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WO2018181570A1 - Tôle d'acier inoxydable épaisse à base d'austénite et son procédé de production - Google Patents

Tôle d'acier inoxydable épaisse à base d'austénite et son procédé de production Download PDF

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Publication number
WO2018181570A1
WO2018181570A1 PCT/JP2018/012965 JP2018012965W WO2018181570A1 WO 2018181570 A1 WO2018181570 A1 WO 2018181570A1 JP 2018012965 W JP2018012965 W JP 2018012965W WO 2018181570 A1 WO2018181570 A1 WO 2018181570A1
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rolling
steel plate
content
austenitic stainless
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PCT/JP2018/012965
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English (en)
Japanese (ja)
Inventor
佳奈 浄▲徳▼
雄介 及川
平田　弘征
純平 犬塚
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Nippon Steel Stainless Steel Corp
Original Assignee
Nippon Steel and Sumikin Stainless Steel Corp
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Application filed by Nippon Steel and Sumikin Stainless Steel Corp filed Critical Nippon Steel and Sumikin Stainless Steel Corp
Priority to CN201880022330.7A priority Critical patent/CN110520549B/zh
Priority to JP2019510035A priority patent/JP6920420B2/ja
Publication of WO2018181570A1 publication Critical patent/WO2018181570A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • 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
    • C22C38/18—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

Definitions

  • the present invention relates to an austenitic stainless steel plate and a method for producing the same.
  • the hydrodesulfurization apparatus is an apparatus that removes sulfur by blowing hydrogen into heavy oil.
  • the hydrocracking apparatus is an apparatus that blows hydrogen into heavy oil to remove the sulfur content and decomposes the heavy oil to produce light oil. Since these devices operate under high temperature and high pressure, austenitic stainless steel is often used as the material used.
  • SCC Stress Corrosion Cracking
  • H 2 S x O 6 reaction product polythionic acid
  • a material containing an element capable of suppressing the precipitation of Cr carbide as much as possible as a countermeasure for suppressing the SCC described above.
  • a so-called stable austenitic stainless steel containing a C-fixing element, such as Ti or Nb which easily forms a carbide as compared with Cr.
  • a steel type such as SUS321 containing Ti and SUS347 containing Nb (based on JIS standard).
  • HAZ Heat Affected Zone
  • Patent Document 1 C is reduced to 0.03% or less, N is added to 0.08 to 0.40%, Nb is added to 0.05 to 0.30%, and Nb / C Stainless steel having improved intergranular corrosion resistance and intergranular SCC resistance by setting ⁇ 4 and N / C ⁇ 5 is disclosed.
  • Non-Patent Document 1 after reducing C to 0.02% or less, it contains less than 0.1% of proper N, and further, as a C-fixing element, an appropriate amount of Nb is 0. SUS347-based austenitic stainless steel with 2 to 0.5% and Nb / C ⁇ 15 added is disclosed. This austenitic stainless steel has good polythionic acid SCC resistance while ensuring high temperature strength.
  • Patent Document 2 discloses an austenitic stainless steel containing an appropriate N after reducing the C content and further containing a C-fixing element.
  • This austenitic stainless steel has welded cracks, HAZ liquefaction crack resistance, and long-term aging, by reducing specific impurity elements such as P and S to a predetermined level or less while ensuring SCC resistance of polythionic acid. It is characterized by excellent resistance to later embrittlement cracking.
  • JP 50-67215 A International Publication No. 2009/044802
  • a thick steel plate of 45 mm for example, is used for the reactor or the internal.
  • the rolling reduction from the slab or steel slab (hereinafter sometimes collectively referred to as “slab”) to the final product is limited, so when producing thin steel sheets or seamless steel pipes. It is not possible to perform processing with a high rolling reduction as used in As a result, it is not always possible to ensure a degree of processing sufficient for recrystallization.
  • Patent Documents 1 and 2 and Non-Patent Document 1 it cannot be said that the above-described problems unique to thick steel sheets have been sufficiently studied.
  • Hot cracking includes liquefaction cracking, ductility degradation cracking, and the like.
