WO2017119415A1 - Austenitic heat-resistant alloy and method for manufacturing same - Google Patents

Austenitic heat-resistant alloy and method for manufacturing same Download PDF

Info

Publication number
WO2017119415A1
WO2017119415A1 PCT/JP2017/000056 JP2017000056W WO2017119415A1 WO 2017119415 A1 WO2017119415 A1 WO 2017119415A1 JP 2017000056 W JP2017000056 W JP 2017000056W WO 2017119415 A1 WO2017119415 A1 WO 2017119415A1
Authority
WO
WIPO (PCT)
Prior art keywords
less
resistant alloy
content
heat
austenitic heat
Prior art date
Application number
PCT/JP2017/000056
Other languages
French (fr)
Japanese (ja)
Inventor
礼文 河内
真木　純
西山　佳孝
Original Assignee
新日鐵住金株式会社
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by 新日鐵住金株式会社 filed Critical 新日鐵住金株式会社
Priority to US16/067,751 priority Critical patent/US20190010565A1/en
Priority to CN201780005402.2A priority patent/CN108474072A/en
Priority to CA3009770A priority patent/CA3009770A1/en
Priority to EP17735952.8A priority patent/EP3401415A4/en
Priority to KR1020187020362A priority patent/KR102090201B1/en
Priority to JP2017560386A priority patent/JP6493566B2/en
Priority to SG11201805206PA priority patent/SG11201805206PA/en
Publication of WO2017119415A1 publication Critical patent/WO2017119415A1/en

Links

Classifications

    • 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
    • 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
    • C21D6/02—Hardening by precipitation
    • 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
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
    • C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/058—Alloys based on nickel or cobalt based on nickel with chromium without Mo and W
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C22C30/02—Alloys containing less than 50% by weight of each constituent containing 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
    • C22C38/001—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
    • C22C38/02—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
    • C22C38/04—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
    • 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
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite

Definitions

  • the present invention relates to a heat resistant alloy and a method for producing the same, and more particularly to an austenitic heat resistant alloy and a method for producing the same.
  • 18-8 stainless steel is used as heat resistant steel in equipment such as boilers and chemical plants used in high temperature environments.
  • 18-8 stainless steel is an austenitic stainless steel containing about 18% Cr and about 8% Ni, and examples thereof include SUS304H, SUS316H, SUS321H, and SUS347H in the JIS standard.
  • Heat resistant materials with improved corrosion resistance have been proposed in, for example, Japanese Patent Application Laid-Open No. 02-115348 (Patent Document 1) and Japanese Patent Application Laid-Open No. 07-316751 (Patent Document 2). Since these Al alloys have a high Al content, an Al 2 O 3 film is formed on the surface at high temperatures during use. This coating provides high corrosion resistance.
  • the heat resistant alloys disclosed in Patent Documents 1 and 2 described above may have a low creep strength in a high temperature environment of 700 ° C. or higher.
  • heat-resistant material having high creep strength in a high temperature environment of 700 ° C. or higher
  • a heat-resistant alloy containing Ni and Co and a ⁇ ′ phase (Ni 3 Al) as a strengthening phase has been developed.
  • Such heat-resistant alloys are, for example, Ni-base alloys such as Alloys 617, 263, and 740.
  • the alloy raw materials for these heat-resistant alloys are expensive. Furthermore, since the processability is low, the manufacturing cost is also increased.
  • Patent Document 3 Japanese Patent Laid-Open No. 2014-43621
  • Patent Document 4 Japanese Patent Laid-Open No. 2013-227644
  • Patent Document 3 describes that the austenitic heat-resistant alloy has excellent high-temperature strength and toughness due to precipitation strengthening of Laves phase and ⁇ ′ phase.
  • the f3 represented has a chemical composition of 0.5 to 5.0.
  • Patent Document 4 describes that the austenitic heat-resistant alloy has excellent high-
  • An object of the present invention is to provide an austenitic heat resistant alloy having high creep strength and high toughness even in a high temperature environment.
  • the austenitic heat-resistant alloy according to the present embodiment is, in mass%, C: 0.03 to less than 0.25%, Si: 0.01 to 2.0%, Mn: 2.0% or less, Cr: 10 to 30 %, Ni: more than 25 to 45%, Al: more than 2.5 to less than 4.5%, Nb: 0.2 to 3.5%, N: 0.025% or less, Ti: 0 to 0.2 %: W: 0-6%, Mo: 0-4%, Zr: 0-0.1%, B: 0-0.01%, Cu: 0-5%, Rare earth elements: 0-0.1 %, Ca: 0 to 0.05%, and Mg: 0 to 0.05%, the balance is made of Fe and impurities, and P and S in the impurities are each P: 0.04% or less, And S: having a chemical composition of 0.01% or less.
  • the total volume ratio of precipitates having an equivalent circle diameter of 6 ⁇ m or more is 5% or less.
  • the precipitate is, for example, carbide, nit
  • the austenitic heat-resistant alloy according to the present embodiment has long-term high-temperature strength and excellent toughness even in a high-temperature environment.
  • the present inventors investigated and examined the creep strength and toughness of the austenitic heat resistant alloy in a high temperature environment of 700 ° C. or higher (hereinafter simply referred to as a high temperature environment), and obtained the following knowledge.
  • a heat-resistant alloy containing a Laves phase or a ⁇ ′ phase such as Ni 3 Al has a high creep strength in a high-temperature environment.
  • these precipitated phases become coarse when used for a long time in a high temperature environment, the creep strength and toughness of the heat-resistant alloy are lowered.
  • a precipitate such as carbide, nitride, NiAl, ⁇ -Cr, etc. can be finely dispersed while using a heat-resistant alloy in a high-temperature environment, high creep strength and high toughness can be maintained even after long-term use.
  • These precipitates increase the grain boundary strength by covering the crystal grain boundaries. Furthermore, if these precipitates precipitate in the grains, the deformation resistance of the heat-resistant alloy increases and the creep strength increases.
  • the structure of the heat-resistant alloy before use is controlled as follows.
  • the total volume ratio of coarse precipitates in the heat-resistant alloy is preferably as low as possible.
  • the total volume fraction of precipitates having an equivalent circle diameter of 6 ⁇ m or more (hereinafter referred to as coarse precipitates) is 5% or less in the structure of the heat-resistant alloy, a sufficient amount can be obtained while using the heat-resistant alloy in a high-temperature environment. Fine precipitates can be deposited, and high creep strength and toughness can be obtained.
  • the C content in the heat-resistant alloy is set to less than 0.25%. Furthermore, the cross-section reduction rate during hot forging is set to 30% or more. In this case, coarse precipitates are uniformly dispersed by hot forging. Therefore, the precipitate can be dissolved in the solution treatment in the subsequent step, and the total volume ratio of the coarse precipitate becomes 5% or less.
  • the austenitic heat-resistant alloy according to the present embodiment completed based on the above knowledge is mass%, C: 0.03 to less than 0.25%, Si: 0.01 to 2.0%, Mn: 2.0. %: Cr: 10 to less than 30%, Ni: more than 25 to 45%, Al: more than 2.5 to less than 4.5%, Nb: 0.2 to 3.5%, N: 0.025% or less Ti: 0 to less than 0.2%, W: 0 to 6%, Mo: 0 to 4%, Zr: 0 to 0.1%, B: 0 to 0.01%, Cu: 0 to 5%, Rare earth elements: 0 to 0.1%, Ca: 0 to 0.05%, and Mg: 0 to 0.05%, the balance is composed of Fe and impurities, and P and S in the impurities are respectively It has a chemical composition of P: 0.04% or less and S: 0.01% or less. In the structure, the total volume ratio of precipitates having an equivalent circle diameter of 6 ⁇ m or more is 5% or less.
  • the chemical composition is, by mass, Ti: 0.005 to less than 0.2%, W: 0.005 to 6%, Mo: 0.005 to 4%, Zr: 0.0005 to 0.1%, And B: One or more selected from the group consisting of 0.0005 to 0.01% may be contained.
  • the chemical composition may contain one or more selected from the group consisting of Cu: 0.05 to 5% and rare earth elements: 0.0005 to 0.1% by mass.
  • the chemical composition may contain at least one selected from the group consisting of Ca: 0.0005 to 0.05% and Mg: 0.0005 to 0.05% by mass.
  • the method for producing the austenitic heat-resistant alloy includes a step of performing hot forging at a cross-section reduction rate of 30% or more on a cast material having the above-described chemical composition, and heating the material after hot forging.
  • the austenitic heat-resistant alloy according to the present embodiment is, for example, an alloy tube.
  • the chemical composition of the austenitic heat-resistant alloy contains the following elements.
  • Carbon (C) forms a carbide and increases the creep strength. Specifically, during use in a high temperature environment, C combines with an alloy element within a grain boundary and within the grains to form fine carbides. Fine carbides increase deformation resistance and increase creep strength. If the C content is too low, this effect cannot be obtained. On the other hand, if the C content is too high, many coarse eutectic carbides are formed in the solidified structure after casting of the heat-resistant alloy. Since the eutectic carbide remains coarse in the structure even after the solution treatment, the toughness of the heat-resistant alloy is lowered.
  • the C content is 0.03 to less than 0.25%.
  • the minimum with preferable C content is 0.05%, More preferably, it is 0.08%.
  • the upper limit with preferable C content is 0.23%, More preferably, it is 0.20%.
  • Si 0.01 to 2.0% Silicon (Si) deoxidizes the heat-resistant alloy. Si further enhances the corrosion resistance (oxidation resistance and steam oxidation resistance) of the heat-resistant alloy. Si is an element inevitably contained, but the content of Si may be as small as possible when deoxidation can be sufficiently performed with other elements. On the other hand, if the Si content is too high, the hot workability decreases. Therefore, the Si content is 0.01 to 2.0%. The minimum with preferable Si content is 0.02%, More preferably, it is 0.03%. The upper limit with preferable Si content is 1.0%.
  • Mn 2.0% or less Manganese (Mn) is unavoidably contained. Mn combines with S contained in the heat-resistant alloy to form MnS and enhances the hot workability of the heat-resistant alloy. However, if the Mn content is too high, the heat-resistant alloy becomes too hard and the hot workability and weldability deteriorate. Therefore, the Mn content is 2.0% or less. The minimum with preferable Mn content is 0.1%, More preferably, it is 0.2%. The upper limit with preferable Mn content is 1.2%.
  • Chromium (Cr) improves the corrosion resistance (oxidation resistance, steam oxidation resistance, etc.) of the heat-resistant alloy in a high-temperature environment. Further, Cr is finely precipitated as ⁇ -Cr during use in a high temperature environment, thereby increasing the creep strength. If the Cr content is too low, these effects cannot be obtained. On the other hand, if the Cr content is too high, the stability of the structure decreases and the creep strength decreases. Therefore, the Cr content is 10 to less than 30%.
  • the minimum with preferable Cr content is 11%, More preferably, it is 12%.
  • the upper limit with preferable Cr content is 28%, More preferably, it is 26%.
  • Ni Over 25-45% Nickel (Ni) stabilizes austenite. Ni further enhances the corrosion resistance of the heat-resistant alloy. If the Ni content is too low, these effects cannot be obtained. On the other hand, if the Ni content is too high, these effects are not only saturated, but hot workability is reduced. If the Ni content is too high, the raw material cost further increases. Therefore, the Ni content is more than 25 to 45%.
  • the minimum with preferable Ni content is 26%, More preferably, it is 28%.
  • the upper limit with preferable Ni content is 44%, More preferably, it is 42%.
  • Al more than 2.5 to less than 4.5%
  • Aluminum (Al) is combined with Ni to form fine NiAl during use in a high temperature environment, and increases the creep strength. Further, Al enhances corrosion resistance in a high temperature environment of 1000 ° C. or higher. 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 more than 2.5 to less than 4.5%.
  • the minimum with preferable Al content is 2.55%, More preferably, it is 2.6%.
  • the upper limit with preferable Al content is 4.4%, More preferably, it is 4.2%.
  • the Al content means the total amount of Al contained in the steel material.
  • Niobium (Nb) forms a Laves phase and a Ni 3 Nb phase as precipitation strengthening phases, and precipitates and strengthens the crystal grain boundaries and crystal grains, thereby increasing the creep strength of the heat-resistant alloy. If the Nb content is too low, the above effect cannot be obtained. On the other hand, if the Nb content is too high, the Laves phase and the Ni 3 Nb phase are excessively generated, and the toughness and hot workability of the alloy are lowered. If the Nb content is too high, the toughness after aging for a long time further decreases. Therefore, the Nb content is 0.2 to 3.5%. The minimum with preferable Nb content is 0.35%, More preferably, it is 0.5%. The upper limit with preferable Nb content is less than 3.2%, More preferably, it is 3.0%.
  • N 0.025% or less Nitrogen (N) stabilizes austenite and is inevitably contained in a normal dissolution method. In addition, during use in a high temperature environment, N combines with the alloy element in the grain boundaries and grains to form fine nitrides. Fine nitride increases deformation resistance and increases creep strength. However, if the N content is too high, coarse nitrides that remain undissolved even after the solution treatment are formed and the toughness of the alloy is lowered. Therefore, the N content is 0.025% or less. The upper limit of the preferable N content is 0.02%, more preferably 0.01%.
  • P 0.04% or less Phosphorus (P) is an impurity. P decreases the weldability and hot workability of the heat-resistant alloy. Therefore, the P content is 0.04% or less. The upper limit with preferable P content is 0.03%. The P content is preferably as low as possible.
  • S 0.01% or less Sulfur (S) is an impurity. S decreases the weldability and hot workability of the heat-resistant alloy. Therefore, the S content is 0.01% or less. The upper limit with preferable S content is 0.008%. The S content is preferably as low as possible.
  • the balance of the chemical composition of the austenitic heat-resistant alloy of this embodiment is composed of Fe and impurities.
  • the impurities are those mixed from the ore, scrap, or production environment as raw materials when industrially producing austenitic heat-resistant alloys, and are allowed within a range that does not adversely affect the present invention. Means what will be done.
  • the chemical composition of the austenitic heat-resistant alloy described above may further contain one or more selected from the group consisting of Ti, W, Mo, Zr and B, instead of a part of Fe. All of these elements are optional elements and increase the creep strength.
  • Titanium (Ti) is an optional element and may not be contained. When it is contained, a Laves phase and a Ni 3 Ti phase that are precipitation strengthening phases are formed, and the creep strength is increased by precipitation strengthening. However, if the Ti content is too high, the Laves phase and the Ni 3 Ti phase are excessively generated, and the hot ductility and hot workability are reduced. If the Ti content is too high, the toughness after aging for a long time further decreases. Therefore, the Ti content is 0 to less than 0.2%. The minimum with preferable Ti content is 0.005%, More preferably, it is 0.01%. The upper limit with preferable Ti content is 0.15%, More preferably, it is 0.1%.
  • W 0-6% Tungsten (W) is an optional element and may not be contained. When contained, it dissolves in the austenite of the matrix (matrix), and increases the creep strength by solid solution strengthening. Further, W forms a Laves phase in the crystal grain boundaries and in the crystal grains, and increases the creep strength by precipitation strengthening. However, if there is too much W content, a Laves phase will be generated excessively and hot ductility, hot workability, and toughness will fall. Accordingly, the W content is 0 to 6%.
  • the minimum with preferable W content is 0.005%, More preferably, it is 0.01%.
  • the upper limit with preferable content of W is 5.5%, More preferably, it is 5%.
  • Mo 0-4% Molybdenum (Mo) is an optional element and may not be contained. When contained, it dissolves in the austenite of the parent phase and increases the creep strength by solid solution strengthening. Mo further forms a Laves phase in the grain boundaries and in the crystal grains, and increases the creep strength by precipitation strengthening. However, if the Mo content is too high, the Laves phase is excessively generated and the hot ductility, hot workability, and toughness are reduced. Therefore, the Mo content is 0 to 4%. The minimum with preferable Mo content is 0.005%, More preferably, it is 0.01%. The upper limit with preferable Mo content is 3.5%, More preferably, it is 3%.
  • Zr 0 to 0.1%
  • Zirconium (Zr) is an optional element and may not be contained. When contained, Zr increases creep strength by grain boundary strengthening. However, if the Zr content is too high, the weldability and hot workability of the heat-resistant alloy are lowered. Therefore, the Zr content is 0 to 0.1%.
  • the minimum with preferable Zr is 0.0005%, More preferably, it is 0.001%.
  • the upper limit with preferable Zr content is 0.06%.
  • B 0 to 0.01%
  • Boron (B) is an optional element and may not be contained. When contained, the creep strength is increased by grain boundary strengthening. However, if the B content is too high, weldability decreases. Therefore, the B content is 0 to 0.01%.
  • a preferable lower limit of B is 0.0005%, and more preferably 0.001%. The upper limit with preferable B content is 0.005%.
  • the chemical composition of the austenitic heat-resistant alloy described above may further contain one or more selected from the group consisting of Cu and rare earth elements instead of a part of Fe. Any of these elements is an arbitrary element and improves the corrosion resistance of the heat-resistant alloy.
  • Copper (Cu) is an optional element and may not be contained. When contained, it promotes the formation of an Al 2 O 3 film in the vicinity of the surface and enhances the corrosion resistance of the heat-resistant alloy. However, if the Cu content is too high, not only the effect is saturated, but also the high temperature ductility is lowered. Therefore, the Cu content is 0 to 5%.
  • the minimum with preferable Cu content is 0.05%, More preferably, it is 0.1%.
  • the upper limit with preferable Cu content is 4.8%, More preferably, it is 4.5%.
  • the rare earth element is an optional element and may not be contained. When it is contained, S is fixed as a sulfide to enhance hot workability. REM further forms oxides to increase corrosion resistance, creep strength, and creep ductility. However, if the REM content is too high, inclusions such as oxides increase, thereby reducing hot workability and weldability and increasing manufacturing costs. Therefore, the REM content is 0 to 0.1%.
  • the minimum with preferable REM content is 0.0005%, More preferably, it is 0.001%.
  • the upper limit with preferable REM content is 0.09%, More preferably, it is 0.08%.
  • REM is a general term for a total of 17 elements of Sc, Y, and a lanthanoid.
  • the REM content means the content of an element when the REM contained in the heat-resistant alloy is one of these elements.
  • the REM content means the total content of these elements.
  • REM is generally contained in misch metal. For this reason, for example, it may be added in the form of misch metal so that the REM content falls within the above range.
  • the chemical composition of the austenitic heat-resistant alloy described above may further include one or more selected from the group consisting of Ca and Mg instead of a part of Fe. Any of these elements is an arbitrary element and improves the hot workability of the heat-resistant alloy.
  • Ca 0 to 0.05%
  • Calcium (Ca) is an optional element and may not be contained. When it is contained, S is fixed as a sulfide to enhance hot workability. On the other hand, if the Ca content is too high, toughness, ductility and cleanliness will be reduced. Therefore, the Ca content is 0 to 0.05%.
  • a preferable lower limit of Ca is 0.0005%.
  • the upper limit with preferable Ca content is 0.01%.
  • Mg 0 to 0.05%
  • Magnesium (Mg) is an optional element and may not be contained. When contained, it fixes S as a sulfide and improves the hot workability of the heat-resistant alloy. On the other hand, if the Ca content is too high, toughness, ductility and cleanliness will be reduced. Therefore, the Ca content is 0 to 0.05%. A preferable lower limit of Ca is 0.0005%. The upper limit with preferable Ca content is 0.01%.
  • the austenitic heat-resistant alloy of the present embodiment precipitates fine precipitates during use in a high temperature environment, increases creep strength, and maintains toughness.
  • the precipitate include carbide, nitride, NiAl, and ⁇ -Cr. If the precipitate is coarse, creep strength and toughness are lowered. Therefore, in the heat-resistant alloy before use, it is preferable that there are few coarse precipitates.
  • the equivalent circle diameter means the diameter ( ⁇ m) when the area of the precipitate is converted into the area of the circle.
  • the total volume ratio of coarse precipitates in the structure of the austenitic heat-resistant alloy of this embodiment can be measured by the following method.
  • the austenitic heat-resistant alloy material is an alloy pipe
  • a test piece is sampled from the central thickness portion of the cross section perpendicular to the axial direction.
  • observation surface After polishing the cross section (observation surface) of the collected specimen, the observation surface is etched with a mixed acid solution of hydrochloric acid and nitric acid.
  • a scanning electron microscope (SEM) is used to photograph 10 fields of view on the observation surface to create an SEM image (reflection electron image). Each field of view is 100 ⁇ m ⁇ 100 ⁇ m.
  • the precipitates and the matrix have different contrasts.
  • the area of the precipitate specified by the difference in contrast is obtained, and the equivalent circle diameter of each precipitate is calculated. After the calculation, a precipitate (coarse precipitate) having an equivalent circle diameter of 6 ⁇ m or more is specified.
  • the shape of the austenitic heat-resistant alloy according to this embodiment is not particularly limited.
  • An austenitic heat-resistant alloy is, for example, an alloy tube.
  • Austenitic heat-resistant alloy pipes are used as boiler pipes and chemical plant reaction pipes.
  • the austenitic heat-resistant alloy may be a plate material, a rod material, or a wire material.
  • the manufacturing method of the present embodiment includes a step of preparing a material having the above-described chemical composition (preparation step), a step of hot forging the prepared material (hot forging step), and a hot forged material. And a step of producing an intermediate material by performing hot working (hot working step) and a step of performing solution heat treatment on the intermediate material (solution heat treatment step).
  • preparation step a step of preparing a material having the above-described chemical composition
  • hot forging step hot forging step
  • a hot forged material a step of producing an intermediate material by performing hot working (hot working step) and a step of performing solution heat treatment on the intermediate material (solution heat treatment step).
  • a molten steel having the above chemical composition is produced.
  • a well-known degassing process is implemented with respect to molten steel as needed.
  • a raw material is manufactured by casting using molten steel.
  • the material may be an ingot obtained by an ingot-making method or a slab such as a slab, bloom or billet obtained by a continuous casting method.
  • precipitates such as eutectic carbides are present in the structure of the material produced by casting. These precipitates are coarse, and there are many that have an equivalent circle diameter of 6 ⁇ m or more. Such coarse precipitates are difficult to dissolve in a solution treatment in a later step.
  • the cross-section reduction rate in the hot forging process is 30% or more, coarse precipitates are destroyed during hot forging and the size is reduced. For this reason, the precipitate is easily dissolved in the solution heat treatment in the subsequent step. As a result, the volume ratio of precipitates having an equivalent circle diameter of 6 ⁇ m or more is 5% or less.
  • the preferable cross-sectional reduction rate is 35% or more, and more preferably 40% or more.
  • the upper limit of the cross-section reduction rate is not particularly limited, it is 90% in consideration of productivity.
  • Hot working is performed on the hot-forged material (cylindrical material) to manufacture an alloy base tube that is an intermediate material.
  • a through hole is formed in the center of a cylindrical material by machining.
  • Hot extrusion is performed on the cylindrical material in which the through holes are formed, and an alloy base tube is manufactured.
  • a cylindrical raw material (intermediate material) may be manufactured by piercing and rolling a cylindrical material.
  • Cold working may be performed on the intermediate material after hot working.
  • the cold working is, for example, cold drawing or the like.
  • An intermediate material is manufactured by the above process.
  • Solution heat treatment process Solution heat treatment is performed on the manufactured intermediate material.
  • the precipitate in the intermediate material is dissolved by solution heat treatment.
  • the heat treatment temperature in the solution heat treatment is 1100 to 1250 ° C. If the heat treatment temperature is less than 1100 ° C., the precipitate is not sufficiently dissolved, and as a result, the volume fraction of the coarse precipitate exceeds 5%. On the other hand, if the heat treatment temperature is too high, the austenite grains are coarsened and the productivity is lowered.
  • the precipitate is sufficiently dissolved, and the total volume ratio of the coarse precipitate is 5% or less.
  • the solution heat treatment time is not particularly limited.
  • the solution heat treatment time is, for example, 1 minute to 1 hour.
  • pickling treatment may be performed for the purpose of removing scale formed on the surface.
  • pickling for example, a mixed acid solution of nitric acid and hydrochloric acid is used.
  • the pickling time is, for example, 30 to 60 minutes.
  • a blasting process using a projection material may be performed on the intermediate material after the pickling process.
  • blasting is performed on the inner surface of the alloy tube.
  • a processed layer is formed on the surface, and corrosion resistance (oxidation resistance and the like) is increased.
  • the austenitic heat-resistant alloy of this embodiment is manufactured by the above manufacturing method.
  • the manufacturing method of the alloy pipe was demonstrated above.
  • a cylindrical ingot (30 kg) having an outer diameter of 120 mm was manufactured using the molten steel.
  • the ingot was hot forged at a cross-sectional reduction rate shown in Table 2 to produce a rectangular material.
  • the rectangular material was hot-rolled and cold-rolled to produce a plate-like intermediate material having a thickness of 1.5 mm.
  • the intermediate material was subjected to a solution treatment for 10 minutes at the heat treatment temperature shown in Table 2. After holding for 10 minutes, the intermediate material was water-cooled to produce an alloy sheet.
  • Test results The test results are shown in Table 2.
  • the chemical compositions of Test No. 1 to Test No. 11 were appropriate, and the volume fraction of coarse precipitates was 5% or less.
  • the creep strength was 140 MPa or more, indicating an excellent creep strength.
  • the Charpy impact value was 40 J / cm 2 or more, and excellent toughness was exhibited even after long-term aging treatment.
  • test number 12 the C content was too high. Therefore, the volume ratio of the coarse precipitate exceeded 5%. As a result, the creep strength was less than 140 MPa, and the Charpy impact value was less than 40 J / cm 2 .
  • test number 17 the cross-sectional reduction rate during hot forging was less than 30%. Therefore, the total volume ratio of coarse precipitates exceeded 5%. As a result, the creep strength was less than 140 MPa, and the Charpy impact value was less than 40 J / cm 2 .
  • test number 18 the solution heat treatment temperature was less than 1100 ° C. Therefore, the total volume ratio of coarse precipitates exceeded 5%. As a result, the creep rupture strength was less than 140 MPa, and the Charpy impact value was less than 40 J / cm 2 .
  • the austenitic heat-resistant alloy of the present invention can be widely used in a high temperature environment of 700 ° C. or higher.
  • it is particularly suitable for use as an alloy pipe in a power generation boiler, a chemical industry plant or the like exposed to a high temperature environment of 700 ° C. or higher.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Heat Treatment Of Steel (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Abstract

Provided is an austenitic heat-resistant alloy having high creep strength and high toughness even in a high-temperature environment. This austenitic heat-resistant alloy has a chemical composition containing, in terms of mass%, 0.03 to less than 0.25% C, 0.01-2.0% Si, 2.0% or less of Mn, 10 to less than 30% Cr, more than 25% to 45% Ni, more than 2.5% to less than 4.5% Al, 0.2-3.5% Nb, and 0.025% or less of N, the remainder comprising Fe and unavoidable impurities, and P and S being 0.04% or less and 0.01% or less, respectively, of the impurities. The gross moment of precipitates 6 µm or larger in the structure of the austenitic heat-resistant alloy is 5% or less.

