A method for producing an oxide dispersion strengthened stainless steel

Abstract

The application belongs to the field of metal materials, and particularly relates to a preparation method of oxide dispersion strengthened stainless steel. The method combines the method of loading oxygen-rich precursors into composite materials by gas-solid two-phase flow and vacuum jet deposition technology. The process can realize the jet deposition of the oxygen-rich precursors in the stainless steel matrix under a negative pressure environment by the driving of the gas-solid two-phase flow to prepare a jet deposition ingot, and realize the preparation of the nano-oxide dispersion strengthened steel by heat treatment, vacuum consumable, forging and hot rolling processes.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of metal materials, and particularly relates to a preparation method of oxide dispersion strengthened stainless steel. BACKGROUND

[0002] Fusion energy is one of the ultimate solutions for clean energy in the future, and is a research hotspot in the fields of energy, materials and engineering at present and even for a period of time. Among them, the first wall which bears the function of energy bearing and transmission is one of the most critical components, and requires comprehensive requirements such as resistance to neutron irradiation, high temperature strength, and resistance to lead bismuth alloy corrosion. The most ideal material for manufacturing the first wall is oxide dispersion strengthened material, i.e. Oxide Dispersion Strength - ODS alloy, in which the size of the oxide needs to be controlled in 2-8nm, and needs to reach x10 24 / m 3 However, the wettability of the oxide and the steel liquid is extremely poor, and the oxide is difficult to be prepared by a smelting method because it aggregates, grows and floats in the liquid phase. The preparation processes of powder metallurgy and mechanical alloying have a series of problems such as high cost, low efficiency and poor batch stability. Therefore, it is of great significance to develop a high-performance, low-cost preparation process and industrialization method of oxide dispersion strengthened stainless steel.

[0003] Under the condition of the existing process flow, the smelting process cannot add a large amount of second phase, and the segregation flow formed in the solidification process directly restricts the development of oxide dispersion strengthened materials. A new generation of composite functional special alloy needs to be developed through rapid solidification technology and experimental equipment. The application is an application process which combines rapid solidification and oxide generation metallurgy by dispersing stainless steel mother alloy liquid through gas-solid two-phase flow injection, and has great application value in the development of high-nitrogen stainless steel, ceramic strong strengthening wear-resistant alloy, and especially oxide dispersion strengthened alloy. SUMMARY

[0004] In view of the problems in the prior art, the application provides a preparation method of oxide dispersion strengthened stainless steel, which is an efficient preparation method of adding nanometer oxide to the matrix based on the smelting method and the gas-solid two-phase flow injection deposition scheme, and solves the common problems of injection deposition porosity defects, difficulty in dispersing a large amount of oxide, excessive amount of injection gas, and high cost of metal composite material preparation.

[0005] The technical scheme of the application is as follows:

[0006] A preparation method of oxide dispersion strengthened stainless steel, comprising the following steps:

[0007] Step (1), the negative pressure environment is realized by using the double vacuum chamber closed structure device: the double vacuum chamber structure device is divided into a smelting chamber, an intermediate chamber and a spraying deposition chamber, the intermediate chamber is connected with the smelting chamber and the spraying deposition chamber, and the connection and isolation are realized by pouring the plug-in valve; the smelting chamber is provided with a smelting ladle, and the intermediate chamber is placed in the intermediate chamber after being preheated outside the chamber; the smelting chamber is connected with a high vacuum pump group, and the vacuum degree of the smelting chamber is ≤5*10 -2 Pa; the spraying deposition chamber is separately provided with a high-speed vacuum pump group, and the environmental pressure under the input condition of the spraying gas is maintained to be ≤6000 Pa;

[0008] Step (2), the vacuum medium frequency induction smelting of the base alloy is realized by the smelting chamber, wherein the base alloy composition is as follows: base alloy: C: 0.015~0.2%, Ti: 0.2~0.5 %, Si: 0.2~0.8%; W: 0.5~1.5 %, Cr: 8.5~20%, V: 0.2~0.5%, RE: 0.05~0.35%, N≤0.002%, O≤0.001%, wherein the rare earth is added in the form of an intermediate alloy at the end of smelting, and the single furnace smelting capacity is more than 1t;