  • the liquefaction crack is a solid solution of carbides such as NbC precipitated in the grains due to heat input during welding, and C fixing elements or elements having a high tendency to segregate at the grain boundaries such as C, P, or S. This is caused by segregation at the grain boundary and formation of a compound having a low melting point.
  • the phenomenon in which the grain boundary is liquefied and cracks occur due to the second and subsequent welding heat cycles is liquefaction cracking.
  • ductile drop cracking is caused by segregation of grain boundary embrittlement elements such as P and S during welding heat cycles and during use at high temperatures in high-temperature HAZ during welding.
  • grain boundary embrittlement elements such as P and S
  • stress concentration occurs at the embrittled grain boundary rather than within the grain where NbC or the like is precipitated in a large amount.
  • An object of the present invention is to provide an austenitic stainless steel plate having excellent polythionic acid SCC resistance, suppressing cracking during welding, and having good weld crack resistance, and a method for producing the same.
  • the present invention has been made to solve the above-described problems, and the gist of the present invention is an austenitic stainless steel plate and a method for producing the same as described below.
  • the chemical composition is mass%, C: less than 0.04%, Si: 1.5% or less, Mn: 2.0% or less, P: 0.04% or less, S: 0.03% or less, N: 0.02 to 0.35%, O: 0.03% or less, Nb: 0.05-0.5% Cr: 15.0-25.0%, Ni: 6.0 to 30.0%, Al: 0.05% or less, Ti: 0 to 0.4%, V: 0 to 0.4%, Ta: 0 to 0.2%, Hf: 0 to 0.2%, Zr: 0 to 0.2%, Cu: 0 to 3.0%, Mo: 0 to 5.0%, W: 0 to 5.0% Co: 0 to 1.0%, B: 0 to 0.012%, Ca: 0 to 0.02%, Mg: 0 to 0.02%, and REM: 0 to 0.1%, Balance: Fe and impurities, An austenitic stainless steel plate having a maximum grain size of less than 0.3 mm and a thickness of 6.0 mm or more in a cross section perpen
  • the chemical composition of the steel sheet is further in mass%, Ti: 0.005 to 0.4%, V: 0.005 to 0.4%, Ta: 0.003 to 0.2%, Hf: 0.003 to 0.2%, Zr: 0.003 to 0.2%, Cu: 0.02 to 3.0%, Mo: 0.05 to 5.0%, W: 0.05-5.0%, Co: 0.03-1.0%, B: 0.0001 to 0.012%, Ca: 0.0001 to 0.02%, Mg: 0.0001 to 0.02%, and REM: 0.001 to 0.1%,
  • the austenitic stainless steel plate according to (1) which contains one or more selected from:
  • a method for producing an austenitic stainless steel plate having the chemical composition (A) heating the slab or steel slab having the chemical composition described in (1) or (2), and primary hot rolling under a condition of a rolling reduction of 30% or more to obtain a steel sheet; (B) The steel sheet is heated to 1100 to 1250 ° C., subjected to secondary hot rolling at a rolling end temperature of 1050 ° C. or less and a rolling reduction of 30% or more, In this step, after the heating, until the end of the secondary hot rolling, a step of holding at a temperature range of 850 to 1100 ° C. for 3 minutes or more; (C) A method for producing an austenitic stainless steel plate, in which a solution heat treatment in a temperature range of 950 to 1150 ° C. is sequentially performed.
  • a method for producing an austenitic stainless steel plate having the chemical composition (A) A step of heating a slab or steel slab having the chemical composition described in (1) or (2), and primary hot rolling under a condition of a rolling reduction of 30% or more to obtain a steel sheet; (B) a step of subjecting the steel sheet to an intermediate heat treatment at 1100 to 1250 ° C .; (C) heating the steel sheet to 950 to 1100 ° C., subjecting the steel sheet to secondary hot rolling at a rolling end temperature of 1050 ° C. or lower and a rolling reduction of 30% or more; (D) A method for producing an austenitic stainless steel plate, in which a solution heat treatment in a temperature range of 950 to 1150 ° C. is sequentially performed.
  • an austenitic stainless steel plate having excellent polythionic acid SCC resistance, suppressing cracking during welding, and having good weld crack resistance.
  • Coarse grains are generated when recrystallization by thermomechanical processing is not completed and a part of the coarse grain structure as cast remains. In order to suppress the maximum particle size of coarse particles, it is necessary to promote recrystallization as much as possible. In that case, it is conceivable to apply a general promotion measure such as accumulating more processing strain or increasing the temperature of the solution heat treatment for a long time.
  • Hot rolling is divided into two stages, and high temperature heat treatment is performed after the first stage of hot rolling. As described above, the final solution heat treatment cannot be heated to promote recrystallization. In order to clear such a restriction, the hot rolling is divided into two stages, and after the first stage of hot rolling, high-temperature heat treatment is performed to recrystallize the coarse crystals of the slab. In this case, since the initial grain size is small in the second stage of the heat treatment, recrystallization proceeds even with a heat treatment at a relatively low temperature.
  • the C content is less than 0.04%.
  • the C content is preferably 0.03% or less, and more preferably 0.02% or less.
  • the C content is preferably 0.005% or more.
  • Si 1.5% or less
  • Si is an element to be contained as a deoxidizer. However, when it is contained excessively, the liquefaction cracking sensitivity is increased and the stability of the austenite phase is lowered. Therefore, the Si content is 1.5% or less.
  • the Si content is preferably 1.0% or less, and more preferably 0.75% or less.
  • the Si content is preferably 0.02% or more, more preferably 0.1% or more, and further preferably 0.2% or more. preferable.
  • Mn 2.0% or less Mn is an element effective for stabilizing the austenite phase and reducing deterioration of hot workability due to S.
  • the Mn content is 2.0% or less.
  • the Mn content is preferably 1.8% or less, and more preferably 1.6% or less.
  • it is preferable that Mn content is 0.5% or more.
  • P 0.04% or less
  • P is an impurity inevitably mixed from raw materials. P is segregated at the grain boundaries of coarse grains (coarse grains HAZ) in the weld zone during the welding heat cycle and during subsequent use at high temperatures, causing not only liquefaction cracks after welding but also ductile deterioration cracks. It is preferable to reduce. Therefore, the P content is 0.04% or less. The P content is preferably 0.03% or less.
  • S 0.03% or less
  • S is an impurity inevitably mixed from raw materials. S, like P, segregates at the grain boundaries and causes liquefaction cracks after welding in the coarse-grained HAZ part and ductile drop cracks. Therefore, the S content is 0.03% or less.
  • the S content is preferably 0.015% or less, more preferably 0.005% or less, and even more preferably 0.001% or less.
  • N 0.02 to 0.35%
  • N is an element effective for stabilizing the austenite phase, forming a solid solution in the austenite phase, and precipitating as fine nitrides in the grains, thereby improving the creep strength. Therefore, the N content is 0.02% or more. However, when N is contained excessively, Cr nitride precipitates at the grain boundary, and the polythionic acid SCC resistance in HAZ is lowered. Therefore, the N content is set to 0.35% or less.
  • N content is preferably 0.04% or more, and more preferably 0.06% or more. Further, the N content is preferably 0.3% or less, more preferably 0.2% or less, and further preferably 0.1% or less.
  • O 0.03% or less
  • O is an impurity inevitably mixed. It is an element constituting an oxide that is representative of non-metallic inclusions, and excessive inclusion inhibits toughness. In addition, the formation of coarse clustered oxides causes surface defects. Therefore, the O content is 0.03% or less.
  • the O content is preferably 0.01% or less, more preferably 0.007% or less, and further preferably 0.005% or less.
  • Nb 0.05 to 0.5% Nb is contained as a C fixing element. Specifically, by combining with C in the steel to precipitate carbide, Cr carbide precipitation at the grain boundary is suppressed, and there is an effect of improving the intergranular corrosion resistance and polythionic acid SCC resistance. Moreover, the fine Nb carbide precipitated in the grains also contributes to the improvement of creep strength. Therefore, the Nb content is 0.05% or more.
