JP6138209B2 - Stainless steel pipe excellent in corrosion resistance and manufacturing method thereof - Google Patents
Stainless steel pipe excellent in corrosion resistance and manufacturing method thereof Download PDFInfo
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- JP6138209B2 JP6138209B2 JP2015197977A JP2015197977A JP6138209B2 JP 6138209 B2 JP6138209 B2 JP 6138209B2 JP 2015197977 A JP2015197977 A JP 2015197977A JP 2015197977 A JP2015197977 A JP 2015197977A JP 6138209 B2 JP6138209 B2 JP 6138209B2
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- 229910001220 stainless steel Inorganic materials 0.000 title claims description 96
- 239000010935 stainless steel Substances 0.000 title claims description 92
- 230000007797 corrosion Effects 0.000 title claims description 53
- 238000005260 corrosion Methods 0.000 title claims description 53
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 238000005498 polishing Methods 0.000 claims description 86
- 230000007547 defect Effects 0.000 claims description 49
- 239000007787 solid Substances 0.000 claims description 27
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000002184 metal Substances 0.000 claims description 13
- 239000000758 substrate Substances 0.000 claims description 10
- 229910000831 Steel Inorganic materials 0.000 description 13
- 239000010959 steel Substances 0.000 description 13
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 235000002639 sodium chloride Nutrition 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 239000011780 sodium chloride Substances 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- 230000003287 optical effect Effects 0.000 description 8
- 239000002436 steel type Substances 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 230000002950 deficient Effects 0.000 description 5
- 230000003746 surface roughness Effects 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- IPCSVZSSVZVIGE-UHFFFAOYSA-N hexadecanoic acid Chemical compound CCCCCCCCCCCCCCCC(O)=O IPCSVZSSVZVIGE-UHFFFAOYSA-N 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 235000014113 dietary fatty acids Nutrition 0.000 description 3
- 239000000194 fatty acid Substances 0.000 description 3
- 229930195729 fatty acid Natural products 0.000 description 3
- 150000004665 fatty acids Chemical class 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 235000010446 mineral oil Nutrition 0.000 description 3
- 239000002480 mineral oil Substances 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 230000037303 wrinkles Effects 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 235000021314 Palmitic acid Nutrition 0.000 description 2
- 235000021355 Stearic acid Nutrition 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 229910000424 chromium(II) oxide Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- WQEPLUUGTLDZJY-UHFFFAOYSA-N n-Pentadecanoic acid Natural products CCCCCCCCCCCCCCC(O)=O WQEPLUUGTLDZJY-UHFFFAOYSA-N 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000004745 nonwoven fabric Substances 0.000 description 2
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 2
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000008117 stearic acid Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- TWJNQYPJQDRXPH-UHFFFAOYSA-N 2-cyanobenzohydrazide Chemical compound NNC(=O)C1=CC=CC=C1C#N TWJNQYPJQDRXPH-UHFFFAOYSA-N 0.000 description 1
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 241001330002 Bambuseae Species 0.000 description 1
- 208000034656 Contusions Diseases 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 235000021360 Myristic acid Nutrition 0.000 description 1
- TUNFSRHWOTWDNC-UHFFFAOYSA-N Myristic acid Natural products CCCCCCCCCCCCCC(O)=O TUNFSRHWOTWDNC-UHFFFAOYSA-N 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 239000000443 aerosol Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000011425 bamboo Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009837 dry grinding Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
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- 239000007921 spray Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B29/00—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents
- B24B29/02—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces
- B24B29/06—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces for elongated workpieces having uniform cross-section in one main direction
- B24B29/08—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces for elongated workpieces having uniform cross-section in one main direction the cross-section being circular, e.g. tubes, wires, needles
-
- 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
Description
本発明は、耐食性に優れたステンレス鋼管及びその製造方法に関する。 The present invention relates to a stainless steel pipe excellent in corrosion resistance and a method for producing the same.
ステンレス鋼は、耐候性、加工性、溶接性等に優れることから、屋根材、壁材、建築部材等の建材用途で多用されている。また、ステンレス鋼管は、意匠性にも優れるため、表面研磨されて手摺、フェンス、パイプシャッター等の用途で使用されている。 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.
このステンレス鋼管の一般的、工業的な研磨は、まず研磨前素管の疵等の除去のために、疵取り研磨を行い、次に仕上げ研磨および光沢研磨等を行っている。この研磨作業における粗研磨、仕上げ研磨では、フラップホイールや研磨ベルト等を使用した乾式研磨が行われている。さらに、上記工程後、所望の表面を得るためにバフ研磨による湿式研磨を行う場合がある。 In general and industrial polishing of the stainless steel pipe, first, removal of wrinkles and the like of the raw pipe before polishing is performed, and then final polishing and gloss polishing are performed. In 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.
