EP3480331A1 - Ferritischer hitzefester stahl und ferritische wärmeübertragungsteil - Google Patents

Ferritischer hitzefester stahl und ferritische wärmeübertragungsteil Download PDF

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EP3480331A1
EP3480331A1 EP17820295.8A EP17820295A EP3480331A1 EP 3480331 A1 EP3480331 A1 EP 3480331A1 EP 17820295 A EP17820295 A EP 17820295A EP 3480331 A1 EP3480331 A1 EP 3480331A1
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Prior art keywords
oxidized layer
base material
heat transfer
content
transfer member
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English (en)
French (fr)
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EP3480331A4 (de
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Yoshitaka Nishiyama
Hiroshi Nogami
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Nippon Steel Corp
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Nippon Steel and Sumitomo Metal Corp
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Publication of EP3480331A1 publication Critical patent/EP3480331A1/de
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • 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
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    • 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
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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    • 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
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt
    • C—CHEMISTRY; METALLURGY
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • C23C8/16—Oxidising using oxygen-containing compounds, e.g. water, carbon dioxide
    • C23C8/18—Oxidising of ferrous surfaces
    • 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
    • C21D2211/005—Ferrite
    • 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
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface 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
    • C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys

Definitions

  • the present invention relates to a heat resistant steel and a heat transfer member, and more particularly relates to a heat resistant ferritic steel and a ferritic heat transfer member which are used under a high-temperature steam oxidation environment or the like.
  • Heat transfer members that are used in thermal power plants are exposed to high temperature and high pressure steam for long time periods.
  • a heat transfer member is, for example, a boiler pipe.
  • oxide scale forms on the surface of the heat transfer member. If the steam oxidation resistance properties of the heat transfer member are insufficient, a large amount of oxide scale will form on the surface of the heat transfer member.
  • the heat transfer member thermally expands and contracts due to starting and stopping of the boiler.
  • the oxide scale will peel off and cause a blockage in the pipe. Furthermore, in a case where a large amount of oxide scale is formed, thermal conduction from outside the pipe to inside the pipe is inhibited by the oxide scale. Therefore, in order to maintain the temperature within the pipe at a high temperature, it will be necessary to apply a greater amount of heat from the outside. An increase in the temperature of the pipe causes a reduction in the creep strength. Therefore, high steam oxidation resistance properties are required for heat transfer members that are to be used in equipment such as thermal power boilers, turbines or steam pipes.
  • a heat resistant austenitic steel and a heat resistant ferritic steel have been developed as materials that meet the demands regarding such properties.
  • a heat resistant austenitic steel is, for example, a heat resistant austenitic steel having a Cr content of 18 to 25 mass%.
  • a heat resistant ferritic steel is, for example, a heat resistant ferritic steel having a Cr content of 8 to 13 mass%.
  • a heat resistant ferritic steel is less expensive than a heat resistant austenitic steel.
  • a heat resistant ferritic steel also has a lower coefficient of thermal expansion and a higher thermal conductivity than a heat resistant austenitic steel. Therefore, a heat resistant ferritic steel is suitable as the material for a pipe in a thermal power plant.
  • the Cr content of a heat resistant ferritic steel is lower than the Cr content of a heat resistant austenitic steel. Consequently, the steam oxidation resistance properties of the heat resistant ferritic steel are lower than the steam oxidation resistance properties of the heat resistant austenitic steel. Therefore, there is a need for a heat resistant ferritic steel that is excellent in steam oxidation resistance properties.
  • Patent Literature 1 A heat resistant ferritic steel which inhibits oxide scale from falling off is disclosed, for example, in Japanese Patent Application Publication No. 11-92880 (Patent Literature 1).
  • the heat resistant ferritic steel disclosed in Patent Literature 1 is a heat resistant ferritic steel containing a high Cr content that forms an oxide film on the surface during use, in which ultra-fine oxides having a diameter of 1 micron or less are formed at the boundary with the oxide film or in the vicinity thereof.
  • Patent Literature 1 describes that, as a result, the adhesiveness between the oxide film and the base metal improves.
  • Patent Literature 2 A method for improving steam oxidation resistance properties by increasing the Cr concentration at the surface of a heat resistant ferritic steel is disclosed, for example, in Japanese Patent Application Publication No. 2007-39745 (Patent Literature 2).
  • Patent Literature 2 powder particles containing Cr are caused to be carried at the surface of a heat resistant ferritic steel containing Cr, and a Cr-oxide layer having a high Cr concentration is formed on the ferritic steel surface under a high temperature.
  • Patent Literature 2 describes that, according to this method, the (steam) oxidation resistance of a ferritic steel containing Cr can be easily and economically improved.
  • Patent Literature 3 A method for improving oxidation resistance by forming a Cr-oxide coating on the surface of a heat resistant ferritic steel is disclosed, for example, in Japanese Patent Application Publication No. 2013-127103 (Patent Literature 3).
  • An antioxidation treatment method for a heat resistant ferritic steel described in Patent Literature 3 includes subjecting a heat resistant ferritic steel containing chromium to a heat treatment under a gas atmosphere with a low oxygen partial pressure that consists of a gaseous mixture of carbon dioxide gas with an inert gas to thereby form an oxide coating that contains chromium on the surface of the heat resistant steel.
  • Patent Literature 3 describes that, according to this method, the Cr concentration in the scale is increased, and the oxidation resistance of the heat resistant ferritic steel can be easily and economically improved.
  • Patent Literature 4 A heat resistant ferritic steel in which steam oxidation resistance properties are improved by depositing Cr on the surface of the heat resistant ferritic steel is disclosed, for example, in Japanese Patent Application Publication No. 2009-179884 (Patent Literature 4).
  • the heat resistant ferritic steel disclosed in Patent Literature 4 is a heat resistant ferritic steel that is used under a high-temperature and highpressure steam environment, and has on its surface a Cr oxide film which is formed by subjecting Cr that was deposited by a shot peening treatment using a shot material of powdery Cr to a pre-oxidizing treatment.
  • Patent Literature 4 describes that, because a protection film of oxides with oxidation resistance is formed on the heat resistant steel prior to use in an oxidation environment, the steam oxidation resistance properties of the heat resistant ferritic steel are improved.
  • An objective of the present invention is to provide a ferritic heat transfer member that is excellent in heat transfer characteristics and steam oxidation resistance properties, and a heat resistant ferritic steel capable of realizing the ferritic heat transfer member.
  • a heat resistant ferritic steel according to the present embodiment includes a base material, and an oxidized layer A on a surface of the base material.
  • the base material has a chemical composition consisting of, in mass%, C: 0.01 to 0.3%, Si: 0.01 to 2.0%, Mn: 0.01 to 2.0%, P: 0.10% or less, S: 0.03% or less, Cr: 7.0 to 14.0%, N: 0.005 to 0.15%, sol.