  • Nb is excessively contained, carbides are excessively precipitated in the grains, and deformation within the grains is hindered. Then, as a result of preventing deformation within the grains, stress concentration occurs at the grain boundaries where the impurity elements segregate, which promotes high-temperature cracking in the HAZ part. Further, recrystallization of Nb dissolved during heating of the slab prevents recrystallization. Therefore, the Nb content is 0.5% or less.
  • the Nb content is preferably 0.10% or more, and more preferably 0.20% or more.
  • the Nb content is preferably 0.4% or less, and more preferably 0.35% or less.
  • Nb / C ⁇ 10 in relation to C is preferable, and Nb / C ⁇ 15 is more preferable.
  • the element symbol in the said formula represents content (mass%) of each element contained in steel.
  • Cr 15.0-25.0% Cr is an element necessary for ensuring oxidation resistance and corrosion resistance at high temperatures. Therefore, the Cr content is 15.0% or more. However, if contained in a large amount, the stability of the austenite phase at a high temperature is lowered, and the creep strength is lowered. Therefore, the Cr content is 25.0% or less.
  • the Cr content is preferably 16.0% or more, and more preferably 17.0% or less.
  • Ni 6.0 to 30.0%
  • Ni is an element that stabilizes the austenite phase, and is an essential element for maintaining the creep strength after long-term use. It is also an element that improves acid resistance and chloride SCC resistance. Therefore, the Ni content is 6.0% or more. However, since Ni is an expensive element, if the content is large, the cost increases. Therefore, the Ni content is 30.0% or less.
  • the Ni content is preferably 7.0% or more, and more preferably 9.0% or more.
  • the Ni content is preferably 13.0% or less.
  • Al 0.05% or less
  • Al is an element used for deoxidation of steel, and is contained together with Si in order to reduce oxygen in the steel.
  • Al is an element having a relatively large affinity with N. If it is excessively contained, AlN is generated and the toughness of the base material is deteriorated. The degree depends on the N content, but if the Al content exceeds 0.05%, the toughness deteriorates remarkably, so the Al content is set to 0.05% or less. On the other hand, in order to acquire the said effect, it is preferable that it is 0.003% or more.
  • V, Ta, Hf and Zr are important as C-fixing elements.
  • V, Ta, Hf and Zr are important as C-fixing elements.
  • Cr nitride precipitation at the grain boundaries is suppressed, and corrosion resistance.
  • the fine carbide precipitated in the grains contributes to the improvement of the creep strength. Therefore, in order to acquire this effect, you may contain 1 or more types selected from these elements as needed.
  • the Ti content is 0.4% or less.
  • V content shall be 0.4% or less.
  • the Ta content is 0.2% or less.
  • the Hf content is 0.2% or less.
  • the Zr content is 0.2% or less.
  • Ti content is 0.005% or more.
  • V content is 0.005% or more.
  • the Ta content is preferably 0.003% or more.
  • the Hf content is preferably 0.003% or more.
  • the Zr content is preferably 0.003% or more.
  • Cu, Mo, W and Co have the effect of increasing the high temperature strength. Therefore, in order to acquire this effect, you may contain 1 or more types of said element as needed.
  • Cu 0 to 3.0%
  • Cu is effective for improving the high temperature strength by finely precipitating at a high temperature, and also has an effect of stabilizing the austenite phase, so it is contained if necessary.
  • the Cu content is 3.0% or less.
  • the Cu content is preferably 2.0% or less.
  • it is preferable that Cu content is 0.02% or more, and it is preferable that it is 0.5% or more.
  • Mo 0 to 5.0%
  • W 0-5.0%
  • Mo and W have an effect of improving the high temperature strength by being dissolved in the matrix, and are elements effective for improving the creep strength particularly at a high temperature.
  • both elements have a high content, the stability of the austenite phase is lowered and the creep strength is lowered.
  • the ductility-reducing cracking susceptibility of coarse-grained HAZ is increased.
  • the contents of Mo and W are set to Mo: 5.0% or less and W: 5.0% or less, respectively.
  • the Mo content is preferably 1.5% or less
  • the W content is preferably 3.0% or less.
