WO2014045476A1 - Acier inoxydable ferritique - Google Patents

Acier inoxydable ferritique Download PDF

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Publication number
WO2014045476A1
WO2014045476A1 PCT/JP2013/001821 JP2013001821W WO2014045476A1 WO 2014045476 A1 WO2014045476 A1 WO 2014045476A1 JP 2013001821 W JP2013001821 W JP 2013001821W WO 2014045476 A1 WO2014045476 A1 WO 2014045476A1
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range
stainless steel
corrosion resistance
ferritic stainless
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PCT/JP2013/001821
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English (en)
Japanese (ja)
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正崇 吉野
太田　裕樹
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Ｊｆｅスチール株式会社
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Priority to CN201380041079.6A priority Critical patent/CN104508168B/zh
Priority to MYPI2015700269A priority patent/MY195207A/en
Priority to JP2013553687A priority patent/JP5590255B1/ja
Priority to KR1020157002655A priority patent/KR101673218B1/ko
Priority to IN368DEN2015 priority patent/IN2015DN00368A/en
Publication of WO2014045476A1 publication Critical patent/WO2014045476A1/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
    • 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
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • 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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling

Definitions

  • the present invention relates to a ferritic stainless steel, particularly a ferritic stainless steel excellent in corrosion resistance of a welded portion.
  • Stainless steel is roughly classified into ferritic stainless steel represented by SUS430 and austenitic stainless steel represented by SUS304.
  • Ferritic stainless steel can be manufactured at low cost because the amount of Ni, which is an expensive element, is small compared to austenitic stainless steel.
  • ferritic stainless steel has excellent properties such as the advantage of less deformation during welding due to its low thermal expansion coefficient and high thermal conductivity, excellent corrosion resistance in outdoor environments, and resistance to stress corrosion cracking. Yes. Therefore, ferritic stainless steel has been widely applied to various building materials, automobile parts, kitchen equipment, home appliances, water heaters, and the like, and the needs thereof have been further increased in recent years.
  • Ferritic stainless steel is often used by being welded with ferritic stainless steels or with austenitic stainless steel (for example, SUS304, etc.), and good corrosion resistance is also required at the welded portion in the same manner as the base material portion.
  • austenitic stainless steel such as SUS304 and ferritic stainless steel, which have higher C and N contents than ferritic steel types, are welded, the corrosion resistance of the weld may be lower than that of the base metal due to a phenomenon called sensitization. is there.
  • Sensitization means that C and N in steel are combined with Cr due to the thermal history of the welded portion, and precipitated as grain carbide as Cr carbide (eg Cr 23 C 6 ) or Cr nitride (Cr 2 N).
  • Patent Documents 1 and 2 there has been proposed a method of adding Ti and Nb to fix C and N in steel as carbides or nitrides and making them harmless.
  • the gas shield is insufficient, sensitization may occur in the welded portion, and the corrosion resistance of the welded portion is not sufficient.
  • the present invention has been made to solve the above-described problems, and an object thereof is to provide a ferritic stainless steel having excellent corrosion resistance of a welded portion.
  • the fixing mechanism of C and N by addition of Ti and Nb is that after Ti and Nb are dissolved in the base material during welding, they are precipitated again as Ti (C, N) or Nb (C, N) during cooling.
  • C and N are fixed, and it is empirically found that it is effective to add Ti and Nb to 8 or more at Ti% / (C% + N%) or Nb% / (C% + N%).
  • the present inventors promoted the precipitation of Ti and Nb carbonitride during cooling after welding by lowering the precipitation peak temperature of these Ti and Nb carbonitrides, so that C, N We examined a method to fix the stencil sufficiently.
  • these precipitates are composite carbonitriding such as (Ti, V) (C, N) or (Nb, V) (C, N), respectively.
  • the precipitation temperature is lower than that of conventional Ti and Nb-based carbonitrides, and these composite carbonitrides including V fix C and N more than conventional Ti and Nb-based carbonitrides. It was found that the corrosion resistance of the welded portion is greatly improved.
  • the present invention has been made based on the above knowledge, and the gist thereof is as follows.
  • Nb is contained in a range satisfying 0.05 to 0.20 or at least one of cases where Nb and Ti are contained, with the balance being Fe and Ferritic stainless steel characterized by inevitable impurities.
  • the C%, the N%, the Ti%, the Nb%, and the V% represent the contents (mass%) of Ti, Nb, and V, respectively.
  • ferritic stainless steel having excellent corrosion resistance of the welded portion can be obtained.
  • the ferritic stainless steel of the present invention has excellent corrosion resistance without causing sensitization even under welding conditions in which carbon and nitrogen enter from a welding partner material or welding conditions in which nitrogen enters from air. Therefore, it can be suitably used for applications in which structures are produced by welding, for example, automobile exhaust system materials such as mufflers, building materials such as fittings, ventilation openings, and ducts, electrical equipment, and kitchen products.
  • composition of the steel of the present invention is specified.
  • component% means the mass% unless there is particular notice.
  • C 0.003% or more and 0.014% or less
  • the workability and the corrosion resistance of the welded part are significantly lowered.
  • a lower C content is preferable from the viewpoint of corrosion resistance and workability, but refining takes time to make the C content less than 0.003%, which is not preferable in production. Therefore, the C content is in the range of 0.003% to 0.014%. Preferably it is 0.004% or more and 0.011% or less of range.
  • N 0.005% or more and 0.016% or less
  • the workability and the corrosion resistance of the welded part are significantly reduced. From the viewpoint of corrosion resistance, the lower the N content, the better.
  • the N content is set in a range of 0.005% to 0.016%. Preferably it is 0.005% or more and 0.011% or less of range.
  • C% + N% 0.023% or less C and N cause a decrease in workability and a decrease in corrosion resistance of the weld.
  • the effect has a synergistic effect.
  • the range of (C% + N%) is set to 0.023% or less. Preferably it is less than 0.020%.
  • Si 0.01% or more and 0.90% or less
  • Si is an element that is effective as a deoxidizing element in the steelmaking process as well as being effective in improving the corrosion resistance of the welded part by concentrating on the oxide film formed during welding. .
  • These effects are obtained by containing 0.01% or more of Si, and the effect increases as the Si content increases.
  • the Si content exceeds 0.90%, the rolling load increases in the hot rolling process and a significant scale is generated.
  • the pickling property decreases due to the formation of the Si concentrated layer on the steel sheet surface layer. Respectively, which causes an increase in surface defects and an increase in manufacturing cost. Therefore, the Si amount is set to 0.01% or more and 0.90% or less.
  • the Si content is preferably in the range of 0.05% to 0.20%.
  • Mn 0.01% or more and 0.50% or less Mn has the effect of increasing the strength of the steel and also acts as a deoxidizer. In order to acquire the effect, it is necessary to contain 0.01% or more. However, if the amount of Mn exceeds 0.50%, precipitation of MnS, which is a starting point of corrosion, is promoted, and the corrosion resistance is lowered. Therefore, the range of the amount of Mn is 0.01% or more and 0.50% or less. Preferably it is 0.05 to 0.40% of range. More preferably, it is 0.10% or more and 0.30% or less of range.
  • P 0.020% or more and 0.040% or less
  • P is an element inevitably contained in steel, but it is an element harmful to corrosion resistance and workability, so the content should be reduced as much as possible. Is preferred. In particular, when it exceeds 0.040%, the workability is remarkably lowered due to solid solution strengthening. However, in order to make it less than 0.020%, it takes time for refining, which is not preferable in production. Therefore, the P content is 0.020% or more and 0.040% or less. Preferably, it is 0.025% or more and 0.030% or less.
  • S 0.008% or less
  • S is an element inevitably contained in steel like P. However, since it is an element harmful to corrosion resistance and workability, its content should be reduced as much as possible. preferable. Particularly when it exceeds 0.008%, the corrosion resistance is remarkably lowered. Therefore, the S amount is 0.008% or less. Preferably it is 0.006% or less. More preferably, it is 0.003% or less.
  • Al 0.001% to 0.090%
  • Al is an effective deoxidizer. Furthermore, since Al has a stronger affinity for nitrogen than Cr, when nitrogen penetrates into the weld zone, nitrogen is precipitated not as Cr nitride but as Al nitride, and has the effect of suppressing sensitization. These effects can be obtained by containing 0.001% or more of Al. However, if Al exceeds 0.090%, the penetration at the time of welding is lowered and the welding workability is lowered, which is not preferable. Therefore, the Al content is set to be in the range of 0.001% to 0.090%. Preferably it is 0.001% or more and 0.060% or less of range. More preferably, it is 0.001% or more and 0.040% or less of range.
