CN112458369B - Precipitation-strengthened ferritic heat-resistant steel and preparation method thereof - Google Patents
Precipitation-strengthened ferritic heat-resistant steel and preparation method thereof Download PDFInfo
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- 238000005728 strengthening Methods 0.000 claims abstract description 5
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- 238000004321 preservation Methods 0.000 claims description 17
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- 239000011159 matrix material Substances 0.000 claims description 10
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
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Abstract
The precipitation strengthening type ferritic heat-resistant steel comprises 0.04 percent of ferrite heat-resistant steel by mass<C<0.08％、0≤N≤0.005％、0≤B≤0.005％、10％≤Cr≤25％、3％≤Al≤15％、3％≤Ni≤15％、0.01％≤Si≤0.05％、0.05％≤Ti≤2％、0<Mo≤3.5％、0<Cu is less than or equal to 1.5 percent, and the balance is Fe. The preparation method comprises the steps of mixing and smelting the components in proportion and then casting the mixture into ingots; then homogenizing the cast ingot; rolling and deforming the cast ingot after the homogenization treatment; finally, heat treatment is carried out to obtain the product which can be thermally grown (Cr, Al)2O3Film precipitation-strengthened ferritic heat-resistant steel. The precipitation-strengthened ferritic heat-resistant steel has excellent steam oxidation resistance and is particularly suitable for high-temperature steam environment with the temperature of over 600 ℃.
Description
Technical Field
The invention belongs to the field of material preparation, and particularly relates to precipitation-strengthened ferritic heat-resistant steel and a preparation method thereof.
Background
Due to the low thermal expansion coefficient, good heat-conducting property and excellent fatigue resistance, the ferrite heat-resistant steel becomes the preferred material for medium-thick wall parts such as a 600 ℃ ultra-supercritical coal-fired boiler main steam pipeline, a header and the like and is widely applied. However, the currently widely used 9-12Cr and improved ferritic heat-resistant steels form poorly protective Fe-Cr oxide films (outer layer of loose porous Fe) in high-temperature steam or supercritical water3O4Layer, inner layer denser FeCr2O4Layer) resulting in insufficient resistance to high temperature steam oxidation, and therefore their recommended service temperature is generally not higher than 620 ℃, which also limits the possibility of ferritic heat-resistant steels for higher parameter ultra supercritical thermal power plant applications. In order to increase the service temperature of the ferrite heat-resistant steel, the surface of the ferrite heat-resistant steel can be thermally grown to form Cr through alloy composition design2O3Or Al2O3And (3) a membrane. The growth rate of the two is far lower than that of Fe under the same temperature condition3O4And FeCr2O4The growth speed of the composite material is higher, and the composite material has better protection. Therefore, development of a thermally growable (Cr, Al)2O3It is highly desirable that the ferritic heat-resistant steel of the film meet the application requirements in ultra-600 ℃ ultra-supercritical coal-fired boilers.
The Oxide Dispersion Strengthened (ODS) ferrite heat-resistant steel has good Al2O3Film forming ability, excellent high temperature creep property and high tensile strength, but its development is mainly through precise process improvement and component control or introductionThe introduction of new processes such as mechanical alloying, thermal sintering, etc. is complicated and too costly, thus limiting their application.
Disclosure of Invention
The invention aims to solve the problem of insufficient high-temperature steam oxidation resistance of the ferrite heat-resistant steel in the prior art, and provides precipitation-strengthened ferrite heat-resistant steel and a preparation method thereof, wherein the precipitation-strengthened ferrite heat-resistant steel can be thermally grown to form (Cr, Al) in a steam environment with the temperature of more than 600 DEG C2O3The film has excellent steam oxidation resistance, and is particularly suitable for high-temperature steam environment with the temperature of over 600 ℃.
In order to achieve the above object, the present invention has the following technical means:
a precipitation-strengthened ferritic heat-resistant steel comprises the following components in parts by mass:
0.04 percent < C <0.08 percent, 0 percent < N < 0.005 percent, 0 percent < B < 0.005 percent, 10 percent < Cr < 25 percent, 2 percent < Al < 15 percent, 3 percent < Ni < 15 percent, 0.01 percent < Si < 0.05 percent, 0.05 percent < Ti < 2 percent, 0< Mo < 3.5 percent, 0< Cu < 1.5 percent and the balance of Fe.
