CN111542639A - Austenitic heat-resistant alloy - Google Patents
Austenitic heat-resistant alloy Download PDFInfo
- Publication number
- CN111542639A CN111542639A CN201880084052.8A CN201880084052A CN111542639A CN 111542639 A CN111542639 A CN 111542639A CN 201880084052 A CN201880084052 A CN 201880084052A CN 111542639 A CN111542639 A CN 111542639A
- Authority
- CN
- China
- Prior art keywords
- content
- resistant alloy
- less
- alloy
- austenitic heat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- 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
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
-
- 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
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- 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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- 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
-
- 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
-
- 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
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- 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
-
- C—CHEMISTRY; METALLURGY
- 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
- C23C8/10—Oxidising
- C23C8/16—Oxidising using oxygen-containing compounds, e.g. water, carbon dioxide
- C23C8/18—Oxidising of ferrous surfaces
Abstract
An austenitic heat-resistant alloy having a chemical composition consisting of, in mass%, C: 0.03 to 0.25%, Si: 0.01-2.0%, Mn: 0.10 to 0.50%, P: 0.030% or less, S: 0.010% or less, Cr: 13.0 to 30.0%, Ni: 25.0-45.0%, Al: 2.5-4.5%, Nb: 0.01-2.00%, N: 0.05% or less, Ti: 0-0.20%, W: 0-6.0%, Mo: 0-4.0%, Zr: 0-0.10%, B: 0-0.0100%, Cu: 0-5.0%, REM: 0-0.10%, Ca: 0-0.050%, Mg: 0-0.050%, and the balance: fe and impurities.
Description
Technical Field
The present invention relates to austenitic heat resistant alloys.
Background
Ethylene (C)2H4) Isoolefin (C)nH2n) Produced by pyrolyzing hydrocarbons (naphtha, natural gas, ethane, etc.). Specifically, hydrocarbons and steam are supplied together into a pipe made of a high Cr-high Ni alloy represented by 25Cr-25Ni series or 25Cr-38Ni series or stainless steel represented by SUS304 or the like and laid in a reactor, and the pipe is heated from the outer surface of the pipe, whereby the hydrocarbons are pyrolyzed on the inner surface of the pipe to obtain olefinic hydrocarbons (ethylene, propylene, and the like).
With the recent increase in the demand for synthetic resins, the use conditions of decomposition furnace tubes for ethylene production facilities are increasingly becoming higher in temperature from the viewpoint of improving the ethylene yield. Since the inner surface of such a decomposition furnace tube is exposed to a carburizing atmosphere, a heat-resistant material having excellent high-temperature strength and carburization resistance is required.
If the carburization is further promoted, a phenomenon called coking occurs in which carbon is precipitated on the inner surface of the decomposition furnace tube in operation. As the amount of coking precipitation increases, operational disadvantages such as an increase in pressure loss and a decrease in heating efficiency occur. Therefore, in actual operation, a so-called decoking operation is performed in which air and steam are periodically supplied to oxidize and remove precipitated carbon, but during this period, operation stoppage, an increase in the number of operation steps, and the like become significant problems.
The prior art has also developed materials that improve carburization resistance. For example, japanese patent application laid-open No. 2001-40443 (patent document 1) proposes a Ni-based heat-resistant alloy having excellent hot workability, weldability, and carburization resistance. However, the Ni-based alloy precipitates a γ' phase as an embrittlement phase at a high temperature, and the temperature range in which hot working is possible is narrow, and is difficult to manufacture.
Therefore, in order to improve hot workability, Fe-based austenitic stainless steels have been developed. For example, international publication No. 2017/119415 (patent document 2) proposes an austenitic heat-resistant alloy having high creep strength and high toughness even in a high-temperature environment.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent application No. 2001-40443
Patent document 2: international publication No. 2017/119415
Disclosure of Invention
Problems to be solved by the invention
When the austenitic heat-resistant alloy described in patent document 2 is used at high temperature, an alumina coating is formed on the surface, and not only high corrosion resistance is obtained, but also high-temperature strength and excellent toughness are obtained for a long time. However, patent document 2 has not sufficiently studied carburization resistance, and there is still room for improvement.
The purpose of the present invention is to provide an austenitic heat-resistant alloy that has high creep strength and excellent carburization resistance even when used in a high-temperature environment.
Means for solving the problems
The present invention has been made to solve the above problems, and the gist thereof is the following austenitic heat-resistant alloy.