  • Al 0.001 to 0.3%, one or more types of element selected from a group consisting of Mo: 0 to 5.0%, Ta: 0 to 5.0%, W: 0 to 5.0% and Re: 0 to 5.0%: 0.5 to 7.0% in total, Cu: 0 to 5.0%, Ni: 0 to 5.0%, Co: 0 to 5.0%, Ti: 0 to 1.0%, V: 0 to 1.0%, Nb: 0 to 1.0%, Hf: 0 to 1.0%, Ca: 0 to 0.1%, Mg: 0 to 0.1%, Zr: 0 to 0.1%, B: 0 to 0.1%, and rare earth metal: 0 to 0.1%, with the balance being Fe and impurities.
  • the oxidized layer A includes a chemical composition containing, in mass%, Cr and Mn in a total amount of 20 to 45%.
  • the oxidized layer A includes a chemical composition containing, in mass%, one or more types of element selected from a group consisting of Mo, Ta, W and Re in a total amount of 0.5 to 10%.
  • a ferritic heat transfer member includes a base material, and an oxide film on a surface of the base material.
  • the base material has the chemical composition described above.
  • the oxide film includes an oxidized layer B and an oxidized layer C.
  • the oxidized layer B contains, in vol%, 80% or more in total of Fe 3 O 4 and Fe 2 O 3 .
  • the oxidized layer C is disposed between the oxidized layer B and the base material.
  • a chemical composition of the oxidized layer C contains, in mass%, Cr and Mn: more than 5% to 30% in total, and one or more types of element selected from a group consisting of Mo, Ta, W and Re: 1 to 15% in total.
  • the heat resistant ferritic steel and the ferritic heat transfer member according to the present embodiment are excellent in heat transfer characteristics and steam oxidation resistance properties.
  • the present inventors conducted various studies regarding heat resistant ferritic steels and ferritic heat transfer members. As a result, the present inventors obtained the following findings.
  • the oxidized layer C contains Cr and Mn in a total amount in a range of more than 5% to 30 mass%.
  • the thermal conductivity of the oxidized layer C increases. However, if the content of these elements is too high, in some cases the steam oxidation resistance properties of the oxidized layer C decrease. Accordingly, the oxidized layer C contains one or more types of element selected from a group consisting of Mo, Ta, W and Re in a total amount in a range of 1 to 15 mass%.
  • the oxidized layer C exhibits excellent heat transfer characteristics and excellent steam oxidation resistance properties.
  • the chemical composition of the oxidized layer A contains, in mass%, Cr and Mn in a total amount in a range of 20 to 45%.
  • the chemical composition of the oxidized layer A contains, in mass%, one or more types of element selected from a group consisting of Mo, Ta, W and Re in a total amount in a range of 0.5 to 10%.
  • the oxidized layer A changes to an oxide film including the oxidized layer B and the oxidized layer C.
  • the term "high temperature” refers to, for example, a temperature in the range of 500 to 650°C.
  • a heat resistant ferritic steel according to the present embodiment that was completed based on the above findings includes a base material, and an oxidized layer A on the surface of the base material.
  • the base material has a chemical composition consisting of, in mass%, C: 0.01 to 0.3%, Si: 0.01 to 2.0%, Mn: 0.01 to 2.0%, P: 0.10% or less, S: 0.03% or less, Cr: 7.0 to 14.0%, N: 0.005 to 0.15%, sol.
  • Al 0.001 to 0.3%, one or more types of element selected from a group consisting of Mo: 0 to 5.0%, Ta: 0 to 5.0%, W: 0 to 5.0% and Re: 0 to 5.0%: 0.5 to 7.0% in total, Cu: 0 to 5.0%, Ni: 0 to 5.0%, Co: 0 to 5.0%, Ti: 0 to 1.0%, V: 0 to 1.0%, Nb: 0 to 1.0%, Hf: 0 to 1.0%, Ca: 0 to 0.1%, Mg: 0 to 0.1%, Zr: 0 to 0.1%, B: 0 to 0.1%, and rare earth metal: 0 to 0.1%, with the balance being Fe and impurities.
  • the oxidized layer A includes a chemical composition containing, in mass%, 20 to 45% in total of Cr and Mn.
  • the oxidized layer A includes a chemical composition containing, in mass%, 0.5 to 10% in total of one or more types of element selected from a group consisting of Mo, Ta, W and Re.
  • the heat resistant ferritic steel according to the present embodiment is excellent in heat transfer characteristics and steam oxidation resistance properties.
  • the chemical composition of the base material of the aforementioned heat resistant ferritic steel may contain one or more types of element selected from a group consisting of Cu: 0.005 to 5.0%, Ni: 0.005 to 5.0% and Co: 0.005 to 5.0%.
  • the chemical composition of the aforementioned base material may contain one or more types of element selected from a group consisting of Ti: 0.01 to 1.0%, V: 0.01 to 1.0%, Nb: 0.01 to 1.0% and Hf: 0.01 to 1.0%.
  • the chemical composition of the aforementioned base material may contain one or more types of element selected from a group consisting of Ca: 0.0015 to 0.1%, Mg: 0.0015 to 0.1%, Zr: 0.0015 to 0.1%, B: 0.0015 to 0.1% and rare earth metal: 0.0015 to 0.1%.
  • a ferritic heat transfer member includes a base material, and an oxide film on the surface of the base material.
  • the base material has the chemical composition described above.
  • the oxide film includes an oxidized layer B and an oxidized layer C.
  • the oxidized layer B contains, in vol%, 80% or more in total of Fe 3 O 4 and Fe 2 O 3 .
  • the oxidized layer C is disposed between the oxidized layer B and the base material.
  • the chemical composition of the oxidized layer C contains Cr and Mn in a total amount in a range of more than 5% to 30 mass%, and contains one or more types of element selected from a group consisting of Mo, Ta, W and Re in a total amount in a range of 1 to 15 mass%.
  • the ferritic heat transfer member according to the present embodiment is excellent in heat transfer characteristics and steam oxidation resistance properties.
  • the oxidized layer B contains Cr and Mn in a total amount of not more than 5 mass%.
  • the oxidized layer C contains not more than 5 vol% of Cr 2 O 3 .
  • the thermal conductivity of the oxide film is improved by suppressing the amount of precipitated Cr 2 O 3 that has low thermal conductivity. Therefore, the heat transfer characteristics of the boiler can be enhanced.
  • the shape of the heat resistant ferritic steel according to the present embodiment is not particularly limited.
  • the heat resistant ferritic steel is, for example, a steel pipe, a steel bar, or a steel plate.
  • the heat resistant ferritic steel is a heat resistant ferritic steel pipe.
  • An oxidation treatment is performed on the base material of the heat resistant ferritic steel according to the present embodiment.
  • An oxidized layer A is formed on the surface of the base material of the heat resistant ferritic steel by the oxidation treatment.
  • FIG. 1 is a sectional view of the heat resistant ferritic steel according to the present embodiment.
  • a heat resistant ferritic steel 1 includes a base material 2 and an oxidized layer A.
  • the heat resistant ferritic steel 1 that includes the base material 2 and the oxidized layer A is used as a heat transfer member under a high-temperature steam environment.
  • the oxidized layer A changes to an oxide film 3 that includes an oxidized layer B and an oxidized layer C.
