Oxide dispersion strengthened RAFM steel as well as preparation method and application thereof

Abstract

The invention relates to oxide dispersion strengthened RAFM steel and a preparation method and application thereof, and belongs to the technical field of fusion reactor first wall material manufacturing. According to the preparation method, Y2O3 powder dispersion strengthening and the SLM technology are combined to obtain the fine-grain high-performance oxide dispersion strengthened RAFM steel, the grains are refined in the SLM rapid cooling process, the mechanical property is high, and even the forged piece standard can be met. The Y2O3 particles are added, so that grain boundary and dislocation can be pinned, dislocation movement is hindered, strength is improved, high-temperature creep life is prolonged, radiation resistance is improved, a solution is provided for manufacturing of a fusion reactor first wall structural part, and the requirement of a fusion service environment is better met.

Description

Technical Field

[0001] The present invention belongs to the technical field of the manufacture of the first wall material of a fusion reactor, and particularly relates to an oxide dispersion strengthened RAFM steel and its preparation method and application. Background Art

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

[0003] The first wall of the water-cooled ceramic blanket of the Chinese Fusion Engineering Test Reactor (CFETR) is in an overall U-shaped thin-wall structure, with a wall thickness of only about 23 mm, and contains 54 flow channels inside for heat dissipation through a coolant. Limited by the complex geometric shape, the processing and manufacturing of the first wall pose severe challenges. The overall U-shaped geometric structure of the first wall plus the internal closed flow channels increase the manufacturing difficulty. The traditional processing and manufacturing processes have many cycles and long periods, and it is difficult to meet the requirements of manufacturing accuracy. Therefore, the use of additive manufacturing technology for integrated forming has become the main trend in the manufacturing of key components for future nuclear fusion. Low activation ferritic / martensitic steel (RAFM steel) has become the most promising candidate material for the first wall of a fusion reactor due to its high thermal conductivity and low thermal expansion coefficient. When the fusion reactor is working, under long-term high temperature and irradiation conditions, the performance of the material will deteriorate. Irradiation damage changes the internal microstructure of the material and simultaneously reduces the mechanical properties of the material. The structural materials in second-generation and third-generation commercial reactors can only work at 350 °C, while the fusion reactor requires a service temperature above 550 °C. Therefore, the material needs to have excellent high-temperature stability.

[0004] Therefore, it is of great significance to prepare a first wall material for a fusion reactor that can still maintain a high creep life and anti-irradiation damage performance 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 provide an oxide dispersion strengthened RAFM steel (ODS-RAFM steel) and its preparation method and application.

[0006] The present invention is realized through the following technical solutions: In the first aspect, the present invention provides a preparation method for an oxide dispersion strengthened RAFM steel, comprising the following steps: (1) Ball-mill and mix RAFM steel powder and Y2O3 powder, and dry to obtain oxide dispersion strengthened RAFM steel powder; the addition amount of the Y2O3 powder is 0.3 wt%-0.7 wt% of the RAFM steel powder; (2) Selectively laser melt (SLM) the oxide dispersion strengthened RAFM steel powder obtained in step (1) to obtain an oxide dispersion strengthened RAFM steel specimen; (3) Perform normalizing heat treatment and tempering heat treatment on the oxide dispersion strengthened RAFM steel specimen obtained in step (2) to obtain the oxide dispersion strengthened RAFM steel.

[0007] The preparation method of the present invention combines Y2O3 powder dispersion strengthening and SLM technology to obtain fine-grained and high-performance oxide dispersion strengthened RAFM steel. The rapid cooling process of SLM refines the grains, resulting in relatively high mechanical properties, even meeting the forging standard. The addition of Y2O3 particles can pin grain boundaries and dislocations, hindering the movement of dislocations, thereby improving strength, high-temperature creep life, and irradiation resistance, providing a solution for the manufacture of the first wall structural components of fusion reactors and better meeting the requirements of the fusion service environment. The present invention further optimizes the addition amount of Y2O3 powder, adjusts the size of Y2O3 particles, and improves the high-temperature creep life and high-temperature irradiation resistance of the oxide dispersion strengthened RAFM steel.

