Yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy and preparation method thereof

Abstract

The present application relates to the technical field of ferritic stainless steel preparation, in particular to an ultra-pure ferritic stainless steel master alloy containing yttrium for heat resistance, which is composed of the following elements: 0.2-0.3% Y, C≤0.009%, N≤0.006%, O≤0.005%, Si≤0.05%, P≤0.02%, S≤0.008%, Ni≤0.05%, 0.4-1% Mn, 16-22% Cr, 0.04-0.12% Ce, 0.05-0.2% Al, 0.05-0.3% Ti, Cu≤0.02%, V≤0.02%, 0.04-0.2% surface modified graphene alloy additive, and the balance is Fe. The ultra-pure ferritic stainless steel master alloy in the present application has good mechanical properties and corrosion resistance, can replace 304 stainless steel, and has relatively better electrical and thermal conductivity advantages, lower thermal expansion coefficient, and excellent processing performance.

Description

Technical Field

[0001] The present application relates to the technical field of ferritic stainless steel preparation, and in particular to an ultra-pure ferritic stainless steel master alloy containing yttrium for heat resistance and a preparation method thereof. Background Art

[0002] Stainless steel has excellent comprehensive properties and is widely used in all walks of life. With the continuous advancement of science and technology, various stainless steel materials of different grades and types have been developed according to the different uses of steel, including martensitic stainless steel, austenitic stainless steel, ferritic stainless steel, α+γ duplex stainless steel, precipitation hardening stainless steel, etc.

[0003] 304 stainless steel, also known as 18-8 stainless steel, has an alloying element composition of Cr greater than 18% and Ni greater than 8%. It has the advantages of excellent corrosion resistance, high heat-resistant operating temperature, good processing performance, excellent weldability, etc. It is widely used in petrochemical, metallurgical machinery, agriculture, ship parts, food industry and other industries. It is currently the most widely used and largest amount of stainless steel material in the world.

[0004] 430 (ferritic / medium chromium) stainless steel contains 16-18% Cr, basically no nickel metal (≤0.05%), C+N≤0.015% (ultra-pure), C+N≤0.05% (high purity), has good corrosion resistance, lower production cost than 304 stainless steel, high thermal conductivity, small thermal expansion coefficient, excellent processing performance, weldability, etc. It can replace 304 stainless steel in some fields. Its main uses include kitchen facilities, washing machines, auto parts, etc.

[0005] Compared with 304 stainless steel, 430 stainless steel has poorer corrosion resistance than 304 stainless steel in high temperature environment and corrosive medium, which is the main problem that limits the application and development of 430 stainless steel. Therefore, the applicant has developed a yttrium-containing heat-resistant ultra-pure ferrite stainless steel master alloy that can replace 304 stainless steel and its preparation method. Summary of the invention

[0006] In order to solve the technical problems existing in the above-mentioned background technology, the present application provides an ultra-pure ferritic stainless steel master alloy containing yttrium for heat resistance and a preparation method thereof.

[0007] In the first aspect, the present application provides an ultra-pure ferrite stainless steel master alloy containing yttrium for heat resistance, which is achieved by the following technical solutions:

[0008] A yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy, comprising the following components in weight percentage: 0.2-0.3% Y, C≤0.009%, N≤0.006%, O≤0.005%, Si≤0.05%, P≤0.02%, S≤0.008%, Ni≤0.05%, 0.4-1.0% Mn, 12-18% Cr, 0.04-0.12% Ce, 0.05-0.20% Al, 0.05-0.30% T i, Cu≤0.02%, V≤0.02%, 0.04-0.20% of surface-modified graphene alloy additives, the balance being Fe; the surface-modified graphene alloy additive comprises a graphene carrier and an interface-modified overplated metal element loaded on the surface of the graphene carrier; the interface-modified overplated metal element is connected to the surface of the graphene carrier in a single-atom form through chemical bonds; the interface-modified overplated metal element is mainly composed of Fe, Cr and at least one of Mn, Y, Ce, and Ti.

[0009] The ultra-pure ferritic stainless steel master alloy in the present application has good mechanical properties and corrosion resistance, can replace 304 stainless steel, and has relatively better electrical and thermal conductivity advantages, lower thermal expansion coefficient, and excellent processing performance. In addition, the ultra-pure ferritic stainless steel modified by the surface-modified graphene alloy additive also has good lubricity, wear resistance, antibacterial and mildew resistance, and biocompatibility, and has a more obvious competitive advantage compared with 304 stainless steel.

[0010] Preferably, the interface modified overplating metal elements are mainly composed of Fe, Cr, Mn, Y, and Ti, and the mass ratio of Fe, Cr, Mn, Y, and Ti is (74-83):(16-22):(0.4-1.0):(0.2-0.3):(0.05-0.3).

[0011] By adopting the above technical scheme, the compatibility of the surface-modified graphene alloy additive and the matrix alloy can be improved, thereby ensuring the mechanical properties, corrosion resistance, electrical conductivity and thermal conductivity of the prepared yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy.