Description

オーステナイト系耐熱合金及びその製造方法Austenitic heat-resistant alloy and manufacturing method thereof
　本発明は耐熱合金及びその製造方法に関し、さらに詳しくは、オーステナイト系耐熱合金及びその製造方法に関する。 The present invention relates to a heat resistant alloy and a method for producing the same, and more particularly to an austenitic heat resistant alloy and a method for producing the same.
　従来、高温環境下で使用されるボイラ及び化学プラント等の設備では、耐熱鋼として、１８－８ステンレス鋼が使用されている。１８－８ステンレス鋼は、１８％程度のＣｒ及び８％程度のＮｉを含有するオーステナイト系ステンレス鋼であり、たとえば、ＪＩＳ規格でいうＳＵＳ３０４Ｈ、ＳＵＳ３１６Ｈ、ＳＵＳ３２１Ｈ、及びＳＵＳ３４７Ｈ等である。 Conventionally, 18-8 stainless steel is used as heat resistant steel in equipment such as boilers and chemical plants used in high temperature environments. 18-8 stainless steel is an austenitic stainless steel containing about 18% Cr and about 8% Ni, and examples thereof include SUS304H, SUS316H, SUS321H, and SUS347H in the JIS standard.
　近年、高温環境下における設備の使用条件が著しく過酷化し、１８－８ステンレス鋼よりもさらに高いクリープ強度が要求されている。最近ではさらに、火力発電用ボイラにおいて、６００℃程度であった従来の蒸気温度を７００℃以上に高める先進的超々臨界圧発電計画が推進されている。また、化学プラントにおいても、操業効率を高めるために、操業温度の上昇が計画されている。これらの高温環境で使用される鋼材には、高いクリープ強度とともに優れた耐食性も求められる。 In recent years, the use conditions of equipment in a high temperature environment have become extremely severe, and higher creep strength is required than 18-8 stainless steel. Recently, an advanced ultra-supercritical power generation program has been promoted to raise the steam temperature of about 600 ° C. to 700 ° C. or higher in a boiler for thermal power generation. Also in the chemical plant, in order to increase the operation efficiency, an increase in the operation temperature is planned. Steel materials used in these high-temperature environments are required to have excellent creep resistance as well as high creep strength.
　耐食性を高めた耐熱材料は、たとえば、特開平０２－１１５３４８号公報（特許文献１）及び特開平０７－３１６７５１号公報（特許文献２）に提案されている。これらの耐熱合金ではＡｌ含有量が高いため、使用中、高温域で、表面にＡｌ2Ｏ3皮膜が形成される。この皮膜により、高い耐食性が得られる。 Heat resistant materials with improved corrosion resistance have been proposed in, for example, Japanese Patent Application Laid-Open No. 02-115348 (Patent Document 1) and Japanese Patent Application Laid-Open No. 07-316751 (Patent Document 2). Since these Al alloys have a high Al content, an Al 2 O 3 film is formed on the surface at high temperatures during use. This coating provides high corrosion resistance.
　しかしながら、上述の特許文献１及び２に開示された耐熱合金では、７００℃以上の高温環境においてクリープ強度が低い場合がある。 However, the heat resistant alloys disclosed in Patent Documents 1 and 2 described above may have a low creep strength in a high temperature environment of 700 ° C. or higher.
　７００℃以上の高温環境で高いクリープ強度を有する耐熱材料として、Ｎｉ及びＣｏを含有し、強化相としてγ’相（Ｎｉ3Ａｌ）を含有する耐熱合金が開発されている。このような耐熱合金はたとえば、Ｎｉ基合金のＡｌｌｏｙ６１７、２６３、及び７４０等である。しかしながら、これらの耐熱合金の合金原料は高価である。さらに、加工性が低いため、製造コストも高くなる。 As a heat-resistant material having high creep strength in a high temperature environment of 700 ° C. or higher, a heat-resistant alloy containing Ni and Co and a γ ′ phase (Ni 3 Al) as a strengthening phase has been developed. Such heat-resistant alloys are, for example, Ni-base alloys such as Alloys 617, 263, and 740. However, the alloy raw materials for these heat-resistant alloys are expensive. Furthermore, since the processability is low, the manufacturing cost is also increased.
　そこで、上記Ｎｉ基合金よりも安価であり、かつ、クリープ強度に優れた耐熱合金が特開２０１４－４３６２１号公報（特許文献３）及び特開２０１３－２２７６４４号公報（特許文献４）に提案されている。 Therefore, a heat-resistant alloy that is less expensive than the Ni-based alloy and has excellent creep strength is proposed in Japanese Patent Laid-Open No. 2014-43621 (Patent Document 3) and Japanese Patent Laid-Open No. 2013-227644 (Patent Document 4). ing.
　特許文献３に開示されたオーステナイト系耐熱合金は、質量％で、Ｃ：０．０２％未満、Ｓｉ：２％以下、Ｍｎ：２％以下、Ｃｒ：１５～２６％、Ｎｉ：２０～３５％、Ａｌ：０．３％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下及びＮ：０．０５％以下を含むとともに、Ｔｉ：３．０％以下（０％を含む）、Ｖ：３．０％以下（０％を含む）、Ｎｂ：２．３％未満（０％を含む）及びＴａ：２．０％以下（０％を含む）から選択される１種以上を含み、かつｆ１＝２Ｔｉ＋２Ｖ＋Ｎｂ＋（１／２）Ｔａで表されるｆ１が１．５～６．０を満たし、残部はＦｅ及び不純物からなる化学組成を有する。上記オーステナイト系耐熱合金は、ラーベス相及びγ’相の析出強化により優れた高温強度及び靭性を有する、と特許文献３には記載されている。 The austenitic heat-resistant alloy disclosed in Patent Document 3 is in mass%, C: less than 0.02%, Si: 2% or less, Mn: 2% or less, Cr: 15-26%, Ni: 20-35% Al: 0.3% or less, P: 0.04% or less, S: 0.01% or less and N: 0.05% or less, Ti: 3.0% or less (including 0%), Including one or more selected from V: 3.0% or less (including 0%), Nb: less than 2.3% (including 0%), and Ta: 2.0% or less (including 0%) F1 represented by f1 = 2Ti + 2V + Nb + (1/2) Ta satisfies 1.5 to 6.0, and the remainder has a chemical composition composed of Fe and impurities. Patent Document 3 describes that the austenitic heat-resistant alloy has excellent high-temperature strength and toughness due to precipitation strengthening of Laves phase and γ ′ phase.
　特許文献４に開示されたオーステナイト系耐熱合金は、質量％で、Ｃ：０．０２％未満、Ｓｉ：０．０１～２％、Ｍｎ：２％以下、Ｃｒ：２０％以上２８％未満、Ｎｉ：３５％を超えて５０％以下、Ｗ：２．０～７．０％、Ｍｏ：２．５％未満（０％を含む）、Ｎｂ：２．５％未満（０％を含む）、Ｔｉ：３．０％未満（０％を含む）、Ａｌ：０．３％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下及びＮ：０．０５％以下を含有し、残部はＦｅおよび不純物からなり、さらに、ｆ１＝１／２Ｗ＋Ｍｏで表されるｆ１が１．０～５．０、ｆ２＝１／２Ｗ＋Ｍｏ＋Ｎｂ＋２Ｔｉで表されるｆ２が２．０～８．０及びｆ３＝Ｎｂ＋２Ｔｉで表されるｆ３が０．５～５．０である化学組成を有する。上記オーステナイト系耐熱合金は、ラーベス相及びγ’相の析出強化により優れた高温強度及び靭性を有する、と特許文献４には記載されている。 The austenitic heat-resistant alloy disclosed in Patent Document 4 is, in mass%, C: less than 0.02%, Si: 0.01-2%, Mn: 2% or less, Cr: 20% or more and less than 28%, Ni : More than 35% to 50% or less, W: 2.0 to 7.0%, Mo: less than 2.5% (including 0%), Nb: less than 2.5% (including 0%), Ti : Less than 3.0% (including 0%), Al: 0.3% or less, P: 0.04% or less, S: 0.01% or less and N: 0.05% or less, the balance being Fe1 and impurities, and f1 represented by f1 = 1 / 2W + Mo is 1.0 to 5.0, f2 represented by f2 = 1 / 2W + Mo + Nb + 2Ti is 2.0 to 8.0, and f3 = Nb + 2Ti. The f3 represented has a chemical composition of 0.5 to 5.0. Patent Document 4 describes that the austenitic heat-resistant alloy has excellent high-temperature strength and toughness due to precipitation strengthening of Laves phase and γ ′ phase.
特開平０２－１１５３４８号公報Japanese Patent Laid-Open No. 02-115348 特開平０７－３１６７５１号公報Japanese Patent Laid-Open No. 07-316751 特開２０１４－４３６２１号公報JP 2014-43621 A 特開２０１３－２２７６４４号公報JP 2013-227644 A
　しかしながら、特許文献３及び４の耐熱合金のように、ラーベス相及びγ’相による強化機構を利用した合金の場合、長時間時効後のクリープ強度及び靭性が低下する場合がある。 However, in the case of an alloy that uses a strengthening mechanism based on the Laves phase and the γ 'phase, such as the heat resistant alloys of Patent Documents 3 and 4, the creep strength and toughness after aging for a long time may decrease.
　本発明の目的は、高温環境においても、高いクリープ強度及び高い靭性を有するオーステナイト系耐熱合金を提供することである。 An object of the present invention is to provide an austenitic heat resistant alloy having high creep strength and high toughness even in a high temperature environment.
　本実施形態によるオーステナイト系耐熱合金は、質量％で、Ｃ：０．０３～０．２５％未満、Ｓｉ：０．０１～２．０％、Ｍｎ：２．０％以下、Ｃｒ：１０～３０％未満、Ｎｉ：２５超～４５％、Ａｌ：２．５超～４．５％未満、Ｎｂ：０．２～３．５％、Ｎ：０．０２５％以下、Ｔｉ：０～０．２％未満、Ｗ：０～６％、Ｍｏ：０～４％、Ｚｒ：０～０．１％、Ｂ：０～０．０１％、Ｃｕ：０～５％、希土類元素：０～０．１％、Ｃａ：０～０．０５％、及び、Ｍｇ：０～０．０５％を含有し、残部がＦｅ及び不純物からなり、不純物中のＰ及びＳが各々、Ｐ：０．０４％以下、及び、Ｓ：０．０１％以下の化学組成を有する。組織中において、円相当径が６μｍ以上の析出物の総体積率は５％以下である。ここで、析出物とはたとえば、炭化物、窒化物、ＮｉＡｌ及びα－Ｃｒである。 The austenitic heat-resistant alloy according to the present embodiment is, in mass%, C: 0.03 to less than 0.25%, Si: 0.01 to 2.0%, Mn: 2.0% or less, Cr: 10 to 30 %, Ni: more than 25 to 45%, Al: more than 2.5 to less than 4.5%, Nb: 0.2 to 3.5%, N: 0.025% or less, Ti: 0 to 0.2 %: W: 0-6%, Mo: 0-4%, Zr: 0-0.1%, B: 0-0.01%, Cu: 0-5%, Rare earth elements: 0-0.1 %, Ca: 0 to 0.05%, and Mg: 0 to 0.05%, the balance is made of Fe and impurities, and P and S in the impurities are each P: 0.04% or less, And S: having a chemical composition of 0.01% or less. In the structure, the total volume ratio of precipitates having an equivalent circle diameter of 6 μm or more is 5% or less. Here, the precipitate is, for example, carbide, nitride, NiAl, and α-Cr.
　本実施形態によるオーステナイト系耐熱合金は、高温環境においても、長時間の高温強度と、優れた靭性とを有する。 The austenitic heat-resistant alloy according to the present embodiment has long-term high-temperature strength and excellent toughness even in a high-temperature environment.
　本発明者らは、７００℃以上の高温環境（以下、単に高温環境という）におけるオーステナイト系耐熱合金のクリープ強度及び靭性について調査及び検討を行い、次の知見を得た。 The present inventors investigated and examined the creep strength and toughness of the austenitic heat resistant alloy in a high temperature environment of 700 ° C. or higher (hereinafter simply referred to as a high temperature environment), and obtained the following knowledge.
　上述のとおり、ラーベス相や、Ｎｉ3Ａｌ等のγ’相を含有する耐熱合金は、高温環境において高いクリープ強度を有する。しかしながらこれらの析出相は、高温環境で長時間使用すると粗大化するため、耐熱合金のクリープ強度及び靭性が低下する。 As described above, a heat-resistant alloy containing a Laves phase or a γ ′ phase such as Ni 3 Al has a high creep strength in a high-temperature environment. However, since these precipitated phases become coarse when used for a long time in a high temperature environment, the creep strength and toughness of the heat-resistant alloy are lowered.
　一方、高温環境で耐熱合金を使用中、炭化物、窒化物、ＮｉＡｌ、α－Ｃｒ等の析出物を微細に分散析出できれば、長時間の使用であっても高いクリープ強度及び高い靭性を維持できる。これらの析出物は、結晶粒界を被覆することで、粒界強度を高める。さらに、これらの析出物が粒内に析出すれば、耐熱合金の変形抵抗が高まり、クリープ強度が高まる。 On the other hand, if a precipitate such as carbide, nitride, NiAl, α-Cr, etc. can be finely dispersed while using a heat-resistant alloy in a high-temperature environment, high creep strength and high toughness can be maintained even after long-term use. These precipitates increase the grain boundary strength by covering the crystal grain boundaries. Furthermore, if these precipitates precipitate in the grains, the deformation resistance of the heat-resistant alloy increases and the creep strength increases.
　上述の微細な析出物によりクリープ強度及び靭性を高めるために、使用前の耐熱合金の組織を次のとおり制御する。 In order to increase the creep strength and toughness by the fine precipitates described above, the structure of the heat-resistant alloy before use is controlled as follows.
　［円相当径が６μｍ以上の析出物の量の制限］
　耐熱合金を鋳造した後の凝固組織には、炭化物、窒化物、ＮｉＡｌ、α－Ｃｒ等の析出物（以下、単に析出物という）が存在する。これらの析出物は、デンドライトの間に存在する溶質元素が濃縮した液相に生成する。これらの析出物は通常は粗大な形状を有し、組織中へ不均一に分散している。そのため、耐熱合金の靭性が低下する。 [Limit of amount of precipitates with equivalent circle diameter of 6 μm or more]
In the solidified structure after casting the heat-resistant alloy, there are precipitates of carbide, nitride, NiAl, α-Cr, etc. (hereinafter simply referred to as precipitates). These precipitates are generated in a liquid phase in which solute elements existing between dendrites are concentrated. These precipitates usually have a coarse shape and are unevenly distributed in the tissue. Therefore, the toughness of the heat resistant alloy is reduced.
　さらに、これらの析出物は溶体化処理を実施しても、固溶しにくく、粗大な状態で残存しやすい。これらの析出物が耐熱合金中に粗大に残存していれば、高温環境での使用中に微細な析出物が形成しにくい。したがって、耐熱合金中の粗大な析出物の総体積率はなるべく低い方が好ましい。 Furthermore, even when the solution treatment is performed, these precipitates are not easily dissolved and remain in a coarse state. If these precipitates remain coarsely in the heat-resistant alloy, it is difficult to form fine precipitates during use in a high temperature environment. Therefore, the total volume ratio of coarse precipitates in the heat-resistant alloy is preferably as low as possible.
　耐熱合金の組織中において、円相当径が６μｍ以上の析出物（以下、粗大析出物という）の総体積率が５％以下であれば、高温環境で耐熱合金を使用中に、十分な量の微細な析出物を析出することができ、高いクリープ強度及び靭性を得ることができる。 If the total volume fraction of precipitates having an equivalent circle diameter of 6 μm or more (hereinafter referred to as coarse precipitates) is 5% or less in the structure of the heat-resistant alloy, a sufficient amount can be obtained while using the heat-resistant alloy in a high-temperature environment. Fine precipitates can be deposited, and high creep strength and toughness can be obtained.
　組織中の粗大析出物の総体積率を５％以下にするために、耐熱合金中のＣ含有量を０．２５％未満とする。さらに、熱間鍛造時の断面減少率を３０％以上とする。この場合、粗大析出物が熱間鍛造によって均一に分散する。そのため、後工程の溶体化処理時において、析出物を固溶することができ、粗大析出物の総体積率が５％以下となる。 In order to make the total volume ratio of coarse precipitates in the structure 5% or less, the C content in the heat-resistant alloy is set to less than 0.25%. Furthermore, the cross-section reduction rate during hot forging is set to 30% or more. In this case, coarse precipitates are uniformly dispersed by hot forging. Therefore, the precipitate can be dissolved in the solution treatment in the subsequent step, and the total volume ratio of the coarse precipitate becomes 5% or less.