(1) An austenitic heat-resistant alloy having a chemical composition comprising, in mass%
C：0.03～0.25％、
Si：0.01～2.0％、
Mn：0.10～0.50％、
P: less than 0.030%,
S: less than 0.010%,
Cr：13.0～30.0％、
Ni：25.0～45.0％、
Al：2.5～4.5％、
Nb：0.05～2.00％、
N: less than 0.05 percent of,
Ti：0～0.20％、
W：0～6.0％、
Mo：0～4.0％、
Zr：0～0.10％、
B：0～0.0100％、
Cu：0～5.0％、
REM：0～0.10％、
Ca：0～0.050％、
Mg：0～0.050％、
And the balance: fe and impurities.
(2) The austenitic heat-resistant alloy according to the above (1), wherein,
the chemical composition contains, in mass%, B: 0.0010-0.0100%.
(3) The austenitic heat-resistant alloy according to the above (1) or (2), wherein,
heating at 900 deg.C for 20 hr in an atmosphere containing water vapor, followed by H2-CH4-CO2And heating at 1100 deg.C for 96 hr in an atmosphere to form a continuous alumina coating with a thickness of 0.5-15 μm on the surface of the alloy.
(4) The austenitic heat-resistant alloy according to the above (3), wherein,
heating at 900 deg.C for 20 hr in an atmosphere containing water vapor, followed by H2-CH4-CO2When the coating film is heated at 1100 ℃ for 96 hours in an atmosphere, the thickness of the coating film having a Cr-Mn spinel structure formed on the alumina coating film is 5 μm or less.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, an austenitic heat-resistant alloy having high creep strength and excellent carburization resistance even when used under a high-temperature environment can be obtained.
Detailed Description
The present inventors investigated and studied the carburization resistance of an austenitic heat-resistant alloy in a high-temperature environment of 1000 ℃ or higher (hereinafter simply referred to as "high-temperature environment"), and found the following.
By forming a continuous alumina coating on the surface of the base material, the carburization resistance at high temperatures can be maintained. The presence of Cr promotes the formation of an alumina coating. This effect is called Third element effect (TEE effect) of Cr. In the earliest stage of oxidation, Cr is preferentially oxidized on the surface of the base material to form a chromium oxide film.
Therefore, oxygen on the surface of the base material is consumed, and the oxygen partial pressure is lowered. Thus, Al forms a continuous alumina coating in the vicinity of the surface without undergoing internal oxidation. Thereafter, oxygen used in the chromium oxide film is taken away by the aluminum oxide film, and finally a protective film in which only aluminum oxide is present is formed. Therefore, in order to form a continuous alumina coating having protection properties, a certain amount or more of Cr needs to be contained.
Here, when a heat-resistant alloy is used as the decomposition furnace tube, occurrence of coking cannot be completely prevented. Therefore, the coking removal operation is performed periodically. At this time, the alumina coating formed on the surface of the base material is also removed by the decoking. Therefore, when used again in a high-temperature environment, the continuous alumina coating is expected to rapidly self-heal.
However, if a coating film having a Cr — Mn spinel structure (also referred to as "Cr — Mn spinel coating film" in the following description) is excessively generated during use, Cr in the surface layer of the base material is in short supply. As a result, the TEE effect is suppressed with the increase in the service time, and Al is internally oxidized to form a discontinuous alumina coating on the surface. As a result, the alumina no longer functions as a protective coating.
That is, in order to maintain the self-replenishing property of the alumina coating for a long time, it is necessary to suppress the formation of the Cr — Mn spinel coating on the surface of the base metal. For this reason, the Mn content in the base material needs to be reduced.
The present invention has been made based on the above findings. Hereinafter, each element of the present invention will be described in detail.
1. Chemical composition
The reasons for limiting the elements are as follows. In the following description, "%" relating to the content means "% by mass".
C：0.03～0.25％
Carbon (C) forms carbides and increases creep strength. Specifically, when C is used in a high-temperature environment, C bonds with alloying elements at grain boundaries and in grains to form fine carbides. The fine carbide increases the deformation resistance and improves the creep strength. If the C content is too low, the effect cannot be obtained. On the other hand, if the C content is too high, a large amount of coarse eutectic carbides are formed in the solidified metallographic structure of the heat-resistant alloy after casting. The eutectic carbide remains in the coarse structure even after the solution treatment, and therefore the toughness of the heat-resistant alloy is reduced. Further, if coarse eutectic carbides remain, fine carbides are less likely to precipitate during use in a high-temperature environment, and creep strength is reduced. Therefore, the C content is 0.03 to 0.25%. The lower limit of the C content is preferably 0.04%, more preferably 0.05%. The upper limit of the C content is preferably 0.23%, more preferably 0.20%.