[0012] Preferably, the surface modified graphene alloy additive is composed of the following components in weight percentage: 0.20-0.30% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, Ni≤0.05%, 0.48-0.64% Mn, 12-15% Cr, 0.05-0.06% Ce, 0.10-0.20% Al, 0.16-0.24% Ti, Cu≤0.02%, V≤0.02%, 0.05-0.10%, and the balance is Fe.

[0013] Preferably, the interface modified overplating metal elements are mainly composed of Fe, Cr, Mn, Y, and Ti in a mass ratio of 810:180:5:3:2.

[0014] Preferably, the yttrium-containing heat-resistant ultrapure ferritic stainless steel master alloy has a tensile strength of ≥480 MPa, a yield strength of ≥205 MPa, an elongation of ≥25%, a thermal conductivity of ≥30 W / (m·K), and a resistivity of ≥2.5*10 6 Ω·m, thermal expansion coefficient ≤11um / (m·K), hardness 80-90HRB, corrosion rate ≤0.05mm / a.

[0015] Preferably, the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.20-0.30% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.48-0.64% Mn, 12.0-13.0% Cr, 0.05-0.06% Ce, 0.10-0.20% Al, 0.16-0.24% Ti, Cu≤0.02%, V≤0.02%, 0.048-0.054% surface-modified graphene alloy additive, and the balance is Fe.

[0016] Preferably, the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.20-0.30% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.48-0.64% Mn, 14.0-15.0% Cr, 0.05-0.06% Ce, 0.10-0.20% Al, 0.16-0.24% Ti, Cu≤0.02%, V≤0.02%, 0.035-0.040% surface-modified graphene alloy additive, and the balance is Fe.

[0017] By adopting the above technical solution, it can be ensured that the present application has good mechanical properties and corrosion resistance, relatively better electrical and thermal conductivity advantages, lower thermal expansion coefficient, and excellent processing performance, and can replace 304 stainless steel.

[0018] Preferably, the preparation method of the surface modified graphene alloy additive is as follows:

[0019] Step 1, preparation of boron-nitrogen doped graphene;

[0020] Step 2, preparing 0.05-0.5 g / L overplating metal salt aqueous solution, wherein the nitrate is iron nitrate nonahydrate, chromium nitrate nonahydrate, manganese nitrate tetrahydrate, cerium nitrate hexahydrate, yttrium nitrate hexahydrate, and titanium acetylacetonate;

[0021] Step 3, mixing the boron-nitrogen-doped graphene with deionized water and then dispersing the mixture by ultrasonic to obtain a boron-nitrogen-doped graphene aqueous solution, wherein the mass ratio of the boron-nitrogen-doped graphene to the deionized water is (1-2): (100-400), adding an overplated metal salt aqueous solution to the boron-nitrogen-doped graphene aqueous solution, wherein the mass ratio of the overplated metal content in the overplated metal salt aqueous solution to the carrier boron-nitrogen-doped graphene is 1: (10-50), dispersing the mixture by ultrasonic for 0.5-2h, stirring the mixture by magnetic stirring for 20-24h, removing the solvent by rotary evaporation, and drying the mixture to obtain a solid powder;

[0022] Step 4: Planetarily ball mill the obtained solid powder at a speed of 50-80rpm for 0.5-2h, heat treat the powder obtained by ball milling at 600-800℃ for 2-4h in an air atmosphere, and then planetarily ball mill the solid material obtained after cooling at a speed of 180-300rpm for 0.5-1.0h to obtain a surface-modified graphene alloy additive with an average particle size of 200-500nm.

[0023] The preparation method provided in this application is relatively simple, has low operating difficulty, and is easy to implement industrial production.

[0024] In the second aspect, the present application provides a method for preparing a heat-resistant ultra-pure ferritic stainless steel master alloy containing yttrium, which is achieved by the following technical solutions:

[0025] A method for preparing a heat-resistant ultrapure ferrite stainless steel master alloy containing yttrium, comprising the following steps:

[0026] S1, ingredients are prepared according to the composition control requirements of the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy;

[0027] Simultaneously, the surface-modified graphene alloy additive is prepared;

[0028] S2, the raw materials prepared in S1 are dried at 100-150°C for 1-4h;

[0029] S3, adding materials in the order of 50wt% Fe, 50wt% Cr, Ti, Ce, the remaining 50wt% Cr, and the remaining 50wt% Fe, and melting under vacuum at a vacuum degree of <10Pa;

[0030] S4, vacuum degree <1.0Pa, refining temperature 1570-1590℃, refining at warm temperature after chemical purification;

[0031] S5, drop the temperature to 1480-1520℃, add Al, stir well, take samples for analysis in front of the furnace, make fine adjustments and add materials according to the analysis results in front of the furnace;

[0032] S6, the temperature of the molten steel is adjusted to 1610-1630°C, and the module is prepared in a heat-insulating state; argon is filled with 50,000Pa, and metal yttrium is added by wrapping it with pure iron sheet. The addition of metal yttrium is controlled according to a yield of 80%, the addition of metal manganese is controlled according to a yield of 95%, and the addition of surface-modified graphene alloy additives is controlled according to a yield of 95%. After adding, stir for 1-2 minutes and quickly cast to obtain an ultra-pure ferritic stainless steel master alloy rod containing yttrium for heat resistance.