  • the base material 2 has the following chemical composition.
  • C also increases the creep strength of the base material by solid-solution strengthening.
  • the C content is set in a range of 0.01 to 0.3%.
  • a preferable lower limit of the C content is 0.03%, and a preferable upper limit of the C content is 0.15%.
  • Si deoxidizes the steel. Si also improves the steam oxidation resistance properties of the base material 2. However, if the Si content is too high, the toughness of the base material 2 decreases. Accordingly, the Si content is set in a range of 0.01 to 2.0%. A preferable lower limit of the Si content is 0.05%, and more preferably is 0.1%. A preferable upper limit of the Si content is 1.0%, and more preferably is 0.5%.
  • Mn Manganese deoxidizes the steel. Mn also combines with S in the base material 2 to form MnS, and suppresses grain-boundary segregation of S. Thus, the hot workability of the base material 2 improves. However, if the Mn content is too high, the base material 2 becomes brittle and, in addition, the creep strength of the base material 2 decreases. Accordingly, the Mn content is set in a range of 0.01 to 2.0%. A preferable lower limit of the Mn content is 0.05%, and more preferably is 0.1%. A preferable upper limit of the Mn content is 1.0%, and more preferably is 0.8%.
  • Phosphorus (P) is an impurity. P segregates at crystal grain boundaries of the base material 2, and decreases the hot workability of the base material 2. P also concentrates at the boundary between the oxide film 3 and the base material 2, and reduces the adhesiveness of the oxide film 3 with respect to the base material 2. Accordingly, the P content is preferably as low as possible.
  • the P content is set to 0.10% or less, and preferably is 0.03% or less. A lower limit of the P content is, for example, 0.005%.
  • S is an impurity. S segregates at crystal grain boundaries of the base material 2, and decreases the hot workability of the base material 2. S also concentrates at the boundary between the oxide film 3 and the base material 2, and reduces the adhesiveness of the oxide film 3 with respect to the base material 2. Accordingly, the S content is preferably as low as possible.
  • the S content is set to 0.03% or less, and preferably is 0.015% or less. A lower limit of the S content is, for example, 0.0001%.
  • Chromium (Cr) improves the steam oxidation resistance properties of the base material 2.
  • Cr is also contained in the oxide film 3 as oxides defined by Cr 2 O 3 and (Fe, Cr) 3 O 4 .
  • the Cr oxides improve the steam oxidation resistance properties of the base material 2.
  • the Cr oxides also improve the adhesiveness of the oxide film 3 with respect to the base material 2.
  • the Cr content is set in a range of 7.0 to 14.0%.
  • a preferable lower limit of the Cr content is 7.5%, and more preferably is 8.0%.
  • a preferable upper limit of the Cr content is 12.0%, and more preferably is 11.0%.
  • N Nitrogen
  • the N content is set in a range of 0.005 to 0.15%.
  • a preferable lower limit of the N content is 0.01%.
  • a preferable upper limit of the N content is 0.10%.
  • One or more types of element selected from a group consisting of molybdenum (Mo), tantalum (Ta), tungsten (W) and rhenium (Re) is contained.
  • these elements are also referred to as "specific oxidized layer forming elements”.
  • the specific oxidized layer forming elements form the oxidized layer A on the surface of the base material 2.
  • the specific oxidized layer forming elements also form the oxide film 3 including the oxidized layer B and the oxidized layer C under a high-temperature steam environment of 500 to 650°C. These effects are obtained if even one type of these elements is contained. However, if the content of the specific oxidized layer forming elements is too high, the toughness, ductility and workability of the base material 2 will decrease.
  • the Mo content is set in a range of 0 to 5.0%
  • the Ta content is set in a range of 0 to 5.0%
  • the W content is set in a range of 0 to 5.0%
  • the Re content is set in a range of 0 to 5.0%.
  • a preferable lower limit of the Mo content is 0.01%, and more preferably is 0.1%.
  • a preferable lower limit of the Ta content is 0.01%, and more preferably is 0.1%.
  • a preferable lower limit of the W content is 0.01%, and more preferably is 0.1%.
  • a preferable lower limit of the Re content is 0.01%, and more preferably is 0.1%.
  • a preferable upper limit of the Mo content is 4.0%, and more preferably is 3.0%.
  • a preferable upper limit of the Ta content is 4.0%, and more preferably is 3.0%.
  • a preferable upper limit of the W content is 4.0%, and more preferably is 3.0%.
  • a preferable upper limit of the Re content is 4.0%, and more preferably is 3.0%.
  • the total content of the specific oxidized layer forming elements is set in the range of 0.5 to 7.0%.
  • a preferable lower limit of the total content of the specific oxidized layer forming elements is 0.6%, and more preferably is 1.0%.
  • a preferable upper limit of the total content of the specific oxidized layer forming elements is 6.5%, and more preferably is 6.0%.
  • the balance of the base material 2 of the heat resistant ferritic steel according to the present embodiment is Fe and impurities.
  • impurities refers to substances which are mixed in from ore or scrap that is utilized as a raw material of the steel or from the environment of the production process or the like, and are substances that are contained within a range that does not adversely affect a heat transfer member 4 according to the present embodiment.
  • the impurities include, for example, oxygen (O), arsenic (As), antimony (Sb), thallium (Tl), lead (Pb) and bismuth (Bi).
  • the base material 2 of the heat resistant ferritic steel according to the present embodiment may further contain the following elements in lieu of a part of Fe.
  • Cu 0 to 5.0% Ni: 0 to 5.0% Co: 0 to 5.0% Copper (Cu), nickel (Ni) and cobalt (Co) are optional elements, and need not be contained. If contained, these elements stabilize austenite. By this means, retention of delta ferrite that lowers the shock resistance of the base material 2 is suppressed. This effect is obtained if even one type of these elements is contained. However, if the content of these elements is too high, the long-term creep strength of the base material 2 will decrease. Accordingly, the Cu content is set in a range of 0 to 5.0%, the Ni content is set in a range of 0 to 5.0%, and the Co content is set in a range of 0 to 5.0%.
  • a preferable upper limit of the Cu content is 3.0%, and more preferably is 2.0%.
  • a preferable upper limit of the Ni content is 3.0%, and more preferably is 2.0%.
  • a preferable upper limit of the Co content is 3.0%, and more preferably is 2.0%.
  • a preferable lower limit of the content of each of these elements is 0.005%.
  • Ti 0 to 1.0% V: 0 to 1.0% Nb: 0 to 1.0% Hf: 0 to 1.0% Titanium (Ti), vanadium (V), niobium (Nb) and hafnium (Hf) are optional elements and need not be contained. If contained, these elements combine with carbon and nitrogen to form carbides, nitrides or carbo-nitrides. These carbides, nitrides and carbo-nitrides act to perform precipitation strengthening of the base material 2. This effect is obtained if even one type of these elements is contained. However, if the content of these elements is too high, the workability of the base material 2 will decrease.
  • the Ti content is set in a range of 0 to 1.0%
  • the V content is set in a range of 0 to 1.0%
  • the Nb content is set in a range of 0 to 1.0%
  • the Hf content is set in a range of 0 to 1.0%.