Preferably, the precipitation-strengthened ferritic heat-resistant steel of the present invention is composed of an α matrix phase and a β 'phase dispersed therein, wherein the α matrix phase is a ferritic matrix, and the β' phase is (Fe, Ni) Al.
Preferably, the beta' phase accounts for 5-35% of the total volume of the precipitation-strengthened ferritic heat-resistant steel.
Preferably, the mass fraction of Cr is 15-20%.
Preferably, the mass fraction of Al is 3-10%.
Preferably, the surface of the film is spontaneously formed (Cr, Al) when exposed to a high-temperature oxidizing atmosphere at a temperature of over 600 DEG C2O3And (5) protecting the film.
The invention also provides a preparation method of the reinforced ferritic heat-resistant steel, which comprises the following steps:
firstly, mixing and smelting C, N, B, Cr, Al, Ni, Si, Ti, Mo, Cu and Fe in proportion, and then casting into ingots; secondly, homogenizing the cast ingot; thirdly, homogenizingRolling and deforming the ingot after the treatment; fourthly, obtaining the (Cr, Al) capable of thermal growth through heat treatment2O3Film precipitation-strengthened ferritic heat-resistant steel.
Preferably, the temperature of the homogenization treatment in the second step is 1000-1100 ℃, the heat preservation time is 0.5h, and the cooling mode is air cooling.
Preferably, the temperature of the third rolling step is 1120-1180 ℃.
Preferably, the heat treatment temperature in the fourth step is 1020-1050 ℃, the heat preservation time is 1h, then air cooling is carried out to the room temperature, the temperature is raised to 750-780 ℃, the heat preservation time is 24h, and finally air cooling is carried out to the room temperature.
Compared with the prior art, the invention has the following beneficial effects: cr in the components is an important element for ensuring that the steel has good oxidation resistance in a high-temperature environment. As the Cr content increases, the corrosion resistance of the ferritic heat-resistant steel of the present invention is enhanced. Al also plays an important role in improving the high-temperature oxidation resistance of the alloy, and when the Cr content is the same, the protection (Cr, Al) can be promoted by increasing the Al content2O3And (3) forming a film, thereby remarkably improving the oxidation resistance of the steel. In view of this, the ferritic heat-resistant steel of the present invention contains Al in an amount of not less than 3% by mass but not more than 15% by mass because too low Al content prevents the formation of β' strengthening phase in the steel, weakening the strength of the steel; and too high Al content deteriorates ductility and toughness of the steel, and lowers hot workability and weldability of the steel. In the invention, the Si has similar action with Al, and the Si improves the high-temperature oxidation resistance of the ferrite heat-resistant steel mainly through two aspects, namely: when the Si content is sufficiently high, SiO is formed2A protective film which prevents further diffusion of corrosive gas into the substrate; ② reducing the formation of protective Cr on the surface of ferrite heat-resistant steel2O3/Al2O3Critical Cr/Al concentration required for film, promoting Cr2O3/Al2O3The rapid growth of (2). In addition, Si can also strengthen ferritic heat-resistant steel, improving its strength and hardness. However, as with Al, too high a Si content may reduce the ductility and weldability of the steel. Therefore, the mass content of Si in the ferritic heat-resistant steel of the invention is controlled0.01 to 0.05 percent of the total weight of the composition. Secondly, Ni, which is the most basic element for ensuring the formation of a beta' precipitation strengthening phase in the ferritic steel, is also added in the ferritic heat-resistant steel of the invention. As the Ni and Al contents increase, the volume fraction of the β' phase in the steel increases, and the strength of the steel increases. Moreover, the invention can strengthen the ferrite matrix by adding Ni, and can also improve the corrosion resistance and low-temperature toughness of the steel. However, Ni is a strong austenite forming element, and too high a mass content thereof causes transformation of the steel matrix into austenite, and therefore, the mass content of Ni in the ferritic heat-resistant steel of the present invention is controlled to 3% to 15%. In order to improve the high-temperature strength of the ferritic heat-resistant steel of the present invention, Ti, Mo and Cu are added in addition to Ni and Al to improve the high-temperature stability of the β' phase. However, the contents of Ti, Mo and Cu should be appropriate to avoid harmful precipitated phases and catastrophic oxidation, so that the mass content of Ti, Mo and Cu is controlled to be 0.05-2%, 0-3.5% and 0-1.5% respectively. The added C can form carbide with Cr, Ti, Mo and the like, so that the mechanical property of the steel is improved, but the oxidation resistance of the steel is reduced, and therefore, the mass content of C in the ferritic heat-resistant steel is not less than 0.04% but not more than 0.08%. In addition, N and B are added in the ferritic heat-resistant steel in an amount of 0-0.005% by mass to strengthen the grain boundary of the steel, thereby improving the strength and long-term structure stability of the steel. When the Cr content is increased to 25% or more, the mechanical properties of the ferritic heat-resistant steel of the present invention are deteriorated due to the change in the structure. This is because when the Cr content in the ferritic heat-resistant steel is higher than 25% by mass, a brittle α -Cr phase precipitates. Therefore, although a high Cr content enables the ferritic heat-resistant steel to satisfy the required oxidation resistance, it is difficult to satisfy the requirements of mechanical properties and long-term structure stability. Therefore, the invention controls the Cr mass content in the alloy to be 10-25%, so that the ferrite heat-resistant steel meets the requirements of oxidation resistance and mechanical property and long-term structure stability.