[0033] The preparation method provided in this application is relatively simple, has low operating difficulty, and is easy to implement industrial production.

[0034] Preferably, the chute or diverter plate used for casting in S6 does not have a filter screen, but a slag retaining dam is required to retain the slag.

[0035] By adopting the above technical solution, the quality of the ultra-pure ferritic stainless steel master alloy and the quality stability within the same batch can be guaranteed.

[0036] In summary, this application has the following advantages:

[0037] 1. The ultra-pure ferritic stainless steel master alloy in this application has good mechanical properties and corrosion resistance, can replace 304 stainless steel, and has relatively better electrical and thermal conductivity advantages, lower thermal expansion coefficient, and excellent processing performance.

[0038] 2. The preparation method provided in this application is relatively simple, has low operating difficulty, and is easy to implement industrial production. DETAILED DESCRIPTION

[0039] In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. Those skilled in the art can refer to the contents of this article and appropriately improve the process parameters to achieve.

[0040] It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Although it is believed that those of ordinary skill in the art fully understand the following terms, the following definitions are still stated to help illustrate the subject matter disclosed in the present invention.

[0041] As used herein, the term "comprising" is synonymous with "including," "containing," or "characterized by," and is inclusive or open-ended and does not exclude additional unrecited elements or method steps. "Comprising" is a technical term used in claim language, meaning that the elements are present, but other elements may also be added and still form a structure or method within the scope of the claim.

[0042] Example

[0043] The invention discloses an ultra-pure ferrite stainless steel master alloy containing yttrium for heat resistance, which is composed of the following components in weight percentage: 0.2-0.3% of Y, C≤0.009%, N≤0.006%, O≤0.005%, Si≤0.05%, P≤0.02%, S≤0.008%, Ni≤0.05%, 0.4-1.0% of Mn, 12-18% of Cr, 0.04-0.12% of Ce, 0.05-0.20% of Al, 0.05-0.30% of Ti, Cu≤0.02%, V≤0.02%, 0.04-0.20% of a surface-modified graphene alloy additive, and the balance of Fe.

[0044] Preferably, the ultrapure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.20-0.30% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, Ni≤0.05%, 0.48-0.64% Mn, 12-15% Cr, 0.05-0.06% Ce, 0.10-0.20% Al, 0.16-0.24% Ti, Cu≤0.02%, V≤0.02%, 0.05-0.10% of surface modified graphene alloy additive, and the balance is Fe.

[0045] Preferably, the ultrapure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.20-0.30% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.48-0.64% Mn, 12.0-13.0% Cr, 0.05-0.06% Ce, 0.10-0.20% Al, 0.16-0.24% Ti, Cu≤0.02%, V≤0.02%, 0.048-0.054% surface modified graphene alloy additive, and the balance is Fe.

[0046] Preferably, the ultrapure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.20-0.30% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.48-0.64% Mn, 14.0-15.0% Cr, 0.05-0.06% Ce, 0.10-0.20% Al, 0.16-0.24% Ti, Cu≤0.02%, V≤0.02%, 0.035-0.040% surface modified graphene alloy additive, and the balance is Fe.

[0047] The surface modified graphene alloy additive comprises a graphene carrier and an interface modified over-plated metal element loaded on the surface of the graphene carrier. The interface modified over-plated metal element is connected to the surface of the graphene carrier by chemical bonds in a single atom form. The interface modified over-plated metal element is mainly composed of at least one of Fe, Cr, Mn, Y, Ce, and Ti. Preferably, the interface modified over-plated metal element is mainly composed of Fe, Cr, Mn, Y, and Ti, and the mass ratio of Fe, Cr, Mn, Y, and Ti is (74-83): (16-22): (0.4-1.0): (0.2-0.3): (0.05-0.3). Further preferably, the interface modified over-plated metal element is mainly composed of Fe, Cr, Mn, Y, and Ti in a mass ratio of 810: 180: 5: 3: 2.

[0048] The tensile strength of the Y-containing heat-resistant ultra-pure ferritic stainless steel master alloy is ≥480MPa, the yield strength is ≥205MPa, the elongation is ≥25%, the thermal conductivity is ≥30W / (m·K), and the resistivity is ≥2.5*10 6 Ω·m, thermal expansion coefficient ≤11um / (m·K), hardness 80-90HRB, corrosion rate ≤0.05mm / a, can replace 304 stainless steel.

