WO2015133551A1 - Alliage austénitique résistant à la chaleur - Google Patents

Alliage austénitique résistant à la chaleur Download PDF

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WO2015133551A1
WO2015133551A1 PCT/JP2015/056433 JP2015056433W WO2015133551A1 WO 2015133551 A1 WO2015133551 A1 WO 2015133551A1 JP 2015056433 W JP2015056433 W JP 2015056433W WO 2015133551 A1 WO2015133551 A1 WO 2015133551A1
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剛夫 宮村
難波　茂信
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株式会社神戸製鋼所
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Priority to CN201580011341.1A priority Critical patent/CN106062230B/zh
Priority to EP15758391.5A priority patent/EP3115476A4/fr
Priority to US15/123,125 priority patent/US20170067139A1/en
Priority to KR1020167023997A priority patent/KR101770536B1/ko
Publication of WO2015133551A1 publication Critical patent/WO2015133551A1/fr

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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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • 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
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • 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
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/004—Dispersions; Precipitations

Definitions

  • the present invention relates to an austenitic heat resistant steel.
  • the method of coarsening the crystal grains inhibits the formation of the Cr 2 O 3 protective film, so that the steam oxidation resistance may be lowered.
  • the element addition amount it is necessary to increase the element addition amount. If the amount of element addition is increased, various basic characteristics other than creep strength may be adversely affected. Further, when the amount of element addition is increased, the raw material cost increases, and there is a possibility that economic efficiency is impaired. For this reason, a method of obtaining a solid solution strengthening action in a heat resistant material is not desirable as a method of obtaining a desired strength.
  • the method of obtaining the effect of precipitation strengthening can strongly suppress the movement of dislocation accompanying deformation and can greatly improve the creep strength.
  • many heat-resistant members are manufactured in the order of softening heat treatment, cold working, and final heat treatment.
  • the final heat treatment is performed by heating to a high temperature followed by a rapid cooling treatment in the actual use environment or in the creep test. It is necessary to previously dissolve the element that precipitates therein.
  • Patent Document 1 discloses an austenitic stainless steel containing one or two of Ti: 0.15 to 0.5 mass% and Nb: 0.3 to 1.5 mass%.
  • the final softening temperature is set to over 1200 ° C. to 1350 ° C. and heated. After cooling at a cooling rate of 500 ° C./hr or more, 20 to 90% of cold working is added. Next, by heating to a temperature of 1070 to 1300 ° C. and 30 ° C. lower than the final softening temperature, and performing a final heat treatment of cooling at a cooling rate of air cooling or higher, the creep strength is high, and the fine grain structure has good corrosion resistance.
  • a method for producing austenitic stainless steel is disclosed.
  • Patent Document 1 a part of the element to be precipitated in an actual use environment or a creep test is precipitated in a small amount in the above-described final heat treatment stage, and crystallized due to the grain boundary pinning effect by the precipitate. This is to suppress grain coarsening. That is, the method disclosed in Patent Document 1 precipitates the difference in the amount of solid solution corresponding to this temperature difference by raising the softening heat treatment temperature before cold working to a certain level or more with respect to the final heat treatment. Thus, by devising two heat treatment temperatures, improvement in creep strength by high-temperature heat treatment and formation of a structure (fine crystal grain structure) containing a lot of fine crystal grains are achieved.
  • the manufacturing equipment used in actual production has an upper limit temperature.
  • the softening heat treatment temperature is raised to the equipment upper limit temperature, in order to provide a difference between the two heat treatment temperatures as in the method disclosed in Patent Document 1, it is necessary to set the final heat treatment temperature lower than the equipment upper limit temperature. .
  • the decrease in the final heat treatment temperature decreases the amount of precipitation formed in the actual use environment or during the creep test, and as a result, the creep strength may not be sufficiently improved.
  • the invention disclosed in Patent Document 1 obtains excellent steam oxidation resistance by making a fine grain structure, and obtains a pinning effect of grain boundaries by precipitating a small amount of precipitates. It has a creep strength.
  • lowering the final heat treatment temperature to obtain a pinning effect means that the deposits that should be formed in the actual use environment or during the creep test are used in advance and sacrificed. Conceivable.