  • Co 0 to 1.0%
  • Co is an element that enhances the stability of the austenite phase and improves the high-temperature strength. Therefore, Co is contained as necessary. However, since Co is a very expensive element, if it is contained in a large amount, the cost increases. Therefore, the Co content is 1.0% or less. The Co content is preferably 0.8% or less. On the other hand, in order to acquire the said effect, it is preferable that Co content is 0.03% or more.
  • B 0 to 0.012% Ca: 0 to 0.02% Mg: 0 to 0.02% REM: 0 to 0.1%
  • B, Ca, Mg, and REM are elements that improve hot workability, and therefore are contained as necessary. However, when these elements are contained excessively, conversely, hot workability and toughness are reduced. Therefore, the contents of these elements are B: 0.012% or less, Ca: 0.02% or less, Mg: 0.02% or less, and REM: 0.1% or less, respectively.
  • the B content is preferably 0.005% or less
  • the Ca content is 0.01% or less
  • the Mg content is 0.01% or less
  • the REM content is preferably 0.05% or less.
  • one or more selected from B: 0.0001% or more, Ca: 0.0001% or more, Mg: 0.0001% or more, and REM: 0.001% or more are contained. Is preferred.
  • REM is a generic name for a total of 17 elements of Sc, Y and lanthanoid, and the content of REM means the total amount of the above elements.
  • the balance is Fe and impurities.
  • impurities are components that are mixed due to various factors of raw materials such as ores and scraps and manufacturing processes when steel is industrially manufactured, and are allowed within a range that does not adversely affect the present invention. Means something.
  • the requirement for a metal structure that can avoid ductile drop cracking during welding is defined as the maximum crystal grain size in a cross section perpendicular to the rolling direction being less than 0.3 mm.
  • the maximum crystal grain size is preferably less than 0.15 mm.
  • the maximum crystal grain size is determined by selecting the observation region so that the total of the observation regions in the plurality of observation fields is 1 mm 2 or more after etching by embedding a cross section perpendicular to the rolling direction in resin.
  • the maximum crystal grain size of each grain observed in the visual field is recorded and obtained as the maximum value among them.
  • the problem of ductile drop cracking in the present invention occurs in the case of a thick steel sheet having a thickness of 6.0 mm or more in which it is difficult to secure a large reduction ratio in relation to the material thickness. Therefore, in the present invention, a thick steel plate having a thickness of 6.0 mm or more is targeted.
  • the plate thickness is preferably 10.0 mm or more, and more preferably 21.0 mm or more.
  • the plate thickness is more preferably 26.0 mm or more, and further preferably 35.0 mm or more.
  • the upper limit is not particularly specified, but is preferably 80.0 mm or less.
  • the austenitic stainless steel sheet according to the present invention promotes recrystallization of a coarse grain structure, so that hot rolling is performed twice. Do it separately.
  • the heating temperature of the first-stage hot-rolled slab or steel slab is preferably a relatively low temperature in order to suppress solid solution of Nb by heating and to accumulate more strain by low-temperature rolling.
  • it is preferably carried out at 1000 to 1200 ° C, more preferably 1050 to 1150 ° C. That is, the rolling end temperature of primary hot rolling is preferably 1200 ° C. or lower.
  • the rolling reduction is set to 30% or more in order to promote recrystallization.
  • heating temperature shall be 1100 degreeC or more.
  • the heating temperature exceeds 1250 ° C., the strength decreases and causes bending due to its own weight, etc., so that it is 1250 ° C. or lower.
  • the rolling end temperature is set to 1050 ° C. or lower, and preferably 1000 ° C. or lower.
  • the secondary hot rolling temperature is preferably 850 to 1150 ° C., more preferably 900 to 1050 ° C.
  • the reduction rate in secondary hot rolling is set to 30% or more.
  • the rolling reduction in secondary hot rolling is preferably 40% or more.
  • Nb precipitates are deposited by holding at 850 ° C. or more and 1100 ° C. or less which is not more than the precipitation temperature for 3 minutes or more.
  • holding temperature shall be 850 degreeC or more.