Compared with the prior art, the preparation method of the precipitation-strengthened ferritic heat-resistant steel has the advantages that the components mixed in proportion are smelted and then cast into ingots, the ingots are subjected to solution treatment and cold deformation processing, and then heat treatment is carried out, so that the preparation can be completed.
Drawings
FIG. 1 is a microstructure under a scanning electron microscope of example 2 of the present invention after heat treatment;
FIG. 2 is a sectional topography of P92 steel after being oxidized for 1000h in pure water vapor at 650 ℃;
FIG. 3 is a cross-sectional profile of Super304H after oxidation in pure water vapor at 650 deg.C for 1000 h;
FIG. 4 is a cross-sectional profile of example 2 of the present invention after oxidation in pure water vapor at 650 deg.C for 1000 hours.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
The invention provides precipitation-strengthened ferritic heat-resistant steel which comprises, by mass, 0.04% C < 0.08%, 0% N < 0.005%, 0% B < 0.005%, 10% Cr < 25%, 2% Al < 15%, 3% Ni < 15%, 0.01% Si < 0.05%, 0.05% Ti < 2%, 0< Mo < 3.5%, 0< Cu < 1.5%, and the balance of Fe.
In accordance with the chemical composition range of the precipitation-strengthened ferritic heat-resistant steel, 6 test steels were produced in the examples of the present invention, and the chemical compositions thereof are shown in table 1. Table 1 shows the chemical composition (in terms of mass fraction) of the ferritic heat-resistant steels of examples 1 to 4 of the present invention, comparative example steel P92 and Super 304H.
TABLE 1
A preparation method of precipitation-strengthened ferritic heat-resistant steel comprises the following steps: first, the step ofN, B, Cr, Al, Ni, Si, Ti, Mo, Cu and Fe are mixed and smelted according to a proportion and then cast into ingots; secondly, homogenizing the cast ingot; the temperature of the homogenization treatment is 1000-1100 ℃, the heat preservation time is 0.5h, and the air cooling is carried out in a cooling mode. Thirdly, rolling and deforming the cast ingot after the homogenization treatment; the rolling temperature is 1120-1180 ℃. Fourthly, obtaining the (Cr, Al) capable of thermal growth through heat treatment2O3Film precipitation-strengthened ferritic heat-resistant steel. The heat treatment temperature is 1020-1050 ℃, the heat preservation time is 1h, then air cooling is carried out to the room temperature, the temperature is raised to 750-780 ℃, the heat preservation time is 24h, and finally air cooling is carried out to the room temperature.
The precipitation strengthening type ferritic heat-resistant steel forms (Cr, Al) on the surface in the steam of 650 ℃ and 1000h2O3Film with oxidation weight gain less than or equal to 0.01g/m2hr, it is completely oxidation resistant, and is suitable for high temperature steam environment of over 600 deg.C. In addition, the precipitation-strengthened ferritic heat-resistant steel has high strength at high temperature, is low in production cost and has an obvious cost performance advantage.
Example 1
According to the mass fraction, 10% of Cr, 15% of Al, 5% of Ni, 0.3% of Ti, 0.02% of Si, 2% of Mo, 0.5% of Cu and the balance of Fe are mixed and smelted, and then the mixture is added into a vacuum induction furnace to be cast into ingots.