  • a preferable upper limit of the Ti content is 0.8%, and more preferably is 0.4%.
  • a preferable upper limit of the V content is 0.8%, and more preferably is 0.4%.
  • a preferable upper limit of the Nb content is 0.8%, and more preferably is 0.4%.
  • a preferable upper limit of the Hf content is 0.8%, and more preferably is 0.4%.
  • a preferable lower limit of the content of each of these elements is 0.01%.
  • Ca 0 to 0.1% Mg: 0 to 0.1% Zr: 0 to 0.1%
  • B 0 to 0.1%
  • Rare earth metal 0 to 0.1% Calcium (Ca), magnesium (Mg), zirconium (Zr), boron (B) and rare earth metal (REM) are optional elements, and need not be contained. If contained, these elements increase the strength, workability and oxidation resistance of the base material 2. This effect is obtained if even one type of these elements is contained. However, if the content of these elements is too high, the toughness and weldability of the base material 2 will decrease.
  • the Ca content is set in a range of 0 to 0.1%
  • the Mg content is set in a range of 0 to 0.1%
  • the Zr content is set in a range of 0 to 0.1%
  • the B content is set in a range of 0 to 0.1%
  • the REM content is set in a range of 0 to 0.1%.
  • a preferable upper limit of the Ca content is 0.05%.
  • a preferable upper limit of the Mg content is 0.05%.
  • a preferable upper limit of the Zr content is 0.05%.
  • a preferable upper limit of the B content is 0.05%.
  • a preferable upper limit of the REM content is 0.05%.
  • a preferable lower limit of the content of each of these elements is 0.0015%.
  • REM refers to one or more types of element selected from a group consisting of yttrium (Y) which is the element with atomic number 39, the elements from lanthanum (La) with atomic number 57 to lutetium (Lu) with atomic number 71 that are lanthanides, and the elements from actinium (Ac) with atomic number 89 to lawrencium (Lr) with atomic number 103 that are actinides.
  • An oxidation treatment is performed on the base material 2 having the aforementioned chemical composition.
  • the oxidized layer A is formed on the surface of the base material 2 by the oxidation treatment.
  • the heat resistant ferritic steel 1 having the base material 2 and the oxidized layer A on the surface of the base material 2 is used under a high-temperature steam environment.
  • the oxidized layer A changes to the oxide film 3 that is excellent in heat transfer characteristics, while maintaining steam oxidation resistance properties. That is, the oxidized layer A is a starting material for forming the oxide film 3 that includes the oxidized layer B and the oxidized layer C.
  • the mechanism by which the oxidized layer A changes into the oxide film 3 is not certain, it is surmised that the oxidized layer A principally contributes to formation of the oxidized layer C.
  • the thickness of the oxidized layer A is not particularly limited. If the oxidized layer A is formed even slightly, the oxide film 3 will be formed.
  • the thickness of the oxidized layer A is preferably not less than 0.2 ⁇ m. In this case, under a high-temperature steam environment, the oxide film 3 can be uniformly formed on the surface of the base material 2 in a stable manner. Therefore, it is easy to completely cover the base material 2 with the oxide film 3. As a result, the thermal conductivity at the surface of the ferritic heat transfer member 4 increases. More preferably, the thickness of the oxidized layer A is not less than 1.0 ⁇ m. Although the upper limit of the thickness of the oxidized layer A is not particularly limited, in consideration of mass productivity, the upper limit is preferably not more than 20 ⁇ m.
  • the thickness of the oxidized layer A is determined by the following method.
  • the heat resistant ferritic steel 1 that was subjected to an oxidation treatment that is described later is cut perpendicularly to the surface thereof.
  • the heat resistant ferritic steel 1 is cut perpendicularly to the axial direction of the steel pipe.
  • a cross-section including the surface of the heat resistant ferritic steel 1 is observed using a scanning electron microscope (SEM) manufactured by JEOL Ltd.
  • SEM scanning electron microscope
  • SEM is used to observe a cross-section that includes the inner surface of the steel pipe. The observation magnification is 2000 times.
  • the thickness of the oxidized layer on the surface of the heat resistant ferritic steel 1 (the inner surface in a case where the heat resistant ferritic steel 1 is a steel pipe) is measured.
  • the measurement is made on four different cross-sections of the heat resistant ferritic steel 1.
  • measurement is performed at four locations at a pitch of 45°. The average value of the measurement results is adopted as the thickness of the oxidized layer A.
  • the chemical composition of the oxidized layer A contains a total content of 20 to 45% of Cr and Mn. If the total content of Cr and Mn in the oxidized layer A is less than 20%, the total content of Cr and Mn in the oxidized layer C will be 5% or less under a high-temperature steam environment. In this case, the thermal conductivity of the oxidized layer C will be too high. In such case, the steam oxidation resistance properties of the ferritic heat transfer member 4 will decrease. On the other hand, if the total content of Cr and Mn in the oxidized layer A is more than 45%, the total content of Cr and Mn in the oxidized layer C will be more than 30% under a high-temperature steam environment.
  • the thermal conductivity of the oxidized layer C will be too low. As a result, the heat transfer characteristics of the ferritic heat transfer member 4 will decrease. Therefore, the chemical composition of the oxidized layer A contains Cr and Mn in a total amount in a range of 20 to 45%.
  • a preferable lower limit of the total content of Cr and Mn in the oxidized layer A is 22%.
  • a preferable upper limit of the total content of Cr and Mn in the oxidized layer A is 40%.
  • the chemical composition of the oxidized layer A further contains a total of 0.5 to 10% of one or more types of element selected from the group consisting of Mo, Ta, W and Re (specific oxidized layer forming elements). If the total content of the specific oxidized layer forming elements of the oxidized layer A is less than 0.5%, the total content of the specific oxidized layer forming elements of the oxidized layer C will be less than 1% under a high-temperature steam environment. In this case, the thermal conductivity of the oxidized layer C will be too low. As a result, the heat transfer characteristics of the ferritic heat transfer member 4 will decrease.
  • the chemical composition of the oxidized layer A contains the specific oxidized layer forming elements in a total amount that is in a range of 0.5 to 10%.
  • a preferable lower limit of the total content of the specific oxidized layer forming elements is 1%.
  • a preferable upper limit of the total content of the specific oxidized layer forming elements is 8%.
  • the total content of Cr and Mn and the total content of the specific oxidized layer forming elements (Mo, Ta, W and Re) in the oxidized layer A is calculated by the following method.
  • the heat resistant ferritic steel 1 that was subjected to an oxidation treatment that is described later is cut perpendicularly to the surface thereof.
  • the heat resistant ferritic steel 1 is cut perpendicularly to the axial direction of the steel pipe.
  • a cross-section including the surface of the heat resistant ferritic steel 1 is observed using a scanning electron microscope (SEM) manufactured by JEOL Ltd.
  • the oxidized layer A that appears with a comparatively white contrast of the surface of the heat resistant ferritic steel 1 is identified.
  • an elemental analysis is performed using a field emission electron probe micro analyzer (FE-EPMA) manufactured by JEOL Ltd.
  • the conditions for the elemental analysis are: detector: 30 mm 2 SD, accelerating voltage: 15 kV, and measurement time period: 60 secs.
  • the elemental analysis is made on four different cross-sections of the heat resistant ferritic steel 1. In a case where the heat resistant ferritic steel 1 is a steel pipe, elemental analysis is performed at four locations at a pitch of 45°.
  • compositions for the respective elements that are obtained a composition from which the quantities of oxygen (O) and carbon (C) are excluded is taken as 100%.
  • the proportion (mass%) of the total amount of Cr and Mn is calculated.
  • the proportion (mass%) of the total content of specific oxidized layer forming elements (Mo, Ta, W and Re) is calculated. Average values of the elemental analysis values obtained at the four locations are adopted as the total content (mass%) of Cr and Mn in the oxidized layer A, and the total content (mass%) of the specific oxidized layer forming elements (Mo, Ta, W and Re) in the oxidized layer A.
  • a method for producing the heat resistant ferritic steel 1 according to the present embodiment includes a preparation process and an oxidation treatment process.
  • the base material 2 having the aforementioned chemical composition is prepared.
  • the base material 2 is produced from a starting material having the aforementioned chemical composition.
  • the starting material may be a slab, a bloom or a billet produced by a continuous casting process.
  • the starting material may also be billet produced by an ingot-making process.
  • a heating temperature when producing the starting material is, for example, in a range of 850 to 1200°C.
  • the prepared starting material is charged into a reheating furnace or a soaking pit and heated.
  • the heated starting material is subjected to hot working to produce the base material 2.
  • the hot working is, for example, the Mannesmann process.
  • the Mannesmann process subjects the starting material to piercing-rolling using a piercing machine to thereby form the starting material into a material pipe.
  • the starting material is subjected to drawing and rolling as well as sizing using a mandrel mill and a sizing mill.
  • the temperature for the hot working is, for example, in a range of 850 to 1200°C.
  • a process for producing the base material 2 is not limited to the Mannesmann process, and the base material 2 may be produced by subjecting the starting material to hot extrusion or hot forging.
  • the base material 2 produced by hot working may be subjected to a heat treatment or may be subjected to cold working.
  • the base material 2 may also be a steel plate.
  • the starting material is subjected to hot working to produce the base material 2 as a steel plate.
  • the steel plate may also be processed into a steel pipe by welding to produce the base material 2 as a welded steel pipe.
  • An oxidation treatment is performed on the aforementioned base material 2.
  • the oxidation treatment is performed by heating the base material 2 in a gas atmosphere containing CO, CO 2 and N 2 .
  • the CO/CO 2 ratio of the gas used for the oxidation treatment is 0.6 or more in volume ratio.
  • preferential oxidation of Fe can be suppressed.
  • the oxidized layer A containing Cr and Mn in a total amount of 20 mass% or more and also containing specific oxidized layer forming elements in a total amount of 0.5 mass% or more is formed on the surface of the base material 2.
  • the oxidized layer A changes into the oxide film 3 after the steam oxidation treatment that is described later.
  • an upper limit of the CO/CO 2 ratio is not particularly provided, an upper limit of 2.0 is preferable in consideration of operational practicability.
  • the (CO+CO 2 )/N 2 ratio of the gas that is used in the oxidation treatment is set as not more than 1.0 in volume ratio. If the (CO+CO 2 )/N 2 ratio is more than 1.0, the base material 2 will carburize. Therefore, Cr and Mn in the oxidized layer A will form carbides. As a result, the total content of Cr and Mn in the oxidized layer A will be less than 20%. Although a lower limit of the (CO+CO 2 )/N 2 ratio is not particularly provided, a lower limit of 0.1 is preferable in consideration of operational practicability.
  • the temperature for the oxidation treatment is in a range of 900 to 1130°C. If the oxidation treatment temperature is less than 900°C, because outward diffusion of specific elements in the base material 2 will be slow, the total content of specific oxidized layer forming elements in the oxidized layer A will be too low. In this case, under a high-temperature steam environment, the total content of specific oxidized layer forming elements in the oxidized layer C will be too low. As a result, the thermal conductivity of the oxidized layer C will be too low. Consequently, the thermal conductivity at the surface of the ferritic heat transfer member 4 will decrease. Therefore, the heat transfer characteristics of the ferritic heat transfer member 4 will decrease.
  • the oxidation treatment temperature is set in the range of 900 to 1130°C.
  • a preferable lower limit of the oxidation treatment temperature is 920°C, and more preferably is 950°C.
  • a preferable upper limit of the oxidation treatment temperature is 1120°C.
  • the oxidation treatment time period is in a range of 1 minute to 1 hour. If the oxidation treatment time period is too short, because concentration of the specific oxidized layer forming elements will occur, the total content of the specific oxidized layer forming elements in the oxidized layer A will be more than 10%. Therefore, under a high-temperature steam environment, the total content of the specific oxidized layer forming elements in the oxidized layer C will be more than 15%. As a result, the thermal conductivity at the surface of the ferritic heat transfer member 4 will be too high. On the other hand, if the oxidation treatment time period is too long, productivity will decrease. When taking productivity into consideration, a shorter oxidation treatment time period is preferable.
  • the oxidation treatment time period is set in the range of 1 minute to 1 hour.
  • an upper limit of the oxidation treatment time period is 30 minutes, and more preferably is 20 minutes.
  • a lower limit of the oxidation treatment time period is 3 minutes.
  • a tempering treatment (low-temperature annealing) may be performed after the oxidation treatment.
  • the oxidation treatment may be performed on the entire base material 2, the oxidation treatment may also be performed only on a face of the base material 2 which comes in contact with high temperature steam (for example, the inner surface of a steel pipe).
  • the oxidation treatment may be performed once, or may be performed multiple times. After the oxidation treatment, degreasing or cleaning or the like may be performed to remove dirt or oil that adhered to the surface of the base material 2. The oxidized layer A will not be affected even if degreasing or cleaning or the like is performed. Even if degreasing or cleaning or the like is performed, it will not affect formation of the oxide film 3 thereafter.
  • the heat resistant ferritic steel 1 of the present embodiment can be produced by the production method described above.
  • the ferritic heat transfer member 4 includes a base material 2 and an oxide film 3.
  • the base material 2 of the ferritic heat transfer member 4 is the same as the base material of the heat resistant ferritic steel 1 that is described above. Accordingly, the chemical composition of the base material 2 of the ferritic heat transfer member 4 is the same as the chemical composition of the base material 2 of the heat resistant ferritic steel 1 that is described above.
  • the shape of the ferritic heat transfer member 4 according to the present embodiment is not particularly limited.
  • the ferritic heat transfer member 4 is, for example, a pipe, a bar or a plate material. In the case where the ferritic heat transfer member 4 has a tubular shape, the ferritic heat transfer member 4 is used, for example, as a boiler pipe. Accordingly, the ferritic heat transfer member 4 is preferably a ferritic heat-transfer pipe.
  • FIG. 2 is a sectional view of the ferritic heat transfer member 4 according to the present embodiment.
  • the ferritic heat transfer member 4 includes the base material 2 and the oxide film 3.
  • the oxide film 3 includes the oxidized layer B and the oxidized layer C.
  • the oxide film 3 is formed on the surface of the base material 2 by performing a steam oxidation treatment on the heat resistant ferritic steel 1 having the base material 2 and the oxidized layer A.
  • the oxide film 3 is an oxide film including two layers, namely, the oxidized layer B and the oxidized layer C. Because the oxide film 3 includes the oxidized layer B, the oxide film 3 is excellent in heat transfer characteristics. Because the oxide film 3 includes the oxidized layer C, the oxide film 3 is excellent in both steam oxidation resistance properties and heat transfer characteristics. That is, the oxide film 3 is not just excellent in steam oxidation resistance properties, but is also excellent in heat transfer characteristics.
  • the oxidized layer B is formed as the uppermost layer of the ferritic heat transfer member 4.
  • the oxidized layer C is disposed between the oxidized layer B and the base material 2.
  • the oxidized layer B corresponds to the inner surface side of the boiler pipe
  • the base material 2 corresponds to the outer surface side of the boiler pipe.
  • the oxidized layer B comes in contact with high temperature steam.
  • the oxidized layer B contains, in vol%, a total of 80% or more of Fe 3 O 4 and Fe 2 O 3 .
  • the thermal conductivity of Fe 3 O 4 and Fe 2 O 3 is high. Accordingly, the thermal conductivity of the oxidized layer B is high, and heat imparted from the outside of the ferritic heat transfer member 4 is transferred to the inside of the ferritic heat transfer member 4 without being significantly decreased. Therefore, the heat transfer characteristics of the boiler can be improved.
  • the oxidized layer B contains, in vol%, a total of 90% or more of Fe 3 O 4 and Fe 2 O 3 .
  • the Fe 2 O 3 content of the oxidized layer B is less than 20 vol%. More preferably, the oxidized layer B is composed of Fe 3 O 4 .
  • the chemical composition of the oxidized layer B preferably contains, in mass%, not more than 5% of Cr and Mn in total. More preferably, the chemical composition of the oxidized layer B contains, in mass%, not more than 3% of Cr and Mn in total.
  • a preferable thickness of the oxidized layer B is 10 to 400 ⁇ m.
  • the oxidized layer C is disposed between the oxidized layer B and the base material 2, and contacts the base material 2.
  • the chemical composition of the oxidized layer C contains Cr and Mn in a total amount in a range of more than 5% to 30%.
  • Cr and Mn are present as oxides represented by the chemical formula (Fe, M) 3 O 4 .
  • Cr and Mn are substituted for M.
  • the oxides represented by the chemical formula (Fe, M) 3 O 4 are oxides that have a so-called spinel crystal structure that is the same as Fe 3 O 4 , and in which a part of Fe is substituted with Cr and Mn. In a case where the total amount of Cr and Mn contained in the oxidized layer C is 5% or less, the proportion of Fe 3 O 4 and Fe 2 O 3 in the oxidized layer C cannot be kept low.
  • the thermal conductivity of the oxidized layer C becomes too high. Consequently, a large amount of oxide scale arises on the inner surface of the ferritic heat transfer member 4.
  • the thermal conductivity of the oxidized layer C becomes too low. In this case, the heat transfer characteristics of the boiler decrease. Accordingly, the content of Cr and Mn in the oxidized layer C is set in a range of more than 5% to 30% in total. By this means, the thermal conductivity of the oxidized layer C can be controlled within an appropriate range while maintaining the steam oxidation resistance properties.
  • a preferable lower limit of the total content of Cr and Mn in the oxidized layer C is 10%, and more preferably is 13%.
  • a preferable upper limit of the total content of Cr and Mn in the oxidized layer C is 28%, and more preferably is 25%.
  • the oxidized layer C contains one or more types of element selected from a group consisting of Mo, Ta, W and Re in a total amount in a range of 1 to 15%. If the total content of the specific oxidized layer forming elements (Mo, Ta, W and Re) of the oxidized layer C is less than 1%, the thermal conductivity of the oxidized layer C will be too low. On the other hand, if the total content of the specific oxidized layer forming elements of the oxidized layer C is more than 15%, the thermal conductivity of the oxidized layer C will be too high. In such case, the steam oxidation resistance properties of the ferritic heat transfer member 4 will decrease.
  • the total content of the specific oxidized layer forming elements in the oxidized layer C is in the range of 1 to 15%.
  • a preferable upper limit of the total content of the specific oxidized layer forming elements (Mo, Ta, W and Re) in the oxidized layer C is 10%, and more preferably is 9%.
  • a preferable lower limit of the total content of the specific oxidized layer forming elements (Mo, Ta, W and Re) in the oxidized layer C is 1.5%.
  • a major portion of the oxidized layer C is oxides having the aforementioned spinel crystal structure, and the oxidized layer C contains Cr 2 O 3 in an amount that is not more than 5 vol%.
  • the thermal conductivity of the oxidized layer C can be controlled to be within an appropriate range.
  • the content of Cr 2 O 3 in the oxidized layer C is preferably 5 vol% or less, and more preferably is 3 vol% or less.
  • the thermal conductivity of the oxidized layer C is preferably controlled within a range of 1.2 to 3.0 W ⁇ m -1 ⁇ K -1 . If the thermal conductivity of the oxidized layer C is 1.2 W ⁇ m -1 ⁇ K -1 or more, thermal conduction from the outside of the ferritic heat transfer member 4 to the inside of the ferritic heat transfer member 4 is not inhibited, and the heat transfer characteristics of the boiler stably increase. On the other hand, if the thermal conductivity of the oxidized layer C is not more than 3.0 W ⁇ m -1 ⁇ K -1 , the heat of high temperature steam that is transferred to the surface of the base material 2 can be stably controlled.
  • the thermal conductivity of the oxidized layer C is preferably controlled within the range of 1.2 to 3.0 W ⁇ m -1 ⁇ K -1 . In this case, it is easy to improve the steam oxidation resistance properties of the ferritic heat transfer member 4 without loss of the heat transfer characteristics.
  • a preferable lower limit of the thermal conductivity is 1.3 W ⁇ m -1 ⁇ K -1 , and more preferably is 1.4 W ⁇ m -1 ⁇ K -1 .
  • a preferable upper limit of the thermal conductivity is 2.8 W ⁇ m -1 ⁇ K -1 , and more preferably is 2.5 W ⁇ m -1 ⁇ K -1 .
  • the volume ratio of Fe 3 O 4 and Fe 2 O 3 in the oxidized layer B is measured by the following method.
  • the ferritic heat transfer member 4 that has undergone a steam oxidation treatment which is described later is cut perpendicularly to the surface thereof.
  • the ferritic heat transfer member 4 is cut perpendicularly to the axial direction of the pipe.
  • a chemical composition analysis of the oxidized layer B is performed using a field emission electron probe micro analyzer (FE-EPMA) manufactured by JEOL Ltd.