　以上の知見に基づいて完成した本実施形態によるオーステナイト系耐熱合金は、質量％で、Ｃ：０．０３～０．２５％未満、Ｓｉ：０．０１～２．０％、Ｍｎ：２．０％以下、Ｃｒ：１０～３０％未満、Ｎｉ：２５超～４５％、Ａｌ：２．５超～４．５％未満、Ｎｂ：０．２～３．５％、Ｎ：０．０２５％以下、Ｔｉ：０～０．２％未満、Ｗ：０～６％、Ｍｏ：０～４％、Ｚｒ：０～０．１％、Ｂ：０～０．０１％、Ｃｕ：０～５％、希土類元素：０～０．１％、Ｃａ：０～０．０５％、及び、Ｍｇ：０～０．０５％を含有し、残部がＦｅ及び不純物からなり、不純物中のＰ及びＳが各々、Ｐ：０．０４％以下、及び、Ｓ：０．０１％以下の化学組成を有する。組織中において、円相当径が６μｍ以上の析出物の総体積率は５％以下である。 The austenitic heat-resistant alloy according to the present embodiment completed based on the above knowledge is mass%, C: 0.03 to less than 0.25%, Si: 0.01 to 2.0%, Mn: 2.0. %: Cr: 10 to less than 30%, Ni: more than 25 to 45%, Al: more than 2.5 to less than 4.5%, Nb: 0.2 to 3.5%, N: 0.025% or less Ti: 0 to less than 0.2%, W: 0 to 6%, Mo: 0 to 4%, Zr: 0 to 0.1%, B: 0 to 0.01%, Cu: 0 to 5%, Rare earth elements: 0 to 0.1%, Ca: 0 to 0.05%, and Mg: 0 to 0.05%, the balance is composed of Fe and impurities, and P and S in the impurities are respectively It has a chemical composition of P: 0.04% or less and S: 0.01% or less. In the structure, the total volume ratio of precipitates having an equivalent circle diameter of 6 μm or more is 5% or less.
　上記化学組成は、質量％で、Ｔｉ：０．００５～０．２％未満、Ｗ：０．００５～６％、Ｍｏ：０．００５～４％、Ｚｒ：０．０００５～０．１％、及びＢ：０．０００５～０．０１％からなる群から選択される１種又は２種以上を含有してもよい。 The chemical composition is, by mass, Ti: 0.005 to less than 0.2%, W: 0.005 to 6%, Mo: 0.005 to 4%, Zr: 0.0005 to 0.1%, And B: One or more selected from the group consisting of 0.0005 to 0.01% may be contained.
　上記化学組成は、質量％で、Ｃｕ：０．０５～５％、及び希土類元素：０．０００５～０．１％からなる群から選択される１種以上を含有してもよい。 The chemical composition may contain one or more selected from the group consisting of Cu: 0.05 to 5% and rare earth elements: 0.0005 to 0.1% by mass.
　上記化学組成は、質量％で、Ｃａ：０．０００５～０．０５％、及びＭｇ：０．０００５～０．０５％からなる群から選択される１種以上を含有してもよい。 The chemical composition may contain at least one selected from the group consisting of Ca: 0.0005 to 0.05% and Mg: 0.0005 to 0.05% by mass.
　上述のオーステナイト系耐熱合金の製造方法は、上述の化学組成を有する鋳造材に対して、３０％以上の断面減少率で熱間鍛造を実施する工程と、熱間鍛造後の素材に対して熱間加工を実施して中間材を製造する工程と、中間材に対して１１００～１２５０℃で溶体化処理を実施する工程とを備える。 The method for producing the austenitic heat-resistant alloy includes a step of performing hot forging at a cross-section reduction rate of 30% or more on a cast material having the above-described chemical composition, and heating the material after hot forging. A step of producing an intermediate material by performing inter-processing, and a step of performing a solution treatment on the intermediate material at 1100 to 1250 ° C.
　以下、本実施形態のオーステナイト系耐熱合金について詳述する。元素に関する「％」は、特に断りがない限り、質量％を意味する。 Hereinafter, the austenitic heat-resistant alloy of this embodiment will be described in detail. “%” Regarding an element means mass% unless otherwise specified.
　［化学組成］
　本実施形態によるオーステナイト系耐熱合金はたとえば、合金管である。オーステナイト系耐熱合金の化学組成は、次の元素を含有する。 [Chemical composition]
The austenitic heat-resistant alloy according to the present embodiment is, for example, an alloy tube. The chemical composition of the austenitic heat-resistant alloy contains the following elements.
　Ｃ：０．０３～０．２５％未満
　炭素（Ｃ）は炭化物を形成し、クリープ強度を高める。具体的には、Ｃは、高温環境での使用中に、結晶粒界及び粒内に合金元素と結合して微細な炭化物を形成する。微細な炭化物は変形抵抗を高め、クリープ強度を高める。Ｃ含有量が低すぎれば、この効果が得られない。一方、Ｃ含有量が高すぎれば、耐熱合金の鋳造後の凝固組織中に粗大な共晶炭化物を多数形成する。共晶炭化物は溶体化処理後も粗大なまま組織中に残存するため、耐熱合金の靭性を低下する。さらに、粗大な共晶炭化物が残存すれば、高温環境での使用中に微細炭化物が析出しにくく、クリープ強度が低下する。したがって、Ｃ含有量は０．０３～０．２５％未満である。Ｃ含有量の好ましい下限は０．０５％であり、より好ましくは０．０８％である。Ｃ含有量の好ましい上限は０．２３％であり、より好ましくは０．２０％である。 C: 0.03 to less than 0.25% Carbon (C) forms a carbide and increases the creep strength. Specifically, during use in a high temperature environment, C combines with an alloy element within a grain boundary and within the grains to form fine carbides. Fine carbides increase deformation resistance and increase creep strength. If the C content is too low, this effect cannot be obtained. On the other hand, if the C content is too high, many coarse eutectic carbides are formed in the solidified structure after casting of the heat-resistant alloy. Since the eutectic carbide remains coarse in the structure even after the solution treatment, the toughness of the heat-resistant alloy is lowered. Furthermore, if coarse eutectic carbides remain, fine carbides are less likely to precipitate during use in a high temperature environment, and the creep strength decreases. Therefore, the C content is 0.03 to less than 0.25%. The minimum with preferable C content is 0.05%, More preferably, it is 0.08%. The upper limit with preferable C content is 0.23%, More preferably, it is 0.20%.
　Ｓｉ：０．０１～２．０％
　シリコン（Ｓｉ）は耐熱合金を脱酸する。Ｓｉはさらに、耐熱合金の耐食性（耐酸化性及び耐水蒸気酸化性）を高める。Ｓｉは不可避的に含有される元素であるが、他の元素で脱酸を十分に実施できる場合、Ｓｉの含有量は出来るだけ少なくてもよい。一方、Ｓｉ含有量が高すぎれば、熱間加工性が低下する。したがって、Ｓｉ含有量は０．０１～２．０％である。Ｓｉ含有量の好ましい下限は０．０２％であり、さらに好ましくは０．０３％である。Ｓｉ含有量の好ましい上限は１．０％である。 Si: 0.01 to 2.0%
Silicon (Si) deoxidizes the heat-resistant alloy. Si further enhances the corrosion resistance (oxidation resistance and steam oxidation resistance) of the heat-resistant alloy. Si is an element inevitably contained, but the content of Si may be as small as possible when deoxidation can be sufficiently performed with other elements. On the other hand, if the Si content is too high, the hot workability decreases. Therefore, the Si content is 0.01 to 2.0%. The minimum with preferable Si content is 0.02%, More preferably, it is 0.03%. The upper limit with preferable Si content is 1.0%.
　Ｍｎ：２．０％以下
　マンガン（Ｍｎ）は不可避に含有される。Ｍｎは耐熱合金中に含まれるＳと結合してＭｎＳを形成し、耐熱合金の熱間加工性を高める。しかしながら、Ｍｎ含有量が高すぎれば、耐熱合金が硬くなりすぎ、熱間加工性及び溶接性が低下する。したがって、Ｍｎ含有量は２．０％以下である。Ｍｎ含有量の好ましい下限は０．１％であり、さらに好ましくは０．２％である。Ｍｎ含有量の好ましい上限は１．２％である。 Mn: 2.0% or less Manganese (Mn) is unavoidably contained. Mn combines with S contained in the heat-resistant alloy to form MnS and enhances the hot workability of the heat-resistant alloy. However, if the Mn content is too high, the heat-resistant alloy becomes too hard and the hot workability and weldability deteriorate. Therefore, the Mn content is 2.0% or less. The minimum with preferable Mn content is 0.1%, More preferably, it is 0.2%. The upper limit with preferable Mn content is 1.2%.
　Ｃｒ：１０～３０％未満
　クロム（Ｃｒ）は、高温環境での耐熱合金の耐食性（耐酸化性、耐水蒸気酸化性等）を高める。Ｃｒはさらに、高温環境での使用中において、α－Ｃｒとして微細析出して、クリープ強度を高める。Ｃｒ含有量が低すぎれば、これらの効果が得られない。一方、Ｃｒ含有量が高すぎれば、組織の安定性が低下してクリープ強度が低下する。したがって、Ｃｒ含有量は１０～３０％未満である。Ｃｒ含有量の好ましい下限は１１％であり、さらに好ましくは１２％である。Ｃｒ含有量の好ましい上限は２８％であり、さらに好ましくは２６％である。 Cr: 10 to less than 30% Chromium (Cr) improves the corrosion resistance (oxidation resistance, steam oxidation resistance, etc.) of the heat-resistant alloy in a high-temperature environment. Further, Cr is finely precipitated as α-Cr during use in a high temperature environment, thereby increasing the creep strength. If the Cr content is too low, these effects cannot be obtained. On the other hand, if the Cr content is too high, the stability of the structure decreases and the creep strength decreases. Therefore, the Cr content is 10 to less than 30%. The minimum with preferable Cr content is 11%, More preferably, it is 12%. The upper limit with preferable Cr content is 28%, More preferably, it is 26%.
　Ｎｉ：２５超～４５％
　ニッケル（Ｎｉ）は、オーステナイトを安定化させる。Ｎｉはさらに、耐熱合金の耐食性を高める。Ｎｉ含有量が低すぎれば、これらの効果が得られない。一方、Ｎｉ含有量が高すぎれば、これらの効果が飽和するだけでなく、熱間加工性が低下する。Ｎｉ含有量が高すぎればさらに、原料コストが高くなる。したがって、Ｎｉ含有量は２５超～４５％である。Ｎｉ含有量の好ましい下限は２６％であり、さらに好ましくは２８％である。Ｎｉ含有量の好ましい上限は４４％であり、さらに好ましくは４２％である。 Ni: Over 25-45%
Nickel (Ni) stabilizes austenite. Ni further enhances the corrosion resistance of the heat-resistant alloy. If the Ni content is too low, these effects cannot be obtained. On the other hand, if the Ni content is too high, these effects are not only saturated, but hot workability is reduced. If the Ni content is too high, the raw material cost further increases. Therefore, the Ni content is more than 25 to 45%. The minimum with preferable Ni content is 26%, More preferably, it is 28%. The upper limit with preferable Ni content is 44%, More preferably, it is 42%.
　Ａｌ：２．５超～４．５％未満
　アルミニウム（Ａｌ）は、高温環境での使用中において、Ｎｉと結合して微細なＮｉＡｌを形成し、クリープ強度を高める。Ａｌはさらに、１０００℃以上の高温環境において耐食性を高める。Ａｌ含有量が低すぎれば、これらの効果が得られない。一方、Ａｌ含有量が高すぎれば、組織安定性が低下し、強度が低下する。したがって、Ａｌ含有量は２．５超～４．５％未満である。Ａｌ含有量の好ましい下限は２．５５％であり、さらに好ましくは２．６％である。Ａｌ含有量の好ましい上限は４．４％であり、さらに好ましくは４．２％である。本発明によるオーステナイト系耐熱合金において、Ａｌ含有量は、鋼材中に含有する全Ａｌ量を意味する。 Al: more than 2.5 to less than 4.5% Aluminum (Al) is combined with Ni to form fine NiAl during use in a high temperature environment, and increases the creep strength. Further, Al enhances corrosion resistance in a high temperature environment of 1000 ° C. or higher. 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 more than 2.5 to less than 4.5%. The minimum with preferable Al content is 2.55%, More preferably, it is 2.6%. The upper limit with preferable Al content is 4.4%, More preferably, it is 4.2%. In the austenitic heat-resistant alloy according to the present invention, the Al content means the total amount of Al contained in the steel material.
　Ｎｂ：０．２～３．５％
　ニオブ（Ｎｂ）は、析出強化相となるラーベス相及びＮｉ3Ｎｂ相を形成して、結晶粒界及び結晶粒内を析出強化し、耐熱合金のクリープ強度を高める。Ｎｂ含有量が低すぎれば、上記効果が得られない。一方、Ｎｂ含有量が高すぎれば、ラーベス相及びＮｉ3Ｎｂ相が過剰に生成して、合金の靭性及び熱間加工性が低下する。Ｎｂ含有量が高すぎればさらに、長時間時効後の靭性も低下する。したがって、Ｎｂ含有量は０．２～３．５％である。Ｎｂ含有量の好ましい下限は０．３５％であり、さらに好ましくは０．５％である。Ｎｂ含有量の好ましい上限は３．２％未満であり、さらに好ましくは３．０％である。 Nb: 0.2-3.5%
Niobium (Nb) forms a Laves phase and a Ni 3 Nb phase as precipitation strengthening phases, and precipitates and strengthens the crystal grain boundaries and crystal grains, thereby increasing the creep strength of the heat-resistant alloy. If the Nb content is too low, the above effect cannot be obtained. On the other hand, if the Nb content is too high, the Laves phase and the Ni 3 Nb phase are excessively generated, and the toughness and hot workability of the alloy are lowered. If the Nb content is too high, the toughness after aging for a long time further decreases. Therefore, the Nb content is 0.2 to 3.5%. The minimum with preferable Nb content is 0.35%, More preferably, it is 0.5%. The upper limit with preferable Nb content is less than 3.2%, More preferably, it is 3.0%.
　Ｎ：０．０２５％以下
　窒素（Ｎ）はオーステナイトを安定化し、通常の溶解法では不可避に含有される。また、Ｎは、高温環境での使用中に、結晶粒界及び粒内に合金元素と結合して微細な窒化物を形成する。微細な窒化物は変形抵抗を高め、クリープ強度を高める。しかしながら、Ｎ含有量が高すぎれば、溶体化処理後でも未固溶で残存する粗大な窒化物を形成して合金の靱性を低下する。したがって、Ｎ含有量は０．０２５％以下である。好ましいＮ含有量の上限は０．０２％であり、さらに好ましくは０．０１％である。 N: 0.025% or less Nitrogen (N) stabilizes austenite and is inevitably contained in a normal dissolution method. In addition, during use in a high temperature environment, N combines with the alloy element in the grain boundaries and grains to form fine nitrides. Fine nitride increases deformation resistance and increases creep strength. However, if the N content is too high, coarse nitrides that remain undissolved even after the solution treatment are formed and the toughness of the alloy is lowered. Therefore, the N content is 0.025% or less. The upper limit of the preferable N content is 0.02%, more preferably 0.01%.
　Ｐ：０．０４％以下
　燐（Ｐ）は不純物である。Ｐは耐熱合金の溶接性及び熱間加工性を低下する。したがって、Ｐ含有量は０．０４％以下である。Ｐ含有量の好ましい上限は０．０３％である。Ｐ含有量はなるべく低い方が好ましい。 P: 0.04% or less Phosphorus (P) is an impurity. P decreases the weldability and hot workability of the heat-resistant alloy. Therefore, the P content is 0.04% or less. The upper limit with preferable P content is 0.03%. The P content is preferably as low as possible.
　Ｓ：０．０１％以下
　硫黄（Ｓ）は不純物である。Ｓは耐熱合金の溶接性及び熱間加工性を低下する。したがって、Ｓ含有量は０．０１％以下である。Ｓ含有量の好ましい上限は０．００８％である。Ｓ含有量はなるべく低い方が好ましい。 S: 0.01% or less Sulfur (S) is an impurity. S decreases the weldability and hot workability of the heat-resistant alloy. Therefore, the S content is 0.01% or less. The upper limit with preferable S content is 0.008%. The S content is preferably as low as possible.
　本実施形態のオーステナイト系耐熱合金の化学組成の残部は、Ｆｅ及び不純物からなる。ここで、不純物とは、オーステナイト系耐熱合金を工業的に製造する際に、原料としての鉱石、スクラップ、又は製造環境などから混入されるものであって、本発明に悪影響を与えない範囲で許容されるものを意味する。 The balance of the chemical composition of the austenitic heat-resistant alloy of this embodiment is composed of Fe and impurities. Here, the impurities are those mixed from the ore, scrap, or production environment as raw materials when industrially producing austenitic heat-resistant alloys, and are allowed within a range that does not adversely affect the present invention. Means what will be done.
　［任意元素について］
　上述のオーステナイト系耐熱合金の化学組成はさらに、Ｆｅの一部に代えて、Ｔｉ、Ｗ、Ｍｏ、Ｚｒ及びＢからなる群から選択される１種又は２種以上を含有してもよい。これらの元素はいずれも任意元素であり、クリープ強度を高める。 [Arbitrary elements]
The chemical composition of the austenitic heat-resistant alloy described above may further contain one or more selected from the group consisting of Ti, W, Mo, Zr and B, instead of a part of Fe. All of these elements are optional elements and increase the creep strength.
　Ｔｉ：０～０．２％未満
　チタン（Ｔｉ）は任意元素であり、含有されなくてもよい。含有される場合、析出強化相となるラーベス相及びＮｉ3Ｔｉ相を形成して、析出強化によりクリープ強度を高める。しかしながら、Ｔｉ含有量が高すぎれば、ラーベス相及びＮｉ3Ｔｉ相が過剰に生成して、高温延性及び熱間加工性が低下する。Ｔｉ含有量が高すぎればさらに、長時間時効後の靭性が低下する。したがって、Ｔｉ含有量は０～０．２％未満である。Ｔｉ含有量の好ましい下限は０．００５％であり、さらに好ましくは、０．０１％である。Ｔｉ含有量の好ましい上限は０．１５％であり、さらに好ましくは、０．１％である。 Ti: 0 to less than 0.2% Titanium (Ti) is an optional element and may not be contained. When it is contained, a Laves phase and a Ni 3 Ti phase that are precipitation strengthening phases are formed, and the creep strength is increased by precipitation strengthening. However, if the Ti content is too high, the Laves phase and the Ni 3 Ti phase are excessively generated, and the hot ductility and hot workability are reduced. If the Ti content is too high, the toughness after aging for a long time further decreases. Therefore, the Ti content is 0 to less than 0.2%. The minimum with preferable Ti content is 0.005%, More preferably, it is 0.01%. The upper limit with preferable Ti content is 0.15%, More preferably, it is 0.1%.