  • the slab heating temperature of the first stage of hot rolling suppresses the solid solution of Nb by heating.
  • a relatively low temperature is preferable.
  • the temperature is preferably carried out at 1000 to 1200 ° C, more preferably 1050 to 1150 ° C. That is, the rolling end temperature of primary hot rolling is preferably 1200 ° C. or lower.
  • the rolling reduction is set to 30% or more in order to promote recrystallization.
  • (C) Secondary hot rolling step In order to accelerate the precipitation of Nb precipitates, in this step, the steel plate is heated to a temperature range of 950 to 1100 ° C and then hot rolled.
  • the rolling end temperature is set to 1050 ° C. or lower, and preferably 1000 ° C. or lower.
  • the secondary hot rolling temperature is preferably 850 to 1100 ° C., more preferably 900 to 1050 ° C.
  • the reduction rate in secondary hot rolling is set to 30% or more.
  • the rolling reduction in secondary hot rolling is preferably 40% or more.
  • Austenitic stainless steel having the chemical composition shown in Table 1 was melted in an electric furnace to obtain a continuous cast slab having a thickness of 150 mm.
  • the hot rolling was performed twice, and the primary hot rolling was performed at 1100 ° C. and then at a rolling end temperature of 950 ° C. to obtain a primary hot rolled steel sheet having a thickness of 90 mm.
  • the rolling reduction was 40%.
  • the secondary hot rolling was performed at 1200 ° C. for 1 hour and then at a rolling end temperature of 950 ° C. to obtain a hot rolled steel sheet having a thickness of 45 mm.
  • the rolling reduction was 50%.
  • the holding time from 1100 ° C. to 800 ° C. was set to 5.3 minutes, and water cooling was performed immediately thereafter.
  • the solution heat treatment was soaked at a temperature of 1100 ° C. for 5 minutes, followed by water cooling.
  • the maximum crystal grain size is that the cross section perpendicular to the rolling direction of the steel sheet is removed from the irregularities and then embedded in the resin and mirror-polished, and after performing aqua regia etching, the total observation area is 1.23 mm 2 Observation was performed at random until the maximum particle size of the grains was obtained.
  • the ductility drop cracking susceptibility was evaluated by the total cracking length by the longi ballast train test. In this test, bending is applied during welding, strain is applied, and the length of cracks generated in the HAZ part at that time is measured. Longe ballast strain test in which strain is applied parallel to the welding direction. Is widely used as an evaluation method for weld hot cracking in the HAZ part.
  • a test piece having a thickness of 12 mm, a width of 50 mm, and a length of 300 mm is collected from the steel plate after solution heat treatment (three pieces taken in the plate thickness direction) manufactured as described above, and cantilevered on a bending block.
  • the bead-on-plate welding was performed by GTAW (Gas Tungsten Arc Welding) in the longitudinal direction of the test piece.
  • the test piece was deformed along the curvature of the bending block on one side of the test piece, and cracks were generated on the weld bead and the HAZ surface. Then, the length of the crack which generate
  • the welding conditions were a welding current of 200 A, a welding voltage of 16 V, a welding speed of 15 cm / min, and a load strain of 2%. When the crack length on the HAZ surface was 1.5 mm or less, it was judged that the HAZ crack sensitivity was low and the hot crack resistance was excellent, and this was the target.
  • the welding material was subjected to a sensitizing heat treatment at 700 ° C. for 1000 hours, and then a Wackerroder solution (H 2 SO 3 saturated by blowing SO 2 gas into distilled water).
  • the immersion test was conducted in a solution in which a large amount of H 2 S gas was blown into the aqueous solution. Evaluation was made by using a U-bend test piece in which a strip with a thickness of 2 mm, a width of 10 mm, and a length of 75 mm with a weld line at the center was constrained with a radius of 5 mm. Were observed with an optical microscope, and those having no cracks were judged to be excellent in polythionic acid SCC resistance.
  • Test No. 1 to 10 are steels according to examples of the present invention that satisfy the provisions of the present invention.
  • the steel sheet of the present invention has a maximum crystal grain size of less than 0.3 mm and a HAZ total crack length of 1.5 mm or less, thus exhibiting good HAZ crack resistance and excellent. Has hot cracking resistance.
