Nuclear grade ferritic stainless steel with high density nano-dispersed particles and preparation method thereof

Abstract

The present invention discloses a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles and a preparation method thereof. Using 5N-grade pure iron, pure chromium, high-purity titanium, 4N-grade pure aluminum, and nano-yttrium oxide powder as raw materials, an Al-Y2O3 master alloy is prepared by an external-field assisted induction melting process protected by high-purity argon, and an Fe-Cr master alloy is prepared by a vacuum arc melting process. Then, vacuum arc melting is carried out in a vacuum arc melting furnace. After the ingot is cooled to room temperature with the furnace, a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles is prepared. The present invention is prepared by combining an external-field assisted induction melting process protected by high-purity argon and a vacuum arc melting process, obtaining fine matrix grains and nano-scale oxide dispersed particles uniformly distributed on the matrix, greatly improving the high-temperature mechanical properties, lead-bismuth corrosion resistance, and service safety of the material, and having better performance compared with ordinary ferritic stainless steel.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion-resistant metal structural materials in extreme service environments, and in particular relates to a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles and a preparation method thereof. Background Art

[0002] Due to the intensification of global warming, humans are in urgent need of seeking energy models that reduce carbon emissions to curb the greenhouse effect. Reducing and replacing fossil energy with renewable energy has become a broad consensus to reduce carbon emissions. Nuclear energy has attracted great attention due to its many advantages such as no carbon emissions, stability, and high efficiency during use. The fourth-generation nuclear reactor reference reactor represented by the lead-cooled fast reactor has become the first choice for the next generation of green energy for humans. Among them, the lead-cooled fast reactor uses lead / lead-bismuth alloy as a coolant, which has the characteristics of high safety, high economy, and high sustainability, and has great application potential. At present, people have dealt with many major problems related to the design of lead-cooled fast reactors and have developed solutions, but there is still a problem that must be solved: the corrosion of liquid alloys to structural materials.

[0003] Stainless steel is widely used in all aspects of production and life because of its good mechanical properties, excellent corrosion resistance and low cost. The fuel cladding of lead-cooled fast reactors has a harsh service environment. It is immersed in liquid lead-bismuth eutectic for a long time and is subjected to high-dose neutron irradiation. Therefore, the cladding material must have excellent corrosion resistance and radiation resistance. Although the neutron absorption cross-section of Fe is larger than that of Zr, and the neutron economy is not as good as that of refractory alloys represented by zirconium alloys, stainless steel has excellent corrosion resistance and low production cost, and has the potential to be widely used in the core components of lead-cooled fast reactors. Adding aluminum to the original ferritic stainless steel makes it have good radiation resistance and excellent corrosion resistance, making it one of the most competitive cladding materials. At present, there are many preparation methods for ferritic stainless steel, but most of them are very easy to introduce impurity elements, and the uniformity and stability of the organization are limited, resulting in a decrease in the high-temperature mechanical properties and corrosion resistance of the material, which poses a safety hazard to the safe service of the cladding material. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles and a preparation method thereof in view of the deficiencies in the above-mentioned prior art, so as to solve the technical problems of purification and large-scale production of nuclear-grade oxide dispersion strengthened steel, and develop new ideas for the application of materials such as oxide dispersion strengthened (ODS) steel in the nuclear industry.

[0005] The present invention adopts the following technical solutions:

[0006] A method for preparing nuclear-grade ferritic stainless steel having high-density nano-dispersed particles comprises the following steps:

[0007] Al-Y 2 O 3 The master alloy and the Fe-Cr master alloy are mixed and then subjected to vacuum arc melting. After the temperature drops to room temperature, nuclear-grade ferritic stainless steel with high-density nano-dispersed particles is prepared.

[0008] A method for preparing nuclear-grade ferritic stainless steel with high-density nano-dispersed particles, characterized by comprising the following steps:

[0009] Al-Y 2 O 3 The master alloy and the Fe-Cr master alloy are mixed and then subjected to vacuum arc melting. After the temperature drops to room temperature, nuclear-grade ferritic stainless steel with high-density nano-dispersed particles is prepared.

[0010] Specifically, Al-Y 2 O 3 In the master alloy, the nano yttrium oxide accounts for 5.00% to 20.00% by mass, and the rest is 4N grade pure aluminum.

[0011] Furthermore, Al-Y 2 O 3 The intermediate alloy is prepared by an external field assisted induction melting process under the protection of high-purity argon. The induction melting furnace is placed in a glove box, and the vacuum is repeatedly evacuated and filled with high-purity argon for 3 times to exhaust the residual gas in the glove box. The glove box is filled with high-purity argon. A high-frequency ultrasonic generator is arranged in the induction furnace. An alumina crucible for melting is placed in the high-frequency ultrasonic generator, and yttrium oxide powder is placed at the bottom of the crucible. During melting, pure aluminum is placed in the crucible and induction heated to 700-720°C. During the melting process, the ultrasonic generator is turned on to apply high-frequency oscillation to the molten metal, and an alumina stirring rod is used for mechanical stirring. After 10-15 minutes, the molten metal is poured into a casting mold and cooled to room temperature to obtain an alloy.

[0012] Specifically, in the Fe-Cr master alloy, by mass percentage, pure chromium is 14.50% to 15.00%, high-purity titanium is 0.45% to 0.55%, and the rest is 5N grade pure iron.

[0013] Furthermore, the Fe-Cr intermediate alloy is prepared by a vacuum arc melting process. Each melting is carried out for 2 to 3 minutes, and each sample is turned over and melted 4 to 6 times. After each melting, the vacuum is re-evacuated and high-purity argon is passed through and high-purity titanium is pre-melted. Before melting, the furnace chamber is cleaned 3 to 5 times with a high-purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed in order from low to high melting points on the bottom of a water-cooled copper mold, and the arc furnace chamber is vacuumed and high-purity argon is continuously passed through, and high-purity titanium is pre-melted to remove residual oxygen in the chamber.