  • the conventional technology cannot sufficiently utilize the precipitation strengthening that can be obtained from the steel material components.
  • the creep strength is a limiting factor that determines the thickness of the member. Therefore, if the creep strength is improved, the thickness can be reduced and the cost can be reduced.
  • austenitic heat-resistant steel has sufficient creep strength, and it can be said that it has not led to cost reduction.
  • the final heat treatment temperature is lowered when the method disclosed in Patent Document 1 is applied. There must be. As described above, when the final heat treatment temperature is lowered, the solid solution amount of the precipitated element is lowered. Therefore, it is presumed that precipitation strengthening cannot be utilized to the maximum and the effect of improving the creep strength cannot be fully expressed.
  • This invention is made
  • the creep strength has been arranged focusing on the solid solution amount of the precipitated element depending on the temperature of the heat treatment. Therefore, generally, when the final heat treatment temperature is lowered, the amount of precipitated elements decreases, and the amount of fine precipitates newly precipitated in the actual use environment or during the creep test is reduced. Has been thought to be lower.
  • the temperature difference between the softening heat treatment and the final heat treatment is set to 30 ° C. or more, and the precipitation of some precipitation elements is suppressed by the final heat treatment, thereby suppressing the coarsening of crystal grains. is doing.
  • the precipitate that is precipitated by this operation is a precipitate that is supposed to be deposited in the actual use environment or during the creep test and contribute to the improvement of the creep strength. That is, the austenitic stainless steel manufactured by the method disclosed in Patent Document 1 cannot sufficiently improve the creep strength by the amount of the precipitated element to suppress the coarsening of crystal grains. The possibility is high.
  • the present inventors have intensively studied whether or not the precipitate formed by this final heat treatment can directly affect the improvement of creep strength.
  • the inventors of the present invention maintain specific amounts of precipitation elements added and solid solution amounts within a certain range, and within a certain range the precipitation particle size and precipitation amount contained in the steel. It was found that the precipitate obtained by performing the final heat treatment at a lower temperature than in the prior art can improve the creep strength. That is, the present inventors have found that precipitates formed by performing final heat treatment under specific heat treatment conditions contribute to improvement of creep strength as fine precipitates as they are. This finding exceeds the concept of the prior art that the creep strength is superior to conventional precipitates obtained by heat treatment at high temperatures. It was also found that the final heat treatment is performed under the specific heat treatment conditions described above (lower temperature than before), so that the fine grain structure can be maintained and the steam oxidation resistance can be maintained.
  • the precipitate formed by the final heat treatment suppresses creep deformation more effectively than the precipitate formed during the creep test.
  • precipitates formed during a creep test on an austenitic heat resistant steel are formed along dislocations introduced with deformation. Since dislocations are concentrated in the vicinity of the grain boundaries, the distribution of precipitates becomes nonuniform.
  • the precipitate formed by the final heat treatment when manufacturing the austenitic heat resistant steel is uniformly formed in the grains.
  • the precipitate formed by the final heat treatment can efficiently suppress the dislocation movement accompanying the creep deformation from the initial stage of deformation throughout the grain. For these reasons, it is presumed that good creep strength can be obtained when the final heat treatment is performed under specific heat treatment conditions as described above. This knowledge goes beyond the concept of the solid solution amount of the precipitation element depending on the temperature of the conventional heat treatment.
  • the austenitic heat-resisting steel according to the present invention which is made on the basis of the above findings and solves the above-mentioned problems, is C: 0.05 to 0.16% by mass, Si: 0.1 to 1% by mass, Mn: 0.0.
  • precipitation cumulative number particle size precipitates in the range of 100nm exceeds the 0nm density 0.1-2.0 units / [mu] m 2, the distribution of the precipitated particles size and the cumulative number density
  • the precipitation particle diameter corresponding to the half value of the cumulative number density is 70 nm or less
  • the average hardness is 160 Hv or less
  • the crystal grain size number is 7.5 or more.
  • the austenitic heat-resisting steel according to the present invention can have precipitates that can be obtained by performing the final heat treatment under a specific heat treatment condition with the steel material component in the above-described range.
  • This precipitate is one in which the particle diameter and the amount of precipitation contained in the steel fall within a certain range, and contributes to the improvement of the creep strength as a fine precipitate as it is after the precipitation.
  • this fine precipitate can improve the creep strength as compared with the conventional precipitate formed by final heat treatment at a high temperature.
  • the final heat treatment is performed at specific heat treatment conditions, specifically at a lower temperature than before, the fine grain structure can be maintained and the steam oxidation resistance is excellent. can do.
  • the austenitic heat-resisting steel according to the present invention further includes Zr: 0.3% by mass or less (not including 0% by mass), rare earth elements: 0.15% by mass or less (not including 0% by mass), and W : It is preferable to contain at least one of 3% by mass or less (not including 0% by mass).
  • the high temperature strength can be improved by precipitation strengthening.
  • the austenitic heat-resisting steel according to the present invention contains a rare earth element in the above-described range, the oxidation resistance of the stainless steel can be improved.
  • the austenitic heat-resisting steel according to the present invention contains W in the above-described range, the high temperature strength can be improved by solid solution strengthening.
  • the austenitic heat-resisting steel according to the present invention has the steel material component in the above-described range, and the precipitate particle diameter and the precipitation amount contained in the steel are within a certain range, so that it is excellent while maintaining a fine grain structure.
  • the steel material components are C: 0.05 to 0.16 mass%, Si: 0.1 to 1 mass%, Mn: 0.1 to 2.5 mass%, P : 0.01 to 0.05 mass%, S: 0.005 mass% or less (excluding 0 mass%), Ni: 7 to 12 mass%, Cr: 16 to 20 mass%, Cu: 2 to 4 mass %, Mo: 0.1 to 0.8 mass%, Nb: 0.1 to 0.6 mass%, Ti: 0.1 to 0.6 mass%, B: 0.0005 to 0.005 mass%, N: 0.001 to 0.15 mass%, Mg: 0.005 mass% or less (not including 0 mass%) and Ca: 0.005 mass% or less (not including 0 mass%)
  • the total of the Nb content and the Ti content is 0.3% by mass
  • the austenitic heat-resistant steel according to the present embodiment further includes Zr: 0.3% by mass or less (excluding 0% by mass), rare earth element: 0.15% by mass or less (not including 0% by mass), and It is preferable to contain at least one of W: 3 mass% or less (excluding 0 mass%).
  • the austenitic heat-resistant steel according to the present embodiment is a fire SUS321J2HTB steel (18 mass% Cr-10 mass% Ni-3 mass% Cu-Nb) using Ti as a precipitation element. , Ti steel).
  • the austenitic heat-resisting steel according to the present embodiment comprising the above-described steel material components has a cumulative number density of precipitates in the range of the precipitate particle diameter exceeding 0 nm and 100 nm, 0.1 to 2.0 pieces / ⁇ m 2 ,
  • the precipitated particle size corresponding to the half value of the cumulative number density is 70 nm or less
  • the average hardness is 160 Hv or less
  • the crystal grain size number is 7.5 or more.
  • the precipitated particle diameter refers to a value calculated as the equivalent-circle diameter of the precipitated particles (precipitate).
  • the means for solving the problem it is possible to obtain a precipitate in which the precipitate particle size and the precipitation amount contained in the steel are within a certain range by performing the final heat treatment under specific heat treatment conditions.
  • the above average hardness and grain size number can also be controlled by controlling the heat treatment temperature. Specific heat treatment conditions and heat treatment temperatures will be described later.
  • the austenitic heat-resistant steel according to the present embodiment is excellent in steam oxidation resistance.
  • the austenitic heat-resistant steel according to the present embodiment is similar to the fire SUS321J2HTB steel using Ti as a precipitation element.
  • the following steel material components have the following effects, and if they deviate from the predetermined contents, the following problems may occur.
  • C has the effect
  • 0.05 mass% or more is contained in order to acquire the effect
  • the lower limit of the C content is preferably 0.08% by mass, and more preferably 0.09% by mass.
  • the upper limit of the C content is preferably 0.15% by mass, and more preferably 0.13% by mass.
  • Si has a deoxidizing action in the molten steel and effectively acts to improve oxidation resistance.
  • Si is contained in an amount of 0.1% by mass or more in order to obtain a deoxidizing action in molten steel and an action for improving oxidation resistance.
  • the steel material may be brittle, which is not preferable.
  • the lower limit of the Si content is preferably 0.2% by mass, and more preferably 0.3% by mass.
  • the upper limit of the Si content is preferably 0.7% by mass, and more preferably 0.5% by mass.
  • Mn has a deoxidizing action in molten steel.
  • 0.1 mass% or more of Mn is contained.
  • the Mn content exceeds 2.5 mass%, it is not preferable because it promotes coarsening of carbide precipitation.
  • the lower limit of the Mn content is preferably 0.2% by mass, and more preferably 0.3% by mass.
  • the upper limit of the Mn content is preferably 2.0% by mass, and more preferably 1.8% by mass.
  • P 0.01 to 0.05% by mass
  • P has the effect of improving the high temperature strength.
  • 0.01 mass% or more of P is contained in order to improve the high temperature strength.
  • the lower limit of the P content is preferably 0.015% by mass, and more preferably 0.02% by mass.
  • the upper limit of the P content is preferably 0.04% by mass, and more preferably 0.03% by mass.
  • S 0.005 mass% or less (excluding 0 mass%)
  • S is an inevitable impurity. If the S content becomes excessive and exceeds 0.005% by mass, the hot workability is deteriorated.
  • the S content is set to 0.005 mass% or less so as not to deteriorate the hot workability. The smaller the S content, the better.
  • the upper limit of the S content is preferably 0.002% by mass, and more preferably 0.001% by mass.
  • Ni has the effect of stabilizing the austenite phase.
  • 7% by mass or more of Ni is contained in order to stabilize the austenite phase.
  • the lower limit of the Ni content is preferably 9% by mass, and more preferably 9.5% by mass.
  • the upper limit of the Ni content is preferably 11.5% by mass, and more preferably 11% by mass.
  • Cr 16 to 20% by mass
  • Cr has the effect of improving the oxidation resistance and corrosion resistance of the steel material.
  • Cr in order to improve the oxidation resistance and corrosion resistance of the steel material, Cr is contained in an amount of 16% by mass or more. However, if the Cr content exceeds 20% by mass, the steel material becomes brittle.
  • the lower limit of the Cr content is preferably 17.5% by mass, and more preferably 18% by mass.
  • the upper limit of the Cr content is preferably 19.5% by mass, and more preferably 19% by mass.
  • Cu has the effect of forming precipitates in steel and improving high temperature strength.
  • 2 mass% or more of Cu is contained.
  • the lower limit of the Cu content is preferably 2.5% by mass, and more preferably 2.8% by mass.
  • the upper limit of the Cu content is preferably 3.5% by mass, and more preferably 3.2% by mass.
  • Mo 0.1 to 0.8% by mass
  • Mo has the effect
  • Mo is contained in an amount of 0.1% by mass or more. However, if the Mo content becomes excessive and exceeds 0.8% by mass, the steel material becomes brittle.
  • the lower limit of the Mo content is preferably 0.2% by mass, and more preferably 0.3% by mass.
  • the upper limit of the Mo content is preferably 0.6% by mass, and more preferably 0.5% by mass.
  • Nb 0.1 to 0.6% by mass
  • Ti 0.1 to 0.6% by mass
  • Total of Nb content and Ti content is 0.3 mass% or more
  • Nb and Ti can be precipitated as carbonitrides (carbides, nitrides or carbonitrides) to improve the high-temperature strength. Moreover, this precipitate suppresses the coarsening of crystal grains and promotes the diffusion of Cr. It can be said that it is a part of the most important element in the present invention because it exerts a secondary effect of improving corrosion resistance (water vapor oxidation resistance) by diffusion of Cr.
  • Nb and Ti precipitates are formed to improve the high-temperature strength and to exert the effect of improving the steam oxidation resistance, so that Nb is 0.1% by mass or more and Ti is 0.1%. It is contained by mass% or more. By simultaneously containing Nb and Ti, the contribution to the improvement of the high temperature strength of the precipitate can be further increased. However, if these are not contained so that the total of the Nb content and the Ti content is 0.3% by mass or more, it is impossible to ensure the minimum necessary precipitation amount.
  • the minimum of Nb content shall be 0.2 mass%.
  • the lower limit of the Ti content is preferably 0.15% by mass.
  • the lower limit of the total content of Nb and Ti is preferably 0.35% by mass.
  • the upper limit of content of Nb and Ti is respectively 0.4 mass%, and it is more preferable to set it as 0.3 mass%.
  • B has the effect of promoting the formation of M 23 C 6 type carbide (M is a carbide forming element) and improving the high temperature strength.
  • M is a carbide forming element
  • B in order to improve high temperature strength, 0.0005 mass% or more of B is contained.
  • the lower limit of the B content is preferably 0.001% by mass, and more preferably 0.0015% by mass.
  • the upper limit of the B content is preferably 0.004% by mass, and more preferably 0.003% by mass.
  • N has the effect of improving the high-temperature strength by solid solution strengthening.
  • N is added in an amount of 0.001% by mass or more in order to improve the high temperature strength.
  • the lower limit of the N content is preferably 0.002% by mass, more preferably 0.003% by mass.
  • the upper limit of the N content is preferably 0.08% by mass, and more preferably 0.04% by mass.
  • Mg and Ca act as desulfurization / deoxidation elements and have an effect of improving the hot workability of the steel material.
  • Ca and Mg may be contained in a range of 0.005% by mass or less.
  • the upper limit of Ca and Mg is preferably 0.002% by mass.
  • Zr 0.3% by mass or less (excluding 0% by mass)
  • Zr is an optional component and has the effect of improving the high-temperature strength by precipitation strengthening. However, if the Zr content becomes excessive and exceeds 0.3% by mass, a coarse intermetallic compound is formed, resulting in a decrease in hot ductility. In addition, it is preferable that the upper limit of Zr content shall be 0.25 mass%. However, since inclusion of Zr increases the cost of the steel material, it may be included as necessary.
  • Rare earth elements are optional components and have the effect of improving the oxidation resistance of stainless steel. That is, the generation of oxide scale can be suppressed by arbitrarily containing rare earth elements. However, if the content of the rare earth element becomes excessive and exceeds 0.15% by mass, a part of the grain boundary is melted in a high temperature environment and hot workability is hindered.
  • the upper limit of the rare earth element content is preferably 0.1% by mass, and more preferably 0.05% by mass.
  • the rare earth element is one or more elements selected from a total of 17 elements including Sc and Y and 15 lanthanoid elements represented by La, Ce, and Nd.
  • the rare earth element content is a total content of one or more elements selected from 17 elements.
  • W 3% by mass or less (excluding 0% by mass)
  • W is an optional component and has the effect of improving the high temperature strength by solid solution strengthening. However, if the W content is excessive and exceeds 3% by mass, a coarse intermetallic compound is formed, resulting in a decrease in high temperature ductility.
  • the upper limit of the W content is preferably 2.5% by mass, and more preferably 2.0% by mass.
  • the steel material component described above exhibits the above-described action by being contained, but at the same time increases the cost. Therefore, what is necessary is just to set content according to a required reinforcement
  • the balance is Fe and inevitable impurities
  • the balance is Fe and other inevitable impurities.
  • other inevitable impurities include Al, Sn, Zn, Pb, As, Bi, Sb, Te, Se, and In. Inevitable impurities are preferably reduced as much as possible.
  • Al is 0.01% by mass or less
  • Sn is 0.005% by mass or less
  • Zn is 0.01% by mass or less
  • Pb is 0.002%.
  • Mass% or less As is 0.01 mass% or less
  • Bi is 0.002 mass% or less
  • Sb is 0.002 mass% or less
  • Te 0.01 mass% or less
  • Se is 0.002 mass% or less
  • In It is recommended that the content be 0.002% by mass or less.
  • the average hardness (Vickers hardness) is set to 160 Hv or less in order to secure the solid solution amount of the elements that are deposited in the actual use environment or the creep test after the above-described component range. If the average hardness exceeds 160 Hv, the solid solution amount of the element that precipitates in the actual use environment or during the creep test cannot be secured, so the creep strength decreases.
  • the upper limit of the average hardness is preferably 140 Hv.
  • the lower limit of the average hardness is preferably 100 Hv, more preferably 110 Hv.
  • Vickers hardness can be measured based on JISZ2244: 2009, for example.
  • the precipitate particle diameter corresponding to half the cumulative number density is kept as fine as 70 nm or less while forming a certain amount of precipitates of 100 nm or less, thus improving the creep strength.
  • the lower limit of the cumulative number density mentioned above is preferably of a 0.3 / ⁇ m 2, and more preferably set to 0.4 / ⁇ m 2.
  • the upper limit of the precipitated particle diameter corresponding to the half value of the cumulative number density is preferably 60 nm, and more preferably 50 nm.
  • the lower limit of the precipitated particle diameter corresponding to the half value of the cumulative number density exceeds 0 nm. The method for measuring the precipitated particle diameter and the cumulative number density will be described later.
  • the metal structure is in a sufficiently fine state and can be referred to as a fine crystal grain structure. Therefore, the steam oxidation resistance can be maintained.
  • the final heat treatment may be performed under specific heat treatment conditions described later.
  • the final heat treatment may be performed under the condition that the coarsening factor is 2000 ° C. ⁇ min or less. This “condition that the coarsening factor of the precipitate is 2000 ° C./min or less” is the specific heat treatment condition described above.
  • the coarsening factor of the precipitate is an index representing the influence of heat on the coarsening of the precipitate, and is a value obtained by integrating over time a temperature of 900 ° C. or higher at which the growth of the precipitate proceeds with respect to the temperature history during the heat treatment. is there. Note that this coarsening factor must include not only the heat treatment holding time but also the heating time and cooling time of 900 ° C. or higher.
  • the coarsening factor of a conventional austenitic heat resistant steel that contains Ti as a precipitation element and has sufficiently increased high-temperature strength, such as fire SUS321J2HTB steel is about 3000 to 7000 ° C./min.
  • the coarsening factor is set to 2000 ° C. ⁇ min or less.
  • the lower limit of the coarsening factor is preferably larger than 473 ° C./min, more preferably 500 ° C./min or more, and even more preferably 821 ° C./min or more.
  • the maximum temperature reached and the holding time can be adjusted according to the constraints of the equipment.
  • the softening heat treatment it is necessary to carry out the softening heat treatment at a temperature higher by 30 ° C. or more than the final heat treatment to dissolve the precipitated elements. That is, the temperature lower by 30 ° C. than the softening heat treatment is the upper limit temperature of the final heat treatment.
  • the “cumulative number density of precipitates having a diameter exceeding 0 nm and in the range of 100 nm” can be understood from numerical values with a horizontal axis of 90 to 100 nm.
  • precipitation particle diameter corresponding to half the cumulative number density of precipitates in the range where the precipitation particle diameter exceeds 0 nm and 100 nm in the example in the figure, the point of 50 to 60 nm and the point of 60 to 70 nm are It can be understood from the numerical value on the horizontal axis that intersects with the half value of the numerical value of 90 to 100 nm.
  • the austenitic heat-resisting steel according to the present embodiment described above has the steel material component in the above-described range and the precipitated particle diameter and precipitation amount contained in the steel are within a certain range, the fine grain structure is While maintaining, it can have excellent creep strength. Therefore, conventionally, the grain size has been reduced while sacrificing the amount of precipitation formed in the actual use environment or during the creep test. However, in the austenitic heat-resisting steel according to the present embodiment, it has been conventionally sacrificed. Precipitation can also contribute to the improvement of creep strength. Therefore, the precipitation strengthening action can be maximized even when the upper limit temperature of the heat treatment exists due to equipment restrictions and the like.
  • the austenitic heat-resistant steel using Ti as a precipitation element it is possible to provide a heat-resistant stainless steel having a further improved creep strength while having a fine grain structure. Since the austenitic heat-resistant steel according to the present embodiment can improve the creep strength, the thickness of the heat-resistant member can be made thinner than before, and the cost reduction as a heat-resistant component can be realized.
  • the heat treatment temperature and time were changed in the range of 1040 to 1215 ° C. and 0.5 to 10 minutes, that is, the coarsening factor [° C./min] of the precipitate was changed, and Table 2 No. Steel materials shown in 1-31 were prepared.
  • the grain size number and the creep rupture time were measured as follows. These measurement results are shown in Table 2 together with the coarsening factor.
  • numerical values represented by underlines and italics indicate that the requirements of the present invention are not satisfied.
  • Vickers hardness [Hv] The Vickers hardness is No. A Vickers hardness test was performed on each of the steel materials 1 to 31 in accordance with JIS Z 2244: 2009, and the hardness was measured. The load in the Vickers hardness test was measured at 10 kg. Those having a Vickers hardness of 160 Hv or less were evaluated as being excellent in average hardness, and those having a Vickers hardness exceeding 160 Hv were evaluated as being inferior in average hardness.
  • the grain size number is No. With respect to each of the steel materials shown in 1-31, the structure was observed with a microscope in accordance with JIS G 0551: 2013, and the crystal grain size number was measured. Those having a crystal grain size number of 7.5 or more were accepted and those less than 7.5 were rejected.
  • Creep rupture time [hours] The creep rupture time is no. Test pieces were prepared from the steel materials shown in 1 to 31 in accordance with JIS Z 2271: 2010, and were tested and measured. Those having a creep rupture time of 650 hours or more were evaluated as being excellent in creep strength, and those having a creep rupture time of less than 650 hours were evaluated as being inferior in creep strength.
  • no. 4 and 7, no. 11 and 14, no. 16 and 18, no. 20 and 23, no. Nos. 25 and 28 are examples in which the latter number is lower than the former number in the heat treatment temperature.
  • 4 and 7, no. 11 and 14, no. Nos. 25 and 28 are examples in which the temperature was lowered by 20 ° C.
  • Nos. 16 and 18 are examples in which the temperature is lowered by 10 ° C. 20 and 23 are examples in which the temperature was lowered by 30 ° C.
  • No. 9 The steel material shown in No. 9 is a comparative example in which the precipitation component could not be sufficiently dissolved because the coarsening factor of the precipitate was too low.
  • the No. Although the steel material shown in No. 9 had a fine grain structure, it was confirmed that the Vickers hardness (average hardness) deviated from the definition of the present invention and the creep rupture time was reduced.
  • the steel materials shown in 29 to 31 are comparative examples in which the chemical composition deviates from the definition of the present invention. Of these, No. Although the steel materials shown in 29 and 30 have coarse grains and include elements desirable for creep strength, the creep strength of all the steel materials is less than 650 hours, and an insufficient strength can be obtained as compared with the examples. It was. No. The steel material shown in No. 31 has a crystal grain size number of 7.5 and a good fine grain structure is obtained, but the creep strength is less than 650 hours, and only an insufficient strength is obtained as compared with the examples. There wasn't.
  • the steel materials shown in 3, 6, 10, 13, 15, 22, and 27 have a good fine crystal grain structure with a crystal grain size number of 7.5 or more.
  • the steel materials shown in 3, 6, 10, 13, 15, 22, and 27 are, in the distribution of the cumulative number density of precipitates and the number of precipitated particles in the range of the precipitate particle diameter exceeding 0 nm and 100 nm, The creep rupture time was inferior when compared with the examples (both were comparative examples) because at least one of the precipitate particle diameters corresponding to the half value of the cumulative number density was not satisfied.
  • the steel material satisfying the provisions of the present invention (steel material according to the embodiment) has a fine grain structure compared with the steel material not satisfying the provisions of the present invention (steel material according to the comparative example). Was confirmed to be excellent.
  • the austenitic heat-resistant steel of the present invention exhibits excellent creep strength even in a high temperature environment, it is useful for energy-related equipment such as boilers and reaction vessels. Excellent creep strength even in high temperature environments.