従来より、ステンレス鋼は、素材として優れた耐候性を有しているものの、研磨仕上げの状態によっては、本来素材がもつ耐候性を発揮せず、著しく発銹を生じる場合があり、ステンレス鋼の耐候性の安定性（信頼性）をなくす要因の一つとなっている。例えば、屋外の手摺等へ施工した後、１ヶ月程度の短期間で発銹する場合がある。 Conventionally, 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.
発銹については、ステンレス鋼管の研磨後の表面に残存している酸化皮膜や研磨目が起点になっていると考えられている。残存する酸化皮膜とは、研磨時の発熱に起因して生成された皮膜であり、酸化皮膜の直下にはＣｒ欠乏層が形成されている。このため、酸化皮膜が残存していると、該酸化皮膜及びその直下のＣｒ欠乏層を起点として発銹が進行し、耐食性が劣化しやすくなる。また、研磨によってステンレス鋼管表面に刻まれた疵である研磨目についても、研磨目の凹部が深いほど、フラップホイール研磨等で生成した酸化皮膜がバフ研磨で除去され難くなって残存する可能性が高くなり、その研磨目の凹部が発銹起点になることから、発銹が進行し、耐食性が劣化しやすくなる。 It is thought that 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. For this reason, if the oxide film remains, the firing proceeds from the oxide film and the Cr-deficient layer immediately below the oxide film, and the corrosion resistance tends to deteriorate. In addition, with respect to 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.
特許文献１では、屋外環境においても短期間で発銹が生じることのない表面研磨状態にして、長期にわたって光沢性、耐候性を維持できるステンレス管を提案している。 Patent Document 1 proposes a stainless steel tube capable of maintaining glossiness and weather resistance over a long period of time in a surface-polished state that does not generate wrinkles in a short period even in an outdoor environment.
特許文献１に記載の発明は、最終研磨後の表面粗さがＲｙ０．６μｍ以下で、残存する酸化皮膜の面積率が７．０％以下のステンレス鋼管である。すなわち、最終研磨後の表面粗さをＲｙ０．６μｍ以下とすることによって、研磨目の凹部に残存する酸化皮膜を少なくしようとしている。また、残存する酸化皮膜の面積率が７．０％以下とすることによって、該酸化皮膜及びその直下のＣｒ欠乏層を起点とした発銹の進行及び耐食性の劣化を抑制しようとしている。 The invention described in Patent Document 1 is a stainless steel pipe having a surface roughness after final polishing of Ry 0.6 μm 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 μm 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.
ここで、特許文献１の実施例を参照すると、耐候性合格品における残存酸化皮膜面積率は３．１〜６．８％であり、酸化皮膜は残存している。このため、残存した酸化皮膜及びその直下のＣｒ欠乏層を起点として発銹が進行し耐食性が劣化し得るという問題は、依然として残っている。 Here, referring to the examples in Patent Document 1, the area ratio of the remaining oxide film 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.
さらに、近年都市再開発などに伴い建築需要が増加しており、ウォーターフロント環境における建築需要が増加している。ウォーターフロント環境においては、大気中に含まれるエアロゾル粒子の一種であって、海水に由来する塩分からなる微粒子である海塩粒子の影響を建築部材が受けやすいという問題がある。このため、高耐食性建築部材のニーズがより高まっている。 In addition, building demand has increased in recent years due to urban redevelopment, etc., and building demand in the waterfront environment has increased. In the waterfront environment, there is a problem that a building member is easily affected by sea salt particles, which are a kind of aerosol particles contained in the atmosphere, and are fine particles composed of salt derived from seawater. For this reason, the need for highly corrosion-resistant building members is increasing.
特許文献１では、耐候性に優れるステンレス鋼管の鋼種の一つとして、ＳＵＳ３０４を挙げている。しかしながら、海塩粒子の影響を受けるウォーターフロント環境では、ＳＵＳ３０４は早期に発銹してしまい、メンテナンスが必要になるという問題がある。 In patent document 1, SUS304 is mentioned as one of the steel types of the stainless steel pipe excellent in a weather resistance. However, in a waterfront environment that is affected by sea salt particles, SUS304 is spawned at an early stage, and there is a problem that maintenance is required.
本発明は、上述した課題を解決し、海塩粒子の影響を受けるウォーターフロント環境でも、早期に発銹することのない、耐食性に優れたステンレス鋼管及びその製造方法を提供することを目的とする。 SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described 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, and a method for producing the same. .
