US20250230532A1 - Alloy - Google Patents

Alloy

Info

Publication number
US20250230532A1
US20250230532A1 US18/852,689 US202318852689A US2025230532A1 US 20250230532 A1 US20250230532 A1 US 20250230532A1 US 202318852689 A US202318852689 A US 202318852689A US 2025230532 A1 US2025230532 A1 US 2025230532A1
Authority
US
United States
Prior art keywords
alloy
content
further preferably
present
high temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
US18/852,689
Other languages
English (en)
Inventor
Takahiro Osuki
Shohgo AOTA
Kana JOTOKU
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel Corp
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 Nippon Steel Corp filed Critical Nippon Steel Corp
Assigned to NIPPON STEEL CORPORATION reassignment NIPPON STEEL CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AOTA, Shohgo, JOTOKU, Kana, OSUKI, TAKAHIRO
Publication of US20250230532A1 publication Critical patent/US20250230532A1/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • 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
    • 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
    • C21D6/001—Heat treatment of ferrous alloys containing 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
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
    • C21D7/10—Modifying the physical properties of iron or steel by deformation by cold working of the whole cross-section, e.g. of concrete reinforcing bars
    • 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 of ferrous metals or ferrous alloys 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties of ferrous metals or ferrous alloys 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
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • 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
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • 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
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • 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
    • 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
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/28—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for plain shafts
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals

Definitions

  • the present disclosure relates to an alloy, and more particularly relates to an alloy which can be utilized in a high temperature environment.
  • Alloy 800, Alloy 800H, and Alloy 800HT each contain large amounts of Cr and Ni. Therefore, it is known that these alloys are excellent in corrosion resistance at high temperature. These alloys also contain Al and Ti. Therefore, in these alloys, a gamma-prime ( ⁇ ′) phase (Ni 3 (Al, Ti)) is formed in the alloy during use in a high temperature environment. Because these alloys are precipitation-strengthened by formation of the ⁇ ′ phase, these alloys have excellent creep strength.
  • Patent Literature 1 discloses a technique for increasing the stress relaxation cracking resistance of an alloy containing Al and Ti.
  • Patent Literature 1 focuses on the ⁇ ′ phase that forms in an alloy during use in a high temperature environment.
  • the chemical composition of the alloy is adjusted in order to form an appropriate amount of ⁇ ′ phase during use in a high temperature environment. It is described in Patent Literature 1 that by this means, excellent stress relaxation cracking resistance is obtained during use in a high temperature environment.
  • An objective of the present disclosure is to provide an alloy which has sufficient creep strength in a high temperature environment and which is capable of achieving both excellent stress relaxation cracking resistance and excellent weld hot cracking resistance.
  • An alloy according to the present disclosure has a chemical composition consisting of, in mass %,
  • the alloy according to the present disclosure has sufficient creep strength in a high temperature environment, and is capable of achieving both excellent stress relaxation cracking resistance and excellent weld hot cracking resistance.
  • FIG. 1 is a view for describing a mechanism by which stress relaxation cracking occurs during use in a high temperature environment in an alloy in which the content of each element in the chemical composition is within the range of the present embodiment.
  • the present inventors initially conducted studies from the viewpoint of the chemical composition with regard to an alloy which has sufficient creep strength in a high temperature environment, and which is capable of achieving both excellent stress relaxation cracking resistance and excellent weld hot cracking resistance.
  • an alloy has a chemical composition consisting of, in mass %, C: 0.050 to 0.100%, Si: 1.00% or less, Mn: 1.50% or less, P: 0.035% or less, S: 0.0015% or less, Cr: 19.00 to 23.00%, Ni: 30.00 to 35.00%, N: 0.100% or less, Al: 0.15 to 0.70%, Ti: 0.15 to 0.70%, B: 0.0010 to 0.0050%, Nb: 0 to 0.30%, Ta: 0 to 0.50%, V: 0 to 1.00%, Zr: 0 to 0.10%, Hf: 0 to 0.10%, Cu: 0 to 1.00%, Mo: 0 to 1.00%, W: 0 to 1.0
  • the present inventors also investigated means for increasing creep strength in a high temperature environment in an alloy having the aforementioned chemical composition. As a result, the present inventors discovered that in an alloy in which the content of each element in the chemical composition is within the aforementioned range, if the following Formula (1) is satisfied, the creep strength in a high temperature environment sufficiently increases:
  • TiC forms in Cr-depleted zones.
  • a certain amount of TiC is already present in the alloy prior to being used in a high temperature environment. Therefore, formation of TiC is saturated in the initial stage of the stress relaxation process. Further, after the formation of TiC is saturated, the TiC that has already been formed coarsens. As a result of the TiC coarsening, dislocations that had been trapped by the TiC are removed from the TiC. As a result, the creep strain amount accumulated in the Cr-depleted zones decreases. Therefore, a curve of the creep strain amount accumulated in the Cr-depleted zones becomes like a curve IS 1 shown in FIG. 1 .
  • the alloy according to the present embodiment which has been completed based on the above findings, is as follows.
  • the alloy of the present embodiment has the following features.
  • the alloy of the present embodiment satisfies the aforementioned Feature 1 to Feature 3. Therefore, the alloy of the present embodiment has sufficient creep strength in a high temperature environment, and enables the achievement of both resistance.
  • Feature 1 to Feature 3 are described.
  • the chemical composition of the alloy of the present embodiment contains the following elements.
  • Carbon (C) increases the creep strength of the alloy in a high temperature environment. If the content of C is less than 0.050%, the aforementioned advantageous effect will not be sufficiently obtained even if the contents of other elements are within the range of the present embodiment.
  • C if the content of C is more than 0.100%, even if the contents of other elements are within the range of the present embodiment, C will form M 23 C 6 -type Cr carbides at grain boundaries. In such case, Cr-depleted zones will form at the grain boundaries. Consequently, the stress relaxation cracking resistance of the alloy will decrease.
  • the content of C is 0.050 to 0.100%.
  • a preferable lower limit of the content of C is 0.053%, more preferably is 0.055%, further preferably is 0.057%, and further preferably is 0.060%.
  • a preferable upper limit of the content of C is 0.095%, more preferably is 0.090%, further preferably is 0.085%, and further preferably is 0.080%.