　Ｗ：０～６％
　タングステン（Ｗ）は任意元素であり、含有されなくてもよい。含有される場合、母相（マトリクス）のオーステナイトに固溶して、固溶強化によりクリープ強度を高める。Ｗはさらに、結晶粒界および結晶粒内にラーベス相を形成して、析出強化によりクリープ強度を高める。しかしながら、Ｗ含有量が多すぎれば、ラーベス相が過剰に生成して高温延性、熱間加工性、及び靭性を低下する。したがって、Ｗ含有量は０～６％である。Ｗ含有量の好ましい下限は０．００５％であり、さらに好ましくは、０．０１％である。Ｗの含有量の好ましい上限は５．５％であり、さらに好ましくは５％である。 W: 0-6%
Tungsten (W) is an optional element and may not be contained. When contained, it dissolves in the austenite of the matrix (matrix), and increases the creep strength by solid solution strengthening. Further, W forms a Laves phase in the crystal grain boundaries and in the crystal grains, and increases the creep strength by precipitation strengthening. However, if there is too much W content, a Laves phase will be generated excessively and hot ductility, hot workability, and toughness will fall. Accordingly, the W content is 0 to 6%. The minimum with preferable W content is 0.005%, More preferably, it is 0.01%. The upper limit with preferable content of W is 5.5%, More preferably, it is 5%.
　Ｍｏ：０～４％
　モリブデン（Ｍｏ）は任意元素であり、含有されなくてもよい。含有される場合、母相のオーステナイトに固溶して、固溶強化によりクリープ強度を高める。Ｍｏはさらに、結晶粒界および結晶粒内にラーベス相を形成して、析出強化によりクリープ強度を高める。しかしながら、Ｍｏ含有量が高すぎれば、ラーベス相が過剰に生成して高温延性、熱間加工性、及び靭性を低下する。したがって、Ｍｏ含有量は０～４％である。Ｍｏ含有量の好ましい下限は０．００５％であり、さらに好ましくは、０．０１％である。Ｍｏの含有量の好ましい上限は３．５％であり、さらに好ましくは３％である。 Mo: 0-4%
Molybdenum (Mo) is an optional element and may not be contained. When contained, it dissolves in the austenite of the parent phase and increases the creep strength by solid solution strengthening. Mo further forms a Laves phase in the grain boundaries and in the crystal grains, and increases the creep strength by precipitation strengthening. However, if the Mo content is too high, the Laves phase is excessively generated and the hot ductility, hot workability, and toughness are reduced. Therefore, the Mo content is 0 to 4%. The minimum with preferable Mo content is 0.005%, More preferably, it is 0.01%. The upper limit with preferable Mo content is 3.5%, More preferably, it is 3%.
　Ｚｒ：０～０．１％
　ジルコニウム（Ｚｒ）は任意元素であり、含有されなくてもよい。含有される場合、Ｚｒは粒界強化によりクリープ強度を高める。しかしながら、Ｚｒ含有量が高すぎれば、耐熱合金の溶接性及び熱間加工性が低下する。したがって、Ｚｒ含有量は０～０．１％である。Ｚｒの好ましい下限は０．０００５％であり、さらに好ましくは、０．００１％である。Ｚｒ含有量の好ましい上限は０．０６％である。 Zr: 0 to 0.1%
Zirconium (Zr) is an optional element and may not be contained. When contained, Zr increases creep strength by grain boundary strengthening. However, if the Zr content is too high, the weldability and hot workability of the heat-resistant alloy are lowered. Therefore, the Zr content is 0 to 0.1%. The minimum with preferable Zr is 0.0005%, More preferably, it is 0.001%. The upper limit with preferable Zr content is 0.06%.
　Ｂ：０～０．０１％
　ホウ素（Ｂ）は任意元素であり、含有されなくてもよい。含有される場合、粒界強化によりクリープ強度を高める。しかしながら、Ｂ含有量が高すぎれば、溶接性が低下する。したがって、Ｂ含有量は０～０．０１％である。Ｂの好ましい下限は０．０００５％であり、さらに好ましくは、０．００１％である。Ｂ含有量の好ましい上限は０．００５％である。 B: 0 to 0.01%
Boron (B) is an optional element and may not be contained. When contained, the creep strength is increased by grain boundary strengthening. However, if the B content is too high, weldability decreases. Therefore, the B content is 0 to 0.01%. A preferable lower limit of B is 0.0005%, and more preferably 0.001%. The upper limit with preferable B content is 0.005%.
　上述のオーステナイト系耐熱合金の化学組成はさらに、Ｆｅの一部に代えて、Ｃｕ及び希土類元素からなる群から選択される１種以上を含有してもよい。これらの元素はいずれも任意元素であり、耐熱合金の耐食性を高める。 The chemical composition of the austenitic heat-resistant alloy described above may further contain one or more selected from the group consisting of Cu and rare earth elements instead of a part of Fe. Any of these elements is an arbitrary element and improves the corrosion resistance of the heat-resistant alloy.
　Ｃｕ：０～５％
　銅（Ｃｕ）は任意元素であり、含有されなくてもよい。含有される場合、表面近傍におけるＡｌ2Ｏ3皮膜の形成を促進して、耐熱合金の耐食性を高める。しかしながら、Ｃｕ含有量が高すぎれば、効果が飽和するだけでなく、高温延性が低下する。したがって、Ｃｕ含有量は０～５％である。Ｃｕ含有量の好ましい下限は０．０５％であり、さらに好ましくは、０．１％である。Ｃｕ含有量の好ましい上限は４．８％であり、さらに好ましくは４．５％である。 Cu: 0 to 5%
Copper (Cu) is an optional element and may not be contained. When contained, it promotes the formation of an Al 2 O 3 film in the vicinity of the surface and enhances the corrosion resistance of the heat-resistant alloy. However, if the Cu content is too high, not only the effect is saturated, but also the high temperature ductility is lowered. Therefore, the Cu content is 0 to 5%. The minimum with preferable Cu content is 0.05%, More preferably, it is 0.1%. The upper limit with preferable Cu content is 4.8%, More preferably, it is 4.5%.
　希土類元素：０～０．１％
　希土類元素（ＲＥＭ）は任意元素であり、含有されなくてもよい。含有される場合、Ｓを硫化物として固定し、熱間加工性を高める。ＲＥＭはさらに、酸化物を形成して、耐食性、クリープ強度、及びクリープ延性を高める。しかしながら、ＲＥＭ含有量が高すぎれば、酸化物等の介在物が多くなり、熱間加工性及び溶接性を低下させ、製造コストが上昇する。したがって、ＲＥＭ含有量は０～０．１％である。ＲＥＭ含有量の好ましい下限は０．０００５％であり、さらに好ましくは、０．００１％である。ＲＥＭ含有量の好ましい上限は０．０９％であり、さらに好ましくは０．０８％である。 Rare earth elements: 0 to 0.1%
The rare earth element (REM) is an optional element and may not be contained. When it is contained, S is fixed as a sulfide to enhance hot workability. REM further forms oxides to increase corrosion resistance, creep strength, and creep ductility. However, if the REM content is too high, inclusions such as oxides increase, thereby reducing hot workability and weldability and increasing manufacturing costs. Therefore, the REM content is 0 to 0.1%. The minimum with preferable REM content is 0.0005%, More preferably, it is 0.001%. The upper limit with preferable REM content is 0.09%, More preferably, it is 0.08%.
　本明細書において、ＲＥＭは、Ｓｃ、Ｙ及びランタノイドの合計１７元素の総称である。ＲＥＭ含有量は、耐熱合金に含有されるＲＥＭがこれらの元素のうち１種である場合、その元素の含有量を意味する。耐熱合金に含有されるＲＥＭが２種以上である場合、ＲＥＭ含有量は、それらの元素の総含有量を意味する。ＲＥＭについては、一般的にミッシュメタルに含有される。このため、例えば、ミッシュメタルの形で添加して、ＲＥＭ含有量が上記の範囲となるように含有させてもよい。 In this specification, REM is a general term for a total of 17 elements of Sc, Y, and a lanthanoid. The REM content means the content of an element when the REM contained in the heat-resistant alloy is one of these elements. When two or more types of REM are contained in the heat-resistant alloy, the REM content means the total content of these elements. REM is generally contained in misch metal. For this reason, for example, it may be added in the form of misch metal so that the REM content falls within the above range.
　上述のオーステナイト系耐熱合金の化学組成はさらに、Ｆｅの一部に代えて、Ｃａ及びＭｇからなる群から選択される１種以上を含有してもよい。これらの元素はいずれも任意元素であり、耐熱合金の熱間加工性を高める。 The chemical composition of the austenitic heat-resistant alloy described above may further include one or more selected from the group consisting of Ca and Mg instead of a part of Fe. Any of these elements is an arbitrary element and improves the hot workability of the heat-resistant alloy.
　Ｃａ：０～０．０５％
　カルシウム（Ｃａ）は任意元素であり、含有されなくてもよい。含有される場合、Ｓを硫化物として固定し、熱間加工性を高める。一方、Ｃａ含有量が高すぎれば、靱性、延性及び清浄性が低下する。したがって、Ｃａ含有量は０～０．０５％である。Ｃａの好ましい下限は０．０００５％である。Ｃａ含有量の好ましい上限は０．０１％である。 Ca: 0 to 0.05%
Calcium (Ca) is an optional element and may not be contained. When it is contained, S is fixed as a sulfide to enhance hot workability. On the other hand, if the Ca content is too high, toughness, ductility and cleanliness will be reduced. Therefore, the Ca content is 0 to 0.05%. A preferable lower limit of Ca is 0.0005%. The upper limit with preferable Ca content is 0.01%.
　Ｍｇ：０～０．０５％
　マグネシウム（Ｍｇ）は任意元素であり、含有されなくてもよい。含有される場合、Ｓを硫化物として固定し、耐熱合金の熱間加工性を高める。一方、Ｃａ含有量が高すぎれば、靱性、延性及び清浄性が低下する。したがって、Ｃａ含有量は０～０．０５％である。Ｃａの好ましい下限は０．０００５％である。Ｃａ含有量の好ましい上限は０．０１％である。 Mg: 0 to 0.05%
Magnesium (Mg) is an optional element and may not be contained. When contained, it fixes S as a sulfide and improves the hot workability of the heat-resistant alloy. On the other hand, if the Ca content is too high, toughness, ductility and cleanliness will be reduced. Therefore, the Ca content is 0 to 0.05%. A preferable lower limit of Ca is 0.0005%. The upper limit with preferable Ca content is 0.01%.
　［円相当径が６μｍ以上の析出物（粗大析出物）の総体積率：５％以下］
　上述のとおり、本実施形態のオーステナイト系耐熱合金は、高温環境での使用中に微細な析出物を析出して、クリープ強度を高め、靭性を維持する。析出物とは例えば炭化物、窒化物、ＮｉＡl及びα－Ｃｒである。析出物が粗大であれば、クリープ強度及び靭性が低下する。そのため、使用前の耐熱合金中では、粗大析出物が少ない方が好ましい。耐熱合金の組織中において、円相当径で６μｍ以上の析出物（粗大析出物）の総体積率が５％以下であれば、高温環境での使用中に微細な析出物が析出して、クリープ強度及び靭性が高まる。粗大析出物の総体積率の好ましい上限は４％であり、さらに好ましくは３％である。ここで、円相当径とは、析出物の面積を円の面積に換算した場合の直径（μｍ）を意味する。 [Total volume ratio of precipitates with coarse equivalent diameter of 6 μm or more (coarse precipitates): 5% or less]
As described above, the austenitic heat-resistant alloy of the present embodiment precipitates fine precipitates during use in a high temperature environment, increases creep strength, and maintains toughness. Examples of the precipitate include carbide, nitride, NiAl, and α-Cr. If the precipitate is coarse, creep strength and toughness are lowered. Therefore, in the heat-resistant alloy before use, it is preferable that there are few coarse precipitates. If the total volume fraction of precipitates (coarse precipitates) with an equivalent circle diameter of 6 μm or more in the microstructure of the heat-resistant alloy is 5% or less, fine precipitates precipitate during use in a high-temperature environment and creep. Strength and toughness are increased. The upper limit with the preferable total volume ratio of a coarse precipitate is 4%, More preferably, it is 3%. Here, the equivalent circle diameter means the diameter (μm) when the area of the precipitate is converted into the area of the circle.
　［組織中の粗大析出物の総体積率の測定方法］
　本実施形態のオーステナイト系耐熱合金の組織中の粗大析出物の総体積率は次の方法で測定できる。 [Method for measuring the total volume fraction of coarse precipitates in the structure]
The total volume ratio of coarse precipitates in the structure of the austenitic heat-resistant alloy of this embodiment can be measured by the following method.
　耐熱合金材の表面から垂直な断面の試験片を採取する。たとえば、オーステナイト系耐熱合金材が合金管の場合、軸方向に垂直な断面の肉厚中央部から試験片を採取する。 Take a specimen with a vertical cross section from the surface of the heat-resistant alloy material. For example, when the austenitic heat-resistant alloy material is an alloy pipe, a test piece is sampled from the central thickness portion of the cross section perpendicular to the axial direction.
　採取された試験片の断面（観察面）を研磨した後、塩酸と硝酸の混酸溶液で観察面をエッチングする。走査型電子顕微鏡（ＳＥＭ）を用いて観察面の任意の１０視野を撮影してＳＥＭ画像（反射電子像）を作成する。各視野は１００μｍ×１００μｍとする。 After polishing the cross section (observation surface) of the collected specimen, the observation surface is etched with a mixed acid solution of hydrochloric acid and nitric acid. A scanning electron microscope (SEM) is used to photograph 10 fields of view on the observation surface to create an SEM image (reflection electron image). Each field of view is 100 μm × 100 μm.
　ＳＥＭ画像において、析出物とマトリクスは、それぞれコントラストが異なる。コントラストの違いにより特定された析出物の面積を求めて、各析出物の円相当径を算出する。算出後、円相当径が６μｍ以上の析出物（粗大析出物）を特定する。 In the SEM image, the precipitates and the matrix have different contrasts. The area of the precipitate specified by the difference in contrast is obtained, and the equivalent circle diameter of each precipitate is calculated. After the calculation, a precipitate (coarse precipitate) having an equivalent circle diameter of 6 μm or more is specified.
　特定された粗大析出物の総面積を求める。粗大析出物の総面積の、視野面積に対する比率（％）を求める。析出物の面積率は体積率に相当するため、求めた粗大析出物の比率を、粗大析出物の総体積率（％）と定義する。 求 め る Calculate the total area of the specified coarse precipitates. The ratio (%) of the total area of coarse precipitates to the visual field area is obtained. Since the area ratio of the precipitate corresponds to the volume ratio, the obtained ratio of the coarse precipitate is defined as the total volume ratio (%) of the coarse precipitate.
　本実施形態によるオーステナイト系耐熱合金の形状は、特に限定されない。オーステナイト系耐熱合金はたとえば、合金管である。オーステナイト系耐熱合金管は、ボイラ用配管や化学プラント用反応管として使用される。オーステナイト系耐熱合金は、板材、棒材、線材であってもよい。 The shape of the austenitic heat-resistant alloy according to this embodiment is not particularly limited. An austenitic heat-resistant alloy is, for example, an alloy tube. Austenitic heat-resistant alloy pipes are used as boiler pipes and chemical plant reaction pipes. The austenitic heat-resistant alloy may be a plate material, a rod material, or a wire material.
　［製造方法］
　本実施形態のオーステナイト系耐熱合金の製造方法の一例として、合金管の製造方法を説明する。本実施形態の製造方法は、上述の化学組成の素材を準備する工程（準備工程）と、準備された素材を熱間鍛造する工程（熱間鍛造工程）と、熱間鍛造された素材に対して熱間加工を実施して中間材を製造する工程（熱間加工工程）と、中間材に対して溶体化熱処理を実施する工程（溶体化熱処理工程）とを備える。以下、各工程について説明する。 [Production method]
As an example of a method for producing the austenitic heat-resistant alloy of the present embodiment, a method for producing an alloy tube will be described. The manufacturing method of the present embodiment includes a step of preparing a material having the above-described chemical composition (preparation step), a step of hot forging the prepared material (hot forging step), and a hot forged material. And a step of producing an intermediate material by performing hot working (hot working step) and a step of performing solution heat treatment on the intermediate material (solution heat treatment step). Hereinafter, each step will be described.
