A high number density oxide dispersion strengthened steel and a method of making the same

Abstract

The application discloses a high-number-density oxide dispersion strengthened steel and a preparation method thereof, and belongs to the field of metal material preparation. The chemical composition of the oxide dispersion strengthened steel and the mass percentage of each component are as follows: C: 0.03-0.15%, Cr: 7-14%, W: 1-3%, V: 0.1-0.3%, Ti: 0.05-0.30%, Zr: 0.05-0.30%, O: 0.005-0.200%, RE1: 0.01-0.50%, RE2: 0.01-0.50%, and the balance of Fe and inevitable impurities, wherein the RE1 is one or two of Er, Ce and Pr, and the RE2 is one or two of Y and La. The application can effectively inhibit the growth of rare earth oxides in the smelting process, form the high-number-density oxide dispersion strengthened steel, and improve the product performance.

Description

Technical Field

[0001] This invention belongs to the field of metal material preparation, and more specifically, relates to a high number-density oxide dispersion strengthened steel and its preparation method. Background Technology

[0002] Oxide dispersion strengthened steel (ODS steel) is a new type of special steel with excellent high-temperature creep resistance and radiation resistance, mainly used in nuclear reactor structural materials. This ODS steel contains a high-density, nano-sized oxide dispersion strengthening phase. This strengthening phase hinders dislocation slip by pinning dislocations and grain boundaries in the matrix, thereby achieving a strengthening effect.

[0003] In existing technologies, ODS steel prepared by smelting suffers from uneven oxide distribution in the microstructure after solidification. This is because oxides migrate along the solid-liquid interface during solidification, leading to a concentration of oxides at grain boundaries that tend to aggregate and grow. This reduces grain boundary strength and impairs material properties. Furthermore, the addition of a single rare earth element, due to its high mass percentage, promotes oxide coarsening and growth, making it difficult to guarantee uniformity in microstructure and properties after solidification.

[0004] For example, Chinese patent application number CN202010124618.4, published on June 30, 2020, discloses a method for preparing oxide dispersion-strengthened steel through high-throughput continuous melting. The specific steps are: S1) Selecting raw materials according to the composition of the oxide dispersion-strengthened steel with different oxide particles or clusters required by the design: iron oxide and a master alloy containing rare earth elements; S2) Placing iron oxides with different proportions into multiple melting containers for later use; S3) Heating and melting the master alloy containing rare earth elements, dripping it into a melting container containing iron oxides, and cooling to obtain various oxide dispersion-strengthened steels with different contents. This method uses a master alloy containing a single rare earth oxide to melt iron oxides. It suffers from the aforementioned problems: oxides move along the solid-liquid interface, causing most oxides to be distributed at grain boundaries and easily aggregate and grow; and the high mass percentage of the single rare earth element makes the oxides prone to coarsening and growth.

[0005] Chinese patent application number CN202210052384.6, published on April 26, 2022, discloses a method for preparing nano-oxide dispersion-strengthened steel. This invention mixes ferrochrome alloy, ferrotungsten alloy, rare-earth element-containing ferroalloy, oxygen source, and reduced iron powder to obtain a mixture; the mixture is then wrapped in a steel strip and drawn to reduce its diameter, yielding a flux-cored wire; the flux-cored wire is then subjected to arc additive manufacturing on a substrate, followed by heat treatment to obtain the nano-oxide particle dispersion-strengthened steel. Although this method uses one or more rare-earth elements in the rare-earth element-containing ferroalloy, during the smelting process, rare-earth elements and oxygen elements mostly form oxides such as Ce₂O₃ and Y₂O₃, which contain only a single rare-earth element. The size of these oxides still tends to increase during smelting, and the oxides also tend to migrate along the solid-liquid interface during solidification. Summary of the Invention

[0006] 1. The problem to be solved

[0007] To address the problem that in existing technologies for preparing oxide dispersion reinforced steel using the smelting method, it is difficult to suppress the size of rare earth oxides generated during the smelting process, resulting in the prepared oxide dispersion reinforced steel failing to meet performance requirements, this invention provides a high number-density oxide dispersion reinforced steel and its preparation method. This method can effectively suppress the growth of rare earth oxides during the smelting process, forming a high number-density oxide dispersion reinforced steel and improving product performance.