  • FE-EPMA field emission electron probe micro analyzer
  • the conditions for the chemical composition analysis are: detector: 30 mm 2 SD, accelerating voltage: 15 kV, and measurement time period: 60 secs.
  • regions in which Fe and O (oxygen) are detected and Cr is not detected are identified.
  • the strength of Fe in the oxidized layer B of the observation surface is subjected to binarization processing.
  • the maximum strength of the grayscale extraction objects is set as 1/10 or more. It is confirmed that all regions other than the identified regions (regions confirmed as having Fe 3 O 4 and Fe 2 O 3 ) are included in black regions after binarization.
  • the area fraction of black regions in the oxidized layer B of the observation surface is determined, and the resulting value is subtracted from 100%.
  • the obtained area fraction is taken as the volume ratio of Fe 3 O 4 and Fe 2 O 3 in the oxidized layer B.
  • the volume ratio of Cr 2 O 3 in the oxidized layer C is measured by the following method.
  • the ferritic heat transfer member 4 that has undergone a steam oxidation treatment which is described later is cut perpendicularly to the surface thereof.
  • the ferritic heat transfer member 4 is a pipe
  • the ferritic heat transfer member 4 is cut perpendicularly to the axial direction of the pipe.
  • SEM is used to observe a cross-section (observation surface) including the oxidized layer B and the oxidized layer C, to thereby identify the oxidized layer C.
  • the oxidized layer B and the oxidized layer C are distinguished from each other by means of a contrast difference obtained with an SEM backscattered electron image (BSE).
  • the contrast of the oxidized layer B is brighter than the contrast of the oxidized layer C.
  • the volume ratio of Cr 2 O 3 in the oxidized layer C is determined by a similar method as the method used for determining the volume ratio of Fe 3 O 4 and Fe 2 O 3 in the oxidized layer B. That is, at a cross-section (observation surface) including the oxidized layer C, a chemical composition analysis is performed using a field emission electron probe micro analyzer (FE-EPMA) manufactured by JEOL Ltd.
  • the conditions for the chemical composition analysis are: detector: 30 mm 2 SD, accelerating voltage: 15 kV, and measurement time period: 60 secs.
  • the strength of Cr in the oxidized layer C of the observation surface is subjected to binarization processing.
  • the maximum strength of the grayscale extraction objects is set as 1/10 or more. It is confirmed that all regions other than the identified regions (regions confirmed as having Cr 2 O 3 ) are included in black regions after binarization.
  • the area fraction of black regions after binarization processing of the observation surface is determined, and the resulting value is subtracted from 100%. The obtained area fraction is taken as the volume ratio of Cr 2 O 3 in the oxidized layer C.
  • the total content of Cr and Mn and the total content of the specific oxidized layer forming elements (Mo, Ta, W and Re) in the oxidized layer B and the oxidized layer C are determined by a similar method as the method used with respect to the oxidized layer A.
  • the oxidized layer B and the oxidized layer C are distinguished from each other by means of a contrast difference obtained with an SEM backscattered electron image (BSE).
  • BSE SEM backscattered electron image
  • the contrast of the oxidized layer B is brighter than the contrast of the oxidized layer C.
  • an elemental analysis is performed at the center of the thickness of the oxidized layer B and the center of the thickness of the oxidized layer C.
  • the total content (mass%) of Cr and Mn and the total content (mass%) of the specific oxidized layer forming elements (Mo, Ta, W and Re) are determined based on the compositions of the respective elements that are obtained.
  • the thermal conductivity of the oxidized layer C is determined by the following method. After mechanically removing the oxidized layer B of the ferritic heat transfer member 4, the bulk density, specific heat and thermal diffusivity of the oxidized layer C including the base material 2 are measured. Next, after mechanically removing the oxidized layer C, the bulk density, specific heat and thermal diffusivity of the base material 2 are measured in a similar manner.
  • the bulk density is substituted for ⁇
  • the specific heat is substituted for C p
  • the thermal diffusivity is substituted for D.
  • a preferable lower limit of the thickness of the oxidized layer C is 10 ⁇ m.
  • the thickness of the oxide film 3 is not particularly limited, a thin thickness is preferable. If the oxide film 3 is thin, the heat transfer characteristics of the ferritic heat transfer member 4 increase. Therefore, the heat transfer characteristics of the boiler can be improved. When the ferritic heat transfer member 4 is used for a long time period, the oxide film 3 thickens. The oxide film 3 also thickens in a case where the temperature for a steam oxidation treatment of the ferritic heat transfer member 4 is high. When an oxidation treatment and a steam oxidation treatment that are described later are performed, the oxidized layer B and the oxidized layer C are formed to almost the same thickness. Accordingly, in a case where the oxidized layer C is thin, the oxide film 3 will also be thin.
  • the thicknesses of the oxidized layer B and the oxidized layer C are determined by the same method as the method used for determining the thickness of the oxidized layer A.
  • the ferritic heat transfer member 4 that has undergone the steam oxidation treatment which is described later is prepared.
  • the prepared ferritic heat transfer member 4 is observed by means of SEM by the same method as the method used for determining the thickness of the oxidized layer A.
  • the oxidized layer B and the oxidized layer C are distinguished from each other by means of a contrast difference obtained with an SEM backscattered electron image.
  • the contrast of the oxidized layer B is darker than the contrast of the oxidized layer C.
  • the respective thicknesses of the oxidized layer B and the oxidized layer C are determined by the same method as the method used for determining the thickness of the oxidized layer A.
  • a method for producing ferritic heat transfer member 4 according to the present embodiment includes a steam oxidation treatment process.
  • a steam oxidation treatment is performed on the heat resistant ferritic steel that underwent the aforementioned oxidation treatment.
  • the steam oxidation treatment is performed by exposing the heat resistant ferritic steel to steam at a temperature in a range from 500 to 650°C.
  • An upper limit of the time period of the steam oxidation treatment is not particularly limited as long as the treatment time period is not less than 100 hours.
  • the ferritic heat transfer member 4 according to the present embodiment can be produced by the above processes.
  • a similar effect as the effect obtained in a case of performing the steam oxidation treatment is obtained by exposing the heat resistant ferritic steel 1 of the present embodiment under a high-temperature steam environment. That is, if the heat resistant ferritic steel 1 of the present embodiment is exposed under a high-temperature steam environment for not less than 100 hours, the ferritic heat transfer member 4 can be produced even without performing a steam oxidation treatment.
  • Respective cast pieces having the chemical compositions shown in Table 1 were produced, and an oxidation treatment and a steam oxidation treatment were performed under the conditions illustrated in Table 2.
  • ingots having the chemical compositions shown in Table 1 were prepared.
  • Each of the obtained ingots was subjected to hot rolling and cold rolling to produce a steel plate, which was adopted as the base material.
  • a test specimen was prepared from each of the obtained base materials, and each test specimen was subjected to an oxidation treatment under the conditions shown in Table 2.
  • the thickness of the oxidized layer A of each test specimen was determined by the method described above. The results are shown in Table 2.