[0049] A method for preparing a heat-resistant ultrapure ferrite stainless steel master alloy containing yttrium, comprising the following steps:

[0050] S1, ingredients are prepared according to the composition control requirements of the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy;

[0051] Simultaneously, the surface modified graphene alloy additive is prepared:

[0052] S1.1, preparation of boron-nitrogen doped graphene;

[0053] S1.2, preparing 0.05-0.5 g / L overplating metal salt aqueous solution, wherein the nitrate is iron nitrate nonahydrate, chromium nitrate nonahydrate, manganese nitrate tetrahydrate, cerium nitrate hexahydrate, yttrium nitrate hexahydrate, and titanium acetylacetonate;

[0054] S1.3, mixing the boron-nitrogen-doped graphene with deionized water and dispersing the mixture by ultrasonic to obtain a boron-nitrogen-doped graphene aqueous solution, wherein the mass ratio of the boron-nitrogen-doped graphene to the deionized water is (1-2): (100-400), adding an overplated metal salt aqueous solution to the boron-nitrogen-doped graphene aqueous solution, wherein the mass ratio of the overplated metal content in the overplated metal salt aqueous solution to the carrier boron-nitrogen-doped graphene is 1: (10-50), dispersing the mixture by ultrasonic for 0.5-2h, stirring the mixture by magnetic stirring for 20-24h, removing the solvent by rotary evaporation, and drying the mixture to obtain a solid powder;

[0055] S1.4, the obtained solid powder is subjected to planetary ball milling at a speed of 50-80 rpm for 0.5-2 h, the powder obtained by ball milling is placed in an air atmosphere and heat treated at 600-800 ° C for 2-4 h, and the solid material obtained after cooling is subjected to planetary ball milling again at a speed of 180-300 rpm for a ball milling time of 0.5-1.0 h to obtain a surface-modified graphene alloy additive with an average particle size of 200-500 nm;

[0056] S2, the raw materials prepared in S1 are dried at 100-150°C for 1-4h;

[0057] S3, adding materials in the order of 50wt% Fe, 50wt% Cr, Ti, Ce, the remaining 50wt% Cr, and the remaining 50wt% Fe, and melting under vacuum at a vacuum degree of <10Pa;

[0058] S4, vacuum degree <1.0Pa, refining temperature 1570-1590℃, refining at warm temperature after chemical purification;

[0059] S5, drop the temperature to 1480-1520℃, add Al, stir well, take samples for analysis in front of the furnace, make fine adjustments and add materials according to the analysis results in front of the furnace;

[0060] S6, adjust the temperature of the molten steel to 1610-1630℃, keep it warm, and prepare the module; fill with 50000Pa of argon, add metal yttrium wrapped with pure iron sheet, add metal yttrium according to the yield rate of 80%, add metal manganese according to the yield rate of 95%, add surface modified graphene alloy additive according to the yield rate of 95%, stir for 1-2 minutes after adding, and pour quickly. No filter is placed in the chute or diverter plate used for pouring, but a slag dam needs to be set to block the slag, so as to obtain yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy rod.

[0061] Embodiment 1: A yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy (composed of single elements), composed of the following components in weight percentage: 0.2% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.04% Ni, 0.6% Mn, 12% Cr, 0.04% Ce, 0.12% Al, 0.2% Ti, 0.016% Cu, 0.014% V, 0.08% surface-modified graphene alloy additive, and the balance is Fe.

[0062] A method for preparing a heat-resistant ultrapure ferrite stainless steel master alloy containing yttrium, comprising the following steps:

[0063] S1, ingredients are prepared according to the composition control requirements of the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy;

[0064] Simultaneously, the surface modified graphene alloy additive is prepared:

[0065] S1.1, preparation of boron-nitrogen doped graphene: weigh 0.5g of graphene (fineness 7-12um, CAS: 7782-42-5, from Shenzhen Turing New Materials Co., Ltd.) and add it to a mixed acid solution (made of 25mL concentrated sulfuric acid and 75mL concentrated nitric acid), first pre-mix and stir with a glass rod for 1-2min, then ultrasonically disperse for 30min, with an ultrasonic power of 800W and an ultrasonic frequency of 44kHz, so that the graphene is evenly dispersed, and then heated to 88-90°C, heated under reflux for 2h, so that the graphene surface is acidified and rich in oxygen-containing groups, weigh 200mg of the surface acidified graphene prepared above, and ultrasonically disperse Dispersed in 100mL deionized water, ultrasonically dispersed for 30min, ultrasonic power 400W, ultrasonic frequency 32kHz, then added 0.4g boric acid and 2g melamine, ultrasonically dispersed for 30min, ultrasonic power 400W, ultrasonic frequency 32kHz, finally the mixture was sealed in a customized 500mL high-pressure reactor, heated to 180℃ at 3℃ / min, pressurized to 0.5MPa and maintained at 180℃ for 12 hours, after the heat treatment, the pressure was released and the high-pressure reactor was opened, and the sample was taken out after natural cooling to room temperature and washed on three sides with ultrapure water, and dried at 80℃ for 4.0h to obtain a boron-nitrogen-doped graphene carrier;

[0066] S1.2, prepare 0.2 g / L overplating metal salt aqueous solution, the nitrate is ferric nitrate nonahydrate, chromium nitrate nonahydrate and manganese nitrate tetrahydrate, wherein the ratio of the iron content in ferric nitrate nonahydrate to the chromium content in chromium nitrate nonahydrate and the manganese content in manganese nitrate tetrahydrate is 87:12:1;