  • Si Silicon
  • Si is unavoidably contained.
  • the content of Si is more than 0%.
  • Si deoxidizes the alloy in the steelmaking process.
  • Si also increases the oxidation resistance of the alloy in a high temperature environment. If even a small amount of Si is contained, the aforementioned advantageous effects will be obtained to a certain extent even when the contents of other elements are within the range of the present embodiment. However, if the content of Si is more than 1.00%, the weld hot cracking resistance will decrease even if the contents of other elements are within the range of the present embodiment. Therefore, the content of Si is 1.00% or less.
  • Manganese (Mn) is unavoidably contained.
  • the content of Mn is more than 0%.
  • Mn deoxidizes a weld zone of the alloy during welding. Mn also stabilizes austenite. If even a small amount of Mn is contained, the aforementioned advantageous effects will be obtained to a certain extent.
  • the content of Mn is more than 1.50%, even if the contents of other elements are within the range of the present embodiment, sigma phase (o phase) will easily form during use in a high temperature environment. The o phase will reduce the toughness and creep ductility of the alloy in a high temperature environment. Therefore, the content of Mn is 1.50% or less.
  • a preferable lower limit of the content of Mn is 0.01%, more preferably is 0.05%, further preferably is 0.10%, further preferably is 0.40%, further preferably is 0.50%, and further preferably is 0.60%.
  • a preferable upper limit of the content of Mn is 1.45%, more preferably is 1.40%, further preferably is 1.35%, further preferably is 1.30%, further preferably is 1.25%, and further preferably is 1.20%.
  • Phosphorus (P) is unavoidably contained. That is, the content of P is more than 0%. P segregates to grain boundaries of the alloy during welding with large heat input. If the content of P is more than 0.035%, even if the contents of other elements are within the range of the present embodiment, the aforementioned segregation will occur and the stress relaxation cracking resistance will decrease. Therefore, the content of P is 0.035% or less.
  • the content of P is preferably as low as possible. However, excessively reducing the content of P will raise the production cost of the alloy. Therefore, when normal industrial manufacturing is taken into consideration, a preferable lower limit of the content of P is 0.001%, more preferably is 0.002%, and further preferably is 0.005%.
  • Sulfur(S) is unavoidably contained.
  • the content of S is more than 0%. S segregates to grain boundaries of the alloy during welding with large heat input. If the content of S is more than 0.0015%, even if the contents of other elements are within the range of the present embodiment, the aforementioned segregation will occur and the stress relaxation cracking resistance will decrease. Therefore, the content of S is 0.0015% or less.
  • the content of S is preferably as low as possible. However, excessively reducing the content of S will raise the production cost of the alloy. Therefore, when normal industrial manufacturing is taken into consideration, a preferable lower limit of the content of S is 0.0001%, and more preferably is 0.0002%.
  • a preferable upper limit of the content of S is 0.0012%, more preferably is 0.0010%, further preferably is 0.0008%, and further preferably is 0.0006%.
  • Chromium (Cr) increases the corrosion resistance of the alloy in a high temperature environment. If the content of Cr is less than 19.00%, the aforementioned advantageous effect will not be sufficiently obtained even if the contents of other elements are within the range of the present embodiment. On the other hand, if the content of Cr is more than 23.00%, the stability of austenite in a high temperature environment will decrease even if the contents of other elements are within the range of the present embodiment. In such case, the creep strength of the alloy will decrease. Therefore, the content of Cr is 19.00 to 23.00%.
  • a preferable lower limit of the content of Cr is 19.20%, more preferably is 19.40%, and further preferably is 19.60%.
  • a preferable upper limit of the content of Cr is 22.50%, more preferably is 22.00%, further preferably is 21.50%, further preferably is 21.00%, further preferably is 20.50%, and further preferably is 20.00%.
  • Nickel (Ni) stabilizes austenite and increases the creep strength of the alloy in a high temperature environment. If the content of Ni is less than 30.00%, the aforementioned advantageous effect will not be sufficiently obtained even if the contents of other elements are within the range of the present embodiment. On the other hand, if the content of Ni is more than 35.00%, the aforementioned advantageous effect will be saturated. In addition, the raw material cost will increase. Therefore, the content of Ni is 30.00 to 35.00%.
  • a preferable lower limit of the content of Ni is 30.20%, more preferably is 30.40%, further preferably is 30.60%, further preferably is 30.80%, further preferably is 31.20%, further preferably is 31.40%, and further preferably is 31.60%.
  • a preferable upper limit of the content of Ni is 34.50%, more preferably is 34.00%, further preferably is 33.50%, and further preferably is 33.00%.
  • N Nitrogen
  • the content of N is more than 0%.
  • N dissolves in the matrix (parent phase) and stabilizes austenite.