[0008] Preferably, in step (1), the RAFM steel powder comprises the following components by 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: ≤300 ppm, O: ≤320 ppm, and the balance is Fe and impurity elements.

[0009] Specifically, the impurity elements include S, P, Al, Cu, Ag, Sn, B, As, Sb, and the mass percentage of the impurity elements ≤0.02%.

[0010] More preferably, in step (1), the RAFM steel powder comprises the following components by 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: ≤300 ppm, O: ≤320 ppm, and the balance is Fe and impurity elements.

[0011] The composition of RAFM steel also affects the properties of oxide dispersion strengthened RAFM steel. In the RAFM steel powder of the present invention, appropriate amounts of Ni and Si are added. Trace amounts of Ni in RAFM steel can improve the toughness of the material, reduce the risk of irradiation-induced intergranular embrittlement. At the same time, as a solid solution strengthening element, Ni can reduce the crack tendency during the SLM process and improve the weldability of the material. However, if the content of Ni is too low, the anti-irradiation performance of the material cannot be effectively improved, and too high a Ni content will cause high activation under irradiation, affecting the material properties; the addition of Si helps with deoxidation, improves the purity of RAFM steel, and enhances its oxidation resistance. As a solute atom, silicon can capture vacancy defects, inhibit cavity swelling and dislocation loop coarsening, and improve the anti-irradiation ability. If the content of Si is too low, the anti-irradiation performance of the material will decline, and excessive Si will lead to the formation of Laves phase, resulting in brittleness. At the same time, the present invention also contains more Ta, which can form MX carbides and Y-Ta-O nano-precipitation compounds, thereby improving the high-temperature creep and anti-irradiation performance of the material.

[0012] The present invention does not limit the preparation method of RAFM steel powder, and those skilled in the art can obtain it according to conventional methods in the field, such as gas atomization preparation. Specifically, the preparation method of the RAFM steel powder can be: melting, refining and degassing the raw materials of RAFM steel components through a vacuum induction furnace, placing the molten alloy into a gas atomization nozzle system, and using an inert gas stream to atomize the alloy liquid into small droplets, followed by rapid solidification to form RAFM steel powder.

[0013] Preferably, in the step (1), the particle size range of the RAFM steel powder is 15μm - 53μm, and D50 = 28.5μm - 33.5μm.

[0014] Preferably, in the step (1), the Y2O3 powder includes the following components by mass percentage: CeO2: ≤0.0001%, Pr6O 11 : ≤0.0005%, Nd2O3: ≤0.0005%, Sm2O3: ≤0.0005%, La2O3: ≤0.0005%, and the rest is Y2O3.

[0015] Specifically, the purity of Y2O3 in the Y2O3 powder is greater than 99.999%.

[0016] Preferably, in the step (1), the particle size range of the Y2O3 powder is 30nm - 70nm, and D50 = 48nm - 52nm.

[0017] Preferably, in the step (1), the ball milling and mixing is carried out by a planetary ball mill in an inert gas environment, the ball-to-material ratio is (2-20):1, the rotation speed is 150 rpm - 300 rpm, the ball milling medium is alcohol accounting for 1 wt%-5wt% of the total mass of the RAFM steel powder and Y2O3 powder, the ball milling time is 10h-50 h, and the ball material is stainless steel balls with a diameter of 5mm-20mm.