Example 2
According to mass fraction, 18% of Cr, 2% of Al, 10% of Ni, 0.5% of Ti, 0.01% of Si, 2% of Mo, 1% of Cu, 0.05% of C, 0.002% of N, 0.003% of B and the balance of Fe are mixed and smelted, and then added into a vacuum induction furnace to be cast into ingots.
Example 3
19% of Cr, 2% of Al, 3% of Ni, 0.3% of Ti, 0.03% of Si, 2.5% of Mo, 1.2% of Cu, 0.05% of C, 0.003% of N, 0.003% of B and the balance of Fe are mixed and smelted by mass percent, and then the mixture is added into a vacuum induction furnace to be cast into ingots.
Example 4
According to mass fraction, 20% of Cr, 3% of Al, 6% of Ni, 1.5% of Ti, 0.05% of Si, 3% of Mo, 1.5% of Cu, 0.07% of C, 0.005% of N, 0.005% of B and the balance of Fe are mixed and smelted, and then the mixture is added into a vacuum induction furnace to be cast into ingots.
Example 5
A preparation method of precipitation-strengthened ferritic heat-resistant steel comprises the following steps:
a first step of mixing 0.04% of C, 0.002% of N, 0.003% of B, 10% of Cr, 2% of Al, 3% of Ni, 0.01% of Si, 0.05% of Ti, 0.2% of Mo, 0.3% of Cu and the balance of Fe in parts by mass in a vacuum induction furnace, and then melting and casting into ingots;
and secondly, homogenizing the cast ingot, wherein the temperature of the homogenizing treatment is 1000 ℃, the heat preservation time is 0.5h, and the cooling mode is air cooling.
And thirdly, rolling and deforming the ingot after the homogenization treatment, wherein the rolling temperature is 1120 ℃.
Fourth, heat treatment to obtain a material capable of thermal growth (Cr, Al)2O3Film precipitation-strengthened ferritic heat-resistant steel. The temperature of the heat treatment is 1020 ℃, the heat preservation time is 1h, then the air cooling is carried out to the room temperature, the temperature is raised to 750 ℃, the heat preservation is carried out for 24h, and finally the air cooling is carried out to the room temperature.
Example 6
A preparation method of precipitation-strengthened ferritic heat-resistant steel comprises the following steps:
a first step of mixing 0.06% of C, 0.003% of N, 0.002% of B, 17% of Cr, 7% of Al, 9% of Ni, 0.03% of Si, 0.13% of Ti, 2.3% of Mo, 0.7% of Cu and the balance of Fe in parts by mass, and then melting and casting the mixture into ingots in a vacuum induction furnace;
and secondly, homogenizing the cast ingot, wherein the temperature of the homogenizing treatment is 1070 ℃, the heat preservation time is 0.5h, and the cooling mode is air cooling.
And thirdly, rolling and deforming the ingot after the homogenization treatment, wherein the rolling temperature is 1160 ℃.
Fourth, heat treatment to obtain a material capable of thermal growth (Cr, Al)2O3Strong precipitation of filmA ferritic heat-resistant steel. The temperature of the heat treatment is 1035 ℃, the heat preservation time is 1h, then the air cooling is carried out to the room temperature, the temperature is increased to 770 ℃, the heat preservation is carried out for 24h, and finally the air cooling is carried out to the room temperature.
Example 7
A preparation method of precipitation-strengthened ferritic heat-resistant steel comprises the following steps:
a first step of mixing 0.08% of C, 0.005% of N, 0.005% of B, 25% of Cr, 15% of Al, 15% of Ni, 0.05% of Si, 0.2% of Ti, 3.5% of Mo, 1.5% of Cu and the balance of Fe in parts by mass, and then melting and casting the mixture into ingots in a vacuum induction furnace;
and secondly, homogenizing the cast ingot, wherein the temperature of the homogenizing treatment is 1100 ℃, the heat preservation time is 0.5h, and the cooling mode is air cooling.
And thirdly, rolling and deforming the ingot after homogenization treatment at 1180 ℃.
Fourth, heat treatment to obtain a material capable of thermal growth (Cr, Al)2O3Film precipitation-strengthened ferritic heat-resistant steel. The temperature of the heat treatment is 1050 ℃, the heat preservation time is 1h, then the air cooling is carried out to the room temperature, the temperature is raised to 780 ℃, the heat preservation is carried out for 24h, and finally the air cooling is carried out to the room temperature.