本発明者らは、特許文献１に記載のステンレス鋼管について検討を行った。特許文献１の実施例においては、フラップホイールによる乾式研磨を行っている。当該研磨方法を用いた特許文献１の実施例のステンレス鋼管表面における酸化皮膜は、面積率で３．１％以上残存している。この原因を検討した結果、乾式研磨であるフラップホイール研磨時にステンレス鋼管表面が高温となり酸化被膜が発生すること、乾式研磨による高い研削抵抗によって刻まれた疵である研磨目とともに、表面欠陥が生じていること、を突き止めた。ここでいう表面欠陥とは、鋼管表面を研磨する時に研磨材や研磨紙が連続して鋼管表面に接触して研磨されることにより、表面の金属が部分的に剥がされ、素地部分に被さった形態を有する欠陥であり、「バリ」や「被さり（かぶさり）」と呼称されている。表面欠陥は、短冊状や笹の葉状のように金属がめくれている部分を含み、素地に接着している部分における一方の端部から剥がれの先端における他方の端部までの最大長さが５μｍ以上の欠陥である。当該表面欠陥は、ステンレス鋼管の表面素地部分と微小な隙間を形成することから、隙間腐食を生じやすく、鋼管の耐食性低下の要因となる。 The present inventors examined the stainless steel pipe described in Patent Document 1. In the Example of patent document 1, the dry grinding | polishing by a flap wheel is performed. The oxide film on the surface of the stainless steel pipe of the example of Patent Document 1 using the polishing method remains 3.1% or more in area ratio. As a result of investigating this cause, the surface of the stainless steel pipe surface is high temperature and the oxide film is generated at the time of flap wheel polishing, which is dry polishing, and surface defects are generated along with the polishing marks that are engraved by the high grinding resistance by dry polishing. I found out. The surface defect here means that when polishing the steel pipe surface, the polishing material or the abrasive paper continuously contacts the steel pipe surface and is polished, so that the metal on the surface is partially peeled and covers the substrate part. It is a defect having a form and is called “burr” or “cover”. 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 μm. It is the above defect. Since the surface defect forms a minute gap with the surface base portion of the stainless steel pipe, crevice corrosion is likely to occur, which causes a reduction in the corrosion resistance of the steel pipe.
本発明者らは、当該分析結果を基に、耐食性に優れたステンレス鋼管及びその製造方法を見出した。 Based on the analysis results, the present inventors have found a stainless steel pipe excellent in corrosion resistance and a method for producing the same.
すなわち、本発明は、以下の（１）〜（３）の耐食性に優れたステンレス鋼管及びその製造方法を提供する。
（１）研磨目をステンレス鋼管の表面に有し、着色を有する酸化皮膜が該表面上に存在せず、前記表面上における５μｍ以上の金属素地の被さりを含む表面欠陥の平均個数が０．０１ｍｍ２当たり５個以内に抑制されている、耐食性に優れたステンレス鋼管。
That is, this invention provides the stainless steel pipe excellent in the corrosion resistance of the following (1)-(3), and its manufacturing method.
(1) The surface of the stainless steel tube has a polished surface, no colored oxide film is present on the surface, and the average number of surface defects including a metal substrate covering of 5 μm or more on the surface is 0.01 mm. Stainless steel pipe with excellent corrosion resistance, limited to 5 per 2 pieces.
本発明のステンレス鋼管は、研磨目をステンレス鋼管の表面に有することから、意匠性や防眩性に優れる。また、着色を有する酸化皮膜がステンレス鋼管表面上に存在しないことから、酸化皮膜及びその直下のＣｒ欠乏層を起点とする発銹が進行しにくく、耐食性が劣化しにくい。さらに、ステンレス鋼管表面上における５μｍ以上の金属素地の被さりを含む表面欠陥の平均個数が０．０１ｍｍ２当たり５個以内に抑制されていることから、隙間腐食を抑制し、耐食性に優れたステンレス鋼管となる。 Since the stainless steel pipe of the present invention has polished eyes on the surface of the stainless steel pipe, it is excellent in design and antiglare properties. In addition, since the colored oxide film does not exist on the surface of the stainless steel pipe, the firing starting from the oxide film and the Cr-deficient layer immediately below the oxide film hardly proceeds, and the corrosion resistance is not easily deteriorated. Furthermore, since the average number of surface defects including the covering of the metal substrate of 5 μm or more on the surface of the stainless steel pipe is suppressed to 5 or less per 0.01 mm 2 , the stainless steel pipe excellent in corrosion resistance is suppressed in crevice corrosion. It becomes.
（２）ステンレス鋼管の表面を、固形研磨剤で研磨する研磨工程を有する、（１）のステンレス鋼管の製造方法。 (2) The method for producing a stainless steel pipe according to (1), comprising a polishing step of polishing the surface of the stainless steel pipe with a solid abrasive.
（３）上記研磨工程において、研磨フラップホイールに固形研磨剤を付着させてステンレス鋼管の表面を研磨する、（２）の製造方法。 (3) The manufacturing method according to (2), wherein in the polishing step, the surface of the stainless steel pipe is polished by attaching a solid abrasive to the polishing flap wheel.
本発明によれば、海塩粒子の影響を受けるウォーターフロント環境でも、早期に発銹することのない、耐食性に優れたステンレス鋼管及びその製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide a stainless steel pipe having excellent corrosion resistance and a method for producing the same, which does not start early even in a waterfront environment affected by sea salt particles.
以下に本発明を実施するための形態について説明する。なお、本発明は当該実施形態によって限定的に解釈されるものではない。 The form for implementing this invention is demonstrated below. The present invention is not construed as being limited by the embodiment.
（ステンレス鋼管）
本発明のステンレス鋼管は、研磨目をステンレス鋼管の表面に有し、着色を有する酸化皮膜が該表面上に存在せず、該表面上における５μｍ以上の金属素地の被さりを含む表面欠陥の平均個数が０．０１ｍｍ２当たり５個以内に抑制されているため、耐食性に優れたステンレス鋼管である。
(Stainless steel pipe)
The stainless steel pipe of the present invention has a polished surface on the surface of the stainless steel pipe, no colored oxide film is present on the surface, and the average number of surface defects including a metal substrate covering of 5 μm or more on the surface Is suppressed to 5 or less per 0.01 mm 2 , and is a stainless steel pipe excellent in corrosion resistance.
本発明において、ステンレス鋼管は表面に凹凸や光沢を付与するために表面の研磨仕上げが行われたものである。これにより、ステンレス鋼管は研磨目を備え、意匠性や防眩性に優れたステンレス鋼管となる。研磨目とは、研磨によってステンレス鋼管表面に刻まれた疵である。 In the present invention, the stainless steel pipe has a surface polished for imparting irregularities and gloss to the surface. As a result, 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.
研磨後の表面の研磨目は、研磨目の凹部が深いほど、フラップホイール研磨等で生成した酸化皮膜が残存する可能性が高くなり、その研磨目の凹部が発銹起点になって、発銹が進行し、耐食性が劣化しやすくなる。よって、本発明におけるステンレス鋼管表面の研磨後の表面粗さＲａは、０．１〜１．０μｍであることが好ましく、０．２〜０．５μｍであることがより好ましい。研磨後の表面粗さは、ＪＩＳ Ｂ ０６０１に準拠し測定されたものであり、例えば接触式の表面粗度計によって測定できる。 As the surface of the polished surface after polishing becomes deeper, the oxide film produced by flap wheel polishing or the like is more likely to remain, and the recessed portion of the polished surface becomes the starting point. Progresses and the corrosion resistance tends to deteriorate. Therefore, the surface roughness Ra after polishing of the stainless steel pipe surface in the present invention is preferably 0.1 to 1.0 μm, and more preferably 0.2 to 0.5 μm. The surface roughness after polishing is measured according to JIS B 0601, and can be measured by, for example, a contact-type surface roughness meter.
研磨仕上げとしては、従来よりフラップホイール等による乾式研磨が行われているが、乾式研磨を行うとステンレス鋼管の表面が高温となり、酸化皮膜が形成される。一方、本発明のステンレス鋼管においては、着色を有する酸化皮膜が表面上に存在しないことを特徴とする。この理由としては、本発明のステンレス鋼管は、固形研磨剤で研磨されることによって、表面の酸化皮膜が除去されることによるものと本発明者らは考えている。また、研磨フラップホイールに固形研磨剤を付着させることによって、酸化皮膜の発生がより抑制される。 As a polishing finish, dry polishing using a flap wheel or the like has been conventionally performed. However, when dry polishing is performed, the surface of the stainless steel pipe becomes high temperature and an oxide film is formed. On the other hand, the stainless steel pipe of the present invention is characterized in that a colored oxide film does not exist on the surface. The present inventors consider that the reason is that the stainless steel pipe of the present invention is caused by removing the oxide film on the surface by polishing with a solid abrasive. Moreover, the generation of an oxide film is further suppressed by attaching a solid abrasive to the polishing flap wheel.
本発明において、着色を有する酸化皮膜が存在するとは、ステンレス鋼管の表面の任意の１０点を光学顕微鏡で４００倍の倍率で観察したときに、着色を有するシミ状物質である酸化皮膜が５０μｍ四方において面積比率で５％以上存在している場合をいう。ここで、着色は特定に限定されず、ステンレス鋼管の金属素地や金属光沢と目視で区別できる色であればよい。着色として代表的な色は、茶褐色である。 In the present invention, 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 μm square. The case where the area ratio is 5% or more. Here, 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.