[0018] In the present invention, the RAFM steel powder and Y2O3 powder are subjected to repeated deformation, cold welding, and crushing through high-energy ball milling, so as to achieve the alloying process at the atomic level between elements and form uniform alloy powder. The ball milling parameters within the above parameter range can enable the powder to be fully mechanically alloyed. Too short ball milling time results in uneven mixing, and too long ball milling time is prone to excessive cold welding and contamination. Too low ball-to-material ratio leads to low mixing efficiency, and too high ball-to-material ratio causes excessive pulverization of the powder. Too high rotation speed may cause temperature rise, affecting the properties of the powder, and too low rotation speed results in insufficient energy and low powder mixing efficiency. Alcohol as the ball milling medium can prevent excessive cold welding, and excessive ball milling medium will hinder metal diffusion and affect the alloying process. Stainless steel with material properties close to those of the ball is selected as the grinding ball to reduce the risk of contamination. The size of the grinding ball being 5mm-20mm can increase the collision frequency and promote uniform mixing. Too large grinding balls have too large impact force and too fine grains, thus affecting the SLM forming.

[0019] Preferably, in the step (1), the drying temperature is 120℃-200 ℃, and the time is 5h-20 h.

[0020] Optionally, in the step (1), the drying is vacuum drying.

[0021] Preferably, in the step (2), the process parameters of selective laser melting forming are: laser power 300W-400 W, 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, the scanning method is bidirectional scanning, and the angle increment is 30°-90°.

[0022] Preferably, in the step (3), the normalizing heat treatment process parameters are: heating at 920℃-1000℃, holding for 30min-60 min, and the heating rate is 8℃ / min - 12 ℃ / min.

[0023] Preferably, in the step (3), the tempering heat treatment process parameters are: heating at 600℃-800℃, holding for 75min-120 min, and the heating rate is 8℃ / min - 12 ℃ / min.

[0024] In a second aspect, the present invention provides an oxide dispersion strengthened RAFM steel prepared by the preparation method of the oxide dispersion strengthened RAFM steel.

[0025] In a third aspect, the present invention provides the application of the oxide dispersion strengthened RAFM steel in nuclear fusion reactor materials.

[0026] The oxide dispersion strengthened RAFM steel obtained by the preparation method of the present invention has excellent high-temperature creep and anti-irradiation properties. Its surface quality, defect grade, and pressure-bearing test all meet the requirements of the fusion reactor for structural materials, and it has very important application prospects in nuclear fusion reactor materials.

[0027] 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.

[0028] The present invention has the following beneficial effects: The preparation method of the present invention combines Y2O3 powder dispersion strengthening and SLM technology to obtain fine-grained and high-performance ODS-RAFM steel. The internal microstructure is regulated by the addition amount of nano-Y2O3 particles. The Y2O3 particles pin grain boundaries and dislocations to improve mechanical properties, high-temperature creep properties, and high-temperature radiation resistance through the mechanisms of fine grain strengthening and dispersion strengthening. Moreover, the preparation method of the present invention can manufacture flexible curvature components with complex structures, especially for the manufacture of the first wall of a fusion reactor with complex hollow channels; at the same time, additive manufacturing is integrated into one molding, the manufacturing cycle is shortened, mechanical processing is reduced, and the material utilization rate is improved; the obtained material meets the requirements of the service environment of the first wall structural component of the fusion reactor. Description of the Drawings

[0029] Figure 1 It is the morphology diagram of RAFM powder and Y2O3 powder in Example 1; where a is RAFM powder and b is Y2O3 powder; Figure 2 It is the microstructural diagram of the oxide dispersion strengthened RAFM steel prepared in Example 1; Figure 3 It is the microstructural diagram of the RAFM steel prepared in Comparative Example 1; Figure 4 It is the microstructural morphology diagram of the oxide dispersion strengthened RAFM steel prepared in Example 1 under different irradiation doses; from left to right are 0 dpa, 2 dpa, and 20 dpa in sequence; Figure 5 It is the microstructural morphology diagram of the RAFM steel prepared in Comparative Example 1 under different irradiation doses; from left to right are 0 dpa, 2 dpa, and 20 dpa in sequence; Figure 6 It is the TEM diagram of the oxide dispersion strengthened RAFM steel prepared in Example 1 under a 20 dpa irradiation environment. Detailed Embodiments

[0030] To better illustrate the purpose, technical solution 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 used to limit the present invention.

[0031] Unless otherwise specified, the test methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can all be obtained from commercial channels.