　［準備工程］
　上述の化学組成を有する溶鋼を製造する。溶鋼に対して、必要に応じて周知の脱ガス処理を実施する。溶鋼を用いて、鋳造により素材を製造する。素材は、造塊法によるインゴットであってもよいし、連続鋳造法によるスラブやブルーム、ビレット等の鋳片であってもよい。 [Preparation process]
A molten steel having the above chemical composition is produced. A well-known degassing process is implemented with respect to molten steel as needed. A raw material is manufactured by casting using molten steel. The material may be an ingot obtained by an ingot-making method or a slab such as a slab, bloom or billet obtained by a continuous casting method.
　［熱間鍛造工程］
　製造された素材に対して熱間鍛造を実施して円柱素材を製造する。熱間鍛造では、式（１）で定義される断面減少率を３０％以上にする。
　断面減少率＝１００－（熱間加工後の素材の断面積／熱間鍛造前の素材の断面積）×１００（％）　（１） [Hot forging process]
A cylindrical material is manufactured by hot forging the manufactured material. In hot forging, the cross-section reduction rate defined by the formula (1) is set to 30% or more.
Cross-sectional reduction rate = 100- (cross-sectional area of material after hot working / cross-sectional area of material before hot forging) × 100 (%) (1)
　上述のとおり、鋳造により製造された素材の組織中には、共晶炭化物等の析出物が存在する。これらの析出物は粗大であり、円相当径で６μｍ以上となるものが多数存在する。このような粗大析出物は後工程の溶体化処理でも固溶しにくい。 As described above, precipitates such as eutectic carbides are present in the structure of the material produced by casting. These precipitates are coarse, and there are many that have an equivalent circle diameter of 6 μm or more. Such coarse precipitates are difficult to dissolve in a solution treatment in a later step.
　熱間鍛造工程での断面減少率が３０％以上であれば、熱間鍛造時に粗大析出物が破壊され、サイズが小さくなる。そのため、後工程の溶体化熱処理で析出物が固溶しやすくなる。その結果、円相当径が６μｍ以上の析出物の体積率が５％以下になる。 If the cross-section reduction rate in the hot forging process is 30% or more, coarse precipitates are destroyed during hot forging and the size is reduced. For this reason, the precipitate is easily dissolved in the solution heat treatment in the subsequent step. As a result, the volume ratio of precipitates having an equivalent circle diameter of 6 μm or more is 5% or less.
　好ましい断面減少率は、３５％以上であり、さらに好ましくは、４０％以上である。断面減少率の上限は特に限定されないが、生産性を考慮すれば、９０％である。 The preferable cross-sectional reduction rate is 35% or more, and more preferably 40% or more. Although the upper limit of the cross-section reduction rate is not particularly limited, it is 90% in consideration of productivity.
　［熱間加工工程］
　熱間鍛造された素材（円柱素材）に対して熱間加工を実施して、中間材である合金素管を製造する。たとえば、機械加工により円柱素材中心に貫通孔を形成する。貫通孔が形成された円柱素材に対して熱間押出を実施して、合金素管を製造する。円柱素材を穿孔圧延して合金素管（中間材）を製造してもよい。熱間加工後の中間材に対して冷間加工を実施してもよい。冷間加工はたとえば、冷間引抜等である。以上の工程により、中間材を製造する。 [Hot working process]
Hot working is performed on the hot-forged material (cylindrical material) to manufacture an alloy base tube that is an intermediate material. For example, a through hole is formed in the center of a cylindrical material by machining. Hot extrusion is performed on the cylindrical material in which the through holes are formed, and an alloy base tube is manufactured. A cylindrical raw material (intermediate material) may be manufactured by piercing and rolling a cylindrical material. Cold working may be performed on the intermediate material after hot working. The cold working is, for example, cold drawing or the like. An intermediate material is manufactured by the above process.
　［溶体化熱処理工程］
　製造された中間材に対して溶体化熱処理を実施する。溶体化熱処理により、中間材中の析出物を固溶する。 [Solution heat treatment process]
Solution heat treatment is performed on the manufactured intermediate material. The precipitate in the intermediate material is dissolved by solution heat treatment.
　溶体化熱処理での熱処理温度は１１００～１２５０℃である。熱処理温度が１１００℃未満であれば、析出物が十分に固溶せず、その結果、粗大析出物の体積率が５％を超える。一方、熱処理温度が高すぎれば、オーステナイト粒が粗大化して、製造性が低下する。 The heat treatment temperature in the solution heat treatment is 1100 to 1250 ° C. If the heat treatment temperature is less than 1100 ° C., the precipitate is not sufficiently dissolved, and as a result, the volume fraction of the coarse precipitate exceeds 5%. On the other hand, if the heat treatment temperature is too high, the austenite grains are coarsened and the productivity is lowered.
　熱処理温度が１１００～１２５０℃であれば、析出物が十分に固溶して、粗大析出物の総体積率が５％以下になる。 When the heat treatment temperature is 1100 to 1250 ° C., the precipitate is sufficiently dissolved, and the total volume ratio of the coarse precipitate is 5% or less.
　溶体化熱処理時間は特に限定されない。溶体化熱処理時間はたとえば１分～１時間である。 The solution heat treatment time is not particularly limited. The solution heat treatment time is, for example, 1 minute to 1 hour.
　溶体化熱処理後の中間材に対して、表面に形成したスケールの除去を目的として酸洗処理を施してもよい。酸洗にはたとえば、硝酸と塩酸の混酸溶液を用いる。酸洗時間はたとえば、３０～６０分である。 For the intermediate material after the solution heat treatment, pickling treatment may be performed for the purpose of removing scale formed on the surface. For pickling, for example, a mixed acid solution of nitric acid and hydrochloric acid is used. The pickling time is, for example, 30 to 60 minutes.
　さらに、酸洗処理後の中間材に対して、投射材を用いたブラスト処理を実施してもよい。たとえば、合金管内面に対してブラスト処理を実施する。この場合、表面に加工層を形成し、耐食性（耐酸化性等）が高まる。 Furthermore, a blasting process using a projection material may be performed on the intermediate material after the pickling process. For example, blasting is performed on the inner surface of the alloy tube. In this case, a processed layer is formed on the surface, and corrosion resistance (oxidation resistance and the like) is increased.
　以上の製造方法により、本実施形態のオーステナイト系耐熱合金が製造される。なお、上記では合金管の製造方法について説明した。しかしながら、同様の製造方法（準備工程、熱間鍛造工程、熱間加工工程、溶体化熱処理工程）により、板材、棒材、線材等を製造してもよい。 The austenitic heat-resistant alloy of this embodiment is manufactured by the above manufacturing method. In addition, the manufacturing method of the alloy pipe was demonstrated above. However, you may manufacture a board | plate material, a bar, a wire, etc. with the same manufacturing method (a preparation process, a hot forging process, a hot working process, a solution heat treatment process).
　［製造方法］
　表１に示す化学組成を有する溶鋼を、真空溶解炉を用いて製造した。 [Production method]
Molten steel having the chemical composition shown in Table 1 was produced using a vacuum melting furnace.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記溶鋼を用いて、外径１２０ｍｍの円柱状のインゴット（３０ｋｇ）を製造した。インゴットに対して表２に示す断面減少率で熱間鍛造を実施して、矩形状素材を製造した。矩形状素材に対して熱間圧延及び冷間圧延を実施して、厚さ１．５ｍｍの板状の中間材を製造した。中間材に対して表２に示す熱処理温度で１０分間保持する溶体化処理を実施した。１０分間保持した後、中間材を水冷して、合金板材を製造した。 A cylindrical ingot (30 kg) having an outer diameter of 120 mm was manufactured using the molten steel. The ingot was hot forged at a cross-sectional reduction rate shown in Table 2 to produce a rectangular material. The rectangular material was hot-rolled and cold-rolled to produce a plate-like intermediate material having a thickness of 1.5 mm. The intermediate material was subjected to a solution treatment for 10 minutes at the heat treatment temperature shown in Table 2. After holding for 10 minutes, the intermediate material was water-cooled to produce an alloy sheet.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　［クリープ破断試験］
　製造された合金板材から、試験片を作製した。試験片は、合金板材の厚さ中心部から長手方向（圧延方向）に平行に採取した。試験片は丸棒試験片であり、平行部の直径は６ｍｍ、標点間距離は３０ｍｍであった。試験片を用いて、クリープ破断試験を行った。クリープ破断試験は７００～８００℃の大気雰囲気において実施した。得られた破断強度に基づいて、ラーソン－ミラーパラメータ法によって、７００℃における１．０×１０4時間でのクリープ強度（ＭＰａ）を求めた。 [Creep rupture test]
A test piece was prepared from the manufactured alloy sheet. The test piece was sampled in parallel to the longitudinal direction (rolling direction) from the thickness center of the alloy sheet. The test piece was a round bar test piece, the diameter of the parallel part was 6 mm, and the distance between the gauge points was 30 mm. A creep rupture test was performed using the test piece. The creep rupture test was conducted in an air atmosphere at 700 to 800 ° C. Based on the obtained breaking strength, the creep strength (MPa) at 700 ° C. at 1.0 × 10 4 hours was determined by the Larson-Miller parameter method.
　［シャルピー衝撃試験］
　製造された合金板材に対して、７００℃で８０００時間保持する時効処理を実施した後、水冷した。時効処理後の板材の厚さ方向中央部から、ＪＩＳ　Ｚ２２４２（２００５）に規定されたＶノッチシャルピー衝撃試験片を採取した。ノッチは、合金板材の長手方向に平行に作製した。試験片の幅は５ｍｍ、高さは１０ｍｍ、長さは５５ｍｍであり、ノッチ深さは２ｍｍであった。０℃にて、ＪＩＳ　Ｚ２２４２（２００５）に準拠したシャルピー衝撃試験を実施して、衝撃値（Ｊ／ｃｍ2）を求めた。 [Charpy impact test]
The manufactured alloy sheet was subjected to aging treatment at 700 ° C. for 8000 hours, followed by water cooling. A V-notch Charpy impact test piece defined in JIS Z2242 (2005) was collected from the thickness direction center of the plate after aging treatment. The notch was made parallel to the longitudinal direction of the alloy sheet. The test piece had a width of 5 mm, a height of 10 mm, a length of 55 mm, and a notch depth of 2 mm. At 0 ° C., a Charpy impact test in accordance with JIS Z2242 (2005) was performed to determine an impact value (J / cm 2 ).
　［試験結果］
　試験結果を表２に示す。 [Test results]
The test results are shown in Table 2.
　表２を参照して、試験番号１～試験番号１１の化学組成は適切であり、粗大析出物の体積率が５％以下であった。その結果、クリープ強度は１４０ＭＰa以上であり、優れたクリープ強度を示した。さらに、シャルピー衝撃値が４０Ｊ／ｃｍ2以上であり、長時間の時効処理後であっても優れた靭性を示した。 Referring to Table 2, the chemical compositions of Test No. 1 to Test No. 11 were appropriate, and the volume fraction of coarse precipitates was 5% or less. As a result, the creep strength was 140 MPa or more, indicating an excellent creep strength. Furthermore, the Charpy impact value was 40 J / cm 2 or more, and excellent toughness was exhibited even after long-term aging treatment.
　一方、試験番号１２では、Ｃ含有量が高すぎた。そのため、粗大析出物の体積率が５％を超えた。その結果、クリープ強度が１４０ＭＰa未満であり、シャルピー衝撃値が４０Ｊ／ｃｍ2未満であった。 On the other hand, in test number 12, the C content was too high. Therefore, the volume ratio of the coarse precipitate exceeded 5%. As a result, the creep strength was less than 140 MPa, and the Charpy impact value was less than 40 J / cm 2 .
　試験番号１３では、Ａｌ含有量が低すぎた。そのため、クリープ強度が１４０ＭＰa未満であった。ＮｉＡｌの析出量が少なかったと考えられる。 In test number 13, the Al content was too low. Therefore, the creep strength was less than 140 MPa. It is considered that the amount of NiAl deposited was small.
　試験番号１４では、Ａｌ含有量が高すぎた。そのため、クリープ強度が１４０ＭＰa未満であった。Ａｌ含有量が高すぎたため、組織が安定せず、クリープ強度が低かったと考えられる。 In test number 14, the Al content was too high. Therefore, the creep strength was less than 140 MPa. It is considered that the structure was not stable and the creep strength was low because the Al content was too high.
　試験番号１５では、Ｃｒ含有量が低すぎた。そのため、クリープ強度が１４０ＭＰa未満であった。α－Ｃｒの析出量が少なかったためと考えられる。 In test number 15, the Cr content was too low. Therefore, the creep strength was less than 140 MPa. This is probably because the amount of α-Cr deposited was small.
　試験番号１６では、Ｃｒ含有量が高すぎた。そのため、クリープ強度が１４０ＭＰa未満であった。Ｃｒ含有量が高すぎたため、組織が安定せず、クリープ強度が低かったと考えられる。 In test number 16, the Cr content was too high. Therefore, the creep strength was less than 140 MPa. It is considered that the structure was not stable and the creep strength was low because the Cr content was too high.
　試験番号１７では、熱間鍛造時の断面減少率が３０％未満であった。そのため、粗大析出物の総体積率が５％を超えた。その結果、クリープ強度が１４０ＭＰa未満であり、シャルピー衝撃値が４０Ｊ／ｃｍ2未満であった。 In test number 17, the cross-sectional reduction rate during hot forging was less than 30%. Therefore, the total volume ratio of coarse precipitates exceeded 5%. As a result, the creep strength was less than 140 MPa, and the Charpy impact value was less than 40 J / cm 2 .
　試験番号１８では、溶体化熱処理温度が１１００℃未満であった。そのため、粗大析出物の総体積率が５％を超えた。その結果、クリープ破断強度が１４０ＭＰa未満であり、シャルピー衝撃値が４０Ｊ／ｃｍ2未満であった。 In test number 18, the solution heat treatment temperature was less than 1100 ° C. Therefore, the total volume ratio of coarse precipitates exceeded 5%. As a result, the creep rupture strength was less than 140 MPa, and the Charpy impact value was less than 40 J / cm 2 .
　試験番号１９では、Ｎｂ含有量が高すぎた。そのため、シャルピー衝撃値が４０Ｊ／ｃｍ2未満であった。 In test number 19, the Nb content was too high. Therefore, the Charpy impact value was less than 40 J / cm 2 .
　試験番号２０では、Ｎｂ含有量が低すぎた。そのため、クリープ強度が１４０ＭＰａ未満であった。 In test number 20, the Nb content was too low. Therefore, the creep strength was less than 140 MPa.
　以上、本発明の実施の形態を説明した。しかしながら、上述した実施の形態は本発明を実施するための例示に過ぎない。したがって、本発明は上述した実施の形態に限定されることなく、その趣旨を逸脱しない範囲内で上述した実施の形態を適宜変更して実施することができる。 The embodiment of the present invention has been described above. However, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately changing the above-described embodiment without departing from the spirit thereof.
　本発明のオーステナイト系耐熱合金は、７００℃以上の高温環境で広く使用することができる。特に、７００℃以上の高温環境に曝される発電用ボイラ、化学工業用プラント等における合金管としての用途に特に好適である。 
  The austenitic heat-resistant alloy of the present invention can be widely used in a high temperature environment of 700 ° C. or higher. In particular, it is particularly suitable for use as an alloy pipe in a power generation boiler, a chemical industry plant or the like exposed to a high temperature environment of 700 ° C. or higher.