[0067] S1.3, after mixing 200 mg of the boron-nitrogen-doped graphene prepared in S1.1 with 50 mL of deionized water, ultrasonic dispersion was performed to obtain an aqueous solution of boron-nitrogen-doped graphene, with an ultrasonic power of 400 W and an ultrasonic frequency of 32 kHz, and then 0.2 g / L of an overplated metal salt aqueous solution prepared in S1.2 was added to the obtained aqueous solution of boron-nitrogen-doped graphene at an addition rate of 20 mg / 60 s, wherein the mass ratio of the overplated metal content in the overplated metal salt aqueous solution to the carrier boron-nitrogen-doped graphene was 1:40, and ultrasonic dispersion was performed for 2 h, with an ultrasonic power of 400 W and an ultrasonic frequency of 32 kHz, and magnetic stirring was performed at 200 rpm for 24 h, the solvent was removed by rotary evaporation, and solid powder was obtained by drying;

[0068] S1.4, the obtained solid powder is planetarily ball-milled at a speed of 60 rpm for 1.0 h, the powder obtained by ball milling is placed in an air atmosphere for heat treatment at 640°C for 4 h, and the solid material obtained after cooling is subjected to planetary ball milling again at a speed of 240 rpm for 0.5 h to obtain a surface-modified graphene alloy additive with an average particle size of 500 nm.

[0069] S2, the raw materials prepared in S1 are dried at 120°C for 4h;

[0070] S3, adding materials in the order of 50wt% Fe, 50wt% Cr, Ti, Ce, the remaining 50wt% Cr, and the remaining 50wt% Fe, and melting under vacuum at a vacuum degree of <10Pa;

[0071] S4, vacuum degree <1.0Pa, refining temperature 1585±2℃, refining at warm temperature after chemical purification;

[0072] S5, reduce the temperature to 1500℃, add Al, stir well, take samples for analysis in front of the furnace, make fine adjustments and add materials according to the analysis results in front of the furnace;

[0073] S6, the temperature of the molten steel is adjusted to 1625±2℃, and the module is prepared in a heat-insulating state; argon is filled with 50000Pa, and metal yttrium (purity 4N) and metal manganese (purity 4N) are added by wrapping pure iron sheet, the addition of metal yttrium is controlled according to the yield of 80%, the addition of metal manganese is controlled according to the yield of 95%, and the addition of surface-modified graphene alloy additives is controlled according to the yield of 95%. After adding, stir for 2 minutes and pour quickly. The pouring uses a chute and a slag dam to block the slag. Naturally cool to 200-205℃ to obtain a yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy rod, and then carry out solid solution treatment, heat up to 880℃ at 10℃ / min and keep warm for 4h, naturally cool to 180℃ and keep warm for 2h, and naturally cool to room temperature to obtain a finished product of yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy rod that can be machined.

[0074] The difference between Example 2 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.25% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.68% Mn, 15% Cr, 0.08% Ce, 0.15% Al, 0.18% Ti, 0.016% Cu, 0.014% V, 0.035% surface-modified graphene alloy additive, and the balance is Fe.

[0075] The difference between Example 3 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.30% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.8% Mn, 18% Cr, 0.06% Ce, 0.18% Al, 0.24% Ti, 0.016% Cu, 0.014% V, 0.03% surface-modified graphene alloy additive, and the balance is Fe.

[0076] The difference between Example 4 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.24% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.54% Mn, 13% Cr, 0.06% Ce, 0.14% Al, 0.20% Ti, 0.016% Cu, 0.014% V, 0.05% surface-modified graphene alloy additive, and the balance is Fe.

[0077] The difference between Example 5 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.24% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.62% Mn, 12.4% Cr, 0.06% Ce, 0.16% Al, 0.24% Ti, 0.016% Cu, 0.014% V, 0.054% surface-modified graphene alloy additive, and the balance is Fe.

[0078] The difference between Example 6 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.24% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.6% Mn, 14% Cr, 0.06% Ce, 0.15% Al, 0.22% Ti, 0.016% Cu, 0.014% V, 0.04% surface-modified graphene alloy additive, and the balance is Fe.

[0079] The difference between Example 7 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.24% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.6% Mn, 14.6% Cr, 0.06% Ce, 0.16% Al, 0.24% Ti, 0.016% Cu, 0.014% V, 0.04% surface-modified graphene alloy additive, and the balance is Fe.

[0080] The difference between Example 8 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.28% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.54% Mn, 12% Cr, 0.08% Ce, 0.16% Al, 0.24% Ti, 0.016% Cu, 0.014% V, 0.06% surface-modified graphene alloy additive, and the balance is Fe.

[0081] The difference between Example 9 and Example 1 is: the surface modified graphene alloy additive is different. Specifically, the difference in the preparation method of the surface modified graphene alloy additive is: S1.2, 0.2 g / L overplating metal salt aqueous solution is prepared, the nitrate is iron nitrate nonahydrate, chromium nitrate nonahydrate, manganese nitrate tetrahydrate, yttrium nitrate hexahydrate, wherein the mass ratio of iron contained in iron nitrate nonahydrate, chromium contained in chromium nitrate nonahydrate, manganese contained in manganese nitrate tetrahydrate, and yttrium contained in yttrium nitrate hexahydrate is 86:12:1:1.