  • the dissolved N also forms fine nitrides in the alloy during use in a high temperature environment.
  • the fine nitrides strengthen Cr-depleted zones, and therefore increase the stress relaxation cracking resistance of the alloy.
  • the fine nitrides that are formed during use in a high temperature environment also increase the creep strength by precipitation strengthening. If even a small amount of N is contained, the aforementioned advantageous effects will be obtained to a certain extent.
  • the content of N is more than 0.100%, coarse TiN will form even if the contents of other elements are within the range of the present embodiment.
  • the coarse TiN will decrease the toughness of the alloy. Therefore, the content of N is 0.100% or less.
  • a preferable lower limit of the content of N is 0.001%.
  • a preferable upper limit of the content of N is 0.090%, more preferably is 0.080%, further preferably is 0.070%, further preferably is 0.060%, further preferably is 0.050%, further preferably is 0.040%, further preferably is 0.030%, further preferably is 0.020%, and further preferably is 0.010%.
  • Aluminum (Al) deoxidizes the alloy in the steelmaking process. Al also increases the oxidation resistance of the alloy in a high temperature environment. In addition, Al forms a ⁇ ′ phase in high temperature environments and thereby increases the creep strength of the alloy in high temperature environments. If the content of Al is less than 0.15%, the aforementioned advantageous effect will not be sufficiently obtained even if the contents of other elements are within the range of the present embodiment.
  • the content of Al is 0.15 to 0.70%.
  • a preferable lower limit of the content of Al is 0.17%, more preferably is 0.19%, further preferably is 0.21%, and further preferably is 0.23%.
  • a preferable upper limit of the content of Al is 0.65%, more preferably is 0.60%, further preferably is 0.57%, further preferably is 0.55%, further preferably is 0.53%, further preferably is 0.51%, further preferably is 0.45%, and further preferably is 0.40%.
  • the term “content of Al” means the content (mass %) of so-called “total Al”.
  • Titanium (Ti) combines with Ni and Al in a high temperature environment to form a ⁇ ′ phase, and thereby increases the creep strength of the alloy in a high temperature environment. If the content of Ti is less than 0.15%, the aforementioned advantageous effect will not be sufficiently obtained even if the contents of other elements are within the range of the present embodiment. On the other hand, if the content of Ti is more than 0.70%, coarse TiC will form even if the contents of other elements are within the range of the present embodiment. In this case, during welding of the alloy, the weld hot cracking resistance in a heat affected zone of the alloy will decrease. In addition, if the content of Ti is more than 0.70%, a large amount of ⁇ ′ phase will be formed during the process for producing the alloy. In such case, the hot workability during the process for producing the alloy will decrease. Therefore, the content of Ti is 0.15 to 0.70%.
  • a preferable lower limit of the content of Ti is 0.17%, more preferably is 0.19%, further preferably is 0.21%, and further preferably is 0.25%.
  • B Boron (B) segregates to grain boundaries in a high temperature environment, and thereby increases the grain boundary strength.
  • B increases the stress relaxation cracking resistance of the alloy. If the content of B is less than 0.0010%, the aforementioned advantageous effect will not be sufficiently obtained even if the contents of other elements are within the range of the present embodiment. On the other hand, if the content of B is more than 0.0050%, even if the contents of other elements are within the range of the present embodiment, B will promote the formation of Cr carbides at the grain boundaries. In such case, the stress relaxation cracking resistance of the alloy will decrease. Therefore, the content of B is 0.0010 to 0.0050%.
  • a preferable lower limit of the content of B is 0.0012%, more preferably is 0.0014%, and further preferably is 0.0015%.
  • a preferable upper limit of the content of B is 0.0045%, more preferably is 0.0040%, further preferably is 0.0035%, and further preferably is 0.0030%.
  • the balance of the chemical composition of the alloy according to the present embodiment is Fe and impurities.
  • impurities means substances which are mixed in from ore and scrap used as the raw material or from the production environment or the like when industrially producing the alloy, and which are not intentionally contained but are permitted within a range that does not adversely affect the alloy of the present embodiment.
  • Representative examples of impurities include Sn, As, Zn, Pb and Sb. The total content of these impurities is 0.1% or less.
  • the chemical composition of the alloy of the present embodiment may further contain, in lieu of a part of Fe, one or more elements selected from the group consisting of:
  • the chemical composition of the alloy according to the present embodiment may further contain one or more elements selected from the group consisting of Nb, Ta, V, Zr and Hf in lieu of a part of Fe.
  • Each of these elements combines with C to form carbides, thereby lowering the amount of dissolved C.
  • Niobium (Nb) is an optional element, and does not have to be contained.
  • the content of Nb may be 0%.