The composition of steel P92 included 9% Cr, 0.01% Al, 0.4% Ni, 0.45% Si, 0.5% Mo, 0.5% Mn, 0.2% V, 0.06% Nb, 1.8% W, 0.1% C, 0.05% N, 0.005% B and the balance Fe.
The composition of Super304H includes 18% Cr, 8% Ni, 0.03% Si, 3% Cu, 0.5% Mn, 0.4% Nb, 0.1% C, 0.08% N, 0.006% B, and the balance Fe.
Referring to fig. 1, it can be seen that the spherical β' - (Fe, Ni) Al phase is dispersed in the ferritic (α) matrix of the present invention. By way of further verification, Table 2 shows the change in mass of the steels according to examples 2 to 4 of the invention, of comparative examples P92 and of Super304H, when they are oxidized in pure water steam at constant temperature of 650 ℃.
TABLE 2
The test result shows that the weight gain of the steel of the invention is lower than that of P92 and Super304H in pure water vapor at 650 ℃, and the oxide film is not peeled off, which shows that the steel of the invention has excellent high-temperature steam oxidation resistance. From the cross-sectional view of the oxide layer, it can be seen that when P92 and Super304H are oxidized in pure water vapor at 650 ℃, the oxide layer has a loose multi-layer structure, and a local oxide film is peeled off during cooling, which reduces the steam oxidation resistance of the steel, as shown in fig. 2 and 3. FIG. 4 is a cross-sectional view of the steel of example 2 according to the present invention oxidized in pure steam at 650 ℃ for 1000 hours, and it can be seen that the steel of example 2 is continuously densified and has a thin oxide layer when oxidized in pure steam at 650 ℃. The oxide layer is mainly Al through energy spectrum surface scanning analysis2O3。
The above embodiments are not intended to limit the technical solution of the present invention in any way, and it should be understood by those skilled in the art that the technical solution can also make several simple modifications and substitutions without departing from the spirit and principle of the present invention, and the modifications and substitutions also fall into the scope of the patent protection covered by the claims.
Claims (8)
1. A precipitation-strengthened ferritic heat-resistant steel characterized by: the components comprise 0.04 percent by mass<C<0.08％、0≤N≤0.005％、0≤B≤0.005％、10％≤Cr≤25％、2％≤Al≤15％、3％≤Ni≤15％、0.01％≤Si≤0.05％、0.05％≤Ti≤2％、0<Mo≤3.5％、0<Cu is less than or equal to 1.5 percent, and the balance is Fe; the composite material consists of an alpha matrix phase and a beta 'phase which is dispersed in the alpha matrix phase, wherein the alpha matrix phase is a ferrite matrix, and the beta' phase is (Fe, Ni) Al; the surface of the material can spontaneously form (Cr, Al) when exposed in a high-temperature oxidizing atmosphere at the temperature of over 600 DEG C2O3And (5) protecting the film.
2. The precipitation-strengthened ferritic heat-resistant steel according to claim 1, characterized in that:
the beta' phase accounts for 5 to 35 percent of the total volume of the precipitation strengthening type ferritic heat-resistant steel.
3. The precipitation-strengthened ferritic heat-resistant steel according to claim 1, characterized in that:
the mass fraction of Cr is 15-20%.
4. The precipitation-strengthened ferritic heat-resistant steel according to claim 1, characterized in that:
the mass fraction of Al is 3-10%.
5. A method for producing the precipitation-strengthened ferritic heat-resistant steel according to claim 1, characterized by comprising the steps of: firstly, mixing and smelting C, N, B, Cr, Al, Ni, Si, Ti, Mo, Cu and Fe in proportion, and then casting into ingots; secondly, homogenizing the cast ingot; thirdly, rolling and deforming the cast ingot after the homogenization treatment; fourthly, obtaining the (Cr, Al) capable of thermal growth through heat treatment2O3Film precipitation-strengthened ferritic heat-resistant steel.
6. The method of claim 5, wherein:
the temperature of the homogenization treatment in the second step is 1000-1100 ℃, the heat preservation time is 0.5h, and the air cooling is carried out in a cooling mode.
7. The method of claim 5, wherein:
the rolling temperature in the third step is 1120-1180 ℃.
8. The method of claim 5, wherein: and fourthly, performing heat treatment at 1020-1050 ℃ for 1h, then performing air cooling to room temperature, heating to 750-780 ℃ and performing heat preservation for 24h, and finally performing air cooling to room temperature.
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