[0082] The difference between Example 10 and Example 1 is: the difference in the surface-modified graphene alloy additive. Specifically, the difference in the preparation method of the surface-modified graphene alloy additive is: S1.2, 0.2 g / L overplating metal salt aqueous solution is prepared, and the nitrate is iron nitrate nonahydrate, chromium nitrate nonahydrate, manganese nitrate tetrahydrate, yttrium nitrate hexahydrate, and titanium acetylacetonate, wherein the mass ratio of iron contained in iron nitrate nonahydrate, chromium contained in chromium nitrate nonahydrate, manganese contained in manganese nitrate tetrahydrate, yttrium contained in yttrium nitrate hexahydrate, and titanium contained in titanium acetylacetonate is 810:180:5:3:2.

[0083] The difference between Example 11 and Example 10 is that the mass ratio of iron contained in ferric nitrate nonahydrate, chromium contained in chromium nitrate nonahydrate, manganese contained in manganese nitrate tetrahydrate, yttrium contained in yttrium nitrate hexahydrate, and titanium contained in titanium acetylacetonate is 750:240:5:3:2.

[0084] The difference between Example 12 and Example 10 is that the mass ratio of iron contained in ferric nitrate nonahydrate, chromium contained in chromium nitrate nonahydrate, manganese contained in manganese nitrate tetrahydrate, yttrium contained in yttrium nitrate hexahydrate, and titanium contained in titanium acetylacetonate is 830:160:5:3:2.

[0085] The difference between Comparative Example 1 and Example 1 is that the yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy is composed of the following weight percentages: 0.2% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.04% Ni, 0.6% Mn, 12% Cr, 0.04% Ce, 0.12% Al, 0.2% Ti, 0.016% Cu, 0.014% V, 0.08% graphene, and the balance is Fe. The graphene is a graphene raw material from Shenzhen Turing New Materials Co., Ltd., with a fineness of 7-12um, CAS: 7782-42-5, and a finished graphene with an average particle size of 500nm is obtained after planetary ball milling.

[0086] The difference between Comparative Example 2 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.2% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.04% Ni, 0.6% Mn, 10% Cr, 0.04% Ce, 0.12% Al, 0.2% Ti, 0.016% Cu, 0.014% V, 0.08% surface-modified graphene alloy additive, and the balance is Fe.

[0087] The difference between Comparative Example 3 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.2% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.04% Ni, 0.6% Mn, 20% Cr, 0.04% Ce, 0.12% Al, 0.2% Ti, 0.016% Cu, 0.014% V, 0.05% surface-modified graphene alloy additive, and the balance is Fe.

[0088] The difference between Comparative Example 4 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.04% Ni, 0.6% Mn, 12% Cr, 0.04% Ce, 0.12% Al, 0.2% Ti, 0.016% Cu, 0.014% V, 0.08% surface-modified graphene alloy additive, and the balance is Fe.

[0089] The difference between Comparative Example 5 and Example 1 is that the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy is composed of the following components in weight percentage: 0.2% Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.04% Ni, 0.6% Mn, 12% Cr, 0.12% Al, 0.2% Ti, 0.016% Cu, 0.014% V, 0.08% surface-modified graphene alloy additive, and the balance is Fe.

[0090] The difference between Comparative Example 6 and Example 10 is: the surface modified graphene alloy additive is different. Specifically, the difference in the preparation method of the surface modified graphene alloy additive is: S1.2, 0.2 g / L overplating metal salt aqueous solution is prepared, and the nitrate is only iron nitrate nonahydrate.

[0091] Performance test: tensile strength, yield strength and elongation are measured according to GB / T 228.1-2010 method. Hardness HRB is measured by Leeb hardness tester portable HRB steel and aluminum plate metal material hardness tester. Thermal conductivity test method: measured by DR-S thermal conductivity tester. Resistivity is measured according to GB / T351-2019 metal material resistivity measurement method. Thermal expansion coefficient is measured according to GB / T 3810.3-2016 "Measurement of thermal expansion coefficient and thermal expansion coefficient difference of metals and alloys".

[0092] Table 1 is a table of conventional test parameters of stainless steel in Examples 1-12 and Comparative Examples 1-6

[0093]

[0094]

[0095]

[0096] Combining Examples 1-12 and Comparative Examples 1-6 and Table 1, it can be seen that compared with Comparative Example 2, in Example 1, the mechanical strength of the ultra-pure ferritic stainless steel master alloy prepared by the unmodified graphene material shows a downward trend and the improvement in the electrical conductivity and thermal conductivity is weak. The surface-modified graphene alloy additive in the present application overcomes the compatibility between the surface-modified graphene alloy additive and the matrix alloy elements, which can improve the mechanical strength while greatly improving the electrical conductivity and thermal conductivity.

[0097] Combining Examples 1-12 and Comparative Examples 1-6 and Table 1, it can be seen that when Examples 1-3 are compared with Comparative Examples 1 and 3, when the addition amount of the surface modified graphene alloy additive is 0.03-0.08%, the Cr content in the ultrapure ferritic stainless steel master alloy is preferably controlled at 12-18wt%, and excessive Cr addition has no obvious improvement on its mechanical strength and electrical and thermal conductivity.