  • Nb When Nb is contained, that is, when the content of Nb is more than 0%, Nb combines with C to form carbides. By forming carbides and thereby immobilizing C, the dissolved C amount in the alloy decreases. By this means, in a high temperature environment, formation of Cr carbides at grain boundaries is suppressed. Consequently, the formation of Cr-depleted zones is suppressed. As a result, the stress relaxation cracking resistance of the alloy increases. In addition, during use in a high temperature environment, Nb forms fine nitrides in the alloy, together with N.
  • the fine nitrides strengthen Cr-depleted zones, and thus the stress relaxation cracking resistance of the alloy increases.
  • the fine nitrides that are formed during use in a high temperature environment also increase the creep strength by precipitation strengthening. If even a small amount of Nb is contained, the aforementioned advantageous effect will be obtained to a certain extent.
  • the content of Nb is more than 0.30%, even if the contents of other elements are within the range of the present embodiment, during welding of the alloy, the weld hot cracking resistance in a heat affected zone of the alloy will decrease. Therefore, the content of Nb is 0 to 0.30%.
  • a preferable upper limit of the content of Nb is 0.25%, more preferably is 0.20%, and further preferably is 0.15%.
  • the content of Ta is more than 0.50%, even if the contents of other elements are within the range of the present embodiment, during welding of the alloy, the weld hot cracking resistance in a heat affected zone of the alloy will decrease. Therefore, the content of Ta is 0 to 0.50%.
  • a preferable lower limit of the content of Ta is 0.01%, more preferably is 0.02%, further preferably is 0.05%, and further preferably is 0.08%.
  • a preferable upper limit of the content of Ta is 0.45%, more preferably is 0.40%, further preferably is 0.35%, and further preferably is 0.30%.
  • Vanadium (V) is an optional element, and does not have to be contained.
  • the content of V may be 0%.
  • V When V is contained, that is, when the content of V is more than 0%, V combines with C to form carbides.
  • carbides By forming carbides and thereby immobilizing C, the dissolved C amount in the alloy decreases.
  • formation of Cr carbides at grain boundaries is suppressed. Consequently, the formation of Cr-depleted zones is suppressed. As a result, the stress relaxation cracking resistance of the alloy increases. If even a small amount of V is contained, the aforementioned advantageous effect will be obtained to a certain extent.
  • the content of V is more than 1.00%, even if the contents of other elements are within the range of the present embodiment, during welding of the alloy, the weld hot cracking resistance in a heat affected zone of the alloy will decrease. Therefore, the content of V is 0 to 1.00%.
  • Zirconium (Zr) is an optional element, and does not have to be contained.
  • the content of Zr may be 0%.
  • Zr When Zr is contained, that is, when the content of Zr is more than 0%, Zr combines with C to form carbides. By forming carbides and thereby immobilizing C, the dissolved C amount in the alloy decreases. By this means, in a high temperature environment, formation of Cr carbides at grain boundaries is suppressed. Consequently, the formation of Cr-depleted zones is suppressed. As a result, the stress relaxation cracking resistance of the alloy increases. If even a small amount of Zr is contained, the aforementioned advantageous effect will be obtained to a certain extent.
  • the content of Zr is more than 0.10%, even if the contents of other elements are within the range of the present embodiment, during welding of the alloy, the weld hot cracking resistance in a heat affected zone of the alloy will decrease. Therefore, the content of Zr is 0 to 0.10%.
  • a preferable lower limit of the content of Zr is 0.01%, and more preferably is 0.02%.
  • a preferable upper limit of the content of Zr is 0.09%, more preferably is 0.08%, further preferably is 0.07%, and further preferably is 0.06%.
  • Copper (Cu) is an optional element, and does not have to be contained.
  • the content of Cu may be 0%.
  • Cu When Cu is contained, that is, when the content of Cu is more than 0%, during use of the alloy in a high temperature environment, Cu precipitates as a Cu phase in the grains. The creep strength of the alloy is increased by this precipitation strengthening. If even a small amount of Cu is contained, the aforementioned advantageous effect will be obtained to a certain extent.
  • a preferable lower limit of the content of Cu is 0.01%, more preferably is 0.02%, further preferably is 0.05%, further preferably is 0.10%, further preferably is 0.15%, and further preferably is 0.20%.
  • a preferable upper limit of the content of Cu is 0.90%, more preferably is 0.80%, further preferably is 0.70%, further preferably is 0.60%, further preferably is 0.55%, and further preferably is 0.50%.
  • Molybdenum (Mo) is an optional element, and does not have to be contained.
  • the content of Mo may be 0%.
  • Mo When Mo is contained, that is, when the content of Mo is more than 0%, during use of the alloy in a high temperature environment, Mo increases the creep strength of the alloy by solid-solution strengthening. If even a small amount of Mo is contained, the aforementioned advantageous effect will be obtained to a certain extent.