  • Cr 14.5% to 23.0% Cr is the most important element for securing the corrosion resistance of stainless steel. If the content is less than 14.5%, sufficient corrosion resistance cannot be obtained in the welded portion with the austenitic stainless steel. On the other hand, if the content exceeds 23.0%, the toughness of the hot-rolled sheet decreases due to the formation of the ⁇ (sigma) phase, and continuous annealing of the hot-rolled sheet becomes difficult. Therefore, the Cr content is set in the range of 14.5% or more and 23.0% or less. Preferably it is 14.5% or more and 22.0% or less of range. More preferably, it is 16.0% or more and 21.5% or less of range.
  • Ni 0.10% to 0.60%
  • Ni is an element that improves the corrosion resistance of stainless steel, and is an element that suppresses the progress of corrosion in a corrosive environment in which a passive film cannot be formed and active dissolution occurs.
  • Ni is a strong austenite generating element, and has the effect of suppressing ferrite formation at the weld and suppressing sensitization due to precipitation of Cr carbonitride. This effect is obtained by containing 0.10% or more of Ni, and increases as the Ni content increases. However, when the content exceeds 0.60%, workability is lowered and stress corrosion cracking is likely to occur.
  • the Ni content is set to 0.10% or more and 0.60% or less. Preferably it is 0.10% or more and 0.50% or less of range. More preferably, it is 0.10% or more and 0.40% or less of range.
  • V 0.010% to 0.040%
  • V is an extremely important element in the present invention.
  • V forms a composite carbonitride with Ti and Nb.
  • This composite carbonitride precipitates with a higher precipitation peak temperature than conventional Ti and Nb carbonitrides and contains more C and N during the cooling process after welding, thereby suppressing sensitization of the weld zone. To do.
  • This effect is acquired by containing V 0.010% or more.
  • the content exceeds 0.040%, workability is remarkably lowered, which is not preferable. Therefore, the V amount is in the range of 0.010% to 0.040%.
  • it is 0.010% or more and 0.030% or less of range.
  • Ti 0.15% or more and 0.34% or less and Ti% + Nb% ⁇ 0.70 and V% / (Ti% + 0.5 ⁇ Nb%): within a range satisfying 0.05 to 0.20 Or Ti and Nb, or Nb: 0.35% to 0.60% and Ti% + Nb% ⁇ 0.70 and V% / (Ti% + 0.5 ⁇ Nb%): 0
  • Nb is contained in a range satisfying .05 to 0.20 or Nb and Ti are contained Ti and Nb are preferentially bonded to C and N, resulting from sensitization by precipitation of Cr carbonitride. It is an element that suppresses the decrease in corrosion resistance.
  • one or two of Ti and Nb are contained at 0.15% or more of Ti or 0.35% or more of Nb.
  • it contains Ti: 0.20% or more, or Nb: 0.40% or more. More preferably, it contains Ti: 0.25% or more, or Nb: 0.45% or more.
  • the Ti amount is set to 0.34% or less. Preferably, it is 0.30% or less.
  • Nb is also an element that raises the recrystallization temperature.
  • the Nb amount is set to 0.60% or less. Preferably it is 0.55% or less.
  • Ti% + Nb% is set to 0.70% or less. Preferably it is 0.65 or less. As described above, all of the Ti amount, the Nb amount, and Ti% + Nb% must be equal to or lower than the upper limit value.
  • V forms a composite carbonitride with Ti and Nb, suppresses sensitization and improves the corrosion resistance of the weld.
  • This composite carbonitride is produced when one or two of Ti and Nb and V are contained so that V% / (Ti% + 0.5 ⁇ Nb%) is 0.05 or more. When V% / (Ti% + 0.5 ⁇ Nb%) is less than 0.05, V required for forming the composite carbonitride is insufficient, and the amount of precipitation of the composite carbonitride is reduced.