[0032] Example 1 A preparation method of oxide dispersion strengthened RAFM steel, comprising the following steps: (1) Mechanically mix the RAFM steel powder prepared by gas atomization and Y2O3 powder in a pure argon inert gas environment using a planetary ball mill, 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 the ball milling material being stainless steel balls with a diameter of 15 mm. Then, perform vacuum drying at a drying temperature of 150 °C for 10 h to obtain oxide dispersion strengthened steel alloy powder; the addition amount of the Y2O3 powder is 0.5 wt% of the RAFM steel powder; 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: 0.26%, N: 0.026%, O: 0.024%, and the rest are Fe and impurity elements; the composition of the Y2O3 powder is: CeO2: ≤0.0001%, Pr6O 11 : ≤0.0005%, Nd2O3: ≤0.0005%, Sm2O3: ≤0.0005%, La2O3: ≤0.0005%, and the rest is Y2O3, with a purity greater than 99.999%; the particle size range of the RAFM steel powder is 15 - 53 μm, D50 = 30.5 μm, the particle size of the Y2O3 powder is 30 - 70 nm, D50 = 51.0 nm; the morphology diagrams of the RAFM powder and the Y2O3 powder are as Figure 1 shown; a is the RAFM powder, b is the Y2O3 powder; (2) SLM form the oxide dispersion strengthened RAFM steel powder obtained in step (1) to obtain an oxide dispersion strengthened RAFM steel specimen; the SLM process parameters are: laser power 320 W, laser scanning speed 600 mm / s, scanning spacing 90 μm, slice thickness 30 μm, preheating temperature 120 °C, and the oxygen content in the forming chamber is less than 100 ppm; (3) The oxide dispersion strengthened RAFM steel specimens obtained in step (2) are subjected to normalizing heat treatment and tempering heat treatment. The process parameters of the normalizing heat treatment are: heating at 980 °C, holding for 50 min, heating rate of 7.5 °C / min, air cooling; the process parameters of the tempering heat treatment are: heating at 750 °C, holding for 100 min, heating rate of 7.5 °C / min, air cooling; thus obtaining the oxide dispersion strengthened RAFM steel; the microstructural diagram of the oxide dispersion strengthened RAFM steel prepared in this example is as shown in Figure 2 shown.

[0033] Example 2 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this example and that in Example 1 lies in that: in step (1), the addition amount of the Y2O3 powder is 0.3 wt% of the RAFM steel powder; the remaining preparation parameters are the same as those in Example 1.

[0034] Example 3 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this example and that in Example 1 lies in that: in step (1), the addition amount of the Y2O3 powder is 0.7 wt% of the RAFM steel powder; the remaining preparation parameters are the same as those in Example 1.

[0035] Example 4 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this example and that in Example 1 lies 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.

[0036] Example 5 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this example and that in Example 1 lies 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 remaining preparation parameters are the same as those in Example 1.

[0037] Example 6 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this example and that in Example 1 lies 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.

[0038] Example 7 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this example and that in Example 1 lies 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.

[0039] Comparative Example 1 The difference between the preparation method of the RAFM steel in this comparative example and that in Example 1 lies in that: in step (1), Y2O3 powder is not added; the remaining preparation parameters are the same as those in Example 1; the microstructural diagram of the RAFM steel prepared in this comparative example is as Figure 3 shown.

[0040] Comparative Example 2 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this comparative example and that in Example 1 lies in that: in step (1), the addition amount of the Y2O3 powder is 0.1 wt% of the RAFM steel powder; the remaining preparation parameters are the same as those in Example 1.

[0041] Comparative Example 3 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this comparative example and that in Example 1 lies in that: in step (1), the addition amount of the Y2O3 powder is 1 wt% of the RAFM steel powder; the remaining preparation parameters are the same as those in Example 1.