  • the content of Mo is more than 1.00%, even if the contents of other elements are within the range of the present embodiment, intermetallic compounds such as Laves phases will form within the grains. In such case, secondary induced precipitation hardening will increase and the strength difference between the inside of the grains and the grain boundaries will be large. Consequently, the stress relaxation cracking resistance will decrease. Therefore, the content of Mo is 0 to 1.00%.
  • a preferable lower limit of the content of Mo is 0.01%, more preferably is 0.02%, further preferably is 0.03%, further preferably is 0.04%, further preferably is 0.05%, further preferably is 0.10%, further preferably is 0.20%, and further preferably is 0.30%.
  • Tungsten (W) is an optional element, and does not have to be contained.
  • the content of W may be 0%.
  • W is contained, that is, when the content of W is more than 0%, during use of the alloy in a high temperature environment, W increases the creep strength of the alloy by solid-solution strengthening. If even a small amount of W is contained, the aforementioned advantageous effect will be obtained to a certain extent.
  • F1 is 1.20 or more, an excessively large amount of the ⁇ ′ phase will form in the alloy. In such case, the weld hot cracking resistance of the alloy will decrease. Therefore, F1 is to be more than 0.60 to less than 1.20.
  • a preferable lower limit of F1 is 0.62, more preferably is 0.64, further preferably is 0.66, further preferably is 0.68, and further preferably is 0.70.
  • a preferable upper limit of F1 is 1.15, more preferably is 1.10, further preferably is 1.05, further preferably is 1.00, and further preferably is 0.95.
  • F2 is an index of the stress relaxation cracking resistance of the alloy in a high temperature environment.
  • the content of Ti is made greater than the content of Al.
  • the alloy contains a certain amount of TiC. Therefore, the grains in the alloy are refined by the TiC. As a result, the creep rupture elongation of the alloy in a high temperature environment increases.
  • the alloy of the present embodiment by making the content of Ti greater than the content of Al, formation of TiC in the initial stage of a stress relaxation process is saturated. After the formation of TiC is saturated, the TiC coarsens with the passage of time. As a result, the amount of creep strain that is accumulated in Cr-depleted zones reaches a peak in the initial stage of the stress relaxation process.
  • a more preferable lower limit of [Ti] R is 0.055, further preferably is 0.060, further preferably is 0.065, further preferably is 0.070, and further preferably is 0.075.
  • a method for producing the alloy of the present embodiment that satisfies Feature 1 to Feature 4 will now be described.
  • the production method described hereunder is one example of a method for producing the alloy of the present embodiment. Therefore, an alloy that satisfies Feature 1 to Feature 4 may also be produced by a production method other than the production method described hereunder. However, the production method described hereunder is a preferable example of a method for producing the alloy of the present embodiment.
  • a method for producing the alloy of the present embodiment includes the following processes.
  • a heat treatment temperature T2 (° C.) in the heat treatment process, and a holding time t2 (mins) at the heat treatment temperature T2 are within the following ranges.
  • a starting material having a chemical composition according to the above Feature 1 is prepared.
  • the starting material may be supplied by a third party or may be produced.
  • the starting material may be an ingot, or may be a slab, a bloom, or a billet.
  • the starting material is produced by the following method.
  • a molten steel that has the chemical composition described above is produced.
  • the produced molten steel is used to produce an ingot by an ingot-making process.
  • the produced molten steel may also be used to produce a slab, a bloom, or a billet by a continuous casting process.
  • Hot working may be performed on the produced ingot, slab, or bloom to produce a billet.
  • hot forging may be performed on the ingot to produce a cylindrical billet, and the billet may be used as the starting material.
  • the temperature of the starting material immediately before the start of the hot forging is, for example, 1000 to 1300° C.
  • the method for cooling the starting material after hot forging is not particularly limited.
  • the intermediate alloy for example, may be an alloy pipe, may be an alloy plate, or may be an alloy bar.
  • the intermediate alloy is an alloy pipe
  • the following working is performed in the hot working process.
  • a cylindrical starting material is prepared.
  • a through-hole is formed along the central axis in the cylindrical starting material by machining.
  • the cylindrical starting material in which the through-hole has been formed is heated.
  • the heated cylindrical starting material is then subjected to a hot-extrusion process, which is typified by the Ugine-Sejournet process, to produce an intermediate alloy (alloy pipe).
  • a hollow forging process may be performed instead of the hot extrusion process.
  • the intermediate alloy is an alloy plate
  • one or a plurality of rolling mills equipped with a pair of work rolls is used in the hot working process.
  • the starting material such as a slab is heated.