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  • Metallurgy (AREA)
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Abstract

L'invention concerne un acier austénitique résistant à la chaleur contenant, en masse, 0,05 à 0,16 % de C, 0,1 à 1 % de Si, 0,1 à 2,5 % de Mn, 0,01 à 0,05 % de P, moins de 0,005 % de S, 7 à 12 % de Ni, 16 à 20 % de Cr, 2 à 4 % de Cu, 0,1 à 0,8 % de Mo, 0,1 à 0,6 % de Nb, 0,1 à 0,6 % de Ti, 0,0005 à 0,005 % de B, 0,001 à 0,15 % de N et 0,005 % ou moins de Mg et/ou 0,005 % ou moins de Ca, les quantités de Nb et de Ti étant supérieures ou égales à 0,3 % au total, le reste étant constitué de Fe et d'impuretés inévitables. La densité en nombre cumulée d'un précipité qui a un diamètre de particule de plus de 0 nm à 100 nm est de 0,1 à 2,0/μm2, le diamètre des particules du précipité correspondant à la moitié de la densité en nombre cumulée dans la distribution de la densité en nombre cumulée et du diamètre des particules de précipité est inférieur ou égal à 70 nm, la dureté moyenne est inférieure ou égale à 160 Hv et l'indice de taille des grains est supérieur ou égal à 7,5.
PCT/JP2015/056433 2014-03-05 2015-03-04 Alliage austénitique résistant à la chaleur WO2015133551A1 (fr)

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CN201580011341.1A CN106062230B (zh) 2014-03-05 2015-03-04 奥氏体系耐热钢
EP15758391.5A EP3115476A4 (fr) 2014-03-05 2015-03-04 Alliage austénitique résistant à la chaleur
US15/123,125 US20170067139A1 (en) 2014-03-05 2015-03-04 Austenitic heat-resistant steel
KR1020167023997A KR101770536B1 (ko) 2014-03-05 2015-03-04 오스테나이트계 내열강

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JP2017014575A (ja) * 2015-07-01 2017-01-19 新日鐵住金株式会社 オーステナイト系耐熱合金及び溶接構造物
JP6623719B2 (ja) * 2015-11-25 2019-12-25 日本製鉄株式会社 オーステナイト系ステンレス鋼
JP6638551B2 (ja) * 2016-05-09 2020-01-29 日本製鉄株式会社 オーステナイト系耐熱鋼溶接金属およびそれを有する溶接継手
CN106544601A (zh) * 2016-12-29 2017-03-29 董世祥 多性能耐高温系列铸钢
CN109554609B (zh) * 2017-09-26 2022-03-15 宝钢德盛不锈钢有限公司 一种表面免起皮的奥氏体耐热钢及其制造方法
JP6870750B2 (ja) * 2017-10-03 2021-05-12 日本製鉄株式会社 オーステナイト系耐熱鋼用溶接材料、溶接金属および溶接構造物ならびに溶接金属および溶接構造物の製造方法
CN109576580B (zh) * 2018-11-29 2020-09-29 武汉华培动力科技有限公司 柴油机可变截面增压器喷嘴组件用耐热钢及冶炼方法
WO2021220913A1 (fr) * 2020-04-30 2021-11-04 日本製鉄株式会社 Procédé de fabrication d'un acier austénitique résistant à la chaleur
JP7457262B2 (ja) * 2020-04-30 2024-03-28 日本製鉄株式会社 オーステナイト系耐熱鋼
US20220145174A1 (en) * 2020-11-05 2022-05-12 Seoul National University R&Db Foundation Perovskite color converter and method of manufacturing the same
FR3143631A1 (fr) * 2022-12-15 2024-06-21 Commissariat A L'energie Atomique Et Aux Energies Alternatives Utilisation d’un acier à triple structuration dans un environnement acide
CN116200668B (zh) * 2023-04-17 2023-11-14 宁波晴力紧固件有限公司 一种耐热高强度紧固件材料及其制备方法

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KR101770536B1 (ko) 2017-08-22
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CN106062230B (zh) 2017-07-14
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EP3115476A4 (fr) 2017-11-01
US20170067139A1 (en) 2017-03-09
JP6289941B2 (ja) 2018-03-07

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