[0098] Combining Examples 1-12 and Comparative Examples 1-6 and Table 1, it can be seen that compared with Comparative Examples 4-5, adding metal elements Y and Ce to the ultra-pure ferritic stainless steel master alloy can improve the mechanical properties and processing properties of the finished product, and can play an auxiliary synergistic role when used in combination with the surface-modified graphene alloy additive.

[0099] Combining Examples 1-12 and Comparative Examples 1-6 and Table 1, it can be seen that compared with Comparative Example 6, Examples 1-3 show that the interface-modified overplated metal elements are mainly composed of Fe, Cr and at least one of Mn, Y, Ce, and Ti, and the compatibility of the surface-modified graphene alloy additives with the matrix alloy elements can improve the mechanical strength while greatly improving the electrical and thermal conductivity.

[0100] Combining Examples 1-12 and Comparative Examples 1-6 and Table 1, it can be seen that compared with Examples 4-8, from the perspective of the comprehensive performance of the ultra-pure ferritic stainless steel master alloy, the ultra-pure ferritic stainless steel master alloys in Examples 2-3 and Examples 6-7 are better, while from the perspective of economic cost and replacement of 304 stainless steel, the ultra-pure ferritic stainless steel master alloy in Examples 4-5 is better.

[0101] Combining Examples 1-12 and Comparative Examples 1-6 and Table 1, it can be seen that compared with Examples 9-12, the interface modified over-plated metal elements in Example 1 are mainly composed of Fe, Cr, Mn, Y, and Ti in a mass ratio of (74-83):(16-22):(0.4-1.0):(0.2-0.3):(0.05-0.3). The prepared surface modified graphene alloy additive has better compatibility with the matrix alloy elements, which can improve the overall mechanical strength while greatly improving its electrical and thermal conductivity.

[0102] Table 2 is a table of test parameters of stainless steel corrosion resistance in Examples 1-3, Example 10 and Comparative Examples 1-6

[0103]

[0104]

[0105] Note: The test standard is still GB / T 24187-2023. Test condition 1 is 80℃ (temperature) / 85° (humidity) exposure test for 2 months to calculate the corrosion rate S1 of stainless steel. Test condition 2 is immersed in 10% nitric acid solution and heated to 100℃ for 2 months to calculate the corrosion rate S2 of stainless steel. Test strip 3 is immersed in 5% sulfuric acid solution and heated to 100℃ for 2 months to calculate the corrosion rate S3 of stainless steel. The test control 430 stainless steel is used in Baosteel 430 stainless steel plate, and 304 stainless steel is used in Baosteel 304 stainless steel plate.

[0106] Combining Examples 1-3, Example 10 and Comparative Examples 1-6 and Table 1-2, it can be seen that the corrosion resistance of the ultrapure ferritic stainless steel master alloys in Examples 1-3 and Example 10 is better than that of conventional 430 stainless steel and comparable to that of 304 stainless steel.

[0107] In combination with Examples 1-3, Example 10 and Comparative Examples 1-6 and in combination with Table 1-2, it can be seen that, compared with Comparative Example 2, the unmodified graphene material has limited improvement in the corrosion resistance of the ultra-pure ferritic stainless steel master alloy, and the conventional commercially available graphene materials cannot meet the actual alloy production needs. The surface-modified graphene alloy additive in the present application overcomes the compatibility of the surface-modified graphene alloy additive with the matrix alloy elements, and can effectively improve the corrosion resistance.

[0108] In summary, the ultrapure ferritic stainless steel master alloy in this application has good mechanical properties and corrosion resistance, relatively better electrical and thermal conductivity, lower thermal expansion coefficient, excellent processing performance, and can replace 304 stainless steel. In addition, the ultrapure ferritic stainless steel modified by the surface-modified graphene alloy additive also has good lubricity, wear resistance, antibacterial and mildew resistance, and biocompatibility, and has more obvious competitive advantages compared with 304 stainless steel.

[0109] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A heat-resistant ultrapure ferrite stainless steel master alloy containing yttrium, characterized in that: The invention is composed of the following components in weight percentage: 0.2-0.3% Y, C≤0.009%, N≤0.006%, O≤0.005%, Si≤0.05%, P≤0.02%, S≤0.008%, Ni≤0.05%, 0.4-1.0% Mn, 12-18% Cr, 0.04-0.12% Ce, 0.05-0.20% Al, 0.05-0.30% Ti, Cu≤0.02%, V≤0.02%, 0.035-0.20% surface modified graphene alloy additive, and the balance is Fe; The surface-modified graphene alloy additive comprises a graphene carrier and an interface-modified transition metal element loaded on the surface of the graphene carrier; The interface-modified transition metal element is connected to the surface of the graphene carrier in the form of a single atom through chemical bonds; The interface modified transition metal elements are composed of Fe, Cr, Mn, Y and Ti. The mass ratio of Fe, Cr, Mn, Y and Ti is (74-83):(16-22):(0.4-1.0):(0.2-0.3):(0.05-0.3); The tensile strength of the yttrium-containing heat-resistant ultra-pure ferrite stainless steel master alloy is ≥480MPa.