[0008] 2. Technical Solution

[0009] To solve the above problems, the present invention adopts the following technical solution.

[0010] A high number-density oxide dispersion-strengthened steel has the following chemical composition and mass percentages: C: 0.03–0.15%, Cr: 7–14%, W: 1–3%, V: 0.1–0.3%, Ti: 0.05–0.30%, Zr: 0.05–0.30%, O: 0.005–0.200%, RE1: 0.01–0.50%, RE2: 0.01–0.50%, with the balance being Fe and unavoidable impurities;

[0011] RE1 is one or two of Er, Ce, and Pr, and RE2 is one or two of Y and La.

[0012] As a further improvement to the technical solution, the mass percentage of RE1 and RE2 is (2:1) to (1:2).

[0013] A method for preparing the above-mentioned high number-density oxide dispersion-strengthened steel includes the following steps:

[0014] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, Zr, and RE2 in a set ratio, and then prepare the raw materials into an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

[0015] 2. After drilling holes in the intermediate alloy, fill the holes with mixed particles according to a set ratio and plug the holes to make an electrode ingot containing mixed particles. The mixed particles are particles formed by mixing intermediate alloy matrix elements, solid oxygen carrier particles and RE1 elemental particles or oxides.

[0016] 3. The electrode ingot is melted and cooled using vacuum consumable arc melting technology to obtain a cast ingot;

[0017] IV. After homogenization heat treatment, the ingot is forged to obtain a forged ingot of the specified specifications.

[0018] V. The forged ingot is heat-treated to obtain oxide dispersion strengthened steel, wherein the chemical composition and mass percentage of the oxide dispersion strengthened steel are as follows: C: 0.03-0.15%, Cr: 7-14%, W: 1-3%, V: 0.1-0.3%, Ti: 0.05-0.30%, Zr: 0.05-0.30%, O: 0.005-0.200%, RE1: 0.01-0.50%, RE2: 0.01-0.50%, with the balance being Fe and unavoidable impurities;

[0019] RE1 is one or two of Er, Ce, and Pr, and RE2 is one or two of Y and La.

[0020] As a further improvement to the technical solution, in step two, the proportion of solid oxygen carrier particles in the mixed particles is 10% to 30%.

[0021] As a further improvement to the technical solution, in step two, the particle size of the solid oxygen carrier particles is 0.1μm to 50mm.

[0022] As a further improvement to the technical solution, in step three, the smelting adopts a zone melting or small pool melting method.

[0023] As a further improvement to the technical solution, in step three, the melting temperature is 1500–1800℃.

[0024] As a further improvement to the technical solution, in step three, the cooling rate is 10. -1 ~10 4 K / s.

[0025] As a further improvement to the technical solution, in step three, a composite rare earth oxide containing two rare earth elements is generated in the ingot, and the size of the composite rare earth oxide is 100nm to 1μm.

[0026] As a further improvement to the technical solution, in step five, the size of the rare earth oxides finally generated in the oxide dispersion strengthened steel is 1nm to 10nm.

[0027] 3. Beneficial effects

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The present invention provides a high number density oxide dispersion reinforced steel and its preparation method. The composition of ODS, especially rare earth elements, is uniquely designed. Two groups of rare earth elements with different properties are added, and the mass ratio of the two groups of rare earth elements is limited. The addition of a single rare earth element is reduced, so that when the rare earth elements in the ingot react with oxygen during the casting solidification process, the two groups of rare earth elements can replace each other to form a composite rare earth oxide with two rare earth elements. This replacement process can effectively inhibit the growth of rare earth oxides during the formation of the ingot. The final size of the composite rare earth oxide can reach 100nm to 1μm, while the size of the rare earth oxide with only a single rare earth element in the conventional ingot often reaches 3μm to 10μm. Such large rare earth oxides will have a significant impact on the performance of ODS steel after the final forming of ODS steel. Therefore, the composite rare earth oxide of the present invention effectively improves the performance of the final formed ODS steel.