Claims (5)

  1. 　質量％で、
    　Ｃ：０．０３～０．２５％未満、
    　Ｓｉ：０．０１～２．０％、
    　Ｍｎ：２．０％以下、
    　Ｃｒ：１０～３０％未満、
    　Ｎｉ：２５超～４５％、
    　Ａｌ：２．５超～４．５％未満、
    　Ｎｂ：０．２～３．５％、
    　Ｎ：０．０２５％以下、
    　Ｔｉ：０～０．２％未満、
    　Ｗ：０～６％、
    　Ｍｏ：０～４％、
    　Ｚｒ：０～０．１％、
    　Ｂ：０～０．０１％、
    　Ｃｕ：０～５％、
    　希土類元素：０～０．１％、
    　Ｃａ：０～０．０５％、及び、
    　Ｍｇ：０～０．０５％を含有し、
    　残部がＦｅ及び不純物からなり、
    　不純物中のＰ及びＳが各々、
    　Ｐ：０．０４％以下、及び
    　Ｓ：０．０１％以下の化学組成を有し、
    　組織中において、円相当径が６μｍ以上の析出物の総体積率が５％以下であることを特徴とする、オーステナイト系耐熱合金。     % By mass
    C: 0.03 to less than 0.25%,
    Si: 0.01 to 2.0%,
    Mn: 2.0% or less,
    Cr: 10 to less than 30%,
    Ni: more than 25 to 45%,
    Al: more than 2.5 to less than 4.5%,
    Nb: 0.2 to 3.5%
    N: 0.025% or less,
    Ti: 0 to less than 0.2%,
    W: 0-6%
    Mo: 0-4%,
    Zr: 0 to 0.1%,
    B: 0 to 0.01%
    Cu: 0 to 5%,
    Rare earth elements: 0-0.1%,
    Ca: 0 to 0.05% and
    Mg: 0 to 0.05% contained,
    The balance consists of Fe and impurities,
    P and S in the impurity are each
    P: has a chemical composition of 0.04% or less, and S: 0.01% or less,
    An austenitic heat-resistant alloy, wherein the total volume fraction of precipitates having an equivalent circle diameter of 6 μm or more in the structure is 5% or less.
  2. 　請求項１に記載のオーステナイト系耐熱合金であって、
    　前記化学組成は、
    　Ｔｉ：０．００５～０．２％未満、
    　Ｗ：０．００５～６％、
    　Ｍｏ：０．００５～４％、
    　Ｚｒ：０．０００５～０．１％、及び、
    　Ｂ：０．０００５～０．０１％からなる群から選択される１種又は２種以上を含有することを特徴とする、オーステナイト系耐熱合金。     The austenitic heat-resistant alloy according to claim 1,
    The chemical composition is
    Ti: 0.005 to less than 0.2%,
    W: 0.005 to 6%,
    Mo: 0.005 to 4%,
    Zr: 0.0005 to 0.1%, and
    B: An austenitic heat-resistant alloy containing one or more selected from the group consisting of 0.0005 to 0.01%.
  3. 　請求項１又は請求項２に記載のオーステナイト系耐熱合金であって、
    　前記化学組成は、
    　Ｃｕ：０．０５～５％、及び、
    　希土類元素：０．０００５～０．１％からなる群から選択される１種以上を含有することを特徴とする、オーステナイト系耐熱合金。     The austenitic heat-resistant alloy according to claim 1 or 2,
    The chemical composition is
    Cu: 0.05 to 5%, and
    Rare earth element: An austenitic heat-resistant alloy characterized by containing at least one selected from the group consisting of 0.0005 to 0.1%.
  4. 　請求項１～請求項３のいずれか１項に記載のオーステナイト系耐熱合金であって、
    　前記化学組成は、
    　Ｃａ：０．０００５～０．０５％、及び、
    　Ｍｇ：０．０００５～０．０５％からなる群から選択される１種以上を含有することを特徴とする、オーステナイト系耐熱合金。     The austenitic heat-resistant alloy according to any one of claims 1 to 3,
    The chemical composition is
    Ca: 0.0005 to 0.05%, and
    Mg: One or more selected from the group consisting of 0.0005 to 0.05%, an austenitic heat resistant alloy.
  5. 　請求項１～請求項４のいずれか１項に記載の化学組成を有する素材に対して、３０％以上の断面減少率で熱間鍛造を実施する工程と、
    　熱間鍛造された前記素材に対して熱間加工を実施して中間材を製造する工程と、
    　前記中間材に対して１１００～１２５０℃で溶体化処理を実施する工程とを備えることを特徴とする、オーステナイト系耐熱合金の製造方法。
          A step of hot forging the material having the chemical composition according to any one of claims 1 to 4 at a cross-section reduction rate of 30% or more;
    A process of producing an intermediate material by performing hot working on the hot forged material;
    And a step of performing a solution treatment on the intermediate material at 1100 to 1250 ° C., and a method for producing an austenitic heat-resistant alloy.
PCT/JP2017/000056 2016-01-05 2017-01-04 Austenitic heat-resistant alloy and method for manufacturing same WO2017119415A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US16/067,751 US20190010565A1 (en) 2016-01-05 2017-01-04 Austenitic Heat Resistant Alloy and Method for Producing the Same
CN201780005402.2A CN108474072A (en) 2016-01-05 2017-01-04 Austenitic heat-resistant alloy and its manufacturing method
CA3009770A CA3009770A1 (en) 2016-01-05 2017-01-04 Austenitic heat resistant alloy and method for producing the same
EP17735952.8A EP3401415A4 (en) 2016-01-05 2017-01-04 Austenitic heat-resistant alloy and method for manufacturing same
KR1020187020362A KR102090201B1 (en) 2016-01-05 2017-01-04 Austenitic heat-resistant alloy and its manufacturing method
JP2017560386A JP6493566B2 (en) 2016-01-05 2017-01-04 Austenitic heat-resistant alloy and manufacturing method thereof
SG11201805206PA SG11201805206PA (en) 2016-01-05 2017-01-04 Austenitic heat resistant alloy and method for producing the same