  • V% / (Ti% + 0.5 ⁇ Nb%) exceeds 0.20, V becomes excessive with respect to Ti and Nb, and the N concentration in the composite carbonitride increases. As a result, the solid solution C in the welded portion cannot be sufficiently fixed as a precipitate, and a sufficient sensitization suppressing effect cannot be obtained. Therefore, V% / (Ti% + 0.5 ⁇ Nb%): 0.05 to 0.20 is set. Preferably, it is in the range of 0.10 to 0.15.
  • the Ti%, the Nb%, and the V% represent the contents (mass%) of Ti, Nb, and V, respectively.
  • the present invention is a ferritic stainless steel characterized in that it contains the above-mentioned essential components and the balance consists of Fe and inevitable impurities. Furthermore, if necessary, one or more selected from Cu and Mo, or one or more selected from Zr, REM, W, Co, B, Mg, Ca, It can contain in the range of.
  • Cu 0.01% or more and 0.80% or less
  • Cu is an element that improves the corrosion resistance, and is an element that is particularly effective for improving the corrosion resistance of the base material and the welded part when an aqueous solution or a weakly acidic water droplet adheres. It is.
  • Cu is a strong austenite-forming element like Ni, and has the effect of suppressing ferrite formation at the weld and suppressing sensitization due to precipitation of Cr carbonitride. These effects are obtained by containing 0.01% or more, and the effect becomes higher as the Cu content increases. However, if Cu is contained in excess of 0.80%, the hot workability is lowered and surface defects are induced, which is not preferable.
  • the Cu content is in the range of 0.01% to 0.80%. Preferably, it is 0.10% or more and 0.60% or less of range. More preferably, it is 0.30% or more and 0.45% or less of range.
  • Mo 0.01% to 1.65% Mo is an element that significantly improves the corrosion resistance of stainless steel. This effect is obtained when the content is 0.01% or more, and the effect improves as the content increases. However, if the Mo content exceeds 1.65%, the rolling load at the time of hot rolling becomes large, the productivity is lowered, and the steel sheet strength is excessively increased. Moreover, since Mo is an expensive element, the addition of a large amount increases the manufacturing cost. Therefore, when contained, the Mo content is 0.01% or more and 1.65% or less. Preferably it is 0.10% or more and 1.40% or less of range. In particular, in Ti-containing steels whose hot-rolled sheet toughness is reduced, the addition of Mo further reduces the toughness and makes hot-rolled sheet annealing difficult. It is preferably 30% or more and 1.40% or less. More preferably, it is the range of 0.4% or more and 1.00% or less.
  • Zr 0.01% or more and 0.20% or less Zr combines with C and N and has an effect of suppressing sensitization. This effect is obtained when the content is 0.01% or more. On the other hand, if the content exceeds 0.20%, workability is remarkably lowered, which is not preferable. Therefore, when it contains, Zr content shall be 0.01% or more and 0.20% or less of range. Preferably, the range is 0.01% or more and 0.10% or less.
  • REM 0.001% or more and 0.100% or less REM has the effect of improving oxidation resistance, and suppresses the formation of a Cr-deficient region directly under the oxide film by suppressing the formation of an oxide film (weld temper color) in the weld zone. To do. In order to acquire this effect, it is necessary to contain REM 0.001% or more. On the other hand, if the content exceeds 0.100%, productivity such as pickling at the time of cold rolling annealing is lowered, which is not preferable. Therefore, when it contains, REM amount shall be 0.001% or more and 0.100% or less of range. Preferably, it is set as 0.001% or more and 0.050% or less of range.
  • Co 0.01% or more and 0.20% or less
  • Co is an element that improves toughness. This effect is obtained when the content is 0.01% or more. On the other hand, if the content exceeds 0.20%, the workability decreases. Therefore, when it contains, Co amount shall be 0.01% or more and 0.20% or less.
  • B 0.0002% or more and 0.0009% or less B is an element effective for improving secondary work embrittlement resistance after deep drawing. This effect is obtained by making the B content 0.0002% or more. On the other hand, if the B content exceeds 0.0009%, workability and toughness deteriorate, which is not preferable. Therefore, when it contains, B amount shall be 0.0002% or more and 0.0009% or less of range. Preferably it is 0.0003% or more and 0.0006% or less of range.
  • Mg 0.0002% or more and 0.0010% or less
  • Mg is an element that improves the equiaxed crystal ratio of the slab and is effective for improving workability and toughness. Furthermore, in the steel containing Ti as in the present invention, when Ti carbonitride is coarsened, the toughness is lowered, but Mg also has an effect of suppressing the coarsening of Ti carbonitride. These effects appear by containing 0.0002% or more of Mg. On the other hand, when the amount of Mg exceeds 0.0010%, the surface properties of steel are deteriorated. Therefore, when it contains, Mg amount shall be 0.0002% or more and 0.0010% or less of range. Preferably it is 0.0002% or more and 0.0004% or less of range.
  • Ca 0.0005% or more and 0.0020% or less
  • Ca is an effective component for preventing nozzle clogging due to crystallization of Ti-based inclusions that are likely to occur during continuous casting. The effect is acquired by containing 0.0005% or more of Ca. However, when it contains exceeding 0.0020%, corrosion resistance falls by the production
  • the ferritic stainless steel of the present invention is obtained by melting a molten steel having the above composition by a known method such as a converter, an electric furnace, a vacuum melting furnace, etc. ).
  • the slab is heated at 1100 to 1250 ° C. for 1 to 24 hours, or directly hot-rolled as cast without heating to form a hot-rolled sheet.
  • the hot-rolled sheet is subjected to continuous annealing at 800 to 1100 ° C. or batch annealing at 600 to 900 ° C., but depending on the application, the hot-rolled sheet annealing may be omitted.
  • hot-rolled sheet pickling it is cold-rolled by cold rolling, and then annealed and pickled to obtain a product.
  • Cold rolling is preferably performed at a rolling reduction of 50% or more from the viewpoints of stretchability, bendability, press formability, and shape correction.
  • the recrystallization annealing of cold-rolled sheets is generally performed according to JIS G 0203 surface finish, No. In the case of a 2B finished product, it is preferable to carry out at 800 to 1100 ° C. from the viewpoint of obtaining good mechanical properties and pickling properties. Further, BA annealing (bright annealing) may be performed in order to obtain more gloss.
  • grinding or polishing may be performed.
  • the surface was judged by visual observation, and a tensile test and a pitting potential measurement were performed.
  • a JIS No. 13B tensile test piece was taken in parallel with the rolling direction, and the tensile test (E1) (breaking ductility) was measured according to JIS Z2201.
  • E1 breaking ductility
  • pitting corrosion potential measurement a 20 mm ⁇ 20 mm test piece was sampled and the surface was polished with No. 600 polishing paper, and then covered with a sealing material leaving a 10 mm ⁇ 10 mm measurement surface, and 3.5% by mass at 30 ° C. Pitting potential was measured in NaCl solution.
  • the test piece was not passivated, but the other measurement methods were based on JIS G 0577 (2005).
  • the cold-rolled annealed pickled plates of each steel type prepared as described above and SUS304 (C: 0.07% by mass, N: 0.05% by mass, Japanese Industrial Standards, JIS G 4305) with a thickness of 0.8 mm are joined together.
  • TIG welded The welding conditions are welding speed: 600 mm / min, welding voltage: 10 to 12 V, welding current: 70 to 120 A.
  • the front side was sealed by flowing 15 L / min of argon gas, the back side was not gas shielded in order to make nitrogen enter the molten pool due to insufficient gas shielding.
  • salt spray cycle test salt spray (5% NaCl, 35 ° C., spray 2 h) ⁇ dry (60 ° C., 4 h, relative humidity 40%) ⁇ wet (50 ° C., 2 h, relative humidity ⁇ 95%) is one cycle. Five cycles were performed.
  • Hot-rolled sheet Charpy test The Charpy impact value at 25 ° C of the hot-rolled sheet was determined to be 50 J / cm 2 or more, and less than 50 J / cm 2 was determined to be unacceptable.
  • the pitting corrosion potential of the base material was determined to be 120 mV or higher, and less than 120 mV was determined to be unacceptable.
  • Salt spray test The area where rust occurred was 20% or less, and 20% or more was judged to be unacceptable.
  • Breaking ductility The elongation at break in the tensile test was determined to be 25% or more, and less than 25% was determined to be unacceptable.
  • Table 2 shows the results obtained as described above.
  • A1 to A14 satisfying the scope of the present invention showed a pitting corrosion potential of 120 mV or more, no sensitization and rusting of the welded portion, and a predetermined corrosion resistance was obtained for both the base material and the welded portion. 25% or more of fracture ductility was obtained, and no surface defects were observed.
  • B1 containing a Cr amount exceeding the range of the present invention could not obtain a predetermined Charpy impact value in the hot-rolled sheet, the subsequent steps and tests were not performed.
  • B2 which is less than the range of the present invention with the Cr amount of 13.8%
  • corrosion occurs from the welded part in the salt spray cycle test, and a predetermined welded part corrosion resistance is obtained. I could not.
  • B3 in which the amount of Nb exceeds the range of the present invention, a predetermined fracture ductility could not be obtained as a result of an uneven metal structure including non-recrystallized grains after annealing.
  • B4 where the amount of Ti exceeds the range of the present invention, surface defects (streak-like defects) due to coarse Ti carbonitrides occurred.
  • Ferritic stainless steel obtained in the present invention is used for the production of structures by welding, for example, automobile exhaust materials such as mufflers, building materials such as fittings, ventilation openings, ducts, electrical equipment, kitchen products, etc. It is suitable for application to.

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  • Metallurgy (AREA)
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Abstract

L'invention porte sur un acier inoxydable ferritique présentant une excellente résistance à la corrosion dans des sections soudées. L'acier inoxydable ferritique est caractérisé en ce qu'il comprend, en % en masse, 0,003-0,014 % de C, 0,005-0,016 % de N, un total inférieur ou égal à 0,023 % de C+N, 0,01-0,90 % de Si, 0,01-0,50 % de Mn, 0,020-0,040 % de P, 0,008 % ou moins de S, 0,001-0,090 % d'Al, 14,5-23,0 % de Cr, 0,10-0,60 % de Ni et 0,010-0,040 % de V ; en ce qu'il comprend du Ti ou du Ti et du Nb dans une plage telle que la teneur en Ti est de 0,15-0,34 % en masse, (% de Ti)+(% de Nb) ≤ 0,70 et (% de V)/((% de Ti)+0,5×(% de Nb)) est de 0,05-0,20 ; et/ou en ce qu'il comprend du Nb ou du Nb et du Ti dans une plage telle que la teneur en Nb est de 0,35-0,60 % en masse, (% de Ti)+(% de Nb) ≤ 0,70 et (% de V)/((% de Ti)+0,5×(% de Nb)) est de 0,05-0,20 ; le reste comprenant du Fe et des impuretés inévitables.
PCT/JP2013/001821 2012-09-24 2013-03-18 Acier inoxydable ferritique WO2014045476A1 (fr)

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CN201380041079.6A CN104508168B (zh) 2012-09-24 2013-03-18 铁素体系不锈钢
MYPI2015700269A MY195207A (en) 2012-09-24 2013-03-18 Ferritic Stainless Steel
JP2013553687A JP5590255B1 (ja) 2012-09-24 2013-03-18 フェライト系ステンレス鋼
KR1020157002655A KR101673218B1 (ko) 2012-09-24 2013-03-18 페라이트계 스테인리스강
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CN104109820A (zh) * 2014-07-29 2014-10-22 山东雅百特金属结构系统有限公司 一种新型金属屋面板材料
JP2018016862A (ja) * 2016-07-29 2018-02-01 新日鐵住金ステンレス株式会社 耐浸炭性及び耐酸化性に優れたフェライト系ステンレス鋼板及びその製造方法

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CN104109820A (zh) * 2014-07-29 2014-10-22 山东雅百特金属结构系统有限公司 一种新型金属屋面板材料
JP2018016862A (ja) * 2016-07-29 2018-02-01 新日鐵住金ステンレス株式会社 耐浸炭性及び耐酸化性に優れたフェライト系ステンレス鋼板及びその製造方法

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JP5556951B2 (ja) 2014-07-23
CN104508168B (zh) 2017-09-26
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MY195207A (en) 2023-01-11
JP5590255B1 (ja) 2014-09-17
KR20150029729A (ko) 2015-03-18

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