  • the heated starting material is subjected to hot working using the rolling mill to produce an alloy plate.
  • condition 3 is satisfied.
  • condition 4 is satisfied.
  • the intermediate alloy After being held at the heat treatment temperature T2 (° C.) for the holding time t2 (mins), the intermediate alloy is cooled. Rapid cooling (water cooling) is preferable as the cooling method.
  • condition 5 is also satisfied.
  • FC influences the amount of TiC in the alloy after production, similarly to FA and FB. If FC is 0.30 or more, it will be easy to obtain a sufficient amount of TiC in the alloy after production. Therefore, [Ti] R will be higher than 0.050.
  • FC is 0.30 or more.
  • FC is 0.33, further preferably is 0.35, and further preferably is 0.38.
  • the upper limit of FC is not particularly limited.
  • the upper limit of FC is, for example, 0.60.
  • the alloy of the present embodiment can be produced by the processes described above.
  • the production method described above is one example of a method for producing the alloy of the present embodiment. Therefore, a method for producing the alloy of the present embodiment is not limited to the above production method. As long as Feature 1 to Feature 3 are satisfied, or Feature 1 to Feature 4 are satisfied, a method for producing the alloy is not limited to the production method described above.
  • a welded joint of the alloy of the present embodiment can be produced by the following method.
  • the alloy of the present embodiment is prepared as a base metal.
  • a bevel is then formed in the prepared base metal.
  • a bevel is formed in an end of the base metal by a well-known processing method.
  • the bevel shape may be a V shape, may be a U shape, may be an X shape, or may be a shape other than a V shape, a U shape or an X shape.
  • Welding is performed on the prepared base metal to produce a welded joint.
  • two base metals in which a bevel has been formed are prepared.
  • the bevels of the prepared base metals are butted together.
  • the portion where the pair of bevels are butted together is then subjected to welding using a well-known welding consumable to thereby form a weld metal having the aforementioned chemical composition.
  • the welding consumable is, for example, a welding consumable with the AWS classification: ER NiCr-3.
  • the welding consumable is not limited to this example.
  • the welding method may be one in which the weld metal is produced by single-pass welding or by multi-pass welding.
  • the welding methods include, for example, gas tungsten arc welding (GTAW), shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), gas metal arc welding (GMAW), and submerged arc welding (SAW).
  • GTAW gas tungsten arc welding
  • SMAW shielded metal arc welding
  • FCAW flux-cored arc welding
  • GMAW gas metal arc welding
  • SAW submerged arc welding
  • a square-shaped test specimen was taken from a position located at the center position of the plate width and the center position of the plate thickness of the alloy (alloy plate) of each test number.
  • a cross section perpendicular to the longitudinal direction of the square-shaped test specimen was a rectangle with dimensions of 10 mm ⁇ 10 mm.
  • the length of the square-shaped test specimen was made 100 mm.
  • the longitudinal direction of the square-shaped test specimen was parallel with the rolling direction of the alloy (alloy plate).
  • a stress relaxation test in accordance with ASTM E328-02 was conducted using the simulated HAZ test specimen. Specifically, a test specimen for a stress relaxation test was prepared from the simulated HAZ test specimen. The test specimen was formed into a flanged creep test specimen having a length of 80 mm and a gauge length GL of 30 mm. An initial cold strain of 20% was applied to the test specimen using a test jig for deflection displacement loading. The test jig to which the test specimen to which the cold strain had been applied was provided was placed into a heating furnace and held at 650° C. for 300 hours.
  • test specimen having a thickness of 12 mm, a width of 40 mm, and a length of 300 mm was taken, which was centered on the central position of the plate width and the central position of the plate thickness of the alloy (alloy plate).
  • the prepared test specimen was subjected to a longitudinal Varestraint test described below.
  • melt run TIG welding was performed in the longitudinal direction at the central position of the plate width of the test specimen under welding conditions of a welding current of 200 A, a voltage of 12 V, and a speed of 15 cm/min.
  • bending stress was momentarily applied in parallel to the welding direction so that strain of 2% was applied to the outer layer.
  • a portion including a place where a weld crack occurred due to application of the bending stress was cut out in a size that could be observed with an optical microscope.
  • the size of the cut sample was 40 mm ⁇ 40 mm ⁇ 12 mm.
  • the weld hot cracking resistance was evaluated as follows based on the obtained averaged total crack length.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Arc Welding In General (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
US18/852,689 2022-04-11 2023-04-10 Alloy Pending US20250230532A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2022065270 2022-04-11
JP2022-065270 2022-04-11
PCT/JP2023/014635 WO2023199902A1 (ja) 2022-04-11 2023-04-10 合金材