また、研磨仕上げとして、フラップホイール等による乾式研磨を行うと、ステンレス鋼管表面に研磨材や研磨紙が連続して接触し、表面の金属が部分的に剥がされ素地部分に被さったバリやかぶさりである表面欠陥が生じる。該表面欠陥は、ステンレス鋼管の表面素地部分と微小な隙間が生じることから、隙間腐食の要因となる。 Also, as a polishing finish, when dry polishing with a flap wheel or the like is performed, the abrasive or abrasive paper continuously contacts the surface of the stainless steel pipe, and the metal on the surface is partially peeled off and the burrs and coverings covered on the substrate part Some surface defects occur. The surface defect causes crevice corrosion because a minute gap is formed between the surface base portion of the stainless steel pipe.
図１は、ステンレス鋼管の表面を光学顕微鏡で拡大した写真であり、（ａ）表面欠陥が抑制された表面と、（ｂ）表面欠陥が生じた表面である。図１（ａ）は本発明のステンレス鋼管の表面であり、研磨目を有しているが表面欠陥は抑制されている。一方、図１（ｂ）はステンレス鋼管表面を乾式研磨したものであり、囲み部分１〜９は、表面の金属が部分的に剥がされ素地部分に被さった表面欠陥を示している。本発明者らは、図１（ａ）のように本発明のステンレス鋼管表面が研磨後に表面欠陥が抑制されている理由として、研磨時に固形研磨剤を用いることによるものと分析している。また、研磨フラップホイールに固形研磨剤を付着させることによって、表面欠陥がより抑制される。なお、図１中の白色の横線は研磨の際にできる凸部を示し、凸部である白色の横線と隣の白色の横線との間の凹部が、研磨目である。 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. FIG. 1 (a) shows the surface of the stainless steel pipe of the present invention, which has polished eyes but suppresses surface defects. On the other hand, FIG.1 (b) is what dry-polished the stainless steel pipe surface, and the surrounding parts 1-9 have shown the surface defect which the surface metal peeled partially and covered the base part. The present inventors have analyzed that the reason why the surface defects of the stainless steel pipe surface of the present invention are suppressed after polishing as shown in FIG. 1A is that a solid abrasive is used during polishing. Moreover, surface defects are further suppressed by attaching a solid abrasive to the polishing flap wheel. In addition, the white horizontal line in FIG. 1 shows the convex part formed in the case of grinding | polishing, and the recessed part between the white horizontal line which is a convex part, and the adjacent white horizontal line is a polishing eye.
本発明において、表面欠陥は、欠陥における最大の長さ部分が５μｍ以上の大きさの金属素地の被さりを有するものをいう。また、光学顕微鏡を用いて研磨されたステンレス鋼管表面の任意の１０点における１００μｍ×１００μｍ（０．０１ｍｍ２）の範囲を２００倍に拡大し観察した場合に、測定した表面欠陥の数の平均が５個以内の場合は、本発明における表面欠陥が抑制された状態とする。研磨されたステンレス鋼管表面上の表面欠陥の数は、１００μｍ×１００μｍ（０．０１ｍｍ２）の単位面積当たり３個以内がより好ましく、さらに好ましくは２個以内である。なお、表面欠陥の最大の長さ部分に上限はないが、測定する際の基準として上限を５０μｍとしてもよい。 In the present invention, the surface defect means that the maximum length portion of the defect has a covering of a metal substrate having a size of 5 μm or more. Moreover, when the range of 100 μm × 100 μm (0.01 mm 2 ) at an arbitrary 10 points on the surface of the stainless steel tube polished using an optical microscope is magnified 200 times, the average number of surface defects measured is In the case of 5 or less, the surface defects in the present invention are suppressed. The number of surface defects on the polished stainless steel tube surface is preferably 3 or less, more preferably 2 or less per unit area of 100 μm × 100 μm (0.01 mm 2 ). In addition, although there is no upper limit in the maximum length part of a surface defect, it is good also considering an upper limit as 50 micrometers as a reference | standard at the time of measuring.
図２及び図３は、表面欠陥と電流密度変化の関係を示す図であり、図２（ａ）はステンレス鋼管の表面欠陥を示す拡大写真、図３（ａ）はステンレス鋼管の表面欠陥が抑制された表面を示す拡大写真であり、図２（ｂ）及び図３（ｂ）は、図２（ａ）及び図３（ａ）のステンレス鋼管の孔食電位測定における電流密度変化を示すグラフである。 2 and 3 are diagrams showing the relationship between surface defects and changes in current density. FIG. 2 (a) is an enlarged photograph showing the surface defects of the stainless steel pipe, and FIG. 3 (a) shows the suppression of the surface defects of the stainless steel pipe. 2 (b) and FIG. 3 (b) are graphs showing current density changes in the pitting corrosion potential measurement of the stainless steel pipes of FIG. 2 (a) and FIG. 3 (a). is there.