Si：0.01～2.0％
Silicon (Si) deacidifies the heat resistant alloy. Si also improves the corrosion resistance (oxidation resistance and steam oxidation resistance) of the heat-resistant alloy. Si is an element that is inevitably contained, and when deacidification can be sufficiently performed using other elements, the content of Si can be reduced as much as possible. On the other hand, if the Si content is too high, the hot workability is lowered. Therefore, the Si content is 0.01 to 2.0%. The lower limit of the Si content is preferably 0.02%, more preferably 0.03%. The upper limit of the Si content is preferably 1.0%, more preferably 0.3%.
Mn：0.10～0.50％
Manganese (Mn) bonds with S contained in the heat-resistant alloy to form MnS, and improves hot workability of the heat-resistant alloy. However, if the Mn content is too high, the heat-resistant alloy becomes too hard, and hot workability and weldability deteriorate. Further, the formation of the Cr — Mn spinel film inhibits the TEE effect and prevents the formation of a uniform alumina film. Therefore, the Mn content is 0.10 to 0.50%. The upper limit of the preferable Mn content is preferably 0.40%, more preferably 0.30%, and still more preferably 0.20%.
P: less than 0.030%
Phosphorus (P) is an impurity. P reduces the weldability and hot workability of the heat-resistant alloy. Therefore, the P content is 0.030% or less. The P content is preferably as low as possible.
S: 0.010% or less
Sulfur (S) is an impurity. S reduces the weldability and hot workability of the heat-resistant alloy. Therefore, the S content is 0.010% or less. The S content is preferably as low as possible.
Cr：13.0～30.0％
Chromium (Cr) improves corrosion resistance (oxidation resistance, steam oxidation resistance, etc.) of the heat-resistant alloy in a high-temperature environment. Cr also promotes the formation of a uniform alumina coating due to the TEE effect. However, if the Cr content is too high, the formation of the chromium oxide film is dominant, and the formation of the aluminum oxide film is repeatedly inhibited. Therefore, the Cr content is 13.0 to 30.0%. The lower limit of the Cr content is preferably 15.0%. The upper limit of the Cr content is preferably 25.0%, and more preferably 20.0%.
Ni：25.0～45.0％
Nickel (Ni) stabilizes austenite. In addition, Ni bonds with Al to form fine NiAl, which improves creep strength. Ni also has the effect of improving the corrosion resistance of the heat-resistant alloy, reducing the diffusion rate of C into steel, and improving carburization resistance. If the Ni content is too low, these effects cannot be obtained. On the other hand, if the Ni content is too high, not only these effects are saturated, but also the hot workability is lowered. Further, if the Ni content is too high, the raw material cost increases. Therefore, the Ni content is 25.0 to 45.0%. The lower limit of the Ni content is preferably 30.0%. The upper limit of the Ni content is preferably 40.0%, and more preferably 35.0%.
Al：2.5～4.5％
Aluminum (Al) forms an alumina coating film having excellent carburization resistance when used in a high-temperature environment. Further, fine NiAl is formed by bonding with Ni, and creep strength is improved. If the Al content is too low, these effects cannot be obtained. On the other hand, if the Al content is too high, the structural stability is lowered and the strength is lowered. Therefore, the Al content is 2.5 to 4.5%. The lower limit of the Al content is preferably 2.8%, more preferably 3.0%. The upper limit of the Al content is preferably 3.8%. In the austenitic heat-resistant alloy according to the present invention, the Al content means the total Al content contained in the alloy.
Nb：0.05～2.00％
Niobium (Nb) forms intermetallic compounds (Laves phase and Ni) as precipitation strengthening phases3Nb phase) to perform precipitation strengthening on grain boundaries and in grains and improve creep of the heat-resistant alloyAnd the strength is changed. On the other hand, if the Nb content is too high, an intermetallic compound is excessively generated, and the toughness and hot workability of the alloy are lowered. If the Nb content is too high, the toughness after long-term aging is further reduced. Therefore, the Nb content is 0.05 to 2.00%. The lower limit of the Nb content is preferably 0.50%, more preferably 0.80%. The upper limit of the Nb content is preferably 1.20%, more preferably 1.00%.
N: less than 0.05%
Nitrogen (N) stabilizes austenite and is inevitably contained in a usual dissolution method. However, if the N content is too high, coarse carbonitrides remaining without solid solution are formed even after the solution treatment, and the toughness of the alloy is lowered. Therefore, the N content is 0.05% or less. The upper limit of the N content is preferably 0.01%.
Ti：0～0.20％
Titanium (Ti) forms intermetallic compounds (Laves phase and Ni) as precipitation strengthening phases3Ti phase) and improves creep strength by precipitation strengthening. Therefore, Ti may be contained as necessary. However, if the Ti content is too high, an intermetallic compound is excessively generated, and the high-temperature ductility and hot workability are degraded. If the Ti content is too high, the toughness after long-term aging is further lowered. Therefore, the Ti content is 0.20% or less. The upper limit of the Ti content is preferably 0.15%, more preferably 0.10%. In order to obtain the above effects, the Ti content is preferably 0.03% or more.
W：0～6.0％
Tungsten (W) is solid-dissolved in austenite of the matrix phase (matrix), and increases creep strength by solid-solution strengthening. W also forms a laves phase in grain boundaries and grains, and increases creep strength by precipitation strengthening. Therefore, W may be contained as necessary. However, if the W content is too high, a laves phase is excessively generated, and the high-temperature ductility, hot workability, and toughness are degraded. Therefore, the W content is 6.0% or less. The upper limit of the W content is preferably 5.5%, more preferably 5.0%. In order to obtain the above-described effects, the W content is preferably 0.005% or more, more preferably 0.01% or more.
Mo：0～4.0％
Molybdenum (Mo) is solid-dissolved in austenite of the matrix phase, and the creep strength is improved by solid-solution strengthening. Mo also forms a laves phase in grain boundaries and grains, and increases creep strength by precipitation strengthening. Therefore, Mo may be contained as necessary. However, if the Mo content is too high, a laves phase is excessively generated, and the high-temperature ductility, hot workability, and toughness are degraded. Therefore, the Mo content is 4.0% or less. The upper limit of the Mo content is preferably 3.5%, more preferably 3.0%. In order to obtain the above effects, the Mo content is preferably 0.005% or more, and more preferably 0.01% or more.
Zr：0～0.10％
Zirconium (Zr) increases creep strength due to grain boundary strengthening. Therefore, Zr may be contained as necessary. However, if the Zr content is too high, weldability and hot workability of the heat-resistant alloy deteriorate. Therefore, the Zr content is 0.10% or less. The upper limit of the Zr content is preferably 0.06%. In order to obtain the above-described effects, the Zr content is preferably 0.0005% or more, and more preferably 0.001% or more.
B：0～0.0100％
Boron (B) enhances creep strength due to grain boundary strengthening. Therefore, B may be contained as necessary. However, if the B content is too high, weldability decreases. Therefore, the B content is 0.0100% or less. The upper limit of the B content is preferably 0.0050%. When the above effects are to be obtained, the content of B is preferably 0.0001% or more. The lower limit of the B content is more preferably 0.0005%, and still more preferably 0.0010%, 0.0020% or more, or 0.0030% or more.
Cu：0～5.0％
Copper (Cu) promotes the formation of an alumina coating near the surface, and improves the corrosion resistance of the heat-resistant alloy. Therefore, Cu may be contained as necessary. However, if the Cu content is too high, not only the effect is saturated but also the high-temperature ductility is reduced. Therefore, the Cu content is 5.0% or less. The upper limit of the Cu content is preferably 4.8%, more preferably 4.5%. In order to obtain the above effects, the Cu content is preferably 0.05% or more, and more preferably 0.10% or more.
REM：0～0.10％
The rare earth element (REM) fixes S as sulfide to improve hot workability. REM also forms oxides that improve corrosion resistance, creep strength, and creep ductility. Therefore, REM may be contained as necessary. However, if the REM content is too high, the number of inclusions such as oxides increases, the hot workability and weldability deteriorate, and the production cost increases. Therefore, the REM content is 0.10% or less. The upper limit of the REM content is preferably 0.09%, more preferably 0.08%. In order to obtain the above-described effects, the REM content is preferably 0.0005% or more, and more preferably 0.001% or more.
Here, in the present invention, REM means a total of 17 elements of Sc, Y and lanthanoid, and the content of REM means the total content of these elements. The lanthanoid element is industrially added in the form of a misch metal.
Ca：0～0.050％
Calcium (Ca) fixes S as sulfide, and improves hot workability. Therefore, Ca may be contained as necessary. However, if the Ca content is too high, toughness, ductility and detergency are deteriorated. Therefore, the Ca content is 0.050% or less. The upper limit of the Ca content is preferably 0.030%, more preferably 0.010%. In order to obtain the above effects, the Ca content is preferably 0.0005% or more.
Mg：0～0.050％
Magnesium (Mg) fixes S as sulfide to improve hot workability. Therefore, Mg may be contained as necessary. However, if the Mg content is too high, toughness, ductility and detergency are reduced. Therefore, the Mg content is 0.050% or less. The upper limit of the Mg content is preferably 0.030%, more preferably 0.010%. In order to obtain the above effects, the Mg content is preferably 0.0005% or more.
The balance of the chemical composition is Fe and impurities. Here, "impurities" means: in the industrial production of an alloy, components mixed in due to raw materials such as ores and scrap irons and various factors of the production process are acceptable within a range not adversely affecting the present invention.
2. Film coating
As described above, the austenitic heat seal of the present inventionGold preferably forms a protective, continuous alumina coating rapidly in a high temperature environment. Specifically, it is preferable that: heating at 900 deg.C for 20 hr in an atmosphere containing water vapor, followed by H2-CH4-CO2When the alloy is heated at 1100 ℃ for 96 hours in an atmosphere, an alumina coating having a thickness of 0.5 to 15 μm is formed continuously on the surface of the alloy. The purpose of the treatment of heating at 900 ℃ for 20 hours in the atmosphere containing water vapor is to remove coking beforehand.
When the thickness of the alumina coating formed by the above treatment is less than 0.5 μm, the coating is broken in a short time in a high-temperature carburizing environment, and corrosion resistance cannot be maintained. On the other hand, if the thickness of the coating is more than 15 μm, the coating is not resistant to the internal stress of the coating itself, and cracks are likely to occur in the coating. Whether the alumina coating was continuous or not was evaluated by observing the cross section of the coating with a Scanning Electron Microscope (SEM).
In addition, in a high-temperature environment, it is preferable that the formation of the Cr — Mn spinel film be suppressed. Specifically, the mixture was heated at 900 ℃ for 20 hours in an atmosphere containing water vapor, and then heated in H2-CH4-CO2When the coating film is heated at 1100 ℃ for 96 hours in an atmosphere, the thickness of the coating film having a Cr-Mn spinel structure formed on the alumina coating film is preferably 5 μm or less.
If the thickness of the Cr — Mn spinel film exceeds 5 μm, a Cr-deficient layer is formed in the surface layer of the base material, and the TEE effect is suppressed as the service life increases.
3. Manufacturing method
As an example of the method for producing the austenitic heat-resistant alloy according to the present invention, a method for producing an alloy pipe will be described. The manufacturing method of the present embodiment includes a preparation step, a hot forging step, a hot working step, a cold working step, and a solution heat treatment step, which are described below. The solid solution heat treatment step may be followed by a scale removing step. Hereinafter, each step will be described.
[ preparation Process ]
Molten steel having the above chemical composition is produced. The molten steel is subjected to a known degassing treatment as required. The billet is manufactured by casting using molten steel. The material may be an ingot by an ingot casting method, or a cast slab such as a slab, a billet, or a bar billet by a continuous casting method.
[ Hot forging Process ]
The cast billet is subjected to hot forging to produce a cylindrical billet. In the hot forging, the reduction rate of the cross section defined by the formula (i) is 30% or more.
The reduction ratio of the cross section was 100 (cross section of billet after hot working/cross section of billet before hot forging) × 100 (%) · (i)
[ Hot working Process ]
The hot-forged cylindrical blank is subjected to hot working to produce an alloy pipe blank. For example, a through hole is formed in the center of a cylindrical blank by machining. The cylindrical billet having the through-hole formed therein is subjected to hot extrusion to produce an alloy shell. The alloy shell may be produced by piercing-rolling a cylindrical billet.
[ Cold working Process ]
The alloy shell after hot working is subjected to cold working to produce an intermediate material. The cold working is, for example, cold drawing.
The reduction rate of the cross section defined by the formula (ii) is 15% or more when cold working is performed.
Section reduction rate 100- (sectional area of cold-worked material/sectional area of material before cold working) × 100 (%) · (ii)
By performing cold working with a reduction in cross section of 15% or more, the structure of the base material is densified by recrystallization during heat treatment, and a more dense alumina coating can be formed.
[ solution Heat treatment Process ]
The produced intermediate material is subjected to a solution heat treatment. The carbides and precipitates contained in the intermediate material are solid-solved by the solution heat treatment.
The heat treatment temperature in the solution heat treatment is 1150-1280 ℃. If the heat treatment temperature is less than 1150 ℃, the carbide and the precipitate are not sufficiently dissolved in a solid state, and as a result, the corrosion resistance is deteriorated. On the other hand, if the heat treatment temperature is too high, the grain boundaries melt. The solution heat treatment time is 1 minute or more during which the carbide and the precipitate are dissolved in a solid solution.
