WO2017061216A1 - 耐食性に優れたステンレス鋼管 - Google Patents

耐食性に優れたステンレス鋼管 Download PDF

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Publication number
WO2017061216A1
WO2017061216A1 PCT/JP2016/076143 JP2016076143W WO2017061216A1 WO 2017061216 A1 WO2017061216 A1 WO 2017061216A1 JP 2016076143 W JP2016076143 W JP 2016076143W WO 2017061216 A1 WO2017061216 A1 WO 2017061216A1
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WIPO (PCT)
Prior art keywords
mass
stainless steel
steel pipe
less
polishing
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PCT/JP2016/076143
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English (en)
French (fr)
Japanese (ja)
Inventor
知明 齋田
善一 田井
一成 今川
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日新製鋼株式会社
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Publication of WO2017061216A1 publication Critical patent/WO2017061216A1/ja

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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
    • 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
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium

Definitions

  • the present invention relates to a stainless steel pipe excellent in corrosion resistance.
  • Stainless steel is widely used in building materials such as roofing materials, wall materials, and building materials because it is excellent in weather resistance, workability, weldability, and the like. Moreover, since the stainless steel pipe is excellent in design, the surface is polished and used for applications such as handrails, fences, and pipe shutters.
  • polishing removal is performed to remove wrinkles and the like of the raw pipe before polishing, and then final polishing and gloss polishing are performed.
  • rough polishing and finish polishing in this polishing operation dry polishing using a flap wheel, a polishing belt, or the like is performed. Further, after the above process, wet polishing by buffing may be performed to obtain a desired surface.
  • stainless steel has excellent weather resistance as a material, but depending on the state of the polished finish, it may not exhibit the weather resistance inherent to the material and may cause significant bruising. This is one of the factors that eliminate the stability (reliability) of weather resistance. For example, it may occur in a short period of about one month after construction on an outdoor handrail.
  • the starting point is the oxide film and polishing marks remaining on the polished surface of the stainless steel pipe.
  • the remaining oxide film is a film generated due to heat generation during polishing, and a Cr-deficient layer is formed immediately below the oxide film.
  • the firing proceeds from the oxide film and the Cr-deficient layer immediately below the oxide film, and the corrosion resistance tends to deteriorate.
  • the polishing marks which are ridges carved on the surface of the stainless steel pipe by polishing, the deeper the recesses in the polishing marks, the more likely the oxide film generated by the flap wheel polishing or the like is difficult to be removed by buffing and remain. Since the height becomes higher and the concave portion of the polished eye becomes the starting point of the cracking, the cracking proceeds and the corrosion resistance tends to deteriorate.
  • Patent Document 1 proposes a stainless steel pipe capable of maintaining glossiness and weather resistance over a long period of time in a surface-polished state that does not generate sprout even in an outdoor environment in a short period of time.
  • Patent Document 1 is a stainless steel pipe having a surface roughness after final polishing of Ry 0.6 ⁇ m or less and an area ratio of the remaining oxide film of 7.0% or less. That is, by setting the surface roughness after final polishing to Ry 0.6 ⁇ m or less, an attempt is made to reduce the oxide film remaining in the recesses of the polishing eyes. Further, by setting the area ratio of the remaining oxide film to 7.0% or less, it is intended to suppress the progress of cracking and deterioration of corrosion resistance starting from the oxide film and the Cr-deficient layer immediately below the oxide film.
  • the remaining oxide film area ratio in the weather-resistant product is 3.1 to 6.8%, and the oxide film remains. For this reason, there still remains a problem that the rusting can progress and the corrosion resistance can be deteriorated starting from the remaining oxide film and the Cr-deficient layer directly therebelow.
  • Patent Document 2 describes that a stainless steel tube is immersed in a mixed solution of hydrofluoric acid and nitric acid to dissolve the oxidized scale on the surface of the stainless steel and the Cr-deficient layer immediately below the scale layer.
  • the object of the present invention is to solve the above-mentioned problems and to provide a stainless steel pipe excellent in corrosion resistance that does not start at an early stage even in a waterfront environment affected by sea salt particles.
  • the present inventors examined the stainless steel pipe described in Patent Document 1.
  • polishing by a flap wheel is performed.
  • the surface of the stainless steel pipe is heated at the time of flap wheel polishing, which is dry polishing, and an oxide film is generated, and there are surface defects along with polishing marks that are engraved by high grinding resistance by dry polishing.
  • the surface defects mentioned here are “burrs” or “covers” that are covered with the base material by polishing materials and paper continuously contacting the steel pipe surface when the steel pipe surface is polished, and the metal on the surface is partially peeled off. ".
  • the surface defect includes a portion where the metal is turned up like a strip shape or a bamboo leaf shape, and the maximum length from one end portion of the portion adhered to the substrate to the other end portion of the peeling tip is 5 ⁇ m. It is the above defect. Since the surface defect forms a minute gap with the surface base portion of the stainless steel pipe, corrosion tends to occur, which causes a reduction in the corrosion resistance of the steel pipe.
  • the stainless steel pipe is likely to be sprinkled, and the ordinary person skilled in the art is able to remove the oxide film and surface defect by pickling treatment.
  • the present inventors are a stainless steel pipe that is easily corroded due to the presence of colored oxide films and surface defects, and is early in the waterfront environment that is affected by sea salt particles even if it is not pickled after polishing.
  • the present invention has been found by investigating a stainless steel pipe excellent in corrosion resistance, which does not cause any problems.
  • the present invention provides the following (1) to (2) stainless steel pipes having excellent corrosion resistance.
  • (1) A longitudinally unidirectional polished surface is provided on the surface of a ferritic stainless steel tube, the pitting corrosion potential is 0.6 V or more, the 60 ° glossiness is 75 or less, and the composition is C: 0.020 mass.
  • the stainless steel pipe of the present invention has excellent design properties because it has a longitudinally polished surface on the surface of the ferritic stainless steel pipe, and has an antiglare property because its 60 degree gloss is 75 or less.
  • the colored oxide film is present on the surface of the stainless steel pipe and has surface defects, it has a predetermined composition and has a high pitting corrosion index (PI) of 30 or more. It is a stainless steel pipe excellent in corrosion resistance having a pitting potential of 0.6 V or more, in which the cracking starting from the Cr-deficient layer immediately below is suppressed.
  • Nb 0.1 to 1.0% by mass
  • Ti 0.05 to 0.3% by mass
  • Al 0.01 to 0.5% by mass
  • the stainless steel pipe of the present invention has a longitudinally polished surface on the surface of the ferritic stainless steel pipe, the pitting corrosion potential is 0.6 V or more, the 60 ° gloss is 75 or less, and the composition is C: 0.020 mass% or less, Si: 0.40 mass% or less, Mn: 0.40 mass% or less, Cr: 25.00-32.00 mass%, Mo: 1.00-4.00 mass%, P : 0.030% by mass or less, S: 0.020% by mass or less, Ni: 0.50% by mass or less, N: 0.020% by mass or less, with the balance being Fe and inevitable impurities, pitting corrosion resistance
  • the stainless steel pipe has a surface polished to give the surface unevenness and gloss.
  • the stainless steel pipe has a polished eye and becomes a stainless steel pipe excellent in design and antiglare properties.
  • Polishing eyes are ridges carved on the surface of a stainless steel pipe by polishing.
  • the polishing eye includes a polishing eye in one longitudinal direction.
  • a stainless steel pipe having a polishing mark in one longitudinal direction is excellent in antiglare property.
  • As the polishing finish in one longitudinal direction since wet polishing is difficult, dry polishing with a flap wheel or the like has been conventionally performed. However, when dry polishing is performed, the surface of the stainless steel tube becomes high temperature and oxidation with coloring is performed. A film is formed.
  • the polishing surface of the surface after polishing the deeper the recess of the polishing eye, the higher the possibility that the oxide film generated by flap wheel polishing or the like remains, the recess of the polishing eye becomes the starting point, Heating progresses and corrosion resistance tends to deteriorate.
  • the presence of a colored oxide film means that when an arbitrary 10 points on the surface of the stainless steel tube are observed with an optical microscope at a magnification of 400 times, the colored oxide film is 50 ⁇ m square. In the case of 10% or more by area ratio.
  • the coloration is not limited to a specific color, and any color that can be visually distinguished from the metal base or metallic luster of the stainless steel pipe is acceptable. A typical color for coloring is brown.
  • FIG. 1 is a photograph of an enlarged surface of a stainless steel tube with an optical microscope, (a) a surface in which surface defects are suppressed and (b) a surface in which surface defects are generated.
  • the surface of the stainless steel pipe in FIG. 1 (a) has polished eyes, but surface defects are suppressed.
  • the surface of the stainless steel pipe in FIG. 1 (b) is dry-polished, and the surrounding portions 1 to 9 show surface defects in which the metal on the surface is partially peeled and covered with the base portion.
  • the surface defect means that the maximum length from one end portion of the portion bonded to the substrate to the other end portion of the peeling tip has a size of 5 ⁇ m or more.
  • the average number of surface defects measured is In the case of 6 or more, the surface defect in the present invention is not suppressed.
  • the ferritic stainless steel pipe of the present invention having the composition and having a pitting corrosion index (PI) of 30 or higher has a high pitting corrosion potential of 0.6 V or higher and excellent corrosion resistance.
  • the SUS304 can be suppressed early, whereas the SUS304 can be suppressed. Moreover, even if there is a colored oxide film or a surface defect generated by polishing, it is possible to suppress the generation of wrinkles.
  • the stainless steel pipe of the present invention further includes Nb: 0.1 to 1.0% by mass, Ti: 0.05 to 0.3% by mass, Al: 0.01 to 0.5% by mass, It is preferable that 2 or more types are included. By containing a predetermined amount of Nb, Ti and / or Al, the corrosion resistance tends to be further improved.
  • C is an element useful for obtaining the strength of steel, but when it is contained in a large amount, it tends to lower the corrosion resistance.
  • the C content is preferably 0.015% by mass or less, and more preferably 0.010% by mass or less.
  • Si is an element useful as a deoxidizer and heat source in the steelmaking process, but when it is contained in a large amount, it tends to harden the steel.
  • the content of Si is preferably 0.35% by mass or less, and more preferably 0.30% by mass or less.
  • Mn is an element useful as deoxidation in the steel making process, but when it is contained in a large amount, it tends to form an austenite phase.
  • the content of Mn is preferably 0.35% by mass or less, and more preferably 0.30% by mass or less.
  • Cr is a useful element for ensuring corrosion resistance, but if it is contained in a large amount, it tends to decrease not only the cost but also the workability.
  • the content of Cr is preferably 25.00 to 31.50% by mass, and more preferably 25.00 to 31.00% by mass.
  • Mo is an element useful for improving the corrosion resistance of stainless steel in the presence of Cr, but if it is contained in a large amount, it tends to reduce not only the cost but also the workability.
  • the Mo content is preferably 1.50 to 4.00 mass%, more preferably 1.80 to 3.80 mass%.
  • the PP tends to reduce corrosion resistance.
  • the P content is preferably 0.025% by mass or less, and more preferably 0.020% by mass or less.
  • S has a tendency to lower the corrosion resistance.
  • the content of S is preferably 0.015% by mass or less, and more preferably 0.010% by mass or less.
  • Ni is preferable because it is effective in suppressing the progress of corrosion and effective in improving the toughness of the ferritic stainless steel pipe, but if it is too much, it will cause the generation of austenite phase and high cost.
  • the content of Ni is preferably 0.45% by mass or less, and more preferably 0.40% by mass or less.
  • the N content is preferably 0.015% by mass or less, and more preferably 0.010% by mass or less.
  • Nb is preferable in that it has a strong affinity with C and N, and suppresses intergranular corrosion of ferritic stainless steel pipes, but a large amount of Nb tends to inhibit toughness.
  • the content of Nb is more preferably 0.1 to 0.9% by mass, and further preferably 0.1 to 0.8% by mass.
  • Ti has a strong affinity with C and N, and is preferable in terms of suppressing intergranular corrosion of ferritic stainless steel pipes. However, a large amount of Ti tends to deteriorate the surface quality of steel.
  • the Ti content is more preferably 0.05 to 0.25% by mass, even more preferably 0.05 to 0.2% by mass.
  • Al is an element effective for refining and casting as a deoxidizer, but if added in excess, it degrades the surface quality and lowers the weldability and low temperature toughness of the steel.
  • the content of Al is more preferably 0.01 to 0.45% by mass, and further preferably 0.01 to 0.4% by mass.
  • FIG. 2 and 3 are diagrams showing surface defects and pitting corrosion potential
  • FIG. 2 (a) is an enlarged photograph showing the surface defects of the stainless steel pipe
  • FIG. 3 (a) shows the surface defects of the stainless steel pipe being suppressed
  • FIG. 2 (b) and FIG. 3 (b) are graphs showing the measurement results of the pitting potential of the stainless steel pipe of FIG. 2 (a) and FIG. 3 (a).
  • 2 and 3 are stainless steel pipes having a pitting corrosion index (PI) of about 24 and lower than the pitting corrosion index (PI) of the present invention.
  • PI pitting corrosion index
  • FIG. 2A there is a surface defect
  • the pitting corrosion potential is a low value of about 0.3 V as shown in FIG. Further, although surface defects are suppressed in FIG.
  • the pitting corrosion potential is a low value of about 0.5 V as shown in FIG. 3B.
  • the stainless steel pipe of the present invention has a high pitting potential of 0.6 V or more and is excellent in corrosion resistance. For this reason, even if there is a colored oxide film or a surface defect, it is possible to suppress the progress of cracking and the deterioration of corrosion resistance.
  • the pitting potential is more preferably 0.65V or more, and further preferably 0.7V or more.
  • Method B is a pitting potential measurement method by a kinetic potential method in a 3.5% by mass sodium chloride aqueous solution.
  • the pH of the aqueous sodium chloride solution is 7 and the temperature is 30 ° C.
  • the potential sweep rate is 20 mV / min.
  • the surface roughness Ra of the stainless steel pipe surface in the present invention is preferably 0.1 to 1.0 ⁇ m, and more preferably 0.2 to 0.5 ⁇ m.
  • the surface roughness Ra is less than 0.1 ⁇ m, the antiglare property is inferior, and the polishing residue is hardly maintained, and the design property tends to be difficult to ensure.
  • the glossiness of the stainless steel tube surface in the present invention is preferably 60 ° glossiness of 75 or less. More preferably, it is 60 or less.
  • the glossiness is measured according to JIS Z 8741, and can be measured by, for example, a gloss meter. Specifically, a light beam with a specified opening angle is incident on the sample surface at the time of glossiness measurement, and a light beam with a specified opening angle reflected in the reflection direction is measured with a light receiver.
  • the 60 degree glossiness is the glossiness when the specified incident angle is 60 degrees. When the 60 degree glossiness is 75 or less, the surface of the stainless steel tube has preferable antiglare properties.
  • Polishing was carried out in a line in which four flap wheels (# 80, # 80, # 80, # 150) were lined up so as to polish the longitudinal direction of the steel pipe surface (giving polishing marks in the longitudinal direction), and dry polishing was performed. . “# 80” or the like indicates the mesh granularity.
  • the stainless steel pipe of Example 1 has polished eyes on the surface of the stainless steel pipe, there are as many as 15 surface defects (see FIG. 4), and a colored oxide film is also present on the surface.
  • the stainless steel pipe of Example 1 was suppressed in sprinkling even by the CCT test (see FIG. 6), and proved to be excellent in corrosion resistance.
  • pitting corrosion did not generate

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Articles (AREA)
PCT/JP2016/076143 2015-10-05 2016-09-06 耐食性に優れたステンレス鋼管 WO2017061216A1 (ja)

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JP2015197978A JP6108497B1 (ja) 2015-10-05 2015-10-05 耐食性に優れたステンレス鋼管

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KR20220105663A (ko) * 2020-05-28 2022-07-27 닛테츠 스테인레스 가부시키가이샤 오스테나이트계 스테인리스 강재 및 내식성 부재

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05163557A (ja) * 1991-12-13 1993-06-29 Kawasaki Steel Corp 防眩性と耐食性を兼ね備えた外装用ステンレス鋼板
JPH06346196A (ja) * 1993-06-14 1994-12-20 Nisshin Steel Co Ltd 防眩性に優れた高耐食性フェライト系ステンレス鋼
JPH07113142A (ja) * 1993-10-15 1995-05-02 Kawasaki Steel Corp 耐汚染性と耐食性に優れた建材用ステンレス鋼板
JPH1094968A (ja) * 1996-09-24 1998-04-14 Nisshin Steel Co Ltd 高Ｃｒフェライト系ステンレス鋼研磨用砥石
JP2003027191A (ja) * 2001-07-23 2003-01-29 Nisshin Steel Co Ltd 耐候性および曲げ加工性に優れたフェライト系ステンレス鋼製装飾管

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05163577A (ja) * 1991-12-11 1993-06-29 Hitachi Chem Co Ltd 無電解めっき用触媒液及びその製造法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05163557A (ja) * 1991-12-13 1993-06-29 Kawasaki Steel Corp 防眩性と耐食性を兼ね備えた外装用ステンレス鋼板
JPH06346196A (ja) * 1993-06-14 1994-12-20 Nisshin Steel Co Ltd 防眩性に優れた高耐食性フェライト系ステンレス鋼
JPH07113142A (ja) * 1993-10-15 1995-05-02 Kawasaki Steel Corp 耐汚染性と耐食性に優れた建材用ステンレス鋼板
JPH1094968A (ja) * 1996-09-24 1998-04-14 Nisshin Steel Co Ltd 高Ｃｒフェライト系ステンレス鋼研磨用砥石
JP2003027191A (ja) * 2001-07-23 2003-01-29 Nisshin Steel Co Ltd 耐候性および曲げ加工性に優れたフェライト系ステンレス鋼製装飾管

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TW201726943A (zh) 2017-08-01
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TWI696710B (zh) 2020-06-21

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