ステンレス鋼の孔食電位測定方法は、ＪＩＳ Ｇ ０５７７に準拠し、Ｂ法を用いる。Ｂ法は、３．５質量％塩化ナトリウム水溶液中における動電位法による孔食電位測定法である。該塩化ナトリウム水溶液のｐＨは７とし、温度は３０℃とする。また、電位掃引速度は２０ｍＶ／分とする。 The method for measuring the pitting corrosion potential of stainless steel is based on JIS G 0577 and uses the B method. 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.
図３（ａ）及び（ｂ）に示すとおり、表面欠陥が抑制された表面を有するステンレス鋼管の場合は、孔食電位測定における電流密度変化において、孔食電位未満の電位における電流密度の値の変化は小さく、自然電位から孔食電位までの間、すなわち電位が０．１〜０．５の範囲（図３（ｂ）のＢ部分）における電流密度の変化率（最大電流密度／最小電流密度）が１０以上を示す部分は認められない。 As shown in FIGS. 3 (a) and 3 (b), in the case of a stainless steel pipe having a surface in which surface defects are suppressed, in the current density change in the pitting corrosion potential measurement, The change is small, and the rate of change in current density (maximum current density / minimum current density) between the natural potential and the pitting potential, that is, in the range where the potential is 0.1 to 0.5 (B portion in FIG. 3B). ) Where 10 or more is not recognized.
一方、図２（ａ）及び２（ｂ）に示すとおり、表面欠陥を有するステンレス鋼管の場合は、孔食電位測定における電流密度変化において、孔食電位未満の電位における電流密度の値の変化が大きく、自然電位から孔食電位までの間、すなわち電位が０．１〜０．３Ｖの範囲（図２（ｂ）のＡ部分）における電流密度の変化率が１０を超えた部分が１０箇所以上ある。この電流密度の大きな変化は、腐食が生じたことに起因する。したがって表面欠陥が存在することで生じた隙間腐食の存在を示すと本発明者らは推察している。よって、本発明においては、孔食電位測定における電流密度変化において、自然電位から孔食電位までの範囲における電流密度の変化率（最大電流密度／最小電流密度）が１０以上となる部分が１０箇所未満、より好ましくは５箇所以下であることが好ましい。 On the other hand, as shown in FIGS. 2 (a) and 2 (b), in the case of a stainless steel pipe having a surface defect, in the current density change in the pitting potential measurement, the value of the current density at a potential lower than the pitting potential is changed. 10 or more portions where the rate of change in current density exceeds 10 in a large range from the natural potential to the pitting corrosion potential, that is, in the range where the potential is 0.1 to 0.3 V (A portion in FIG. 2B). is there. This large change in current density is due to the occurrence of corrosion. Therefore, the present inventors speculate that the presence of crevice corrosion caused by the presence of surface defects is shown. Therefore, in the present invention, in the current density change in pitting potential measurement, there are 10 portions where the rate of change of current density (maximum current density / minimum current density) is 10 or more in the range from the natural potential to the pitting potential. Less than, more preferably 5 or less.
本発明のステンレス鋼管の素材として、フェライト系ステンレス鋼を用いる場合の組成としては、例えば、Ｃは、鋼の強度を得るために有用な元素であるが、多量に含むと耐食性を低下させる傾向にあることから、０．０２質量％以下が好ましい。Ｓｉは、製鋼工程における脱酸剤及び熱源として有用な元素であるが、多量に含むと鋼を硬化させる傾向にあることから、１．００質量％以下が好ましい。Ｍｎは、製鋼工程における脱酸として有用な元素であるが、多量に含むとオーステナイト相を形成する傾向にあることから、２．００質量％以下が好ましく、１．００質量％以下がより好ましい。Ｃｒは、耐食性を確保するために有用な元素であるが、多量に含むと高コストだけでなく加工性が低下する傾向にあることから、１７．００〜３０．００質量％が好ましく、２０．００〜２４．００質量％がより好ましい。Ｍｏは、Ｃｒの存在下でステンレス鋼の耐食性を向上させるために有用な元素であるが、多量に含むと高コストだけでなく加工性が低下する傾向にあることから、１．００〜２．５０質量％が好ましく、１．００〜１．５０質量％がより好ましい。Ｐは、耐食性を低下させるので少ない方が好ましく、０．０４０質量％以下が好ましい。Ｓは、耐食性を低下させるので少ない方が好ましく、０．０３０質量％以下が好ましい。Ｎｉは、腐食の進行を抑制する効果やフェライト系ステンレス鋼管の靱性改善に有効である点で好ましいが、多すぎるとオーステナイト相の生成やコスト高の原因となることから、０．６質量％以下が好ましい。ＴｉおよびＮｂは、これらを１種または２種含むのが好ましい。Ｔｉは、Ｃ、Ｎとの親和力が強くフェライト系ステンレス鋼管の粒界腐食を抑制する点で好ましいが、多量のＴｉ含有は鋼の表面品質を低下させる傾向にあることから０．０５〜０．５質量％が好ましい。Ｎｂは、Ｃ、Ｎとの親和力が強くフェライト系ステンレス鋼管の粒界腐食を抑制する点で好ましいが、多量のＮｂ含有は靱性を阻害する傾向にあることから、０．１〜０．６質量％が好ましい。Ｎは、Ｃと同様に多量に含むと耐食性を低下させる傾向にあることから、０．０２５質量％以下が好ましい。Ａｌは、脱酸剤として精錬や鋳造に有効な元素であるが、過剰に添加すると表面品質を劣化させるとともに、鋼の溶接性や低温靭性を低下させることから、０．０１〜０．５０質量％が好ましい。残部はＦｅと不可避的不純物であることが好ましい。また、例えば、Ｃが０．０２質量％以下、Ｓｉが０．４０質量％以下、Ｍｎが０．４０質量％以下、Ｃｒが２１．００〜２３．００質量％、Ｍｏが１．００〜１．５０質量％、Ｐが０．０４０質量％以下、Ｓが０．０３０質量％以下、Ｎｉが０．