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2016000375 2016-01-05
JP2016-000375 2016-01-08

Publications (1)

Publication Number Publication Date
WO2017119415A1 true WO2017119415A1 (en) 2017-07-13

Family

ID=59274572

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2017/000056 WO2017119415A1 (en) 2016-01-05 2017-01-04 Austenitic heat-resistant alloy and method for manufacturing same

Country Status (8)

Country Link
US (1) US20190010565A1 (en)
EP (1) EP3401415A4 (en)
JP (1) JP6493566B2 (en)
KR (1) KR102090201B1 (en)
CN (1) CN108474072A (en)
CA (1) CA3009770A1 (en)
SG (1) SG11201805206PA (en)
WO (1) WO2017119415A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019131954A1 (en) 2017-12-28 2019-07-04 日本製鉄株式会社 Austenite-based heat-resistant alloy
WO2019189576A1 (en) * 2018-03-28 2019-10-03 日鉄ステンレス株式会社 Alloy sheet and production method thereof
WO2020067444A1 (en) * 2018-09-27 2020-04-02 日本製鉄株式会社 Austenitic alloy
JP2020079437A (en) * 2018-11-14 2020-05-28 日本製鉄株式会社 Austenite stainless steel
JP2020132919A (en) * 2019-02-14 2020-08-31 日本製鉄株式会社 Heat-resistant alloy and method for producing the same
WO2021039266A1 (en) * 2019-08-29 2021-03-04 日本製鉄株式会社 Austenitic heat-resistant steel

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11268195B2 (en) * 2018-01-10 2022-03-08 Nippon Steel Corporation Austenitic heat resistant alloy and method for producing the same
KR102471375B1 (en) * 2018-01-10 2022-11-28 닛폰세이테츠 가부시키가이샤 Austenitic heat-resistant alloy, manufacturing method thereof, and austenitic heat-resistant alloy material
CN109898028B (en) * 2019-03-15 2021-09-28 山西太钢不锈钢股份有限公司 High-temperature oxidation resistant austenitic heat-resistant stainless steel and preparation method and application thereof
CN110079737B (en) * 2019-05-27 2021-04-27 山西太钢不锈钢股份有限公司 Twin crystal strengthened aluminum-containing austenitic heat-resistant stainless steel and preparation method and application thereof
CN110551932A (en) * 2019-09-23 2019-12-10 广东鑫发精密金属科技有限公司 304 thin strip stainless steel battery heating piece and preparation method thereof
CN110484841B (en) * 2019-09-29 2020-09-29 北京钢研高纳科技股份有限公司 Heat treatment method of GH4780 alloy forging
CN115023509A (en) * 2020-01-31 2022-09-06 日本制铁株式会社 Antioxidant for heating alloy material and method for heating alloy material using same
JP2021127517A (en) * 2020-02-14 2021-09-02 日本製鉄株式会社 Austenitic stainless steel material
CN111455161B (en) * 2020-04-08 2021-11-16 山西太钢不锈钢股份有限公司 Method for regulating and controlling structure performance of austenitic heat-resistant stainless steel seamless tube
JPWO2022123812A1 (en) * 2020-12-10 2022-06-16
CN114032440A (en) * 2021-11-23 2022-02-11 北京科技大学 Laves phase strengthened austenitic heat-resistant steel and preparation method thereof
CN115141984B (en) * 2021-11-23 2023-02-24 燕山大学 High-entropy austenitic stainless steel and preparation method thereof
CN115011879B (en) * 2022-06-23 2024-02-06 西北工业大学 Austenitic heat-resistant steel and heat treatment method thereof
CN115233105B (en) * 2022-07-28 2023-03-28 中国核动力研究设计院 Austenitic stainless steel alloy for supercritical gas-cooled reactor fuel cladding and preparation method thereof
CN115233107A (en) * 2022-07-28 2022-10-25 中国核动力研究设计院 Al-containing austenitic stainless steel for supercritical fluid gas-cooled reactor cladding and preparation method thereof
CN115505820B (en) * 2022-09-15 2024-01-05 山西太钢不锈钢股份有限公司 Continuous casting method of niobium-containing high-nitrogen nickel-based alloy
CN115772635A (en) * 2022-11-23 2023-03-10 江苏新华合金有限公司 Cr25Ni20Si2 heat-resistant steel bar and manufacturing method thereof
CN116288029B (en) * 2023-01-06 2023-09-05 清华大学 Light ultra-high strength austenitic stainless steel and preparation method thereof

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5610983B2 (en) * 1975-06-03 1981-03-11
JPS59229468A (en) * 1983-06-09 1984-12-22 Sumitomo Metal Ind Ltd Austenitic stainless steel with resistance to sulfurization at high temperature
JPH02115348A (en) 1988-10-24 1990-04-27 Nippon Steel Corp High al austenitic heat-resistant steel having excellent hot workability
JPH07316751A (en) 1994-05-20 1995-12-05 Nkk Corp Stainless steel excellent in repeated oxidation resistance
US20080304996A1 (en) * 2007-01-04 2008-12-11 Ut-Battelle, Llc High Nb, Ta, and Al Creep- and Oxidation-Resistant Austenitic Stainless Steels
US20130266477A1 (en) * 2012-04-05 2013-10-10 Ut-Battelle, Llc Alumina Forming Iron Base Superalloy
JP2013227644A (en) 2012-03-28 2013-11-07 Nippon Steel & Sumitomo Metal Corp Austenite-based heat resistant alloy
JP2014043621A (en) 2012-08-28 2014-03-13 Nippon Steel & Sumitomo Metal Austenitic heat resistant steel
CN103774056A (en) * 2014-01-13 2014-05-07 江苏大学 Novel austenitic stainless steel for ultra (super) critical coal-fired unit
CN104561821A (en) * 2014-11-13 2015-04-29 江苏大学 Austenitic stainless steel and preparation method thereof

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5923855A (en) * 1982-07-28 1984-02-07 Nippon Kokan Kk <Nkk> Steel having high strength at high temperature containing carbide forming element
JPS60262945A (en) * 1984-06-11 1985-12-26 Kawasaki Steel Corp Oxidation resistant austenitic steel and its manufacture
JP3515770B2 (en) * 2001-09-05 2004-04-05 住友電工スチールワイヤー株式会社 Heat-resistant steel wire and spring
JP2004107777A (en) * 2002-09-20 2004-04-08 Toshiba Corp Austenitic heat resistant alloy, production method therefor and steam turbine parts
JP5610983B2 (en) * 2010-11-01 2014-10-22 三菱電機株式会社 Radar equipment
CN104073739B (en) * 2014-07-25 2016-09-21 太原钢铁(集团)有限公司 A kind of manufacture method of heat-resistance stainless steel seamless steel pipe and rustless steel and seamless steel pipe

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5610983B2 (en) * 1975-06-03 1981-03-11
JPS59229468A (en) * 1983-06-09 1984-12-22 Sumitomo Metal Ind Ltd Austenitic stainless steel with resistance to sulfurization at high temperature
JPH02115348A (en) 1988-10-24 1990-04-27 Nippon Steel Corp High al austenitic heat-resistant steel having excellent hot workability
JPH07316751A (en) 1994-05-20 1995-12-05 Nkk Corp Stainless steel excellent in repeated oxidation resistance
US20080304996A1 (en) * 2007-01-04 2008-12-11 Ut-Battelle, Llc High Nb, Ta, and Al Creep- and Oxidation-Resistant Austenitic Stainless Steels
JP2013227644A (en) 2012-03-28 2013-11-07 Nippon Steel & Sumitomo Metal Corp Austenite-based heat resistant alloy
US20130266477A1 (en) * 2012-04-05 2013-10-10 Ut-Battelle, Llc Alumina Forming Iron Base Superalloy
JP2014043621A (en) 2012-08-28 2014-03-13 Nippon Steel & Sumitomo Metal Austenitic heat resistant steel
CN103774056A (en) * 2014-01-13 2014-05-07 江苏大学 Novel austenitic stainless steel for ultra (super) critical coal-fired unit
CN104561821A (en) * 2014-11-13 2015-04-29 江苏大学 Austenitic stainless steel and preparation method thereof

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
See also references of EP3401415A4 *
YAMAMOTO,Y. ET AL.: "Alloying effects on creep and oxidation resistance of austenitic stainless steel alloys employing intermetallic precipitates", INTERMETALLICS, vol. 16, no. 3, March 2008 (2008-03-01), pages 453 - 462, XP022500387 *
ZHOU,D.Q ET AL.: "Precipitate characteristics and their effects on the high-temperature creep resistance of alumina-forming austenitic stainless steels", MATERIALS SCIENCE & ENGINEERING A, vol. 622, 12 January 2015 (2015-01-12), pages 91 - 100, XP029115889 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019131954A1 (en) 2017-12-28 2019-07-04 日本製鉄株式会社 Austenite-based heat-resistant alloy
CN111542639A (en) * 2017-12-28 2020-08-14 日本制铁株式会社 Austenitic heat-resistant alloy
WO2019189576A1 (en) * 2018-03-28 2019-10-03 日鉄ステンレス株式会社 Alloy sheet and production method thereof
JP6609727B1 (en) * 2018-03-28 2019-11-20 日鉄ステンレス株式会社 Alloy plate and manufacturing method thereof
WO2020067444A1 (en) * 2018-09-27 2020-04-02 日本製鉄株式会社 Austenitic alloy
JP2020079437A (en) * 2018-11-14 2020-05-28 日本製鉄株式会社 Austenite stainless steel
JP7131318B2 (en) 2018-11-14 2022-09-06 日本製鉄株式会社 austenitic stainless steel
JP2020132919A (en) * 2019-02-14 2020-08-31 日本製鉄株式会社 Heat-resistant alloy and method for producing the same
JP7205277B2 (en) 2019-02-14 2023-01-17 日本製鉄株式会社 Heat-resistant alloy and its manufacturing method
WO2021039266A1 (en) * 2019-08-29 2021-03-04 日本製鉄株式会社 Austenitic heat-resistant steel
JPWO2021039266A1 (en) * 2019-08-29 2021-03-04
JP7265203B2 (en) 2019-08-29 2023-04-26 日本製鉄株式会社 Austenitic heat resistant steel

Also Published As

Publication number Publication date
EP3401415A1 (en) 2018-11-14
CA3009770A1 (en) 2017-07-13
US20190010565A1 (en) 2019-01-10
KR102090201B1 (en) 2020-04-23
EP3401415A4 (en) 2019-08-07
JPWO2017119415A1 (en) 2018-09-27
KR20180095640A (en) 2018-08-27
CN108474072A (en) 2018-08-31
JP6493566B2 (en) 2019-04-03
SG11201805206PA (en) 2018-07-30

Similar Documents

Publication Publication Date Title
JP6493566B2 (en) Austenitic heat-resistant alloy and manufacturing method thereof
JP6705508B2 (en) NiCrFe alloy
JP5201297B2 (en) Austenitic stainless steel and method for producing austenitic stainless steel
JP7052807B2 (en) Manufacturing method of Ni-based alloy and Ni-based alloy
WO2021033672A1 (en) Duplex stainless steel material
JP6816779B2 (en) Austenitic heat-resistant alloy member and its manufacturing method
US20210062314A1 (en) Austenitic heat resistant alloy
JP2021167445A (en) Duplex stainless steel
US20190127832A1 (en) Austenitic Stainless Steel
JP6520546B2 (en) Austenitic heat-resistant alloy member and method of manufacturing the same
JP4070695B2 (en) Heat-resistant alloy parts material
WO2023132339A1 (en) Fe-Cr-Ni ALLOY MATERIAL
WO2020067444A1 (en) Austenitic alloy
WO2021225103A1 (en) Duplex stainless steel seamless pipe
JP2021080564A (en) Austenitic stainless steel material
JP6627662B2 (en) Austenitic stainless steel
JP7464817B2 (en) Austenitic stainless steel
WO2023238851A1 (en) Austenitic stainless alloy material
JP6575266B2 (en) Austenitic stainless steel
JP2017039983A (en) Seamless steel pipe and method for producing the same
JP2021080565A (en) Austenitic stainless steel material
US20220235445A1 (en) Ferritic heat-resistant steel
JP2020079437A (en) Austenite stainless steel

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17735952

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2017560386

Country of ref document: JP

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 11201805206P

Country of ref document: SG

ENP Entry into the national phase

Ref document number: 3009770

Country of ref document: CA

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 20187020362

Country of ref document: KR

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 1020187020362

Country of ref document: KR