[0009] Step (3), the overheat degree of the alloy solution after smelting in step (2) is controlled to be +40~100℃, the intermediate chamber sealing door is closed, the bottom argon blowing and degassing treatment is realized by the smelting ladle, the control valve is opened, the pouring plug-in valve is closed, then the pouring plug-in valves of the smelting chamber and the spraying deposition chamber are opened, the high-speed vacuum pump group is started, the intermediate chamber is lowered to be 350~750mm away from the deposition blank, the smelting ladle controls the flow through the bottom slide gate nozzle and pours the alloy solution into the intermediate chamber to stabilize the liquid level of 80~200mm, and the preheating temperature of the intermediate chamber is ≥1200℃;

[0010] Step (4), the surface modification of the precursor particles: the precursor particles are TiO2 powder, the 20-50nm particle size TiO2 powder is mixed with low carbon steel or Fe-Cr-Y alloy matrix powder in liquid argon, the particle size of the Fe-Cr-Y alloy matrix powder is 10-20μm, the mass fraction of the TiO2 powder is 50-90%, the ball milling time is more than 24 hours, the metal powder is attached to the surface of the TiO2 powder, the TiO2 powder and the alloy solution are fully wetted, and the proportion of the particles providing solidification heat transfer is ≤20%;

[0011] Step (5), the TiO2 powder mixed with the low carbon steel or Fe-Cr alloy powder after the surface modification in step (4) is mixed with inert gas Ar in the gas-solid two-phase flow mixing and preheating device, is uniformly mixed with the inert gas Ar after being preheated, forms a gas-solid two-phase flow, is divided into two paths and enters the spraying mechanism through two-phase flow pipelines, the alloy solution is sprayed out through the spraying mechanism, the inert gas Ar blows the TiO2 powder into the alloy solution in the spraying through the two-phase flow pipelines, the two are converged and deposited on the deposition blank.

[0012] Step (6), the gas-solid two-phase flow disperses the alloy solution flowing out of the two sprue gates of the spraying mechanism into uniform liquid drops in the spraying deposition cabin, and completes the spraying of the deposition blank on the deposition disc;

[0013] Step (7), after the spraying is completed, the temperature of the top of the ingot blank is controlled to be ≤1400℃, the temperature of the bottom of the ingot blank is controlled to be ≤1300℃, the ingot blank is taken out and then is sent into a 1180℃ forging holding furnace to be uniformly heated for 2h, is forged into a suitable size of a vacuum consumable electrode, and then is subjected to primary vacuum arc melting, the height of the molten pool is controlled to be ≤3mm, and then the round blank is forged into a square blank and is hot-rolled, and the final rolling thickness is 2.0-30mm.

[0014] Further, in the above method for preparing the oxide dispersion strengthened stainless steel, the number of pores on the solidification end face in the spraying deposition cabin is ≤5 per 10mm 2 , and the pore diameter is ≤1μm, and all the pores are completely closed after the forging of step (7).

[0015] Further, in the above method for preparing the oxide dispersion strengthened stainless steel, after the hot rolling of step (7), the number of 2-8nm rare earth oxide in the matrix is ≥1×10 24 per m 3 , and is uniformly distributed on the matrix, and the volume ratio of the rare earth oxide with a size of more than 10nm is not more than 20%.

[0016] Further, in the above method for preparing the oxide dispersion strengthened stainless steel, the preheating temperature of step (5) is ≥600℃, the feeding amount of the 200-500nm particle size precursor particle TiO2 powder is 100-500g / min, and the powder addition amount in the alloy is controlled to be 0.5-2%.

[0017] Further, in the above method for preparing the oxide dispersion strengthened stainless steel, in step (1), two water outlets are horizontally arranged at the lower edge of the tundish, the water outlet diameter is φ3-9mm, the single nozzle flow is 15-55kg / min, the nozzle outlet flow speed is 0.5-2.0m / min, the water outlet position is opposite to the 1 / 3 and 2 / 3 positions of the radius of the deposition blank, and the outer nozzle aperture area is 20% larger than the inner nozzle aperture.

[0018] Further, in the above method for preparing the oxide dispersion strengthened stainless steel, in step (5), the spraying deposition ring of the spraying mechanism has 6-18 opening numbers, the aperture diameter is 2.5-10mm, and the focal length is 50-100mm below the plane; the spraying deposition ring is made of heat-resistant stainless steel, the inner surface is plated with hard chromium, and the HRC is above 52; the spraying deposition ring has an inclination angle of -20° to +40°, the scanning frequency is 0-2Hz, the gas spraying pressure is 0.3-0.8MPa, and the single spraying deposition ring gas spraying amount is 10-50m 3 / min.

[0019] Further, in the step (6) of the preparation method of the oxide dispersion strengthened stainless steel, the distance between the deposition disc and the lower end of the spray deposition ring is controlled to be 150-500 mm, the diameter of the deposition blank is 200-800 mm, the rotation speed of the deposition disc is 30-100 r / min, the falling speed is 60-150 mm / min, and the surface molten pool depth is controlled to be 0.5-2.5 mm.

[0020] Further, in the preparation method of the oxide dispersion strengthened stainless steel, the gas-solid two-phase flow drives the liquid phase, and the solid phase simultaneously plays the roles of the coolant, the nucleating agent and the oxygen-rich precursor.

[0021] Advantages and beneficial effects of the present application:

[0022] 1. The present application combines the oxygen-rich precursor loading composite material method of the gas-solid two-phase flow and the vacuum spray deposition technology. The process can realize the spray deposition ingot preparation of the oxygen-rich precursor in the stainless steel matrix under the negative pressure environment through the driving of the gas-solid two-phase flow, and realize the preparation of the nano-oxide dispersion strengthened steel through the heat treatment, vacuum self-consumption, forging and hot rolling process;

[0023] 2. The rapid solidification process can realize the oxide dispersion strengthening, the uniform solid solution of the high alloy, the fine-grain strengthening and the reduction of the solidification defects, so as to significantly improve the high-temperature mechanical properties, the radiation resistance, the corrosion resistance and the thermal stability of the material. This has important significance for meeting the high-performance material demand in the fields of thermal energy, chemical industry and energy;

[0024] 3. The gas-solid two-phase flow driven metal vacuum spray deposition process has high process flexibility. The gas pressure, the type and content of the solid phase particle precursor, the deposition temperature and other parameters can be adjusted according to the needs, so that the oxide dispersion strengthened alloy and other composite materials with different properties and purposes can be prepared. This flexibility provides more possibilities for the design and preparation of various stainless steel matrix alloys;

[0025] 4. The deposition process in the vacuum environment of the present application reduces the oxidation and pollution of the material and reduces the subsequent processing cost;

[0026] 5. The process introduces the solid phase medium particle precursor on the basis of the gas atomization, and forms the gas-solid two-phase mixed flow. This new atomization mechanism significantly improves the atomization efficiency, refines the particle size of the atomized powder, and improves the uniformity of the oxygen-rich precursor in the matrix alloy. This innovative forming process provides a new idea and method for the preparation of high-performance nano-oxide dispersion strengthened materials. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Process diagram for preparing oxide dispersion strengthened stainless steel of the present application;

[0028] In the figure: 1 - high vacuum pump set; 2 - control valve a; 3 - smelting cabin; 4 - smelting ladle; 5 - tundish; 6 - pouring plug valve; 7 - tundish cabin sealing door; 8 - tundish cabin; 9 - gas-solid two-phase flow mixing and preheating device; 10 - two-phase flow pipeline; 11 - injection mechanism; 12 - injection deposition cabin; 13 - deposited billet; 14 - deposition disc; 15 - control valve b; 16 - solid phase particle cyclone separator; 17 - control valve c; 18 - high-speed vacuum pump set. DETAILED DESCRIPTION

[0029] Process diagram for preparing oxide dispersion strengthened stainless steel of the present application is shown in Figure 1 The specific embodiments of the present application are described in further detail below in conjunction with the accompanying drawings and examples of the present application. The following examples are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0030] In the following examples, a double vacuum cabin closed structure device is used to realize negative pressure environment injection: the double vacuum cabin structure device is divided into smelting cabin 3, tundish cabin 8 and injection deposition cabin 12, the tundish cabin 8 is connected to the smelting cabin 3 and the injection deposition cabin 12, and the communication and isolation are realized through the pouring plug valve 6; the smelting cabin 3 is provided with a smelting ladle 4, and the liftable tundish 5 is placed in the tundish cabin 8 after being preheated outside the cabin; the smelting cabin 3 is connected to the high vacuum pump set 1, and the injection deposition cabin 12 is separately provided with a high-speed vacuum pump set 18. Example 1

[0031] In this embodiment, a preparation method of oxide dispersion strengthened stainless steel includes the following steps:

[0032] Step (1) open control valve a 2, close pouring plug valve 6, adjust the vacuum degree of smelting cabin 3 ≤ 5 × 10 -2 Pa, the environmental pressure under the input condition of injection gas is ≤ 6000 Pa; two water outlets are horizontally arranged at the lower edge of tundish 5, the water outlet diameter is φ6 and φ8 mm, the single nozzle flow is 38 and 50 kg / min, the nozzle outlet flow speed is 1.0 m / min, the water outlet position is opposite to the 1 / 3 and 2 / 3 positions of the radius of the deposited billet, and the outer nozzle aperture area is 20% larger than the inner nozzle aperture;

[0033] Step (2) vacuum medium frequency induction smelting of base alloy is carried out through smelting cabin 3, wherein the base alloy composition is: C: 0.08%, Ti: 0.2%, Si: 0.2%; W: 0.5%, Cr: 8.5%, V: 0.2%, RE: 0.1%, N: 0.002%, O: 0.001%, wherein the rare earth is an intermediate alloy and is added at the end of smelting, and the single furnace smelting capacity is 1 t;

[0034] Step (3) The alloy solution after smelting is controlled at +40℃ overheat, and is subjected to argon bottom blowing deslagging and degassing treatment from the smelting ladle 4, the control valve a2 and the tundish cabin sealing door 7 are closed, then the control valve b15 and the control valve c17 are opened, then the smelting cabin 3 and the injection deposition cabin 12 pouring plug valve 6 are opened, the high-speed vacuum pump group 18 is started, the tundish 5 is lowered to 400mm from the deposition blank, the smelting ladle 4 controls the flow through the bottom slide gate nozzle and pours the alloy solution into the tundish 100mm stably, the tundish 5 is preheated to 1200℃;

[0035] Step (4) Surface modification of the precursor particles: the precursor particles are TiO2 powder, the 20nm particle size TiO2 powder is mixed with low carbon steel matrix powder in liquid argon, the Fe-Cr-Y alloy matrix powder has a particle size of 10μm, the mass fraction of the TiO2 powder is 50%, the ball milling time is more than 24 hours, the metal powder is attached to the surface of the TiO2 precursor particles, and the TiO2 powder and the alloy solution are fully wetted, wherein the proportion of the particles providing solidification heat transfer is ≤20%;

[0036] Step (5) The TiO2 powder mixed with the low carbon steel or Fe-Cr alloy powder after the surface modification in step (4) is mixed with inert gas Ar in the gas-solid two-phase flow mixing and preheating device 9, and is preheated to form a gas-solid two-phase flow, and is divided into two paths by the two-phase flow pipeline 10 into the injection mechanism 11, the alloy solution is sprayed out through the injection mechanism 11, the inert gas Ar blows the precursor particles into the alloy solution in the injection through the two-phase flow pipeline 10, and the two are converged and deposited on the deposition blank 13; the preheating temperature of the surface modified precursor particles is 600℃, the powder feeding amount of the 50nm particle size precursor particles is 100g / min; the injection deposition ring of the injection mechanism 11 has 18 opening numbers with a hole diameter of 4mm, and the focal length method surface is below 60mm; the injection deposition ring is made of heat-resistant stainless steel, the inner surface is plated with hard chromium with HRC above 52; the injection deposition ring has an inclination angle of -20~+30°, and a scanning frequency of 1Hz; the gas injection pressure is 0.5MPa, and the gas injection amount of a single injection deposition ring is 20m 3 / min;

[0037] Step (6) The gas-solid two-phase flow disperses the alloy solution flowing out of the two sprue gates of the injection mechanism 11 into uniform droplets in the injection deposition cabin 12, and completes the injection of the deposition blank 13 on the deposition disc 14; during the injection deposition process, the distance between the deposition disc 14 and the lower end of the injection deposition ring is controlled to be 300mm, the diameter of the deposition blank 13 is 500mm, the rotation speed of the deposition disc is 45r / min, the descending speed is 45mm / min, and the surface molten pool depth is controlled to be 1.5mm;

[0038] After the spraying in step (7) is completed, the temperature of the top of the ingot blank is controlled at 1350℃, and the temperature of the bottom of the ingot blank is controlled at 1250℃. After the ingot blank is taken out, it is sent into a 1180℃ forging holding furnace to be evenly heated for 2h, forged into a suitable size of vacuum consumable electrode, and then subjected to primary vacuum arc melting, with the height of the molten pool controlled at 3mm. Then, the round blank is forged into a square blank, and then hot-rolled, with the final rolling thickness being 8mm.

[0039] The number of pores on the solidified end face in the spray deposition cabin is 5 per 10mm 2 , and the pore diameter is 1.5μm. After forging in step (7), all the pores are completely closed.

[0040] In this embodiment, the number of 2-8nm rare earth oxides in the hot-rolled plate substrate is 1×10 24 / m 3 , which is uniformly distributed on the substrate, and the volume ratio of the rare earth oxides above 10nm is 20%. Embodiment 2

[0041] In this embodiment, a preparation method of an oxide dispersion strengthened stainless steel comprises the following steps:

[0042] In step (1), control valve a2 is opened, pouring plug valve 6 is closed, the vacuum degree of melting cabin 3 is adjusted to be ≤5×10 -2 Pa, and the environmental pressure under the input condition of the spraying gas is ≤4000Pa. Two water outlets are horizontally arranged at the lower edge of tundish 5, with the diameters of the water outlets being φ5 and φ8mm, the single nozzle flow being 37 and 52kg / min, the nozzle outlet flow speed being 1.2m / min, the water outlet position being opposite to the 1 / 3 and 2 / 3 positions of the deposition blank, and the outer nozzle aperture area being 20% larger than the inner nozzle aperture.

[0043] In step (2), vacuum medium-frequency induction melting of the base alloy is performed through melting cabin 3, wherein the composition of the base alloy is: C: 0.2%, Ti: 0.3%, Si: 0.8%, W: 1.5%, Cr: 20%, V: 0.5%, RE: 0.35%, N: 0.002%, O: 0.001%, and the rare earth is added in the form of an intermediate alloy at the end of melting, with the single furnace melting capacity being 5t.

[0044] In step (3), the overheat degree of the alloy solution after melting in step (2) is controlled at +100℃, bottom argon blowing and degassing treatment is performed on the molten steel ladle 4, control valve a2 and tundish cabin sealing door 7 are closed, control valve b15 and control valve c17 are opened, pouring plug valve 6 of melting cabin 3 and spray deposition cabin 12 is opened, high-speed vacuum pump group 18 is started, tundish 5 is lowered to a distance of 400mm from the deposition blank, the flow rate of the alloy solution is controlled through the bottom sliding plate water outlet of molten steel ladle 4, and the alloy solution is injected into tundish 180mm to stabilize the liquid level, and the preheating temperature of tundish 5 is 1250℃.

[0045] Step (4) precursor particle surface modification: precursor particles are TiO2 powder, 20-50 nm particle size TiO2 powder is mixed with Fe-Cr-Y alloy matrix powder in liquid argon, Fe-Cr-Y alloy matrix powder particle size is 15 μm, wherein the mass fraction of TiO2 powder is 90%, the ball milling time is 48 hours, the metal powder is attached to the surface of the TiO2 precursor particles, and the TiO2 powder and the alloy solution are fully wetted, wherein the particle provides a solidification heat transfer ratio of 15%;

[0046] Step (5) after the TiO2 powder surface modified in step (4) is mixed with low carbon steel or Fe-Cr alloy powder in a gas-solid two-phase flow mixing and preheating device 9, the mixture is uniformly mixed with inert gas Ar and preheated to form a gas-solid two-phase flow, and the two-phase flow is divided into two paths by two-phase flow pipeline 10 and enters the injection mechanism 11, the alloy solution is sprayed out of the injection mechanism 11, the inert gas Ar blows the precursor particles into the alloy solution in the injection through the two-phase flow pipeline 10, and the two are converged and deposited on the deposition billet 13; the preheating temperature of the surface modified precursor particles is 650℃, the powder feeding amount of the 200 nm particle size precursor particles is 500 g / min; the injection deposition ring of the injection mechanism 11 has 20 openings with a diameter of 8 mm, and the focal length is below the surface by 80 mm; the injection deposition ring is made of heat-resistant stainless steel, the inner surface is plated with hard chromium with HRC above 52; the inclination angle of the injection deposition ring is -20~+30°, and the scanning frequency is 2 Hz; the gas injection pressure is 0.85 MPa, and the gas injection amount of a single injection deposition ring is 30 m 3 / min;

[0047] Step (6) the gas-solid two-phase flow disperses the alloy solution flowing out of the two sprue gates of the injection mechanism 11 into uniform droplets in the injection deposition cabin 12, and completes the injection of the deposition billet 13 on the deposition disc 14; during the injection deposition process, the distance between the deposition disc 14 and the lower end of the injection deposition ring is controlled to be 450 mm, the diameter of the deposition billet 13 is 500 mm, the rotation speed of the deposition disc is 80 r / min, the descending speed is 78 mm / min, and the surface molten pool depth is controlled to be 2 mm;

[0048] Step (7) after the injection is completed, the temperature of the top of the ingot billet is controlled to be 1300℃, the temperature of the bottom of the ingot billet is controlled to be 1200℃, the ingot billet is taken out and sent to a 1180℃ forging holding furnace for 2 hours, then vacuum arc melting is carried out, the molten pool height is controlled to be 2 mm, then the round billet is forged into a square billet and hot rolled, and the final rolling thickness is 30 mm.

[0049] The number of pores on the solidification end face in the injection deposition cabin is 4 / 10 mm 2 , and the pore diameter is 1.5 μm, and all the pores are pressed after forging in step (7).

[0050] In the embodiment, the number of 2-8 nm rare earth oxides in the hot-rolled plate substrate is 8×10 24 / m 3 , which is uniformly distributed on the substrate, and the volume ratio of rare earth oxides above 10 nm is 15%.

Claims

1. A method for preparing oxide dispersion strengthened stainless steel, characterized in that, Includes the following steps: Step (1): A negative pressure environment for spraying is achieved by using a double vacuum chamber closed structure device: The double vacuum chamber closed structure device is divided into a smelting chamber, an intermediate ladle chamber and a spray deposition chamber. The intermediate ladle chamber is connected to the smelting chamber and the spray deposition chamber, and the connection and isolation are achieved by a pouring gate valve; the smelting chamber is equipped with a smelting ladle, and the liftable intermediate ladle is preheated to the temperature outside the chamber and then placed into the intermediate ladle chamber. The melting chamber is connected to a high-vacuum pump unit, and the vacuum degree of the melting chamber is ≤5×10⁻⁶. -2 Pa; The jet deposition chamber is equipped with a separate high-speed vacuum pump group to maintain an ambient pressure ≤6000Pa under jet gas input conditions; Step (2): Vacuum induction melting of the base alloy is carried out in the melting chamber. The composition of the base alloy is as follows: C: 0.015~0.2%, Ti: 0.2~0.5%, Si: 0.2~0.8%; W: 0.5~1.5%, Cr: 8.5~20%, V: 0.2~0.5%, RE: 0.05~0.35%, N≤0.002%, O≤0.001%, wherein rare earth is used as an intermediate alloy and added at the end of smelting, and the smelting capacity of a single furnace is more than 1 t; After melting, the alloy solution in steps (3) and (2) is controlled to have a superheat of +40~100℃. The sealing door of the tundish is closed. The bottom blowing argon deslag removal and degassing treatment is carried out by the melting ladle. The control valve is opened and the casting gate valve is closed. Then the casting gate valves of the melting chamber and the jet deposition chamber are opened. The high-speed vacuum pump group is started. The tundish is lowered to a distance of 350~750mm from the deposition billet. The melting ladle controls the flow rate through the bottom slide gate and injects the alloy solution into the tundish at a stable liquid level of 80~200mm. The preheating temperature of the tundish is ≥1200℃. Step (4) Surface modification of precursor particles: The precursor particles are TiO2 powder. TiO2 powder with a particle size of 20-50 nm is mixed with low carbon steel or Fe-Cr-Y alloy matrix powder in liquid argon. The Fe-Cr-Y alloy matrix powder has a particle size of 10-20 μm. The mass fraction of TiO2 powder is 50-90%. The ball milling time is more than 24 hours to promote the adhesion of metal powder to the surface of TiO2 powder of the precursor particles and to promote the full wetting of TiO2 powder and alloy solution. The proportion of solidification heat transfer provided by the particles is ≤20%. Step (5): The TiO2 powder modified by step (4) and the low carbon steel or Fe-Cr alloy powder ball milled mixture are mixed evenly with inert gas Ar in a gas-solid two-phase flow mixing and preheating device and then preheated to form a gas-solid two-phase flow. The mixture is divided into two routes and enters the spraying mechanism through the two-phase flow pipe. The alloy solution is sprayed out through the spraying mechanism. The inert gas Ar blows the TiO2 powder into the sprayed alloy solution through the two-phase flow pipe. The two converge and are deposited on the deposited billet. Step (6): The gas-solid two-phase flow fully disperses the alloy solution flowing out of the two gate ingots of the spraying mechanism into uniform droplets in the spraying deposition chamber, and completes the spraying of the deposited billet on the deposition plate. Step (7): After the spraying is completed, the temperature of the top of the billet is controlled to be ≤1400℃ and the temperature of the bottom of the billet is controlled to be ≤1300℃. After the billet is taken out, it is sent to a 1180℃ forging holding furnace for uniform temperature for 2 hours. The billet is forged into a vacuum consumable electrode of appropriate size. Then, a vacuum arc melting is carried out, and the height of the molten pool is controlled to be ≤3mm. Then, the round billet is forged into a square billet and hot rolled, with a final rolling thickness of 2.0-30mm.

2. The method for preparing oxide dispersion strengthened stainless steel according to claim 1, characterized in that, The number of pores on the solidification end face inside the jet deposition chamber is ≤5 / 10mm 2 And the pore size is ≤1μm, and all the pores are pressed together after forging in step (7).

3. The method for preparing oxide dispersion strengthened stainless steel according to claim 1, characterized in that, After hot rolling in step (7), the number of rare earth oxides in the matrix at 2~8 nm is ≥1×10 24 pcs / m 3 The rare earth oxides above 10 nm are evenly distributed on the matrix, and the volume ratio of rare earth oxides does not exceed 20%.

4. The method for preparing oxide dispersion strengthened stainless steel according to claim 1, characterized in that, The preheating temperature in step (5) is ≥600℃, the feed rate of TiO2 precursor particles with a particle size of 200~500nm is 100~500g / min, and the amount of powder added in the alloy is controlled to be 0.5~2%.

5. The method for preparing oxide dispersion strengthened stainless steel according to claim 1, characterized in that, In step (1), two nozzles are arranged horizontally along the lower edge of the tundish. The nozzle diameter is φ3~9mm, the single nozzle flow rate is 15~55kg / min, the nozzle outlet velocity is 0.5~2.0m / min, and the nozzle positions are directly opposite the 1 / 3 and 2 / 3 of the radius of the deposited billet. The outer nozzle orifice area is 20% larger than the inner orifice area.

6. The method for preparing oxide dispersion strengthened stainless steel according to claim 1, characterized in that, In step (5), the number of openings in the jet deposition ring of the jetting mechanism is 6 to 18, the diameter of the openings is 2.5 to 10 mm, and the diameter of the openings is 50 to 100 mm below the focal length normal. The jet deposition ring is made of heat-resistant stainless steel with hard chromium plating on the inner surface, and the diameter is HRC52 or higher. The tilt angle of the jet deposition ring is -20 to +40°, the scanning frequency is 0 to 2 Hz, the gas jet pressure is 0.3 to 0.8 MPa, and the gas jet volume of a single jet deposition ring is 10 to 50 m³. 3 / min.

7. The method for preparing oxide dispersion strengthened stainless steel according to claim 1, characterized in that, In step (6) during the spray deposition process, the distance between the deposition disk and the lower end of the spray deposition ring is controlled to be 150~500mm, the diameter of the deposition blank is 200~800mm, the rotation speed of the deposition disk is 30~100r / min, the descent speed is 60~150mm / min, and the depth of the surface molten pool is controlled to be 0.5~2.5mm.

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