６０質量％以下、Ｔｉが０．０５〜０．５質量％、Ｎｂが０．１０〜０．６質量％、Ｎが０．０２５質量％以下、Ａｌが０．１５質量％以下、残部はＦｅのものを本発明のステンレス鋼管として使用することもできる。 As a composition in the case of using ferritic stainless steel as a material for the stainless steel pipe of the present invention, for example, C is an element useful for obtaining the strength of the steel, but if included in a large amount, it tends to lower the corrosion resistance. Therefore, 0.02% by mass or less is preferable. Si is an element useful as a deoxidizer and a heat source in the steelmaking process, but when it is contained in a large amount, it tends to harden the steel, so 1.00% by mass or less is preferable. Mn is an element useful as deoxidation in the steelmaking process. However, when it is contained in a large amount, Mn tends to form an austenite phase, and is preferably 2.00% by mass or less, and more preferably 1.00% by mass or less. Although Cr is an element useful for ensuring corrosion resistance, when it is contained in a large amount, it tends to decrease not only the high cost but also the workability, so that it is preferably 17.00 to 30.00% by mass. More preferably, it is 00-24.00 mass%. Mo is an element useful for improving the corrosion resistance of stainless steel in the presence of Cr, but if it is included in a large amount, it tends to decrease not only the high cost but also the workability. 50 mass% is preferable and 1.00-1.50 mass% is more preferable. Since P reduces corrosion resistance, the smaller one is preferable and 0.040 mass% or less is preferable. Since S reduces corrosion resistance, the smaller one is preferable, and 0.030% by mass or less is preferable. Ni is preferable in terms of the effect of suppressing the progress of corrosion and the effect of improving the toughness of ferritic stainless steel pipes, but if it is too much, it will cause generation of austenite phase and high cost, so 0.6 mass% or less Is preferred. Ti and Nb preferably contain one or two of these. Ti is preferable in that it has a strong affinity for C and N, and suppresses intergranular corrosion of ferritic stainless steel pipes. However, since a large amount of Ti tends to lower the surface quality of the steel, 0.05 to 0. 5 mass% is preferable. Nb has a strong affinity with C and N, and is preferable in terms of suppressing intergranular corrosion of ferritic stainless steel pipes. However, since a large amount of Nb tends to inhibit toughness, 0.1 to 0.6 mass is preferable. % Is preferred. N, if included in a large amount like C, tends to lower the corrosion resistance, so 0.025% by mass or less is preferable. Al is an element effective for refining and casting as a deoxidizer, but when added in excess, it degrades the surface quality and lowers the weldability and low temperature toughness of the steel, so 0.01 to 0.50 mass. % Is preferred. The balance is preferably Fe and inevitable impurities. For example, C is 0.02 mass% or less, Si is 0.40 mass% or less, Mn is 0.40 mass% or less, Cr is 21.00 to 23.00 mass%, Mo is 1.00 to 1 .50 mass%, P is 0.040 mass% or less, S is 0.030 mass% or less, Ni is 0.60 mass% or less, Ti is 0.05 to 0.5 mass%, and Nb is 0.10. The stainless steel pipe of the present invention may be 0.6% by mass, N is 0.025% by mass or less, Al is 0.15% by mass or less, and the balance is Fe.
本発明のステンレス鋼管の素材として、耐孔食指数（ＰＩ）が２０以上であることが好ましい。ＰＩは以下の式（１）で与えられる。
ＰＩ＝Ｃｒ＋３Ｍｏ 式（１）
The material of the stainless steel pipe of the present invention preferably has a pitting corrosion index (PI) of 20 or more. PI is given by the following formula (1).