2. The yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy according to claim 1, characterized in that: The invention is composed of the following components in weight percentage: 0.20-0.30% of Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, Ni≤0.05%, 0.48-0.64% of Mn, 12-15% of Cr, 0.05-0.06% of Ce, 0.10-0.20% of Al, 0.16-0.24% of Ti, Cu≤0.02%, V≤0.02%, 0.05-0.10% of surface modified graphene alloy additive, and the balance is Fe.

3. The yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy according to claim 2, characterized in that: The interface modified transition metal elements are composed of Fe, Cr, Mn, Y and Ti in a mass ratio of 810:180:5:3:

2.

4. A yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy according to any one of claims 2 or 3, characterized in that: The yield strength of the yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy is ≥205MPa, the elongation is ≥25%, the thermal conductivity is ≥30 W / (m·K), and the resistivity is ≥2.5*10 6 Ω·m, thermal expansion coefficient ≤11 um / (m·K), hardness 80-90HRB, corrosion rate ≤0.05mm / a.

5. The yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy according to claim 1, characterized in that: The invention is composed of the following components in weight percentage: 0.20-0.30% of Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.48-0.64% of Mn, 12.0-13.0% of Cr, 0.05-0.06% of Ce, 0.10-0.20% of Al, 0.16-0.24% of Ti, Cu≤0.02%, V≤0.02%, 0.048-0.054% of surface modified graphene alloy additive, and the balance is Fe.

6. The yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy according to claim 1, characterized in that: The invention is composed of the following components in weight percentage: 0.20-0.30% of Y, C≤0.006%, N≤0.002%, O≤0.002%, Si≤0.02%, P≤0.01%, S≤0.005%, 0.48-0.64% of Mn, 14.0-15.0% of Cr, 0.05-0.06% of Ce, 0.10-0.20% of Al, 0.16-0.24% of Ti, Cu≤0.02%, V≤0.02%, 0.035-0.040% of surface modified graphene alloy additive, and the balance is Fe.

7. The yttrium-containing heat-resistant ultrapure ferrite stainless steel master alloy according to claim 1, characterized in that: The preparation method of the surface modified graphene alloy additive is as follows: Step 1, preparation of boron-nitrogen doped graphene; Step 2, preparing a 0.05-0.5 g / L transition metal salt aqueous solution, wherein the nitrate is iron nitrate nonahydrate, chromium nitrate nonahydrate, manganese nitrate tetrahydrate, yttrium nitrate hexahydrate, and titanium acetylacetonate; Step 3, mixing the boron-nitrogen-doped graphene with deionized water and then dispersing the mixture by ultrasonic to obtain a boron-nitrogen-doped graphene aqueous solution, wherein the mass ratio of the boron-nitrogen-doped graphene to the deionized water is (1-2): (100-400), adding a transition metal salt aqueous solution to the boron-nitrogen-doped graphene aqueous solution, wherein the mass ratio of the transition metal content in the transition metal salt aqueous solution to the carrier boron-nitrogen-doped graphene is 1: (10-50), dispersing the mixture by ultrasonic for 0.5-2h, stirring the mixture by magnetic stirring for 20-24h, removing the solvent by rotary evaporation, and drying the mixture to obtain a solid powder; Step 4: Planetarily ball mill the obtained solid powder at a speed of 50-80rpm for 0.5-2h, heat treat the powder obtained by ball milling at 600-800℃ for 2-4h in an air atmosphere, and then planetarily ball mill the solid material obtained after cooling at a speed of 180-300rpm for 0.5-1.0h to obtain a surface-modified graphene alloy additive with an average particle size of 200-500nm.

8. A method for preparing the yttrium-containing heat-resistant ultrapure ferritic stainless steel master alloy according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, ingredients are prepared according to the composition control requirements of the yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy; Simultaneously, the surface-modified graphene alloy additive is prepared; S2, the raw materials prepared in S1 are dried at 100-150°C for 1-4h; S3, adding materials in the order of 50wt% Fe, 50wt% Cr, Ti, Ce, the remaining 50wt% Cr, and the remaining 50wt% Fe, and melting under vacuum at a vacuum degree of <10Pa; S4, vacuum degree <1.0Pa, refining temperature 1570-1590℃, refining at warm temperature after chemical purification; S5, drop the temperature to 1480-1520℃, add Al, stir well, take samples for analysis in front of the furnace, make fine adjustments and add materials according to the analysis results in front of the furnace; S6, the temperature of the molten steel is adjusted to 1610-1630°C, and the module is prepared in a heat-insulating state; argon is filled with 50,000Pa, and metal yttrium is added by wrapping it with pure iron sheet. The addition of metal yttrium is controlled according to a yield of 80%, the addition of metal manganese is controlled according to a yield of 95%, and the addition of surface-modified graphene alloy additives is controlled according to a yield of 95%. After adding, stir for 1-2 minutes and quickly cast to obtain yttrium-containing heat-resistant ultra-pure ferritic stainless steel master alloy rods.

9. The preparation method according to claim 8, characterized in that: The chute or diverter plate used for pouring in S6 does not have a filter screen, but a slag retaining dam needs to be set to retain slag.

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