[0014] Furthermore, before smelting, 5N grade pure iron, pure chromium, high purity titanium, 4N grade pure aluminum, and nano yttrium oxide powder are ultrasonically cleaned with dilute hydrochloric acid and anhydrous ethanol in turn, and then vacuum dried for later use.

[0015] Specifically, Al-Y 2 O 3 The mass ratio of the master alloy to the Fe-Cr master alloy is 19:1.

[0016] Furthermore, each smelting is performed for 2 to 3 minutes, and each sample is turned over and smelted 4 to 10 times. After each smelting, the furnace is vacuumed and high-purity argon is passed through and high-purity titanium is pre-melted. Before smelting, the furnace chamber is cleaned 3 to 5 times with a high-purity argon atmosphere, and then the cerium tungsten electrode is used to strike the arc under high current. Before striking the arc, the raw materials are placed on the bottom of the water-cooled copper mold in order from low to high melting points, and the arc furnace chamber is vacuumed and high-purity argon is continuously passed through to pre-smelt high-purity titanium to remove residual oxygen in the chamber.

[0017] Another technical solution of the present invention is a nuclear grade ferrite stainless steel with high density nano dispersed particles, comprising a metal matrix and nano oxide dispersed particles, wherein by weight percentage, Al: 3.60% to 5.23%, Cr: 13.70% to 14.33%, Y 2 O 3 : 0.23%~1.10%, Ti: 0.43%~0.53%, and the rest are Fe and inevitable trace impurities.

[0018] Specifically, the metal matrix is ​​α-Fe, the average particle size is 110 μm, the average particle size of the dispersed oxide particles is 200 nm, and the average distribution density of the dispersed particles is 2.5×10 13 m -3 .

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The preparation method of the nuclear-grade ferritic stainless steel with high-density nano-dispersed particles of the present invention is conducive to the composition design of the ferritic stainless steel resistant to lead-bismuth corrosion, the homogenization of raw materials and alloy structures and the melt purification treatment, the uniform distribution regulation of the dispersed particles and the regulation of the grain morphology of the steel matrix, so that the nuclear-grade ferritic stainless steel with high-density nano-dispersed particles has fine grains and uniformly distributed nano-scale oxide dispersed particles, and the various properties of the material are greatly improved, and the performance is better than that of ordinary ferritic stainless steel.

[0021] Furthermore, Al-Y was prepared by using an external field assisted induction melting process protected by high purity argon. 2 O 3 Master alloy, change the Y in the master alloy 2 O 3 The relative content of Y in the alloy obtained by arc melting can be regulated. 2 O 3 content, and at the same time avoid the coarsening and agglomeration of nano-oxides that occurs when nano-yttrium oxide directly contacts molten steel during direct smelting, thereby reducing the loss of yttrium oxide.

[0022] Furthermore, Al-Y was prepared by external field assisted induction melting under high purity argon protection. 2 O 3 The intermediate alloy avoids the introduction of impurity elements and the burning of raw materials. The oxide dispersed particles are evenly distributed, which is beneficial to control the content of oxide dispersed particles in nuclear-grade ferritic stainless steel, effectively avoid the introduction of impurity elements, improve the purity of the prepared materials, and avoid defects and inclusions in the samples to the greatest extent, thereby improving the service safety of the materials. The external field assisted induction melting under high-purity argon protection is evacuated and high-purity argon is passed in the glove box, which is beneficial to remove the residual oxygen and nitrogen in the glove box and reduce the burning of raw materials and the introduction of impurity elements during the smelting process. The addition of high-frequency ultrasonic vibration and mechanical stirring effectively avoids Y 2 O 3 The coarsening and agglomeration of Y 2 O 3 The uniform distribution of particles in the matrix and the refinement of the matrix structure.

[0023] Furthermore, the Fe-Cr master alloy is prepared by vacuum arc melting process, which improves the alloy element recovery rate and improves the composition uniformity of the alloy matrix, thus avoiding the segregation of alloy components to the greatest extent.

[0024] Furthermore, the use of a water-cooled copper mold vacuum arc furnace for smelting can effectively avoid the introduction of impurity elements, improve the purity of the prepared materials, avoid defects and inclusions in the samples to the greatest extent, and improve the service safety of the materials; vacuuming, passing high-purity argon, pre-melting high-purity titanium and other operations before vacuum arc melting are beneficial to remove residual oxygen and nitrogen in the vacuum arc melting furnace cavity, avoid reaction with raw materials during the smelting process, further avoid the introduction of impurity elements, avoid the formation of defects and inclusions, further optimize the organizational morphology of the steel, and improve its service safety.

[0025] Furthermore, the raw materials are purified before smelting and then smelted, which reduces various defects and inclusions in the preparation process of the smelted parts and ensures the yield of the added elements, so that the castings obtained from the dense and fine samples have excellent thermal shock and oxidation resistance, long fatigue life, and high high-temperature creep resistance; the fine dispersed particles are evenly distributed in the matrix, which further improves the high-temperature mechanical properties and lead-bismuth corrosion resistance of the material.

[0026] Furthermore, Al-Y 2 O 3 The master alloy and the Fe-Cr master alloy are vacuum arc melted in a specific mass ratio, which improves the recovery rate of the Al element and ensures that the Al element improves the corrosion resistance of the alloy and inhibits the thermal aging embrittlement tendency of the matrix, thereby improving the uniformity of the alloy composition.

[0027] Furthermore, the vacuum arc melting furnace uses argon arc as the heat source, which has high energy density, is conducive to the rapid melting of raw materials and improves the melting efficiency; it uses water-cooled copper mold vacuum suction casting to form a temperature gradient with a specific direction, which is conducive to regulating the growth orientation of the organization and inhibiting the occurrence of casting defects such as shrinkage cavities and shrinkage.