  • Table 3 shows the results of evaluating the maximum crystal grain size and the HAZ cracking susceptibility of steel plates having the components A to F in Table 1 under various production conditions.
  • test No. which does not satisfy the production conditions of the present invention.
  • Steels 25 to 33 did not satisfy the required properties for the following reasons.
  • test no. In No. 33 very coarse unrecrystallized grains remain by not performing rolling twice.
  • Nos. 25 and 27 to 31 coarse non-recrystallized grains remain by not carrying out the production conditions specified in the present invention, and the HAZ total crack length exceeds 1.5 mm, and the HAZ crack resistance is reduced. It was.
  • Test No. 26 and no. No. 32 did not satisfy the production conditions specified by the present invention, and hot rolling occurred.
  • an austenitic stainless steel sheet excellent in polythionic acid SCC resistance and weld crack resistance can be obtained even with a thick steel sheet having a thickness of 6.0 mm or more.
  • an austenitic stainless steel sheet that is also used in equipment can be provided.

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Abstract

L'invention concerne une tôle d'acier inoxydable épaisse à base d'austénite ayant une épaisseur qui est égale ou supérieure à 6,0 mm, et une composition chimique comprenant, en % en poids, moins de 0,04 % de C, pas moins de 1,5 % de Si, pas moins de 2,0 % de Mn, pas moins de 0,04 % de P, pas moins de 0,03 % de S, de 0,02 à 0,35 % de N, pas moins de 0,03 % de O, de 0,05 à 0,5 % de Nb, de 15,0 à 25,0 % de Cr, de 6,0 à 30,0 % de Ni, de 0 à 0,05 % de Al, de 0 à 0,4 % de Ti, de 0 à 0,4 % de V, de 0 à 0,2 % de Ta, de 0 à 0,2 % de Hf, de 0 à 0,2 % de Zr, de 0 à 3,0 % de Cu, de 0 à 5,0 % de Mo, de 0 à 5,0 % de W, de 0 à 1,0 % de Co, de 0 à 0,012 % de B, de 0 à 0,02 % de Ca, de 0 à 0,02 % de Mg, et de 0 à 0,1 % de REM, le reste étant du Fe et des impuretés, où, dans une coupe transversale perpendiculaire au sens de laminage, la taille de grain maximale est inférieure à 0,3 mm.
PCT/JP2018/012965 2017-03-31 2018-03-28 Tôle d'acier inoxydable épaisse à base d'austénite et son procédé de production Ceased WO2018181570A1 (fr)

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JP2022181632A (ja) * 2021-05-26 2022-12-08 日鉄ステンレス株式会社 オーステナイト系ステンレス鋼材及び溶接構造体
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CN120608248A (zh) * 2025-08-12 2025-09-09 东北大学 一种超低温环境用高氮奥氏体不锈钢及其制备方法

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CN109355472A (zh) * 2018-12-22 2019-02-19 中南大学 一种铜铌钴改性奥氏体不锈钢及其加工与热处理方法
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WO2021141107A1 (fr) * 2020-01-10 2021-07-15 日本製鉄株式会社 Matériau d'acier inoxydable austénitique
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JP2022181633A (ja) * 2021-05-26 2022-12-08 日鉄ステンレス株式会社 オーステナイト系ステンレス鋼材及びその製造方法、並びに加工製品
JP2022181632A (ja) * 2021-05-26 2022-12-08 日鉄ステンレス株式会社 オーステナイト系ステンレス鋼材及び溶接構造体
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CN118460934A (zh) * 2024-04-24 2024-08-09 鞍钢股份有限公司 低碳高硅具有强韧性能的耐蚀容器用不锈钢及制造方法
CN118460934B (zh) * 2024-04-24 2025-09-30 鞍钢股份有限公司 低碳高硅具有强韧性能的耐蚀容器用不锈钢及制造方法
CN120608248A (zh) * 2025-08-12 2025-09-09 东北大学 一种超低温环境用高氮奥氏体不锈钢及其制备方法

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