[0042] Comparative Example 4 The difference between the preparation method of the oxide dispersion strengthened RAFM steel in this comparative example and that in Example 1 lies in that: in step (1), the method of mixing the RAFM steel powder and the Y2O3 powder adopts the direct mixing method, and the oxide powder is directly mixed with the RAFM powder manually through a vibrating screen, and the remaining preparation methods are the same as those in Example 1.

[0043] The mechanical properties, high-temperature creep properties, and high-temperature irradiation properties of the RAFM steels and oxide dispersion-strengthened RAFM steels obtained from the examples and comparative examples were tested. The test methods are as follows: 1. Mechanical properties: The dimensions and test methods of the specimens for room-temperature quasi-static tensile testing refer to Standard GB / T 228.1-2021, with a strain rate of 5×10 -4 s -1 , and the static toughness is expressed as . The dimensions and test methods of the specimens for the Charpy impact test refer to Standard GB / T 229-2007, using a 45° V-notch.

[0044] 2. High-temperature creep properties: The dimensions and test methods of high-temperature creep refer to Standard GB / T 2039-1997, with a creep temperature of 600 °C, creep stresses of 200 MPa, 240 MPa, and 280 MPa. The creep life model under low stress can be predicted by the Larson-Miller parameter method. , where 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.

[0045] 3. High-temperature irradiation properties: The irradiation source is Fe 3+ ions, the irradiation temperature is 500 °C, and the irradiation doses are 0 dpa, 2 dpa, and 20 dpa. The grain size and hardness of the material after irradiation were observed, and the test referred to ASTM E521 standard.

[0046] The test results are shown in Tables 1-3.

[0047] Table 1 Test results of the mechanical properties of the oxide dispersion-strengthened RAFM steels obtained from the examples and comparative examples Table 2 Test results of the high-temperature creep properties of the oxide dispersion-strengthened RAFM steels obtained from the examples and comparative examples Table 3 Test results of the high-temperature irradiation properties of the oxide dispersion-strengthened RAFM steels obtained from the examples and comparative examples As can be seen from Table 1, the ultimate tensile strength of the high-performance ODS-RAFM steel obtained in the present invention at room temperature can reach 772.27 MPa, the yield strength can reach 685.24 MPa, the elongation is 13.02%, the static toughness is 9488.39 MPa∙%, and the average impact absorption energy is 95.52 J. The material as a whole exhibits the characteristics of high strength and low toughness; compared with the RAFM steel without Y2O3 addition, the tensile strength is significantly improved, and the comprehensive mechanical properties are improved.

[0048] As can be seen from Table 2, the high-performance ODS-RAFM steel obtained in the present invention has a high creep life at a high temperature of 600 °C and a stress of 200 MPa. Compared with the RAFM steel of Comparative Example 1 without the addition of Y2O3, the high-temperature creep life is significantly improved. In Comparative Example 2, the content of Y2O3 is too low to achieve the strengthening effect, and grain boundary slip is likely to occur in the material at high temperature, resulting in poor creep performance. In Comparative Example 3, the addition amount of Y2O3 particles is too large, which may lead to the agglomeration of oxides, and local stress concentration areas are formed around the particles, accelerating creep fracture and reducing the high-temperature creep resistance. In Comparative Example 4, the powder is not ball-milled, and alloying cannot be fully achieved, seriously affecting the performance of the material.

[0049] Figure 4 Figure showing the microstructural morphology of the oxide dispersion strengthened RAFM steel prepared in Example 1 at different irradiation doses; from left to right are 0 dpa, 2 dpa, and 20 dpa in sequence; Figure 5 Figure showing the microstructural morphology of the RAFM steel prepared in Comparative Example 1 at different irradiation doses; from left to right are 0 dpa, 2 dpa, and 20 dpa in sequence; Figure 6 TEM image of the oxide dispersion strengthened RAFM steel prepared in Example 1 under an irradiation environment of 20 dpa; As can be seen from Table 3 and Figures 4 - 6 it can be seen that under the condition of high-temperature iron ion irradiation at 500 °C, as the irradiation dose increases, the number of pores increases, the dislocation loop density increases, and the number of second-phase precipitates increases. Therefore, the material performance continuously decreases. Compared with the RAFM steel of Comparative Example 1 without the addition of Y2O3, the ODS-RAFM steel with the addition of Y2O3 particles in the present invention has more excellent anti-irradiation performance, more precipitates, and a lower dislocation loop density.