[ Scale removal step ]
After the solution heat treatment step, shot blasting may be performed for the purpose of removing scale formed on the surface. Further, for the purpose of removing scale, pickling treatment may be performed. In this case, the substrate is immersed in hydrofluoric acid-nitric acid mixed with 5% hydrofluoric acid and 10% nitric acid at 20 to 40 ℃ for 2 to 10 minutes.
The austenitic heat-resistant alloy according to the present embodiment is produced by the above-described production method. Although the above description has been made of the method for producing an alloy pipe, a plate, a bar, a wire, and the like can be produced by the same production method.
The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.
Examples
Molten steels having chemical compositions shown in table 1 were produced using a vacuum melting furnace. A columnar ingot having an outer diameter of 120mm was produced using the molten steel. The ingot was subjected to hot forging with a reduction in section of 60% to produce a rectangular ingot. Then, the rectangular slab was subjected to hot rolling and cold rolling to produce a plate-like intermediate material having a thickness of 1.5 mm. The reduction in cross section in the cold rolling was 50%. Subsequently, the intermediate material was held at 1200 ℃ for 10 minutes, and then water-cooled to produce an alloy plate.
[ Table 1]
First, from a rectangular billet obtained by holding the rectangular billet at 1200 ℃ for 10 minutes and then water-cooling the rectangular billet, a round bar creep rupture test piece having a diameter of 6mm and a punctuation distance of 30mm as defined in JIS Z2241 (2011) was used, and a creep rupture test was performed under conditions of 1000 ℃ and 10 MPa. The test was carried out in accordance with JIS Z2271 (2010). The creep rupture time was rated as "no" when it was less than 2000 hours, good "when it reached 2000 to 3000 hours, and good" when it exceeded 3000 hours.
Next, 2 pieces of each of the alloy plate materials were prepared, and each of the prepared alloy plate materials was subjected to carburizing treatment as described below. For one, the implementation is in H2-CH4-CO2And (3) carburizing treatment (1 treatment of the material) by heating at 1100 ℃ for 96 hours in an atmosphere.
The carburized 1-time treated material was half-cut perpendicular to the rolling direction. For one half, the test piece for observation was prepared by filling the test piece in a resin and polishing the observation surface. Then, the kind, thickness, and morphology of the formed coating film were observed by SEM. Further, for the other half, the carburized surface was polished by #600 and then dry-hand polished to remove scale and the like on the surface.
For the other, is carried out at H2-CH4-CO2The above steps were repeated 5 times (5 times of treatment of the material) after carburizing treatment in which the material was heated at 1100 ℃ for 96 hours in the atmosphere and then heating at 900 ℃ for 20 hours in the atmosphere containing water vapor.
Then, 4 layers of analysis chips were collected at a distance of 0.5mm from the surface of each of the 1 st and 5 th scale-treated materials after descaling, and the C concentration was measured for the analysis chips by a high-frequency combustion infrared absorption method. The amount of C entering is determined by subtracting the C concentration contained in the material from the above concentration. In the present invention, when the amount of the introduced C is 0.3% or less, the carburization resistance is evaluated to be excellent.
The above observation results and test results are summarized in table 2.
[ Table 2]
TABLE 2
Referring to table 2, since the chemical compositions of test nos. 1 to 13 satisfy the specification of the present invention, the formation of Cr — Mn spinel film is suppressed, and a good alumina film is formed. As a result, excellent carburization resistance was exhibited.
Among these, in the steels other than the steels of test nos. 4, 7 and 11, since the Mn content was reduced to 0.35% or less, no Cr — Mn spinel coating was observed, and the carburization resistance was further improved. In addition, in test nos. 3, 5, 7, 9, 10 and 13 containing at least one of B and W, the creep strength was more excellent than the case where they were not contained or the content thereof was insufficient.
In contrast, test nos. 14 to 20 are comparative examples which do not satisfy the specification of the present invention. Specifically, test No. 14 had a high C content and test No. 17 had a low Nb content, and therefore the creep strength was poor.
In addition, in test nos. 14 to 16, 19 and 20, since the content of Mn was high, a Cr — Mn spinel film was formed, and a Cr-deficient layer was formed on the surface layer of the base material, and therefore, the TEE effect was suppressed, and the formation of an alumina film was inhibited. In addition, in test nos. 16 and 18, the Al content was low, and therefore, the formation of the alumina coating film became insufficient.
As a result, in test nos. 14, 15 and 18 to 20, the formation of the alumina coating was discontinued, and in test No. 16, the alumina coating was not formed. Therefore, in these comparative examples, both the 1 st treatment material and the 5 th treatment material exhibited poor carburization resistance.
Claims (4)
1. An austenitic heat-resistant alloy having a chemical composition comprising, in mass%
C：0.03～0.25％、
Si：0.01～2.0％、
Mn：0.10～0.50％、
P: less than 0.030%,
S: less than 0.010%,
Cr：13.0～30.0％、
Ni：25.0～45.0％、
Al：2.5～4.5％、
Nb：0.05～2.00％、
N: less than 0.05 percent of,
Ti：0～0.20％、
W：0～6.0％、
Mo：0～4.0％、
Zr：0～0.10％、
B：0～0.0100％、
Cu：0～5.0％、
REM：0～0.10％、
Ca：0～0.050％、
Mg：0～0.050％、
And the balance: fe and impurities.
2. The austenitic heat resistant alloy of claim 1, wherein,
the chemical composition contains, in mass%, B: 0.0010-0.0100%.
3. The austenitic heat resistant alloy of claim 1 or 2, wherein,
heating at 900 deg.C for 20 hr in an atmosphere containing water vapor, followed by H2-CH4-CO2And heating the alloy at 1100 ℃ for 96 hours in an atmosphere to form a continuous alumina coating having a thickness of 0.5 to 15 [ mu ] m on the surface of the alloy.
4. The austenitic heat resistant alloy of claim 3, wherein,
heating at 900 deg.C for 20 hr in an atmosphere containing water vapor, followed by H2-CH4-CO2When the aluminum oxide film is heated at 1100 ℃ for 96 hours in an atmosphere, the thickness of the Cr-Mn spinel structure-containing film formed on the aluminum oxide film is 5 [ mu ] m or less.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017-253350 | 2017-12-28 | ||
| JP2017253350 | 2017-12-28 | ||
| PCT/JP2018/048342 WO2019131954A1 (en) | 2017-12-28 | 2018-12-27 | Austenite-based heat-resistant alloy |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111542639A true CN111542639A (en) | 2020-08-14 |
Family
ID=67063820
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201880084052.8A Withdrawn CN111542639A (en) | 2017-12-28 | 2018-12-27 | Austenitic heat-resistant alloy |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US20210062314A1 (en) |
| EP (1) | EP3733913A1 (en) |
| JP (1) | JPWO2019131954A1 (en) |
| CN (1) | CN111542639A (en) |
| WO (1) | WO2019131954A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA3085156A1 (en) * | 2018-01-10 | 2019-07-18 | Nippon Steel Corporation | Austenitic heat resistant alloy and method for producing the same |
| CN111566257B (en) * | 2018-01-10 | 2023-05-30 | 日本制铁株式会社 | Austenitic heat-resistant alloy, method for producing same, and austenitic heat-resistant alloy material |
| JP7415144B2 (en) | 2019-12-04 | 2024-01-17 | 日本製鉄株式会社 | austenitic stainless steel |
| JP2021127517A (en) * | 2020-02-14 | 2021-09-02 | 日本製鉄株式会社 | Austenitic stainless steel material |
| CN113981328B (en) * | 2021-09-18 | 2022-05-24 | 四川大学 | Aluminum-containing austenitic stainless steel with surface spontaneously and continuously generating aluminum oxide film and preparation method thereof |
| GB2611082A (en) * | 2021-09-27 | 2023-03-29 | Alloyed Ltd | A stainless steel |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07331390A (en) * | 1994-06-08 | 1995-12-19 | Sumitomo Metal Ind Ltd | High chromium austenitic heat resistant alloy |
| JPH10140296A (en) * | 1996-09-11 | 1998-05-26 | Sumitomo Metal Ind Ltd | Al-containing austenitic stainless steel excellent in hot workability |
| CN1576381A (en) * | 2003-07-17 | 2005-02-09 | 住友金属工业株式会社 | Stainless steel and stainless steel pipe having resistance to carburization and coking |
| CN102308015A (en) * | 2009-02-16 | 2012-01-04 | 住友金属工业株式会社 | Method for manufacturing metal pipe |
| CN103774056A (en) * | 2014-01-13 | 2014-05-07 | 江苏大学 | Novel austenitic stainless steel for ultra (super) critical coal-fired unit |
| CN105154793A (en) * | 2015-09-25 | 2015-12-16 | 安阳工学院 | High-strength high-corrosion-resistance double-phase heat resistant steel |
| WO2017119415A1 (en) * | 2016-01-05 | 2017-07-13 | 新日鐵住金株式会社 | Austenitic heat-resistant alloy and method for manufacturing same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09243284A (en) * | 1996-03-12 | 1997-09-19 | Kubota Corp | Heat exchanging pipe with internal surface projection |