[0028] The invention discloses a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles. The Cr content is 13.78% to 14.25%. The Cr element can be dissolved in the Fe lattice to stabilize the ferrite and improve the strength of the matrix. The strength of the ferrite matrix is ​​improved by solid solution, and the corrosion resistance of the steel is improved. The Al content is 4.00% to 4.75%. The Al element can improve the lead-bismuth corrosion resistance of the matrix and improve the solid solubility of the Cr element in the ferrite, curb the thermal aging embrittlement tendency of the ferrite, improve the lead-bismuth corrosion resistance of the steel, and avoid the segregation of Cr in the ferrite matrix. The Ti content is 0.43% to 0.52%. The matrix and the oxide dispersed particles are refined, and the thermal stability and the lead-bismuth corrosion resistance of the ferritic stainless steel are improved. 2 O 3 The content of Y is 0.26% to 1.05%, 2 O 3The addition of can form nano-scale dispersed particles, improve the high-temperature mechanical properties and lead-bismuth corrosion resistance of the material, and strictly follow the addition amount of the oxide dispersion strengthening phase to achieve the best strengthening and toughening effect, which is beneficial to further improve the material's high-temperature creep resistance, high-temperature fatigue life, lead-bismuth corrosion resistance and other important performance indicators.

[0029] In summary, the preparation method of the present invention can effectively improve the high-temperature mechanical properties, lead-bismuth corrosion resistance, and service safety of the material.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a process flow chart of the present invention;

[0032] Figure 2 Schematic diagram of the external field assisted induction melting device protected by high purity argon gas of the present invention;

[0033] Figure 3 It is a schematic diagram of the vacuum arc melting device of the present invention;

[0034] Figure 4 This is a schematic diagram of the OM photo of the sample obtained in Example 1;

[0035] Figure 5 OM photo of FeCrAl alloy prepared by arc melting. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0038] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0039] In the present invention, unless otherwise specified, percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0040] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0041] In the present invention, unless otherwise specified, the numerical range "a-b" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "6-22" means that all real numbers between "6-22" have been listed in this document, and "6-22" is just an abbreviation of these numerical combinations.

[0042] The “range” disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.

[0043] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0044] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0045] Unless otherwise specified, the professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content may also be applied to the present invention.

[0046] The invention provides a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles and a preparation method thereof. The stainless steel is prepared by combining external field assisted induction melting under high-purity argon protection with a vacuum arc melting process. The prepared nuclear-grade ferritic stainless steel with high-density nano-dispersed particles is prepared by combining external field assisted induction melting under high-purity argon protection with a vacuum arc melting process, and fine matrix grains and nano-scale oxide dispersed particles are uniformly distributed on the matrix, so that the high-temperature mechanical properties, lead-bismuth corrosion resistance and service safety of the material are greatly improved, and the material has better performance than ordinary ferritic stainless steel; a structure with uniform composition, fine grains and uniformly distributed nano-scale oxide dispersed particles is obtained, so as to obtain a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles having fine grain structure, fine oxide dispersed particles uniformly distributed in the matrix and certain strength, thereby improving the corrosion resistance of the stainless steel in service in a lead-cooled fast reactor, and providing a new idea for the development of materials such as aluminum-containing ferritic stainless steel in a lead-cooled fast reactor.

[0047] See also Figure 1 The present invention provides a method for preparing nuclear-grade ferritic stainless steel having high-density nano-dispersed particles, comprising the following steps:

[0048] S1. Weigh 5N grade pure iron, pure chromium, high purity titanium, 4N grade pure aluminum, and nano yttrium oxide powder according to the mass fraction ratio and use them as raw materials for later use;

[0049] The ingredients are:

[0050] According to the required proportion of ingredients, pure iron, pure chromium and pure aluminum were weighed respectively, ultrasonically cleaned with dilute hydrochloric acid and anhydrous ethanol in turn, placed in a vacuum drying oven, and dried for later use.

[0051] Use a 1 / 10,000 balance to weigh the nano yttrium oxide powder, place it in a vacuum drying oven, and dry it for later use.

[0052] S2, the raw materials 4N grade pure aluminum and nano yttrium oxide powder prepared in step S1 are melted in a vacuum induction melting furnace, and the melting process is carried out in a high-purity argon atmosphere. After the melting is thoroughly mixed, the molten metal is poured into a mold and cooled to room temperature to prepare Al-Y with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles. 2 O 3 Master alloys;

[0053] Al-Y 2 O 3 In the master alloy, the mass fraction of nano-yttrium oxide is 5.00% to 20.00%, and the rest is 4N grade pure aluminum.

[0054] See also Figure 2 , using high-purity argon protection external field assisted induction melting to prepare Al-Y 2 O 3 The intermediate alloy effectively avoids the introduction of impurities during the smelting process, making Y 2 O 3 The particles are evenly distributed in the α-Al matrix, and the crystal grains are uniform and fine.

[0055] The induction melting furnace is placed in a glove box, and the vacuum is repeatedly evacuated and filled with high-purity argon three times to exhaust the residual gas in the glove box. After that, the glove box is filled with high-purity argon (99.99%). A high-frequency ultrasonic generator is arranged in the induction furnace, and an alumina crucible for smelting is placed in the ultrasonic generator, and yttrium oxide powder is placed at the bottom of the crucible.

[0056] During smelting, pure aluminum is placed in a crucible and induction heated to 700-720°C. During the smelting process, an ultrasonic generator is turned on to apply high-frequency oscillations to the molten metal. At the same time, an alumina stirring rod is used for mechanical stirring. After 10 minutes, the molten metal is poured into a casting mold and cooled to room temperature to obtain an alloy.

[0057] A glove box, a high-frequency induction melting furnace, a mechanical vacuum pump, a molecular diffusion pump, an ultrasonic generator, and a mechanical stirrer are used for induction melting, and a graphite mold is used for molten metal casting.

[0058] S3, the raw materials 5N grade pure iron, pure chromium and high purity titanium prepared in step S1 are melted in a vacuum arc melting furnace, the melting process is carried out in a high purity argon atmosphere, after being thoroughly melted and cut evenly, they are cooled to room temperature in a protective cavity to prepare a Fe-Cr master alloy;

[0059] For the Fe-Cr master alloy, the mass fraction of pure chromium is 14.50% to 15.00%, the mass fraction of high-purity titanium is 0.45% to 0.55%, and the rest is 5N grade pure iron.

[0060] See also Figure 3 The vacuum arc melting furnace uses cerium tungsten electrodes to draw out argon arcs, which have concentrated arcs, high heat source energy density, and high melting efficiency; the water-cooled copper mold is used as a casting mold, which has a fast solidification speed and is conducive to Y 2 O 3 The particles are evenly dispersed in the matrix; before smelting the alloy, a mechanical vacuum pump and a molecular diffusion pump are used in turn to evacuate the cavity and melt high-purity titanium, which absorbs the residual oxygen and nitrogen in the cavity, avoids the introduction of impurities, and realizes pure smelting.

[0061] Before smelting, the furnace chamber is cleaned 3 to 5 times with high-purity argon atmosphere, and then the arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed at the bottom of the water-cooled copper mold in order from low to high melting points, and the arc furnace chamber is evacuated and high-purity argon is continuously introduced to pre-smelt high-purity titanium to remove residual oxygen in the chamber.

[0062] Each melting is carried out for 2 to 3 minutes, and each sample is turned over and melted 4 to 6 times. After each melting, the vacuum is re-evacuated and high-purity argon is passed through to pre-melt high-purity titanium.

[0063] Vacuum arc melting is carried out using a vacuum arc melting furnace, an inverter DC power supply, a mechanical vacuum pump, and a molecular vacuum pump.

[0064] S4. The intermediate alloy obtained by smelting in steps S2 and S3 is smelted in a vacuum arc melting furnace according to a certain mass fraction ratio. The smelting process is carried out in a high-purity argon atmosphere. After the melting is thorough and uniform, the alloy is cooled to room temperature in a protective cavity to prepare a ferritic stainless steel with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles.

[0065] Before smelting, the furnace chamber is cleaned 3 to 5 times with high-purity argon atmosphere, and then the arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed at the bottom of the water-cooled copper mold in order from low to high melting points, and the arc furnace chamber is evacuated and high-purity argon is continuously introduced to pre-smelt high-purity titanium to remove residual oxygen in the chamber.

[0066] Each melting is carried out for 2 to 3 minutes, and each sample is turned over and melted 4 to 10 times. After each melting, the vacuum is re-evacuated and high-purity argon gas is passed through to pre-melt high-purity titanium.

[0067] Vacuum arc melting is carried out using a vacuum arc melting furnace, an inverter DC power supply, a mechanical vacuum pump, and a molecular vacuum pump.

[0068] Fe-Cr master alloy and Al-Y 2 O 3 The mass ratio of the intermediate alloy is (18.9-19.1):(0.9-1.1).

[0069] After smelting, vacuum casting is performed through a copper mold and cooled to room temperature.

[0070] The nuclear grade ferrite stainless steel with high density nano dispersed particles prepared by the method of the present invention comprises a ferrite matrix and dispersed particles distributed on the matrix and the grain boundaries, and comprises Cr: 13.78% to 14.25%, Al: 4.00% to 4.75%, Y 2 O 3 : 0.26%~1.05%, Ti: 0.43%~0.52%, and the rest are Fe and inevitable trace impurities.

[0071] The XRD and SEM characterization results show that the metal matrix of nuclear-grade ferritic stainless steel is α-Fe, the shape factor and average particle size are 0.66 and 110.63 μm respectively, and the oxide dispersed particles are Y 2 O 3 The average particle size of the dispersed oxide particles is 200 nm, and the average distribution density of the dispersed particles is 2.5×10 13 m -3 .

[0072] Cr and Al are important additive elements in nuclear-grade ferritic stainless steel with high-density nano-dispersed particles. Their main function is to improve the corrosion resistance of steel and optimize its high-temperature mechanical properties. In addition, Cr solid solution in the matrix can also improve the hardenability of the alloy.

[0073] According to previous research results, the present invention selects Cr and Al contents of 13.78% to 14.25% and 4.00% to 4.75% respectively, and the obtained microstructure and performance are the best.

[0074] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0075] Example 1

[0076] Alloy sample preparation

[0077] The present invention selects pure iron, pure aluminum, nano yttrium oxide powder, pure chromium and pure titanium as raw materials. In the raw materials of Fe-Cr master alloy, 84.48% pure iron (the chemical composition mass fraction of pure iron is 99.9996% Fe), 15.00% pure chromium (the chemical composition mass fraction of pure chromium is 99.95% Cr), and 0.52% pure titanium (the chemical composition mass fraction of pure titanium is 99.996% Ti) are added respectively; 2 O 3 90.00% pure aluminum (the chemical composition mass fraction of pure aluminum is 99.996% Al) and 10.00% nano yttrium oxide powder (the chemical composition mass fraction of nano yttrium oxide powder is 99.9% Y 2 O 3 ).

[0078] The specific preparation and smelting process of the present invention is as follows:

[0079] S1. According to the requirements of the composition ratio, weigh pure iron, pure chromium, and pure aluminum respectively, clean them with dilute hydrochloric acid and anhydrous ethanol ultrasonically in turn, place them in a vacuum drying oven, dry them and set them aside. Use a 1 / 10,000 balance to weigh the nano yttrium oxide powder, place it in a vacuum drying oven, dry it and set it aside.

[0080] S2, the raw materials 4N grade pure aluminum and nano yttrium oxide powder prepared in step S1 are melted in a vacuum induction melting furnace, the induction melting furnace is placed in a glove box, and the vacuum is repeatedly pumped and filled with high-purity argon gas for 3 times to exhaust the residual gas in the glove box, and then the glove box is filled with high-purity argon gas. A high-frequency ultrasonic generator is arranged in the induction furnace, and an alumina crucible for melting is placed in the ultrasonic generator, and the yttrium oxide powder is placed at the bottom of the crucible. During the melting, the melting temperature is 704°C. During the melting process, the ultrasonic generator is turned on to apply 30kHz high-frequency oscillation to the molten metal, and an alumina stirring rod is used to mechanically stir at a speed of 120rmp. After 12 minutes, the molten metal is poured into a graphite casting mold and cooled to room temperature to obtain Al-Y with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles. 2 O 3 Master alloy.

[0081] S3. The raw materials 5N grade pure iron, pure chromium and high purity titanium configured in step S1 are melted in a vacuum arc melting furnace. Before melting, the furnace chamber is cleaned 5 times with a high purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before striking the arc, the raw materials are placed on the bottom of a water-cooled copper mold in order from low to high melting points. The mechanical vacuum pump and the molecular diffusion pump are turned on in turn in the arc furnace cavity to evacuate to 0.00014MPa, and then high purity argon is introduced to pre-melt high purity titanium to remove residual oxygen in the cavity. Each melting is carried out for 150s, and each sample is turned over and melted 6 times. After each melting, the high purity argon is re-evacuated and high purity titanium is pre-melted. After the melting is thorough and evenly cut, the Fe-Cr intermediate alloy is prepared after cooling to room temperature in a protective cavity, such as Figure 5 shown.

[0082] S4, the Fe-Cr master alloy and Al-Y master alloy obtained by smelting in steps S2 and S3 2 O 3 The intermediate alloy is melted in a vacuum arc melting furnace at a mass ratio of 19:1. Before melting, the furnace chamber is cleaned 5 times with a high-purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before striking the arc, the raw materials are placed at the bottom of a water-cooled copper mold in order from low to high melting points. The mechanical vacuum pump and molecular diffusion pump are turned on in the arc furnace chamber to evacuate to 0.00012MPa, and then high-purity argon is introduced to pre-melt high-purity titanium to remove residual oxygen in the chamber. Each melting is performed for 170s, and each sample is turned over and melted 10 times. After each melting, vacuum is re-evacuated and high-purity argon is passed and high-purity titanium is pre-melted. After the melting is thoroughly and evenly cut, a water-cooled copper mold is used for vacuum casting. After cooling to room temperature, ferritic stainless steel with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles is prepared.

[0083] See also Figure 4 , prepared Y 2 O 3Nuclear grade ferritic stainless steel with high density nano-dispersed particles, Y 2 O 3 The addition of can refine the grains and promote the formation of dispersed particles at the grain boundaries and inside the grains of the material.

[0084] Example 2

[0085] Alloy sample preparation

[0086] The present invention selects pure iron, pure aluminum, nano yttrium oxide powder, pure chromium and pure titanium as raw materials. In the raw materials of Fe-Cr master alloy, 85.00% pure iron (the chemical composition mass fraction of pure iron is 99.9996% Fe), 14.55% pure chromium (the chemical composition mass fraction of pure chromium is 99.95% Cr), and 0.45% pure titanium (the chemical composition mass fraction of pure titanium is 99.996% Ti) are added respectively; 2 O 3 The raw materials of the intermediate alloy are respectively added with 94.56% pure aluminum (the chemical composition mass fraction of pure aluminum is 99.996% Al) and 5.44% nano yttrium oxide powder (the chemical composition mass fraction of nano yttrium oxide powder is 99.9% Y 2 O 3 ).

[0087] The specific preparation and smelting process of the present invention is as follows:

[0088] S1. According to the requirements of the composition ratio, weigh pure iron, pure chromium, and pure aluminum respectively, clean them with dilute hydrochloric acid and anhydrous ethanol ultrasonically in turn, place them in a vacuum drying oven, dry them and set them aside. Use a 1 / 10,000 balance to weigh the nano yttrium oxide powder, place it in a vacuum drying oven, dry it and set it aside.

[0089] S2, the raw materials 4N grade pure aluminum and nano yttrium oxide powder prepared in step S1 are melted in a vacuum induction melting furnace, the induction melting furnace is placed in a glove box, and the vacuum is repeatedly pumped and filled with high-purity argon gas for 3 times to exhaust the residual gas in the glove box, and then the glove box is filled with high-purity argon gas. A high-frequency ultrasonic generator is arranged in the induction furnace, and an alumina crucible for melting is placed in the ultrasonic generator, and the yttrium oxide powder is placed at the bottom of the crucible. During the melting, the melting temperature is 700°C, and the ultrasonic generator is turned on during the melting process to apply 25kHz high-frequency oscillation to the molten metal, and an alumina stirring rod is used to mechanically stir at a speed of 127rmp. After 14 minutes, the molten metal is poured into a graphite casting mold and cooled to room temperature to obtain Al-Y with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles. 2 O 3 Master alloy.

[0090] S3, the raw materials 5N grade pure iron, pure chromium and high purity titanium configured in step S1 are melted by a vacuum arc melting furnace. Before melting, the furnace chamber is cleaned 3 times with a high purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed at the bottom of a water-cooled copper mold in order from low to high melting points, and a mechanical vacuum pump and a molecular diffusion pump are turned on in the arc furnace cavity to evacuate to 0.00011MPa and then high purity argon is introduced to pre-melt high purity titanium to remove residual oxygen in the cavity. Each melting is performed for 165s, and each sample is turned over and melted 5 times. After each melting, high purity argon is re-evacuated and high purity titanium is pre-melted. After being thoroughly melted and cut evenly, the Fe-Cr master alloy is prepared after cooling to room temperature in the protective cavity.

[0091] S4, the Fe-Cr master alloy and Al-Y master alloy obtained by smelting in steps S2 and S3 2 O 3 The intermediate alloy was melted in a vacuum arc melting furnace at a mass ratio of 19:1. Before melting, the furnace chamber was cleaned three times with a high-purity argon atmosphere, and then an arc was struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials were placed at the bottom of a water-cooled copper mold in order from low to high melting points. The mechanical vacuum pump and molecular diffusion pump were turned on in the arc furnace chamber to evacuate to 0.00009MPa, and then high-purity argon was introduced to pre-melt high-purity titanium to remove residual oxygen in the chamber. Each melting was performed for 180s, and each sample was turned over and melted 6 times. After each melting, high-purity argon was re-evacuated and high-purity titanium was pre-melted. After the melting was thoroughly and evenly cut, a water-cooled copper mold was used for vacuum casting. After cooling to room temperature, ferritic stainless steel with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles was prepared.

[0092] Example 3

[0093] Alloy sample preparation

[0094] The invention selects pure iron, pure aluminum, nano yttrium oxide powder, pure chromium and pure titanium as raw materials. In the raw materials of Fe-Cr master alloy, 84.75% pure iron (the chemical composition mass fraction of pure iron is 99.9996% Fe), 14.75% pure chromium (the chemical composition mass fraction of pure chromium is 99.95% Cr), and 0.50% pure titanium (the chemical composition mass fraction of pure titanium is 99.996% Ti) are added respectively; 2 O 3 80.50% pure aluminum (the chemical composition of pure aluminum is 99.996% Al) and 19.50% nano yttrium oxide powder (the chemical composition of nano yttrium oxide powder is 99.9% Y) are added to the raw materials of the intermediate alloy. 2 O 3 ).

[0095] The specific preparation and smelting process of the present invention is as follows:

[0096] S1. According to the requirements of the composition ratio, weigh pure iron, pure chromium, and pure aluminum respectively, clean them with dilute hydrochloric acid and anhydrous ethanol ultrasonically in turn, place them in a vacuum drying oven, dry them and set them aside. Use a 1 / 10,000 balance to weigh the nano yttrium oxide powder, place it in a vacuum drying oven, dry it and set it aside.

[0097] S2, the raw materials 4N grade pure aluminum and nano yttrium oxide powder prepared in step S1 are melted in a vacuum induction melting furnace, the induction melting furnace is placed in a glove box, and the vacuum is repeatedly pumped and filled with high-purity argon gas for 4 times to exhaust the residual gas in the glove box, and then the glove box is filled with high-purity argon gas. A high-frequency ultrasonic generator is arranged in the induction furnace, and an alumina crucible for melting is placed in the ultrasonic generator, and the yttrium oxide powder is placed at the bottom of the crucible. During the melting, the melting temperature is 720°C, and the ultrasonic generator is turned on during the melting process to apply 20kHz high-frequency oscillation to the molten metal, and an alumina stirring rod is used to mechanically stir at a speed of 120rmp. After 11 minutes, the molten metal is poured into a graphite casting mold and cooled to room temperature to obtain Al-Y with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles. 2 O 3 Master alloy.

[0098] S3, the raw materials 5N grade pure iron, pure chromium and high purity titanium configured in step S1 are melted by a vacuum arc melting furnace. Before melting, the furnace chamber is cleaned 5 times with a high purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed at the bottom of a water-cooled copper mold in order from low to high melting points, and a mechanical vacuum pump and a molecular diffusion pump are turned on in the arc furnace cavity to evacuate to 0.00017MPa and then high purity argon is introduced to pre-melt high purity titanium to remove residual oxygen in the cavity. Each melting is performed for 125s, and each sample is turned over and melted 4 times. After each melting, high purity argon is re-evacuated and high purity titanium is pre-melted. After being thoroughly melted and cut evenly, the Fe-Cr master alloy is prepared after cooling to room temperature in the protective cavity.

[0099] S4, the Fe-Cr master alloy and Al-Y master alloy obtained by smelting in steps S2 and S3 2 O 3The intermediate alloy was melted in a vacuum arc melting furnace at a mass ratio of 19:1. Before melting, the furnace chamber was cleaned 5 times with a high-purity argon atmosphere, and then an arc was struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials were placed at the bottom of a water-cooled copper mold in order from low to high melting points. The mechanical vacuum pump and molecular diffusion pump were turned on in the arc furnace chamber to evacuate to 0.00016MPa, and then high-purity argon was introduced to pre-melt high-purity titanium to remove residual oxygen in the chamber. Each melting was performed for 130s, and each sample was turned over and melted 4 times. After each melting, high-purity argon was re-evacuated and high-purity titanium was pre-melted. After the melting was thoroughly and evenly cut, a water-cooled copper mold was used for vacuum casting. After cooling to room temperature, ferritic stainless steel with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles was prepared.

[0100] Example 4

[0101] Alloy sample preparation

[0102] The present invention selects pure iron, pure aluminum, nano yttrium oxide powder, pure chromium and pure titanium as raw materials. In the raw materials of Fe-Cr master alloy, 84.85% pure iron (the chemical composition mass fraction of pure iron is 99.9996% Fe), 14.62% pure chromium (the chemical composition mass fraction of pure chromium is 99.95% Cr), and 0.53% pure titanium (the chemical composition mass fraction of pure titanium is 99.996% Ti) are added respectively; 2 O 3 85.00% pure aluminum (the chemical composition mass fraction of pure aluminum is 99.996% Al) and 5.00% nano yttrium oxide powder (the chemical composition mass fraction of nano yttrium oxide powder is 99.9% Y 2 O 3 ).

[0103] The specific preparation and smelting process of the present invention is as follows:

[0104] S1. According to the requirements of the composition ratio, weigh pure iron, pure chromium, and pure aluminum respectively, clean them with dilute hydrochloric acid and anhydrous ethanol ultrasonically in turn, place them in a vacuum drying oven, dry them and set them aside. Use a 1 / 10,000 balance to weigh the nano yttrium oxide powder, place it in a vacuum drying oven, dry it and set it aside.

[0105] S2, the raw materials 4N grade pure aluminum and nano yttrium oxide powder prepared in step S1 are melted in a vacuum induction melting furnace, the induction melting furnace is placed in a glove box, and the vacuum is repeatedly pumped and filled with high-purity argon gas for 3 times to exhaust the residual gas in the glove box, and then the glove box is filled with high-purity argon gas. A high-frequency ultrasonic generator is arranged in the induction furnace, and an alumina crucible for melting is placed in the ultrasonic generator, and the yttrium oxide powder is placed at the bottom of the crucible. During the melting, the melting temperature is 715°C, and the ultrasonic generator is turned on during the melting process to apply 19kHz high-frequency oscillation to the molten metal, and an alumina stirring rod is used to mechanically stir at a speed of 117rmp. After 10 minutes, the molten metal is poured into a graphite casting mold and cooled to room temperature to obtain Al-Y with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles. 2 O 3 Master alloy.

[0106] S3, the raw materials 5N grade pure iron, pure chromium and high purity titanium configured in step S1 are melted by a vacuum arc melting furnace. Before melting, the furnace chamber is cleaned 5 times with a high purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed at the bottom of a water-cooled copper mold in order from low to high melting points, and a mechanical vacuum pump and a molecular diffusion pump are turned on in the arc furnace cavity to evacuate to 0.00015MPa and then high purity argon is introduced to pre-melt high purity titanium to eliminate residual oxygen in the cavity. Each melting is performed for 140s, and each sample is turned over and melted 4 times. After each melting, high purity argon is re-evacuated and high purity titanium is pre-melted. After being thoroughly melted and cut evenly, the Fe-Cr master alloy is prepared after cooling to room temperature in the protective cavity.

[0107] S4, the Fe-Cr master alloy and Al-Y master alloy obtained by smelting in steps S2 and S3 2 O 3 The intermediate alloy was melted in a vacuum arc melting furnace at a mass ratio of 19.1:0.9. Before melting, the furnace chamber was cleaned 5 times with a high-purity argon atmosphere, and then an arc was struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials were placed at the bottom of a water-cooled copper mold in order from low to high melting points. The mechanical vacuum pump and molecular diffusion pump were turned on in the arc furnace chamber to evacuate to 0.00011MPa, and then high-purity argon was introduced to pre-melt high-purity titanium to remove residual oxygen in the chamber. Each melting was performed for 155s, and each sample was turned over and melted 4 times. After each melting, high-purity argon was re-evacuated and high-purity titanium was pre-melted. After the melting was thoroughly and evenly cut, a water-cooled copper mold was used for vacuum casting. After cooling to room temperature, ferritic stainless steel with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles was prepared.

[0108] Example 5

[0109] Alloy sample preparation

[0110] The present invention selects pure iron, pure aluminum, nano yttrium oxide powder, pure chromium and pure titanium as raw materials. In the raw materials of Fe-Cr master alloy, 84.65% pure iron (the chemical composition mass fraction of pure iron is 99.9996% Fe), 14.83% pure chromium (the chemical composition mass fraction of pure chromium is 99.95% Cr), and 0.52% pure titanium (the chemical composition mass fraction of pure titanium is 99.996% Ti) are added respectively; 2 O 3 89.00% pure aluminum (the chemical composition mass fraction of pure aluminum is 99.996% Al) and 20.00% nano yttrium oxide powder (the chemical composition mass fraction of nano yttrium oxide powder is 99.9% Y 2 O 3 ).

[0111] The specific preparation and smelting process of the present invention is as follows:

[0112] S1. According to the requirements of the composition ratio, weigh pure iron, pure chromium, and pure aluminum respectively, clean them with dilute hydrochloric acid and anhydrous ethanol ultrasonically in turn, place them in a vacuum drying oven, dry them and set them aside. Use a 1 / 10,000 balance to weigh the nano yttrium oxide powder, place it in a vacuum drying oven, dry it and set it aside.

[0113] S2, the raw materials 4N grade pure aluminum and nano yttrium oxide powder prepared in step S1 are melted in a vacuum induction melting furnace, the induction melting furnace is placed in a glove box, and the vacuum is repeatedly pumped and filled with high-purity argon gas for 3 times to exhaust the residual gas in the glove box, and then the glove box is filled with high-purity argon gas. A high-frequency ultrasonic generator is arranged in the induction furnace, and an alumina crucible for melting is placed in the ultrasonic generator, and the yttrium oxide powder is placed at the bottom of the crucible. During the melting, the melting temperature is 705°C, and the ultrasonic generator is turned on during the melting process to apply 19kHz high-frequency oscillation to the molten metal, and an alumina stirring rod is used to mechanically stir at a speed of 117rmp. After 10 minutes, the molten metal is poured into a graphite casting mold and cooled to room temperature to obtain Al-Y with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles. 2 O 3 Master alloy.

[0114] S3, the raw materials 5N grade pure iron, pure chromium and high purity titanium configured in step S1 are melted by a vacuum arc melting furnace. Before melting, the furnace chamber is cleaned 3 times with a high purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed at the bottom of a water-cooled copper mold in order from low to high melting points, and a mechanical vacuum pump and a molecular diffusion pump are turned on in the arc furnace cavity to evacuate to 0.00013MPa and then high purity argon is introduced, and high purity titanium is pre-melted to remove residual oxygen in the cavity. Each melting is performed for 145s, and each sample is turned over and melted 4 times. After each melting, high purity argon is re-evacuated and high purity titanium is pre-melted. After being thoroughly melted and cut evenly, the Fe-Cr master alloy is prepared after cooling to room temperature in the protective cavity.

[0115] S4, the Fe-Cr master alloy and Al-Y master alloy obtained by smelting in steps S2 and S3 2 O 3 The intermediate alloy was melted in a vacuum arc melting furnace at a mass ratio of 18.9:1.1. Before melting, the furnace chamber was cleaned 5 times with a high-purity argon atmosphere, and then an arc was struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials were placed at the bottom of a water-cooled copper mold in order from low to high melting points. The mechanical vacuum pump and molecular diffusion pump were turned on in the arc furnace chamber to evacuate to 0.00008MPa, and then high-purity argon was introduced to pre-melt high-purity titanium to remove residual oxygen in the chamber. Each melting was performed for 120s, and each sample was turned over and melted 4 times. After each melting, high-purity argon was re-evacuated and high-purity titanium was pre-melted. After the melting was thoroughly and evenly cut, a water-cooled copper mold was used for vacuum casting. After cooling to room temperature, ferritic stainless steel with uniform composition, fine grains, and uniformly distributed nano-scale dispersed particles was prepared.

[0116] In summary, the present invention provides a nuclear-grade ferritic stainless steel with high-density nano-dispersed particles and a preparation method thereof, which is prepared by combining an external field assisted induction melting process with high-purity argon protection and a vacuum arc melting process, so that the nuclear-grade ferritic stainless steel with high-density nano-dispersed particles has fine grains and fine oxide dispersed particles, so that various properties of the material are greatly improved, and the performance is better than that of ordinary ferritic stainless steel.

[0117] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Preparation method of nuclear grade ferritic stainless steel with high density nano dispersed particles, It is characterized in that The following steps are involved: Al-Y 2 O 3 The master alloy and Fe-Cr master alloy are mixed and then vacuum arc melted. 2 O 3 In the master alloy, by mass percentage, nano yttrium oxide is 5.00%~20.00%, and the rest is 4N grade pure aluminum. In the Fe-Cr master alloy, by mass percentage, pure chromium is 14.50%~15.00%, high purity titanium is 0.45%~0.55%, and the rest is 5N grade pure iron. 2 O 3 The mass ratio of the master alloy to the Fe-Cr master alloy is 19:

1. Each smelting takes 2 to 3 minutes. Each sample is turned over and smelted 4 to 10 times. After each smelting, the furnace is vacuumed and high-purity argon is passed through and high-purity titanium is pre-melted. Before smelting, the furnace chamber is cleaned 3 to 5 times with a high-purity argon atmosphere, and then an arc is struck with a cerium tungsten electrode under high current. Before arc striking, the raw materials are placed on the bottom of a water-cooled copper mold in order from low to high melting points. The arc furnace chamber is vacuumed and high-purity argon is continuously passed through. High-purity titanium is pre-melted to remove residual oxygen in the chamber. After the temperature drops to room temperature, nuclear-grade ferritic stainless steel with high-density nano-dispersed particles is prepared.

2. The method for preparing nuclear-grade ferritic stainless steel having high-density nano-dispersed particles according to claim 1, It is characterized in that Al-Y 2 O 3 The intermediate alloy is prepared by an external field assisted induction melting process protected by high-purity argon. The induction melting furnace is placed in a glove box, and the vacuum is repeatedly evacuated and filled with high-purity argon for three times to exhaust the residual gas in the glove box. The glove box is filled with high-purity argon. A high-frequency ultrasonic generator is arranged in the induction furnace, and an alumina crucible for melting is placed in the high-frequency ultrasonic generator. Yttrium oxide powder is placed at the bottom of the crucible. During melting, pure aluminum is placed in the crucible and induction heated to 700~720℃. During the melting process, the ultrasonic generator is turned on to apply high-frequency oscillation to the molten metal, and an alumina stirring rod is used for mechanical stirring. After 10~15 minutes, the molten metal is poured into a casting mold and cooled to room temperature to obtain an alloy.

3. The method for preparing nuclear-grade ferritic stainless steel having high-density nano-dispersed particles according to claim 1, It is characterized in that The Fe-Cr intermediate alloy is prepared by vacuum arc melting process. Each melting takes 2 to 3 minutes. Each sample is turned over and melted 4 to 6 times. After each melting, the vacuum is pumped again, high-purity argon is passed through, and high-purity titanium is pre-melted. Before melting, the furnace chamber is cleaned 3 to 5 times with high-purity argon atmosphere, and then the arc is struck with cerium tungsten electrode under high current. Before arc striking, the raw materials are placed on the bottom of the water-cooled copper mold in order from low to high melting point. The arc furnace chamber is vacuumed and high-purity argon is continuously passed through to pre-melt high-purity titanium to remove residual oxygen in the chamber.

4. The method for preparing nuclear-grade ferritic stainless steel having high-density nano-dispersed particles according to claim 1, It is characterized in that Before smelting, 5N grade pure iron, pure chromium, high purity titanium, 4N grade pure aluminum and nano yttrium oxide powder are ultrasonically cleaned with dilute hydrochloric acid and anhydrous ethanol in turn, and then vacuum dried for later use.

5. A nuclear grade ferritic stainless steel with high density nano-dispersed particles, It is characterized in that The method for preparing a nuclear-grade ferrite stainless steel having high-density nano-dispersed particles according to any one of claims 1 to 4 comprises a metal matrix and nano-oxide dispersed particles, wherein, by weight percentage, Al: 3.60% to 5.23, Cr: 13.70% to 14.33%, Y 2 O 3 : 0.23%~1.10%, Ti: 0.43%~0.53%, and the rest are Fe and inevitable trace impurities.

6. The nuclear grade ferritic stainless steel with high density nano dispersed particles according to claim 5, It is characterized in that The metal matrix is ​​α-Fe with an average particle size of 110 μm, the average particle size of the dispersed oxide particles is 200 nm, and the average distribution density of the dispersed particles is 2.5×10 13 m -3 .

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