  • each metallic element in a cross-section of each test specimen was determined by the method described above.
  • the total content (mass%) of Cr and Mn, and the total content (mass%) of Mo, Ta, W and Re were determined. The results are shown in Table 2.
  • test specimen was subjected to a steam oxidation treatment under the conditions in Table 2.
  • test specimens was subjected to the following measurement tests.
  • the total volume ratio of Fe 3 O 4 and Fe 2 O 3 in a cross-section (that is, a cross-section of the oxidized layer B) of each test specimen was determined by the method described above. Furthermore, the volume ratio of Cr 2 O 3 in a cross-section of the oxidized layer C was determined. The results are shown in Table 2.
  • each metallic element in a cross-section of each test specimen was determined by the method described above.
  • the total content (mass%) of Cr and Mn was determined.
  • the results are shown in Table 2.
  • the total content (mass%) of Cr and Mn, and the total content (mass%) of Mo, Ta, W and Re were determined. The results are shown in Table 2.
  • the thickness of the oxidized layer C of each test specimen was determined by the method described above. The results are shown in Table 2.
  • the oxidized layer A of each of these Test Nos. contained Cr and Mn in a total amount in a range of 20 to 45%, and contained one or more types of element selected from the group consisting of Mo, Ta, W and Re in a total amount in a range of 0.5 to 10%.
  • the oxidized layer B formed on the base material after the steam oxidation treatment contained Fe 3 O 4 and Fe 2 O 3 in a total amount of 80% or more in vol%.
  • the total content of Cr+Mn in the oxidized layer C was in a range of more than 5% to 30%, and the total content of the specific oxidized layer forming elements was in a range of 1 to 15%.
  • the thermal conductivity of the oxidized layer C was within the range of 1.2 to 3.0 W ⁇ m -1 ⁇ K -1 , and thus exhibited excellent thermal conductivity.
  • the thickness of the oxidized layer C was not more than 60 ⁇ m, and thus exhibited excellent steam oxidation resistance properties.
  • the CO/CO 2 ratio in the oxidation treatment was less than 0.6. Therefore, the total content of Cr and Mn in the oxidized layer A was less than 20%. Consequently, the total content of Cr and Mn in the oxidized layer C was not more than 5%, and the thermal conductivity of the oxidized layer C was more than 3.0 W ⁇ m -1 ⁇ K -1 . Further, because the Fe 3 O 4 volume ratio in the oxidized layer B was less than 80%, the inward flux of oxygen was large and growth of the oxidized layer C was promoted, and the thickness of the oxidized layer C was more than 60 ⁇ m.
  • the steel did not contain any of the specific oxidized layer forming elements. Therefore, even though the production method was appropriate, the total content of the specific oxidized layer forming elements in the oxidized layer A was less than 0.1%, which was too low. Consequently, the total content of the specific oxidized layer forming elements in the oxidized layer C was less than 0.1%, which was too low. As a result, the thermal conductivity of the oxidized layer C was 1.1 W ⁇ m -1 ⁇ K -1 , which was too low.
  • the Cr content was too high. Therefore, even though the production method was appropriate, the total content of Cr and Mn in the oxidized layer A was 47.6%, which was too high. Consequently, the total content of Cr and Mn in the oxidized layer C was 56.7%, which was too high. As a result, the thermal conductivity of the oxidized layer C was 0.8 W ⁇ m -1 ⁇ K -1 , which was too low.
  • the Cr content was too low. Therefore, even though the production method was appropriate, the total content of Cr and Mn in the oxidized layer A was 16.3%, which was too low. Consequently, the total content of Cr and Mn in the oxidized layer C was 1.3%, which was too low. As a result, the thermal conductivity of the oxidized layer C was 3.3 W ⁇ m -1 ⁇ K -1 , which was too high. Furthermore, in Test No. 20, the thickness of the oxidized layer C was more than 60 ⁇ m. It is considered that this was because the thermal conductivity of the oxidized layer C was too high.
  • the content of the specific oxidized layer forming elements was too high. Therefore, the total content of the specific oxidized layer forming elements in the oxidized layer A was 13.9%, which was too high. Consequently, the total content of the specific oxidized layer forming elements in the oxidized layer C was 18.6%, which was too high. As a result, the thermal conductivity of the oxidized layer C was 3.8 W ⁇ m -1 ⁇ K -1 , which was too high. Furthermore, in Test No. 21 the thickness of the oxidized layer C was more than 60 ⁇ m. It is considered that this was because the thermal conductivity of the oxidized layer C was too high.

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EP17820295.8A 2016-06-29 2017-06-29 Ferritischer hitzefester stahl und ferritische wärmeübertragungsteil Pending EP3480331A4 (de)

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MX2023010534A (es) * 2021-03-17 2023-09-19 Jfe Steel Corp Tubo de acero inoxidable duplex y metodo para fabricar el mismo.
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US5520751A (en) * 1993-09-24 1996-05-28 Exxon Research And Engineering Company Oxidation of low chromium steels
JP3367216B2 (ja) * 1994-09-20 2003-01-14 住友金属工業株式会社 高Ｃｒフェライト系耐熱鋼
JPH1192880A (ja) * 1997-09-22 1999-04-06 Natl Res Inst For Metals 耐酸化性・耐水蒸気酸化特性に優れた 高Ｃｒフェライト系耐熱鋼とその製造方法
CN100580119C (zh) * 2005-04-07 2010-01-13 住友金属工业株式会社 铁素体类耐热钢
JP2007039745A (ja) 2005-08-03 2007-02-15 Babcock Hitachi Kk フェライト系耐熱鋼の耐水蒸気酸化性改善方法及び耐水蒸気酸化性に優れたフェライト系耐熱鋼並びにボイラ用耐熱鋼
US20090007991A1 (en) * 2006-02-06 2009-01-08 Toshio Fujita Ferritic Heat-Resistant Steel
KR20090130334A (ko) * 2007-06-04 2009-12-22 수미도모 메탈 인더스트리즈, 리미티드 페라이트계 내열강
JP2009007601A (ja) * 2007-06-26 2009-01-15 Nisshin Steel Co Ltd 集熱機器用フェライト系ステンレス鋼材
JP4990323B2 (ja) 2009-05-18 2012-08-01 独立行政法人物質・材料研究機構 フェライト系耐熱鋼
ES2604714T3 (es) * 2011-11-22 2017-03-08 Nippon Steel & Sumitomo Metal Corporation Acero ferrítico resistente al calor, y el método de fabricación del mismo
JP6049256B2 (ja) * 2011-12-19 2016-12-21 三菱日立パワーシステムズ株式会社 フェライト系耐熱鋼の耐酸化処理方法
CN103336102B (zh) * 2012-06-12 2015-01-14 武汉大学 9-12%Cr马氏体耐热钢焊缝中δ-铁素体含量的测定方法
CN103334056A (zh) * 2013-03-25 2013-10-02 天津理工大学 一种用于火力发电锅炉管的高Cr铁素体耐热钢及应用

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JPWO2018003941A1 (ja) 2019-04-25
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