[0030] (2) The present invention discloses a high number-density oxide dispersion-strengthened steel and its preparation method. During the subsequent heat treatment of the ingot and forged ingot, the rare earth elements in the resulting composite rare earth oxide are replaced by another group of rare earth elements. During the replacement process, the unstable free rare earth elements that are replaced can more easily react with titanium and oxygen to form various rare earth nano-oxides with a size of less than 10 nanometers, such as Y-Ti-O and Ce-Ti-O. In contrast, the rare earth elements in conventional rare earth oxides are relatively stable. Compared with the scheme of the present invention, it is more difficult to react with titanium and oxygen to form rare earth nano-oxides with a size of less than 10 nanometers under the same environment. Therefore, the scheme of the present invention can more stably form a dispersion-strengthened steel with a high number density of rare earth nano-oxides, and the final number density can be stably higher than 10. 23 m -3 ;

[0031] (3) The present invention provides a high number density oxide dispersion strengthened steel and its preparation method. By using a consumable electrode or other method with regional melting or small molten pool melting characteristics, the steel liquid can obtain a faster solidification rate during the solidification process, which can suppress element segregation and the growth of micron-sized coarse oxides, and obtain a fine and uniform billet structure. Attached Figure Description

[0032] Figure 1This is an EPMA diagram of the composite rare earth oxide in Example 1 of the present invention;

[0033] Figure 2 This is a high-resolution TEM image of various rare earth nano-oxides in Example 1 of the present invention. Detailed Implementation

[0034] Exemplary embodiments of the present invention are described in detail below. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from its spirit and scope. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and does not limit the description of the features and characteristics of the invention, in order to suggest the best mode for carrying out the invention and to enable those skilled in the art to practice it. Therefore, the scope of the invention is defined only by the appended claims.

[0035] A high number-density oxide dispersion-strengthened steel has the following chemical composition and mass percentages: C: 0.03–0.15%, Cr: 7–14%, W: 1–3%, V: 0.1–0.3%, Ti: 0.05–0.30%, Zr: 0.05–0.30%, O: 0.005–0.200%, RE1: 0.01–0.50%, RE2: 0.01–0.50%, with the balance being Fe and unavoidable impurities. RE1 is one or two of Er, Ce, and Pr, and RE2 is one or two of Y and La, with the mass percentages of RE1 and RE2 being (2:1) to (1:2).

[0036] The preparation method of this high number-density oxide dispersion strengthened steel includes the following steps:

[0037] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, Zr, and RE2 in a set ratio, and then prepare the raw materials into an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

[0038] 2. The master alloy is processed into a round rod shape, and a hole is drilled along its height. The mixed particles are then filled into the hole according to a set ratio and the hole is plugged to form an electrode ingot containing the mixed particles. The mixed particles are a mixture of master alloy matrix elements, solid oxygen carrier particles, and elemental or oxide particles of RE1. The proportion of solid oxygen carrier particles in the mixed particles is 10% to 30%, and the particle size of the solid oxygen carrier particles is 0.1 μm to 50 mm.

[0039] Third, the electrode ingot is melted and cooled using vacuum consumable arc melting technology to obtain the cast ingot. Specifically, zone melting or small-pool melting methods are employed during melting to achieve a faster solidification rate in the molten steel. This suppresses elemental segregation and the growth of micron-sized coarse oxides, resulting in a fine and uniform ingot structure. In this step, the melting temperature is 1500–1800℃, and the cooling rate is 10... -1 ~10 4 The ingots prepared at K / s contain composite rare earth oxides containing two rare earth elements, such as (Er,Y)₂O₃, (Ce,Y)₂O₃, (Pr,Y)₂O₃, (Er,La)₂O₃, (Ce,La)₂O₃ and (Pr,La)₂O₃, with sizes ranging from 100 nm to 1 μm.

[0040] Fourth, after homogenization heat treatment, the ingot is forged to obtain a forged ingot of the specified specifications.

[0041] V. The forged ingot is heat-treated to obtain oxide dispersion strengthened steel. The chemical composition and mass percentage of the oxide dispersion strengthened steel are as follows: C: 0.03-0.15%, Cr: 7-14%, W: 1-3%, V: 0.1-0.3%, Ti: 0.05-0.30%, Zr: 0.05-0.30%, O: 0.005-0.200%, RE1: 0.01-0.50%, RE2: 0.01-0.50%, with the balance being Fe and unavoidable impurities. Among them, RE1 is one or two of Er, Ce, and Pr, and RE2 is one or two of Y and La, and the mass percentage of RE1 and RE2 is (2:1) to (1:2).