Publications (1)

Publication Number Publication Date
US20250230532A1 true US20250230532A1 (en) 2025-07-17

Family

ID=88329805

Family Applications (1)

Application Number Title Priority Date Filing Date
US18/852,689 Pending US20250230532A1 (en) 2022-04-11 2023-04-10 Alloy

Country Status (6)

Country Link
US (1) US20250230532A1 (https=)
EP (1) EP4509619A4 (https=)
JP (1) JPWO2023199902A1 (https=)
KR (1) KR20240172218A (https=)
CN (1) CN118974299A (https=)
WO (1) WO2023199902A1 (https=)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024204622A1 (ja) * 2023-03-28 2024-10-03 日本製鉄株式会社 合金材
JP2025130572A (ja) * 2024-02-27 2025-09-08 日本製鉄株式会社 高Ｎｉ合金板
WO2026023681A1 (ja) * 2024-07-26 2026-01-29 日本製鉄株式会社 オーステナイト系耐熱鋼

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59136464A (ja) * 1983-01-26 1984-08-06 Hitachi Ltd ボイラチユ−ブ
AT391484B (de) * 1986-09-08 1990-10-10 Boehler Gmbh Hochwarmfeste, austenitische legierung und verfahren zu ihrer herstellung
JPS63121641A (ja) * 1986-11-10 1988-05-25 Nippon Yakin Kogyo Co Ltd オ−ステナイトステンレス鋼製シ−ズヒ−タ外部被覆
US7118636B2 (en) * 2003-04-14 2006-10-10 General Electric Company Precipitation-strengthened nickel-iron-chromium alloy
JP6066412B2 (ja) * 2013-03-27 2017-01-25 日本冶金工業株式会社 表面性状に優れるＦｅ−Ｎｉ−Ｃｒ系合金とその製造方法
JP6791711B2 (ja) * 2016-10-04 2020-11-25 日本冶金工業株式会社 Ｆｅ−Ｃｒ−Ｎｉ合金およびその製造方法
KR20190065352A (ko) * 2016-10-05 2019-06-11 닛폰세이테츠 가부시키가이샤 NiCrFe 합금
JP7187605B2 (ja) * 2021-04-14 2022-12-12 日鉄ステンレス株式会社 耐溶接高温割れ性に優れた高Ｎｉ合金

Also Published As

Publication number Publication date
WO2023199902A1 (ja) 2023-10-19
KR20240172218A (ko) 2024-12-09
EP4509619A1 (en) 2025-02-19
EP4509619A4 (en) 2026-03-18
CN118974299A (zh) 2024-11-15
JPWO2023199902A1 (https=) 2023-10-19

Similar Documents

Publication Publication Date Title
US20230203632A1 (en) Austenitic stainless steel weld joint
US12188111B2 (en) Austenitic stainless steel material
US12054797B2 (en) Austenitic stainless steel material and welded joint
US20250230532A1 (en) Alloy
JP7277752B2 (ja) オーステナイト系ステンレス鋼材
US20200010931A1 (en) Ni-Based Heat Resistant Alloy and Method for Producing the Same
WO2018181570A1 (ja) オーステナイト系ステンレス厚鋼板およびその製造方法
JP7339526B2 (ja) オーステナイト系ステンレス鋼材
WO2024204622A1 (ja) 合金材
US20250333827A1 (en) Austenitic stainless alloy welded joint and austenitic stainless alloy welding material
JP7457262B2 (ja) オーステナイト系耐熱鋼
JP7381967B2 (ja) オーステナイト系耐熱鋼の製造方法
JP6482075B2 (ja) 溶接二相ステンレス鋼管とその製造方法
WO2023190526A1 (ja) ＮｉＣｒＦｅ合金材
RU2581318C1 (ru) Жаропрочный сплав
KR20230122548A (ko) 오스테나이트계 스테인리스강 및 내수소성 부재
US20250327159A1 (en) Austenitic stainless alloy material
WO2026075177A1 (ja) 合金材

Legal Events

Date Code Title Description
AS Assignment

Owner name: NIPPON STEEL CORPORATION, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OSUKI, TAKAHIRO;AOTA, SHOHGO;JOTOKU, KANA;REEL/FRAME:068738/0507

Effective date: 20240829

STPP Information on status: patent application and granting procedure in general

Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION