Oxide dispersion strengthened RAFM steel and its preparation method and application

Abstract

The present invention relates to oxide-dispersion-strengthened (RAFM) steel, its preparation method, and its application, and belongs to the technical field of fusion reactor first wall material manufacturing. The preparation method of the present invention combines Y2O3 powder dispersion strengthening with SLM technology to produce fine-grained, high-performance oxide-dispersion-strengthened (RAFM) steel. The SLM rapid cooling process refines the grains, resulting in high mechanical properties that can even meet forging standards. The addition of Y2O3 particles can pin grain boundaries and dislocations, hindering dislocation movement, thereby improving strength, high-temperature creep life, and radiation resistance. This provides a solution for the manufacture of fusion reactor first wall structural components, better meeting the requirements of the fusion service environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of manufacturing first wall materials of fusion reactors, and in particular relates to oxide dispersion strengthened RAFM steel and a preparation method and application thereof. Background Art

[0002] In fusion reactors, key structural materials face very harsh service environments. The first wall of the blanket is the component directly facing the plasma in nuclear fusion. Its complex service environment requires the first wall structural material to have high temperature resistance, corrosion resistance, neutron irradiation resistance, low thermal expansion, high thermal conductivity, high mechanical properties and low activation requirements.

[0003] The first wall of the water-cooled ceramic cladding of the China Fusion Engineering Test Reactor (CFETR) features a thin, U-shaped structure, approximately 23 mm thick, and contains 54 internal flow channels for coolant heat dissipation. Due to its complex geometry, the processing and manufacturing of this first wall presents significant challenges. The overall U-shaped geometry and internal closed flow channels increase manufacturing complexity. Traditional machining processes require long cycles and struggle to meet precision requirements. Therefore, the use of additive manufacturing (AM) for integrated forming is becoming a key trend in the future manufacture of key fusion components. Low-activation ferrite / martensitic steel (RAFM steel) has become the most promising candidate material for the first wall of fusion reactors due to its high thermal conductivity and low coefficient of thermal expansion. However, during fusion reactor operation, prolonged exposure to high temperatures and irradiation can degrade material properties. Radiation damage alters the material's internal microstructure and reduces its mechanical properties. Structural materials used in second- and third-generation commercial reactors can only operate at temperatures below 350°C, while fusion reactors require service temperatures above 550°C, requiring materials with excellent high-temperature stability.

[0004] Therefore, it is of great significance to prepare a fusion reactor first wall material that can maintain a high creep life and resistance to radiation damage at high temperatures. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and to provide an oxide dispersion strengthened RAFM steel (ODS-RAFM steel) and a preparation method and application thereof.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing oxide dispersion strengthened RAFM steel, comprising the following steps:

[0008] (1) ball-milling RAFM steel powder and Y2O3 powder, and drying to obtain oxide dispersion-strengthened RAFM steel powder; the amount of Y2O3 powder added is 0.3wt%-0.7wt% of the RAFM steel powder;

[0009] (2) subjecting the oxide dispersion strengthened RAFM steel powder obtained in step (1) to selective laser melting (SLM) to obtain an oxide dispersion strengthened RAFM steel sample;

[0010] (3) The oxide dispersion strengthened RAFM steel sample obtained in step (2) is subjected to normalizing heat treatment and tempering heat treatment to obtain the oxide dispersion strengthened RAFM steel.

[0011] The preparation method of the present invention combines Y2O3 powder dispersion strengthening with SLM technology to produce fine-grained, high-performance oxide-dispersion-strengthened RAFM steel. The rapid cooling process of SLM refines the grains, resulting in high mechanical properties that can even meet forging standards. The addition of Y2O3 particles pins grain boundaries and dislocations, hindering dislocation movement, thereby improving strength, high-temperature creep life, and radiation resistance. This provides a solution for the manufacture of first-wall structural components for fusion reactors and better meets the requirements of fusion service environments. The present invention further improves the high-temperature creep life and high-temperature radiation resistance of oxide-dispersion-strengthened RAFM steel by optimizing the amount of Y2O3 powder added and adjusting the size of the Y2O3 particles.

[0012] Preferably, in step (1), the RAFM steel powder comprises the following components in mass percentage: Cr: 7.5%-10.1%, W: 0.5%-1.8%, Mn: 0.3%-1.0%, V: 0.3%-0.6%, Ni: 0.01%-0.03%, Si: 0.01%-0.2%, C: 0.06%-0.15%, Ta: 0.2%-0.35%, N: ≤300ppm, O: ≤320ppm, and the rest are Fe and impurity elements.

[0013] Specifically, the impurity elements include S, P, Al, Cu, Ag, Sn, B, As, and Sb, and the mass percentage of the impurity elements is ≤0.02%.

[0014] More preferably, in step (1), the RAFM steel powder comprises the following components in mass percentage: Cr: 7.5%-10.1%, W: 0.5%-1.8%, Mn: 0.3%-1.0%, V: 0.3%-0.6%, Ni: 0.02%-0.03%, Si: 0.01%-0.05%, C: 0.06%-0.15%, Ta: 0.26%-0.35%, N: ≤300ppm, O: ≤320ppm, and the rest are Fe and impurity elements.

[0015] The composition of RAFM steel also affects the performance of oxide-dispersion-strengthened RAFM steel. The RAFM steel powder of the present invention incorporates appropriate amounts of Ni and Si. A trace amount of Ni in the RAFM steel can improve the material's toughness and reduce the risk of radiation-induced grain boundary embrittlement. Ni, as a solid solution strengthening element, can reduce cracking during the SLM process and improve the material's weldability. However, if the Ni content is too low, the material's radiation resistance cannot be effectively improved. Excessive Ni content can cause high activation under irradiation, affecting material performance. The addition of Si helps deoxidize, improve the purity of the RAFM steel, and enhance its oxidation resistance. Silicon, as a solute atom, can capture vacancy defects, inhibit void swelling and dislocation loop coarsening, and improve radiation resistance. If the Si content is too low, the material's radiation resistance decreases, while excessive Si can lead to the formation of Laves phases, resulting in brittleness. Furthermore, the present invention also contains a relatively high amount of Ta, which can generate MX carbides and Y-Ta-O nanoprecipitated compounds, thereby improving the material's high-temperature creep and radiation resistance.

[0016] The present invention does not limit the preparation method of RAFM steel powder. Those skilled in the art can obtain the RAFM steel powder according to conventional methods in the field, such as gas atomization preparation. Specifically, the preparation method of the RAFM steel powder can include: melting, refining and degassing the raw materials of the RAFM steel components in a vacuum induction furnace, placing the molten alloy into a gas atomization nozzle system, and atomizing the alloy liquid into small droplets using an inert gas flow, followed by rapid solidification to form the RAFM steel powder.

[0017] Preferably, in step (1), the particle size range of the RAFM steel powder is 15 μm-53 μm, and D50 is 28.5 μm-33.5 μm.

[0018] Preferably, in step (1), the Y2O3 powder comprises the following components in mass percentage: CeO2: ≤0.0001%, Pr6O 11 :≤0.0005%, Nd2O3: ≤0.0005%, Sm2O3: ≤0.0005%, La2O3: ≤0.0005%, and the rest are Y2O3.

[0019] Specifically, the purity of Y2O3 in the Y2O3 powder is greater than 99.999%.

[0020] Preferably, in step (1), the particle size of the Y2O3 powder is in the range of 30nm-70nm, and D50 is 48nm-52nm.

[0021] Preferably, in the step (1), the ball milling mixing is carried out in an inert gas environment using a planetary ball mill, with a ball-to-material ratio of (2-20):1, a rotation speed of 150 rpm-300 rpm, an alcohol accounting for 1 wt%-5wt% of the total mass of the RAFM steel powder and the Y2O3 powder, a ball milling time of 10h-50h, and a grinding ball material of stainless steel balls with a diameter of 5mm-20mm.

[0022] The present invention uses high-energy ball milling to subject RAFM steel powder and Y2O3 powder to repeated deformation, cold welding, and crushing, thereby achieving an alloying process at the atomic level between elements and forming a uniform alloy powder. The ball milling parameters within the above parameter range can enable the powder to be fully mechanically alloyed. Too short a ball milling time leads to uneven mixing, while too long a ball milling time easily causes excessive cold welding and contamination. Too low a ball-to-material ratio results in low mixing efficiency, while too high a ball-to-material ratio results in excessive powder crushing. Too high a rotation speed may cause a temperature increase, affecting the properties of the powder, while too low a rotation speed results in insufficient energy and low powder mixing efficiency. Alcohol is used as a ball milling medium to prevent excessive cold welding, while excessive ball milling medium will hinder metal diffusion and affect the alloying process. Stainless steel with properties close to the material is selected for the grinding balls to reduce the risk of contamination. A grinding ball size of 5mm-20mm can increase the collision frequency and promote uniform mixing. Too large a grinding ball will have too much impact force and too fine grains, thus affecting SLM forming.

[0023] Preferably, in step (1), the drying temperature is 120°C-200°C, and the drying time is 5h-20h.

[0024] Optionally, in step (1), the drying is vacuum drying.

[0025] Preferably, in step (2), the process parameters of the selective laser melting forming are: laser power 300W-400W, laser scanning speed 500 mm / s-900 mm / s, scanning spacing 60μm-100 μm, slice thickness 25μm-35 μm, preheating temperature 80℃-120℃, cooling time 100s-200s, scanning mode is bidirectional scanning, and angle increment is 30°-90°.

[0026] Preferably, in step (3), the normalizing heat treatment process parameters are: heating at 920°C-1000°C, keeping warm for 30 min-60 min, and a heating rate of 8°C / min-12°C / min.

[0027] Preferably, in step (3), the tempering heat treatment process parameters are: heating at 600°C-800°C, keeping warm for 75min-120min, and a heating rate of 8°C / min-12°C / min.

[0028] In a second aspect, the present invention provides oxide dispersion strengthened RAFM steel produced by the method for producing oxide dispersion strengthened RAFM steel.

[0029] In a third aspect, the present invention provides the use of the oxide dispersion strengthened RAFM steel in nuclear fusion reactor materials.

[0030] The oxide dispersion strengthened RAFM steel prepared by the preparation method of the present invention has excellent high temperature creep and radiation resistance, and its surface quality, defect level and pressure test all meet the requirements of fusion reactors for structural materials, and has very important application prospects in nuclear fusion reactor materials.

[0031] In a fourth aspect, the present invention provides a first wall structural component of a fusion reactor, which is made of the oxide dispersion strengthened RAFM steel.

[0032] The present invention has the following beneficial effects: The preparation method combines Y2O3 powder dispersion strengthening with SLM technology to produce fine-grained, high-performance ODS-RAFM steel. The internal microstructure is regulated by the addition of nano-Y2O3 particles. The Y2O3 particles pin grain boundaries and dislocations through fine-grain strengthening and dispersion strengthening mechanisms, improving mechanical properties, high-temperature creep resistance, and high-temperature radiation resistance. Furthermore, the preparation method can be used to manufacture complex, flexible curvature components, particularly those in the first wall of a fusion reactor containing complex hollow flow channels. Furthermore, the integrated additive manufacturing process shortens the manufacturing cycle, reduces machining processes, and improves material utilization. The resulting material meets the service environment requirements of fusion reactor first wall components. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The morphology of RAFM powder and Y2O3 powder in Example 1 is shown in Figure 1; a is RAFM powder and b is Y2O3 powder;

[0034] Figure 2 This is the microstructure of the oxide dispersion strengthened RAFM steel prepared in Example 1;

[0035] Figure 3 is the microstructure of the RAFM steel prepared in Comparative Example 1;

[0036] Figure 4 The microstructures of the oxide dispersion strengthened RAFM steel prepared in Example 1 at different irradiation doses are shown in Figure 1; from left to right: 0 dpa, 2 dpa, and 20 dpa;

[0037] Figure 5 The microstructures of the RAFM steel prepared in Comparative Example 1 at different irradiation doses are shown in Figure 1; from left to right: 0 dpa, 2 dpa, and 20 dpa;

[0038] Figure 6 This is a TEM image of the oxide dispersion strengthened RAFM steel prepared in Example 1 under 20 dpa irradiation environment. DETAILED DESCRIPTION

[0039] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0041] Example 1

[0042] A method for preparing oxide dispersion strengthened RAFM steel comprises the following steps:

[0043] (1) The RAFM steel powder prepared by gas atomization and Y2O3 powder were mechanically mixed in a planetary ball mill under a pure argon inert gas environment with a ball-to-material ratio of 2:1, a rotation speed of 150 rpm, a ball milling medium of 2.5 wt% alcohol, a ball milling time of 20 h, and a grinding ball material of stainless steel balls with a diameter of 15 mm. The mixture was then vacuum dried at a temperature of 150 °C for 10 h to obtain oxide dispersion strengthened steel alloy powder. The amount of Y2O3 powder added was 0.5 wt% of the RAFM steel powder.

[0044] The composition of RAFM powder is: Cr: 8.79%, W: 1.46%, Mn: 0.4%, V: 0.45%, Ni: 0.03%, Si: 0.01%, C: 0.081%, Ta: 0.26%, N: 0.026%, O: 0.024%, and the rest is Fe and impurity elements; the composition of Y2O3 powder is: CeO2: ≤0.0001%, Pr6O 11 :≤0.0005%,Nd2O3: ≤0.0005%,Sm2O3: ≤0.0005%,La2O3:≤0.0005%,the remainder is Y2O3, the purity is greater than 99.999%; the RAFM steel powder particle size range is 15-53 μm, D50=30.5 μm, the Y2O3 powder particle size is 30-70 nm, D50=51.0 nm; the morphology of RAFM powder and Y2O3 powder is shown in Figure 1 As shown; a is RAFM powder, b is Y2O3 powder;

[0045] (2) The oxide dispersion strengthened RAFM steel powder obtained in step (1) was subjected to SLM forming to obtain oxide dispersion strengthened RAFM steel specimens; the SLM process parameters were: laser power 320 W, laser scanning speed 600 mm / s, scanning spacing 90 μm, slice thickness 30 μm, preheating temperature 120 °C, and oxygen content in the forming chamber less than 100 ppm;

[0046] (3) The oxide dispersion strengthened RAFM steel sample obtained in step (2) was subjected to normalizing heat treatment and tempering heat treatment, wherein the normalizing heat treatment process parameters were: heating at 980°C, holding for 50 min, heating rate of 7.5°C / min, and air cooling; the tempering heat treatment process parameters were: heating at 750°C, holding for 100 min, heating rate of 7.5°C / min, and air cooling; thus, the oxide dispersion strengthened RAFM steel was obtained; the microstructure of the oxide dispersion strengthened RAFM steel obtained in this embodiment is shown in FIG. Figure 2 shown.

[0047] Example 2

[0048] The difference between the preparation method of oxide dispersion strengthened RAFM steel in this embodiment and that in Example 1 is that in step (1), the amount of Y2O3 powder added is 0.3wt% of the RAFM steel powder; the other preparation parameters are the same as those in Example 1.

[0049] Example 3

[0050] The difference between the preparation method of oxide dispersion strengthened RAFM steel in this embodiment and that in Example 1 is that in step (1), the amount of Y2O3 powder added is 0.7wt% of the RAFM steel powder; and the other preparation parameters are the same as those in Example 1.

[0051] Example 4

[0052] The preparation method of oxide dispersion strengthened RAFM steel in this embodiment differs from that in Example 1 in that: in step (1), the composition of the RAFM powder is: Cr: 8.79%, W: 1.46%, Mn: 0.4%, V: 0.45%, Ni: 0.02%, Si: 0.05%, C: 0.081%, Ta: 0.35%, N: 0.026%, O: 0.024%, and the rest are Fe and impurity elements; the remaining preparation parameters are the same as those in Example 1.

[0053] Example 5

[0054] The preparation method of oxide dispersion strengthened RAFM steel in this embodiment differs from that in Example 1 in that: in step (1), the composition of the RAFM powder is: Cr: 8.79%, W: 1.46%, Mn: 0.4%, V: 0.45%, Ni: 0.01%, Si: 0.01%, C: 0.081%, Ta: 0.26%, N: 0.026%, O: 0.024%, and the rest are Fe and impurity elements; the other preparation parameters are the same as those in Example 1.

[0055] Example 6

[0056] The preparation method of oxide dispersion strengthened RAFM steel in this embodiment differs from that in Example 1 in that: in step (1), the composition of the RAFM powder is: Cr: 8.79%, W: 1.46%, Mn: 0.4%, V: 0.45%, Ni: 0.03%, Si: 0.01%, C: 0.081%, Ta: 0.2%, N: 0.026%, O: 0.024%, and the rest are Fe and impurity elements; the remaining preparation parameters are the same as those in Example 1.

[0057] Example 7

[0058] The preparation method of oxide dispersion strengthened RAFM steel in this embodiment differs from that in Example 1 in that: in step (1), the composition of the RAFM powder is: Cr: 8.79%, W: 1.46%, Mn: 0.4%, V: 0.45%, Ni: 0.03%, Si: 0.1%, C: 0.081%, Ta: 0.26%, N: 0.026%, O: 0.024%, and the rest are Fe and impurity elements; the remaining preparation parameters are the same as those in Example 1.

[0059] Comparative Example 1

[0060] The difference between the preparation method of RAFM steel in this comparative example and that in Example 1 is that: in step (1), no Y2O3 powder is added; the other preparation parameters are the same as those in Example 1; the microstructure of the RAFM steel prepared in this comparative example is shown in FIG. Figure 3 shown.

[0061] Comparative Example 2

[0062] The difference between the preparation method of oxide dispersion strengthened RAFM steel in this comparative example and that in Example 1 is that in step (1), the amount of Y2O3 powder added is 0.1wt% of the RAFM steel powder; and the other preparation parameters are the same as those in Example 1.

[0063] Comparative Example 3

[0064] The difference between the preparation method of oxide dispersion strengthened RAFM steel in this comparative example and that in Example 1 is that in step (1), the amount of Y2O3 powder added is 1wt% of the RAFM steel powder; the other preparation parameters are the same as those in Example 1.

[0065] Comparative Example 4

[0066] The difference between the preparation method of oxide dispersion strengthened RAFM steel in this comparative example and that in Example 1 is that in step (1), the method of mixing the RAFM steel powder and the Y2O3 powder adopts a direct mixing method, in which the oxide powder is directly mixed with the RAFM powder manually through a vibrating screen. The rest of the preparation method is the same as that in Example 1.

[0067] The RAFM steel and oxide dispersion strengthened RAFM steel obtained in the examples and comparative examples were tested for mechanical properties, high temperature creep properties and high temperature irradiation properties. The test methods are as follows:

[0068] 1. Mechanical properties: Room temperature quasi-static tensile test specimen size and test method refer to standard GB / T228.1-2021, strain rate 5×10 -4 s -1 , static toughness The Charpy impact test specimen size and test method refer to the standard GB / T229-2007, using a 45° V-notch.

[0069] 2. High temperature creep performance: The high temperature creep dimensions and test methods refer to the standard GB / T 2039-1997, the creep temperature is 600℃, the creep stress is 200MPa, 240MPa, and 280MPa. The creep life model under low stress can be predicted using the Larson-Miller parameter method. , LMP is a stress-related parameter defined as , where A and n are constants, C is the material coefficient, T is the test temperature, and σ is the stress.

[0070] 3. High temperature irradiation performance: irradiation source Fe 3+ ions, irradiation temperature 500℃, irradiation doses of 0dPa, 2dPa, and 20dPa, observe the grain size and hardness of the material after irradiation, and the test refers to ASTM E521 standard.

[0071] The test results are shown in Tables 1 to 3.

[0072] Table 1 Mechanical properties test results of oxide dispersion strengthened RAFM steel obtained in Examples and Comparative Examples

[0073]

[0074] Table 2 High temperature creep performance test results of oxide dispersion strengthened RAFM steel obtained in Examples and Comparative Examples

[0075]

[0076] Table 3 High temperature irradiation performance test results of oxide dispersion strengthened RAFM steel obtained in Examples and Comparative Examples

[0077]

[0078] As can be seen from Table 1, the high-performance ODS-RAFM steel obtained in the present invention has an ultimate tensile strength of 772.27 MPa and a yield strength of 685.24 MPa at room temperature, an elongation of 13.02%, a static toughness of 9488.39 MPa∙%, and an average impact absorbed energy of 95.52 J. The material as a whole exhibits the characteristics of high strength and low toughness. Compared with RAFM steel without Y2O3 addition, the tensile strength is significantly improved, and the overall mechanical properties are improved.

[0079] As shown in Table 2, the high-performance ODS-RAFM steel obtained by the present invention exhibits a high creep life at 600°C and 200 MPa stress. This high-temperature creep life is significantly improved compared to the RAFM steel of Comparative Example 1, which lacks Y2O3 addition. The low Y2O3 content in Comparative Example 2, however, fails to provide a strengthening effect, leading to grain boundary sliding at high temperatures and poor creep performance. The excessive addition of Y2O3 particles in Comparative Example 3 may lead to oxide agglomeration, resulting in localized stress concentration zones around the particles, accelerating creep rupture and reducing high-temperature creep resistance. The powder in Comparative Example 4 was not ball-milled, resulting in inadequate alloying, which severely impacts the material's performance.

[0080] Figure 4 The microstructures of the oxide dispersion strengthened RAFM steel prepared in Example 1 at different irradiation doses are shown in Figure 1; from left to right: 0 dpa, 2 dpa, and 20 dpa; Figure 5 The microstructures of the RAFM steel prepared in Comparative Example 1 at different irradiation doses are shown in Figure 1; from left to right: 0 dpa, 2 dpa, and 20 dpa; Figure 6 TEM images of the oxide dispersion strengthened RAFM steel prepared in Example 1 under 20 dpa irradiation environment; from Table 3 and Figure 4-Figure 6 As can be seen in the figure, under 500°C iron ion irradiation conditions, as the irradiation dose increases, the number of pores increases, the dislocation loop density increases, and the number of second-phase precipitates increases, resulting in a continuous decline in material properties. Compared to the RAFM steel of Comparative Example 1 without Y2O3 addition, the ODS-RAFM steel with Y2O3 particles added in the present invention has superior radiation resistance, more precipitates, and lower dislocation loop density.

[0081] The high-performance additively manufactured dispersion-strengthened RAFM steel provided by the present invention incorporates nano-Y2O3 particles to regulate the internal microstructure. High-strength oxide particles pin grain boundaries and dislocations, improving mechanical properties through fine grain strengthening and dispersion strengthening. Under room temperature tensile and impact conditions, the strength of ODS-RAFM steel is significantly higher than that of RAFM steel, its elongation is slightly lower, and its static toughness is significantly higher than that of RAFM steel. Under high-temperature creep and high-temperature irradiation conditions, the prolonged high-temperature environment causes grain coarsening and carbide nucleation and growth. Under the same test conditions, the creep life of ODS-RAFM steel is greater than that of RAFM steel. The degree of grain growth of ODS-RAFM steel under irradiation is less than that of RAFM steel. The presence of precipitated phase pins dislocations to avoid the formation of dislocation loops, thereby improving the radiation resistance. From the perspective of nanohardness, the hardness of ODS-RAFM steel under non-irradiation conditions is significantly higher than that of RAFM steel. This is due to the strengthening effect of Y2O3 particles. At low irradiation doses, the hardness of both steels does not change much. At high irradiation doses, ODS-RAFM steel has stronger radiation resistance and smaller hardness changes, while RAFM steel has large hardness changes and relatively poor radiation resistance.

[0082] The present invention further employed the preparation method of Example 1 to SLM-print oxide-dispersion-strengthened RAFM steel into a scaled-down structural component for the first wall of a fusion reactor. The scaled-down structural component measured 240 × 212 × 265 mm, had an R4 flow channel dimension, a forming accuracy of ±0.05 mm, and an average surface roughness of 10 μm. No defects, such as cracks or pores, were observed. A flow channel pressure test using 15 MPa cooling water for 30 minutes revealed no cracking. This demonstrates the suitability of the present preparation method for the production of fusion reactor first wall structural materials.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing oxide dispersion strengthened RAFM steel, characterized in that: The following steps are involved: (1) ball-milling RAFM steel powder and Y2O3 powder, and drying to obtain oxide dispersion-strengthened RAFM steel powder; the amount of Y2O3 powder added is 0.3wt%-0.7wt% of the RAFM steel powder; (2) subjecting the oxide dispersion strengthened RAFM steel powder obtained in step (1) to selective laser melting to obtain an oxide dispersion strengthened RAFM steel sample; (3) subjecting the oxide dispersion strengthened RAFM steel sample obtained in step (2) to normalizing heat treatment and tempering heat treatment to obtain the oxide dispersion strengthened RAFM steel; In the step (1), the RAFM steel powder comprises the following components in mass percentage: Cr: 7.5%-10.1%, W: 0.5%-1.8%, Mn: 0.3%-1.0%, V: 0.3%-0.6%, Ni: 0.02%-0.03%, Si: 0.01%-0.05%, C: 0.06%-0.15%, Ta: 0.26%-0.35%, N: ≤300ppm, O: ≤320ppm, and the rest are Fe and impurity elements.

2. The method for preparing oxide dispersion strengthened RAFM steel according to claim 1, characterized in that: In the step (1), the particle size of the RAFM steel powder is 15 μm-53 μm, and D50 is 28.5 μm-33.5 μm; and / or the particle size of the Y2O3 powder is 30 nm-70 nm, and D50 is 48 nm-52 nm.

3. The method for preparing oxide dispersion strengthened RAFM steel according to claim 1, characterized in that: In the step (1), the ball milling mixing is carried out in an inert gas environment using a planetary ball mill, with a ball-to-material ratio of (2-20):1, a rotation speed of 150 rpm-300 rpm, an alcohol accounting for 1 wt%-5 wt% of the total mass of the RAFM steel powder and the Y2O3 powder, a ball milling time of 10 h-50 h, and a grinding ball material of stainless steel balls with a diameter of 5 mm-20 mm.

4. The method for preparing oxide dispersion strengthened RAFM steel according to claim 1, characterized in that: In the step (1), the drying temperature is 120°C-200°C and the drying time is 5h-20h.

5. The method for preparing oxide dispersion strengthened RAFM steel according to claim 1, characterized in that: In step (2), the process parameters of the selective laser melting forming are: laser power 300W-400W, laser scanning speed 500mm / s-900mm / s, scanning spacing 60μm-100μm, slice thickness 25μm-35μm, preheating temperature 80℃-120℃, cooling time 100s-200s, scanning mode is bidirectional scanning, and angle increment is 30°-90°.

6. The method for preparing oxide dispersion strengthened RAFM steel according to claim 1, characterized in that: In step (3), the normalizing heat treatment process parameters are: heating at 920°C-1000°C, keeping warm for 30min-60min, and a heating rate of 8°C / min-12°C / min; and / or, the tempering heat treatment process parameters are: heating at 600°C-800°C, keeping warm for 75min-120min, and a heating rate of 8°C / min-12°C / min.

7. Oxide dispersion strengthened RAFM steel produced by the method for producing oxide dispersion strengthened RAFM steel according to any one of claims 1 to 6.

8. Use of the oxide dispersion strengthened RAFM steel according to claim 7 in nuclear fusion reactor materials.

9. A fusion reactor first wall structural member, characterized in that: It is made from the oxide dispersion strengthened RAFM steel described in claim 7.

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