[0042] like Figure 1 and Figure 2 As shown, this high number-density oxide dispersion-strengthened steel and its preparation method feature a unique design for the composition of the ODS, particularly the rare earth elements. Two groups of rare earth elements with different properties are added, and the mass ratio of these two groups is limited, reducing the addition of single rare earth elements. This allows the two groups of rare earth elements to replace each other during the casting solidification process, forming a composite rare earth oxide containing both rare earth elements. This replacement process effectively inhibits the growth of rare earth oxides during ingot formation, resulting in a final composite rare earth oxide size of 100 nm to 1 μm. In contrast, the size of rare earth oxides in conventional ingots containing only a single rare earth element often reaches 3 μm to 10 μm. Such large rare earth oxides can significantly impact the performance of the final ODS steel. Therefore, this composite rare earth oxide effectively improves the performance of the final ODS steel.

[0043] During the subsequent heat treatment of cast and forged ingots, rare earth elements in the resulting composite rare earth oxides are replaced by another group of rare earth elements. During this replacement process, the unstable free rare earth elements that are replaced react more readily with titanium and oxygen to form various rare earth nano-oxides with sizes smaller than 10 nanometers, such as Y-Ti-O and Ce-Ti-O. In contrast, the rare earth elements in conventional rare earth oxides are relatively stable. Compared to the method described in this invention, these oxides are less likely to react with titanium and oxygen to form rare earth nano-oxides smaller than 10 nanometers under the same conditions. Therefore, the method of this invention can more stably form dispersion-strengthened steel with high number density of rare earth nano-oxides, ultimately achieving a number density consistently higher than 10. 23 m -3 ;

[0044] Example 1

[0045] The composition design and preparation method of a high number density oxide dispersion strengthened steel containing cerium and yttrium, wherein the chemical composition and its mass percentage are as follows: C content is 0.09 wt.%, Cr content is 8.53 wt.%, W content is 1.48 wt.%, V content is 0.15 wt.%, Ti content is 0.09 wt.%, Ce content is 0.1 wt.%, Y content is 0.1 wt.%, the O content of the ingot after smelting is 0.03 wt.%, and the balance is Fe and unavoidable impurities.

[0046] The ODS steel is prepared by combining smelting and heat treatment processes. The specific steps are as follows:

[0047] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, and Y in a set ratio, and then prepare an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

[0048] 2. The intermediate alloy is processed into a round bar shape and a hole is drilled along the height direction. The mixed particles are loaded into the hole according to the design amount and the two ends are plugged to make an electrode ingot containing mixed particles. The mixed particles are particles composed of the intermediate alloy matrix element Fe-9Cr-1.5W, solid oxygen carrier particles FeO and Ce, and the proportion of solid oxygen carrier particles is 20%.

[0049] III. The electrode ingots are melted and cooled using vacuum consumable arc melting technology to obtain cast ingots. The melting temperature is 1500℃, and the cooling rate is 10. -1 K / s, (Ce,Y)2O3 rare earth oxide is generated in the ingot.

[0050] Fourth, after the ingot is subjected to a homogenization heat treatment at 1150℃ for 5 hours, it is forged, and then subjected to a second homogenization heat treatment at 1050℃ for 3 hours before forging to obtain an ingot of the specified specifications.

[0051] 5. The forged ingot is heat-treated at 750℃ for 30 hours to obtain multi-element rare earth ODS steel, in which the rare earth nano-oxides are all smaller than 10 nanometers and have a number density higher than 10. 23 m -3 .

[0052] Example 2

[0053] The composition design and preparation method of a high number density oxide dispersion strengthened steel containing praseodymium and yttrium, wherein the chemical composition and its mass percentage are as follows: C content is 0.09 wt.%, Cr content is 8.53 wt.%, W content is 1.48 wt.%, V content is 0.15 wt.%, Ti content is 0.09 wt.%, Pr content is 0.05 wt.%, Y content is 0.1 wt.%, and the O content of the ingot after smelting is 0.05 wt.%, with the balance being Fe and unavoidable impurities.

[0054] The ODS steel is prepared by combining smelting and heat treatment processes. The specific steps are as follows:

[0055] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, and Y in a set ratio, and then prepare an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

[0056] 2. The intermediate alloy is processed into a round bar shape and a hole is drilled along the height direction. The mixed particles are loaded into the hole according to the design amount and the two ends are plugged to make an electrode ingot containing mixed particles. The mixed particles are particles composed of the intermediate alloy matrix element Fe-9Cr-1.5W, solid oxygen carrier particles FeO and Pr oxide particles. The proportion of solid oxygen carrier particles is 10%.

[0057] III. The electrode ingots are melted and cooled using vacuum consumable arc melting technology to obtain cast ingots. The melting temperature is 1600℃, and the cooling rate is 10. -2 K / s, (Pr,Y)2O3 rare earth oxide is generated in the ingot.

[0058] Fourth, after the ingot is subjected to a homogenization heat treatment at 1150℃ for 5 hours, it is forged, and then subjected to a second homogenization heat treatment at 1050℃ for 3 hours before forging to obtain an ingot of the specified specifications.

[0059] 5. The forged ingot is heat-treated at 750℃ for 30 hours to obtain multi-element rare earth ODS steel, in which the rare earth nano-oxides are all smaller than 10 nanometers and have a number density higher than 10. 23 m -3 .

[0060] Example 3

[0061] The composition design and preparation method of a high number density oxide dispersion strengthened steel containing erbium and yttrium, wherein the chemical composition and its mass percentage are as follows: C content is 0.09 wt.%, Cr content is 8.53 wt.%, W content is 1.48 wt.%, V content is 0.15 wt.%, Ti content is 0.09 wt.%, Er content is 0.1 wt.%, Y content is 0.15 wt.%, the O content of the ingot after smelting is 0.03 wt.%, and the balance is Fe and unavoidable impurities.

[0062] The ODS steel is prepared by combining smelting and heat treatment processes. The specific steps are as follows:

[0063] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, and Y in a set ratio, and then prepare an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

[0064] 2. The intermediate alloy is processed into a round bar shape and a hole is drilled along the height direction. The mixed particles are loaded into the hole according to the design amount and the two ends are plugged to make an electrode ingot containing mixed particles. The mixed particles are particles composed of the intermediate alloy matrix element Fe-9Cr-1.5W, solid oxygen carrier particles FeO and Er elemental particles, with the solid oxygen carrier particles accounting for 30%.

[0065] III. The electrode ingots are melted and cooled using vacuum consumable arc melting technology to obtain cast ingots. The melting temperature is 1800℃, and the cooling rate is 10. -4 K / s, (Er,Y)2O3 rare earth oxide is generated in the ingot.

[0066] Fourth, after the ingot is subjected to a homogenization heat treatment at 1150℃ for 5 hours, it is forged, and then subjected to a second homogenization heat treatment at 1050℃ for 3 hours before forging to obtain an ingot of the specified specifications.

[0067] 5. The forged ingot is heat-treated at 750℃ for 30 hours to obtain multi-element rare earth ODS steel, in which the rare earth nano-oxides are all smaller than 10 nanometers and have a number density higher than 10. 23 m -3 .

[0068] Example 4

[0069] The composition design and preparation method of a high number density oxide dispersion strengthened steel containing erbium and lanthanum, wherein the chemical composition and its mass percentage are as follows: C content is 0.09 wt.%, Cr content is 8.53 wt.%, W content is 1.48 wt.%, V content is 0.15 wt.%, Ti content is 0.09 wt.%, Er content is 0.1 wt.%, La content is 0.05 wt.%, and the O content of the ingot after smelting is 0.06 wt.%, with the balance being Fe and unavoidable impurities.

[0070] The ODS steel is prepared by combining smelting and heat treatment processes. The specific steps are as follows:

[0071] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, and La in a set ratio, and then prepare intermediate alloys containing rare earth elements but not oxygen elements by smelting.

[0072] 2. The intermediate alloy is processed into a round bar shape and a hole is drilled along the height direction. The mixed particles are loaded into the hole according to the design amount and the two ends are plugged to make an electrode ingot containing mixed particles. The mixed particles are particles composed of the intermediate alloy matrix element Fe-9Cr-1.5W, solid oxygen carrier particles FeO and Er oxide particles. The proportion of solid oxygen carrier particles is 25%.

[0073] III. The electrode ingots are melted and cooled using vacuum consumable arc melting technology to obtain cast ingots. The melting temperature is 1700℃, and the cooling rate is 10. -3 K / s, (Er,La)2O3 rare earth oxide is generated in the ingot.

[0074] Fourth, after the ingot is subjected to a homogenization heat treatment at 1150℃ for 5 hours, it is forged, and then subjected to a second homogenization heat treatment at 1050℃ for 3 hours before forging to obtain an ingot of the specified specifications.

[0075] 5. The forged ingot is heat-treated at 750℃ for 30 hours to obtain multi-element rare earth ODS steel, in which the rare earth nano-oxides are all smaller than 10 nanometers and have a number density higher than 10. 23 m -3 .

[0076] Example 5

[0077] The composition design and preparation method of a high number density oxide dispersion strengthened steel containing erbium and yttrium, wherein the chemical composition and its mass percentage are as follows: C content is 0.09 wt.%, Cr content is 8.53 wt.%, W content is 1.48 wt.%, V content is 0.15 wt.%, Ti content is 0.09 wt.%, Er content is 0.15 wt.%, Y content is 0.1 wt.%, the O content of the ingot after smelting is 0.06 wt.%, and the balance is Fe and unavoidable impurities.

[0078] The ODS steel is prepared by combining smelting and heat treatment processes. The specific steps are as follows:

[0079] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, and Y in a set ratio, and then prepare an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

[0080] 2. The intermediate alloy is processed into a round bar shape and a hole is drilled along the height direction. The mixed particles are loaded into the hole according to the design amount and the two ends are plugged to make an electrode ingot containing mixed particles. The mixed particles are particles composed of the intermediate alloy matrix element Fe-9Cr-1.5W, solid oxygen carrier particles FeO and Er elemental particles. The proportion of solid oxygen carrier particles is 15%.

[0081] III. The electrode ingots are melted and cooled using vacuum consumable arc melting technology to obtain cast ingots. The melting temperature is 1700℃, and the cooling rate is 10. -3 K / s, (Er,Y)2O3 rare earth oxide is generated in the ingot.

[0082] Fourth, after the ingot is subjected to a homogenization heat treatment at 1150℃ for 5 hours, it is forged, and then subjected to a second homogenization heat treatment at 1050℃ for 3 hours before forging to obtain an ingot of the specified specifications.

[0083] 5. The forged ingot is heat-treated at 750℃ for 30 hours to obtain multi-element rare earth ODS steel, in which the rare earth nano-oxides are all smaller than 10 nanometers and have a number density higher than 10. 23 m -3 .

[0084] Example 6

[0085] The composition design and preparation method of a high number density oxide dispersion strengthened steel containing cerium, erbium and yttrium, wherein the chemical composition and its mass percentage are as follows: C content is 0.09 wt.%, Cr content is 8.53 wt.%, W content is 1.48 wt.%, V content is 0.15 wt.%, Ti content is 0.09 wt.%, Ce content is 0.1 wt.%, Er content is 0.1 wt.%, Y content is 0.1 wt.%, and the O content of the ingot after smelting is 0.03 wt.%, with the balance being Fe and unavoidable impurities.

[0086] The ODS steel is prepared by combining smelting and heat treatment processes. The specific steps are as follows:

[0087] 1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, Er, and Y in a set ratio, and then prepare the raw materials into an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

[0088] 2. The intermediate alloy is processed into a round bar shape and a hole is drilled along the height direction. The mixed particles are loaded into the hole according to the design amount and the two ends are plugged to make an electrode ingot containing mixed particles. The mixed particles are particles composed of the intermediate alloy matrix element Fe-9Cr-1.5W, solid oxygen carrier particles FeO, and elemental particles of Ce and Er. The proportion of solid oxygen carrier particles is 20%.

[0089] III. The electrode ingots are melted and cooled using vacuum consumable arc melting technology to obtain cast ingots. The melting temperature is 1700℃, and the cooling rate is 10. -3 K / s, rare earth oxides (Er,Y)2O3 and (Ce,Y)2O3 are generated in the ingot.

[0090] Fourth, after the ingot is subjected to a homogenization heat treatment at 1150℃ for 5 hours, it is forged, and then subjected to a second homogenization heat treatment at 1050℃ for 3 hours before forging to obtain an ingot of the specified specifications.

[0091] 5. The forged ingot is heat-treated at 750℃ for 30 hours to obtain multi-element rare earth ODS steel, in which the rare earth nano-oxides are all smaller than 10 nanometers and have a number density higher than 10. 23 m -3 .

[0092] The examples described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

Claims

1. A method of producing a high number density oxide dispersion strengthened steel, characterized in that: Includes the following steps:

1. Prepare raw materials by mixing pure elements of Fe, Cr, V, W, C, Ti, Zr, and RE2 in a set ratio, and then prepare the raw materials into an intermediate alloy containing rare earth elements but not oxygen elements by smelting.

2. After drilling holes in the intermediate alloy, fill the holes with mixed particles according to a set ratio and plug the holes to make an electrode ingot containing mixed particles. The mixed particles are particles made by mixing the intermediate alloy matrix element Fe-9Cr-1.5W, solid oxygen carrier particles and RE1 elemental particles or oxides.

3. The electrode ingot is melted and cooled using vacuum consumable arc melting technology to obtain a cast ingot; IV. After homogenization heat treatment, the ingot is forged to obtain a forged ingot of the specified specifications. V. Heat treatment of the forged ingot yields oxide dispersion strengthened steel, wherein the chemical composition and mass percentage of the oxide dispersion strengthened steel are as follows: C: 0.03 ~ 0.15%, Cr: 7 ~ 14%, W: 1 ~ 3%, V: 0.1 ~ 0.3%, Ti: 0.05 ~ 0.30%, Zr: 0.05 ~ 0.30%, O: 0.005 ~ 0.200%, RE1: 0.01 ~ 0.50%, RE2: 0.01 ~ 0.50%, with the balance being Fe and unavoidable impurities; RE1 is one or two of Er, Ce, and Pr, and RE2 is one or two of Y and La.

2. The method of claim 1, wherein the high number density oxide dispersion strengthened steel is prepared by the steps of: In step two, the proportion of solid oxygen carrier particles in the mixed particles is 10% to 30%. ​ 3. The method of claim 2, wherein the high number density oxide dispersion strengthened steel is prepared by the steps of: In step two, the particle size of the solid oxygen carrier particles is 0.1 μm ~ 50 mm. ​ 4. The method for preparing high number-density oxide dispersion-strengthened steel according to claim 1, characterized in that: In step three, the smelting adopts zone melting or small pool melting methods.

5. The method for preparing high number-density oxide dispersion-strengthened steel according to claim 4, characterized in that: In step three, the melting temperature is 1500~1800℃.

6. A method for preparing high number-density oxide dispersion-strengthened steel according to claim 4, characterized in that: In step three, the cooling rate is 10 -1 ~ 10 4 K / s.

7. A method for preparing high number-density oxide dispersion-strengthened steel according to any one of claims 2-6, characterized in that: In step three, a composite rare earth oxide containing two rare earth elements is generated in the ingot, and the size of the composite rare earth oxide is 100 nm ~ 1 μm.

8. A method for preparing high number-density oxide dispersion-strengthened steel according to claim 7, characterized in that: In step five, the size of the high number-density rare earth nano-oxides finally generated in the oxide dispersion-strengthened steel after heat treatment is 1 nm to 10 nm.

9. A high number-density oxide dispersion-strengthened steel, characterized in that: Obtained by any one of the preparation methods of claims 1 to 8, The chemical composition and mass percentage of the oxide dispersion strengthened steel are as follows: C: 0.03 ~ 0.15%, Cr: 7 ~ 14%, W: 1 ~ 3%, V: 0.1 ~ 0.3%, Ti: 0.05 ~ 0.30%, Zr: 0.05 ~ 0.30%, O: 0.005 ~ 0.200%, RE1: 0.01 ~ 0.50%, RE2: 0.01 ~ 0.50%, with the balance being Fe and unavoidable impurities; RE1 is one or two of Er, Ce, and Pr, and RE2 is one or two of Y and La.

10. A high number-density oxide dispersion-strengthened steel according to claim 9, characterized in that: The mass percentage of RE1 and RE2 is (2:1) to (1:2).

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