| JP3644532B2 (en) | 1999-07-27 | 2005-04-27 | 住友金属工業株式会社 | Ni-base heat-resistant alloy with excellent hot workability, weldability and carburization resistance |
| JP6434306B2 (en) * | 2014-12-26 | 2018-12-05 | 株式会社クボタ | Heat resistant tube with an alumina barrier layer |
-
2018
- 2018-12-27 CN CN201880084052.8A patent/CN111542639A/en not_active Withdrawn
- 2018-12-27 EP EP18897323.4A patent/EP3733913A1/en not_active Withdrawn
- 2018-12-27 US US16/958,550 patent/US20210062314A1/en not_active Abandoned
- 2018-12-27 WO PCT/JP2018/048342 patent/WO2019131954A1/en unknown
- 2018-12-27 JP JP2019562475A patent/JPWO2019131954A1/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07331390A (en) * | 1994-06-08 | 1995-12-19 | Sumitomo Metal Ind Ltd | High chromium austenitic heat resistant alloy |
| JPH10140296A (en) * | 1996-09-11 | 1998-05-26 | Sumitomo Metal Ind Ltd | Al-containing austenitic stainless steel excellent in hot workability |
| CN1576381A (en) * | 2003-07-17 | 2005-02-09 | 住友金属工业株式会社 | Stainless steel and stainless steel pipe having resistance to carburization and coking |
| CN102308015A (en) * | 2009-02-16 | 2012-01-04 | 住友金属工业株式会社 | Method for manufacturing metal pipe |
| CN103774056A (en) * | 2014-01-13 | 2014-05-07 | 江苏大学 | Novel austenitic stainless steel for ultra (super) critical coal-fired unit |
| CN105154793A (en) * | 2015-09-25 | 2015-12-16 | 安阳工学院 | High-strength high-corrosion-resistance double-phase heat resistant steel |
| WO2017119415A1 (en) * | 2016-01-05 | 2017-07-13 | 新日鐵住金株式会社 | Austenitic heat-resistant alloy and method for manufacturing same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2019131954A1 (en) | 2020-11-19 |
| EP3733913A1 (en) | 2020-11-04 |
| US20210062314A1 (en) | 2021-03-04 |
| WO2019131954A1 (en) | 2019-07-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3391989B1 (en) | Welding material for ferrite heat-resistant steel, welding joint for ferrite heat-resistant steel, and method for producing welding joint for ferrite heat-resistant steel | |
| JP6004140B1 (en) | Austenitic stainless steel and manufacturing method thereof | |
| CN111542639A (en) | Austenitic heat-resistant alloy | |
| JP5896089B1 (en) | Austenitic stainless steel and manufacturing method thereof | |
| JP5880788B2 (en) | High strength oil well steel and oil well pipe | |
| JP6614347B2 (en) | Austenitic stainless steel | |
| WO2006109664A1 (en) | Ferritic heat-resistant steel | |
| JP2003268503A (en) | Austenitic stainless steel tube having excellent water vapor oxidation resistance and production method thereof | |
| JP5633489B2 (en) | Ni-base alloy and method for producing Ni-base alloy | |
| JPWO2018066579A1 (en) | NiCrFe alloy | |
| JP6805574B2 (en) | Austenitic heat resistant steel and austenitic heat transfer member | |
| JP6547599B2 (en) | Austenitic heat resistant steel | |
| JP2011195880A (en) | Austenitic stainless steel | |
| RU108037U1 (en) | PRODUCT FROM CORROSION-RESISTANT ALLOY BASED ON Fe-Cr-Ni | |
| JP2021127517A (en) | Austenitic stainless steel material | |
| KR20080070726A (en) | Heat-resistant alloy capable of depositing fine ti-nb-cr carbide or ti-nb-zr-cr carbide | |
| JP5782753B2 (en) | Manufacturing method of high Cr high Ni alloy tube and high Cr high Ni alloy | |
| WO2016052271A1 (en) | Steel material, and oil-well steel pipe for expansion | |
| JP6627662B2 (en) | Austenitic stainless steel | |
| JP6690499B2 (en) | Austenitic stainless steel sheet and method for producing the same | |
| JP7131318B2 (en) | austenitic stainless steel | |
| JP2021113354A (en) | Austenitic stainless steel | |
| JP2021195602A (en) | Low-alloy heat-resistant steel | |
| JPWO2018066709A1 (en) | Nickel material and method of manufacturing nickel material |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20200814 |