[0050] The dispersion-strengthened RAFM steel for high-performance additive manufacturing provided by the present invention adds nano Y2O3 particles to regulate the internal microstructure. By pinning grain boundaries and dislocations with high-strength oxide particles, the mechanical properties are improved through the mechanisms of fine grain strengthening and dispersion strengthening. Under room temperature tensile and impact conditions, the strength of the ODS-RAFM steel is significantly higher than that of the RAFM steel, the elongation is slightly lower than that of the RAFM steel, and the static toughness is significantly higher than that of the RAFM steel. Under high-temperature creep and high-temperature irradiation conditions, the long-term high-temperature environment causes grain coarsening and the nucleation and growth of carbides. The creep life of the ODS-RAFM steel is greater than that of the RAFM steel under the same test conditions. The degree of grain growth of the ODS-RAFM steel under irradiation is less than that of the RAFM steel. The presence of the precipitated phase pins dislocations and avoids the formation of dislocation loops, improving the anti-irradiation performance. From the perspective of nano-hardness, the hardness of the ODS-RAFM steel under non-irradiated conditions is significantly higher than that of the RAFM steel, which is due to the strengthening effect of the Y2O3 particles. Under low irradiation doses, the hardness changes of both are not significant, while under high irradiation doses, the ODS-RAFM steel has stronger anti-irradiation ability and smaller hardness changes, while the hardness of the RAFM steel changes greatly and its anti-irradiation ability is relatively poor.

[0051] The present invention further uses the preparation method of Example 1 to SLM form and print the oxide dispersion-strengthened RAFM steel into a scaled-down structure of the first wall of a fusion reactor. The size of the first wall scaled-down structure is 240×212×265 mm, the size of the flow channel is R4, the forming accuracy is ±0.05 mm, and the surface roughness of the formed part is an average of 10 μm. No defects such as cracks and pores are observed. The pressure test of the flow channel uses 15 MPa cooling water to hold for 30 min, and no cracking is observed. It shows that the preparation method of the present invention can be used to prepare the structural material of the first wall of a fusion reactor.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A preparation method of oxide dispersion strengthened RAFM steel, characterized in that, It includes the following steps: (1) Ball-milling and mixing RAFM steel powder and Y2O3 powder, and drying to obtain oxide dispersion strengthened RAFM steel powder; the addition amount of the Y2O3 powder is 0.3wt%-0.7wt% of the RAFM steel powder; (2) Selective laser melting and forming the oxide dispersion strengthened RAFM steel powder obtained in step (1) to obtain an oxide dispersion strengthened RAFM steel specimen; (3) Normalizing heat treatment and tempering heat treatment are carried out on the oxide dispersion strengthened RAFM steel specimen obtained in step (2), and the oxide dispersion strengthened RAFM steel is obtained.

2. The preparation method of the oxide dispersion strengthened RAFM steel according to claim 1, characterized in that, In step (1), the RAFM steel powder includes the following components by 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.

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

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

5. The preparation method of the oxide dispersion strengthened RAFM steel according to claim 1, wherein In step (1), the drying temperature is 120℃-200℃, and the time is 5h-20 h.

6. The preparation method of the oxide dispersion strengthened RAFM steel according to claim 1, characterized in that, In step (2), the process parameters of the selective laser melting and 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, the scanning method is two-way scanning, and the angle increment is 30°-90°.

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

8. Oxide dispersion strengthened RAFM steel prepared by the preparation method of the oxide dispersion strengthened RAFM steel according to any one of claims 1-7.

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

10. A first wall structural member of a fusion reactor, characterized in that, Manufactured from the oxide dispersion strengthened RAFM steel according to claim 8.

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