled precursor powder is loaded into a graphite sintering mold, and the mold wall is isolated from the powder with carbon paper. The mold is placed in a discharge plasma sintering furnace and the furnace is evacuated. The initial pressure is set to 10 MPa, the sintering temperature to 1050℃, the heating rate to 100℃ / min, the holding time to 10 min, and the sintering pressure to 50 MPa. The pressure is manually increased to the sintering pressure during the heating process. After the holding time is completed, the product is cooled in the furnace under vacuum conditions, and the carbon paper on the surface is polished with a grinding wheel.

[0050] (4) Annealing treatment: The sintered sample is placed in a heat treatment furnace and heated to 1050°C at a heating rate of 5°C / min under an argon atmosphere. The temperature is held for 30 min. After cooling to room temperature, the sample is heated to 750°C and held for 60 min. After cooling, the sample is taken out.

[0051] The room temperature tensile properties were tested according to GB / T 228.1-2021 standard and passed. Figure 2 It can be seen that the tensile strengths of ODS steels prepared using yttrium acetate and yttrium carbonate as yttrium precursors are 948.09 MPa and 767.16 MPa, respectively, with elongations of 18.31% and 24.92%, respectively. The ultimate tensile strengths of ODS steels prepared by directly adding yttrium oxide (Comparative Examples 2 and 3) and without yttrium addition are 628.38 MPa, 688.26 MPa, and 648.60 MPa, respectively, with elongations of 8.69%, 6.70%, and 25.43%, respectively. ODS steels prepared using yttrium carbonate and yttrium acetate as yttrium precursors can significantly improve their tensile strength while maintaining good plasticity. Figure 3 It is known that using yttrium precursors to prepare ODS steel can achieve a uniform distribution of the dispersed phase in a shorter ball milling time.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ODS steel, characterized in that, The raw materials for its preparation include steel alloy and yttrium salt, wherein the amount of yttrium salt is 0.4%-1.1% of the mass of the steel alloy; wherein the yttrium salt is selected from one or two of yttrium acetate and yttrium carbonate; the composition of the steel alloy by mass percentage includes: 0.1%-0.3% C, 0.5%-2.0% Si, 9%-12% Cr, 1.0%-2.0% W, 0.2%-0.3% V, 0.08%-0.15% Ta, 0.4%-0.5% Mn, 0.07%-0.08% Ni, with the balance being Fe.

2. The ODS steel according to claim 1, characterized in that, The yttrium salt has a particle size of 80nm-120nm.

3. The ODS steel according to claim 1, characterized in that, The particle size of the steel alloy is ≤25µm.

4. The ODS steel according to any one of claims 1-3, characterized in that, The ultimate tensile strength of the ODS steel is 750MPa-950MPa, and the elongation is 18%-25%.

5. The method for preparing ODS steel according to any one of claims 1-4, characterized in that, Includes the following steps: Steel alloy powder was prepared by gas atomization. The steel alloy powder was mixed with yttrium salt powder and then ball-milled to obtain precursor powder. The precursor powder was sintered using spark plasma technology. The sintered alloy is then subjected to heat treatment.

6. The method for preparing ODS steel according to claim 5, characterized in that, The diameter of the grinding balls in the ball mill is 3mm-5mm, the ball-to-powder mass ratio is (4-6):1, the grinding time is 15h-24h, and the grinding speed is 250rpm-350rpm.

7. The method for preparing ODS steel according to claim 5, characterized in that, The initial pressure of the sintering is 8MPa-12MPa, the sintering temperature is 950℃-1100℃, the heating rate is 80℃ / min-120℃ / min, the holding time is 3min-10min, and the sintering pressure is 40MPa-50MPa; the sintering atmosphere is a vacuum environment.

8. The method for preparing ODS steel according to claim 5, characterized in that, The heat treatment involves heating the sintered alloy to 1000℃-1100℃ at a heating rate of 3℃ / min-10℃ / min and holding it at that temperature for 20min-40min; then cooling it to room temperature and heating the alloy to 700℃-800℃ again and holding it at that temperature for 50min-70min; the heat treatment is carried out in an argon atmosphere.

9. The method for preparing ODS steel according to claim 5, characterized in that, The gas atomization method is carried out under inert gas protection and with an atomization pressure of 0.5MPa-2.0MPa.

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