PI = Cr + 3Mo Formula (1)
耐孔食指数（ＰＩ）が２０以上の本発明のステンレス鋼管は、耐食性に優れる。このため、耐孔食指数が１９と低いＳＵＳ３０４は、海塩粒子の影響を受けるウォーターフロント環境では早期に発銹するのに対して、本発明のステンレス鋼管は発銹を抑制することができる。耐孔食指数（ＰＩ）は、耐食性の観点からは、２４以上がより好ましく、３０以上がさらに好ましい。 The stainless steel pipe of the present invention having a pitting corrosion index (PI) of 20 or more is excellent in corrosion resistance. For this reason, SUS304 having a pitting resistance index as low as 19 starts early in a waterfront environment affected by sea salt particles, whereas the stainless steel pipe of the present invention can suppress the start. The pitting corrosion index (PI) is more preferably 24 or more and further preferably 30 or more from the viewpoint of corrosion resistance.
（製造方法）
本発明のステンレス鋼管の製造方法は、ステンレス鋼管の表面を、固形研磨剤で研磨する研磨工程を有する、製造方法である。
(Production method)
The manufacturing method of the stainless steel pipe of the present invention is a manufacturing method having a polishing step of polishing the surface of the stainless steel pipe with a solid abrasive.
固形研磨剤としては、脂肪酸及び鉱物性油脂を含有するものであれば特に制限されずに用いることができる。 The solid abrasive can be used without particular limitation as long as it contains a fatty acid and mineral oil.
固形研磨剤は、ＳｉＯ２、Ａｌ２Ｏ３、ＣｒＯ２などの酸化物を含むことが好ましい。ＳｉＯ２、Ａｌ２Ｏ３、ＣｒＯ２などの酸化物の含有量は、５０〜８０質量％であることが好ましく、５５〜７５質量％であることがより好ましく、６０〜７０質量％であることが特に好ましい。 The solid abrasive preferably contains an oxide such as SiO 2 , Al 2 O 3 , or CrO 2 . The content of oxides such as SiO 2 , Al 2 O 3 and CrO 2 is preferably 50 to 80% by mass, more preferably 55 to 75% by mass, and 60 to 70% by mass. Is particularly preferred.
脂肪酸としては、ステアリン酸、ミリスチン酸などを用いることが好ましい。鉱物性油脂としては、パルチミン酸などを用いることが好ましい。 As the fatty acid, stearic acid, myristic acid or the like is preferably used. As the mineral oil or fat, it is preferable to use palmitic acid or the like.
本ステンレス鋼管の製造方法においては、研磨工程において、研磨フラップホイールでステンレス鋼管の表面を研磨し、該研磨フラップホイールに固形研磨剤を付着させることが好ましい。 In the method for producing a stainless steel pipe, in the polishing step, the surface of the stainless steel pipe is preferably polished with a polishing flap wheel, and a solid abrasive is adhered to the polishing flap wheel.
上述のとおり、研磨仕上げとして、フラップホイール等による乾式研磨を行うと、ステンレス鋼管表面に研磨材や研磨紙が連続して接触し、表面の金属が部分的に剥がされ素地部分に被さったバリやかぶさりである表面欠陥が生じる。これに対し、本発明のステンレス鋼管の製造方法においては、研磨フラップホイールに固形研磨剤を付着させることによって湿式研磨を行うことが好ましい。これにより、ステンレス鋼管表面に研磨材や研磨紙が連続して接触した場合でも、研磨抵抗を低くすることができ、表面の金属が部分的に剥がされ、素地部分に被さったバリやかぶさりである表面欠陥の発生をより抑制しやすくなる。 As described above, when dry polishing with a flap wheel or the like is performed as the polishing finish, the abrasive or polishing paper continuously contacts the surface of the stainless steel tube, and the metal on the surface is partially peeled off to cover the base portion A surface defect that is a fogging occurs. On the other hand, in the method for manufacturing a stainless steel pipe of the present invention, it is preferable to perform wet polishing by attaching a solid abrasive to the polishing flap wheel. As a result, even when an abrasive or abrasive paper contacts the stainless steel tube surface continuously, the polishing resistance can be lowered, and the metal on the surface is partially peeled off, which is a burr or cover over the substrate portion. It becomes easier to suppress the occurrence of surface defects.
なお、本発明は上記実施形態によって制限されない。例えば、研磨フラップホイールに固形研磨剤を付着させることによって湿式研磨を行った後に、固形研磨剤を用いたバフ研磨を行ってもよい。また、固形研磨剤を塗布し湿式研磨を行った後に、不織布を取り付けた研磨装置（エアーサンダー）を用い、偏心運動と回転運動をあわせた動きによる研磨を手作業で行うことによっても、ランダムな研磨目をステンレス鋼管の表面に有し、着色を有する酸化皮膜や表面欠陥が抑制されたステンレス鋼管を製造することができる。 In addition, this invention is not restrict | limited by the said embodiment. For example, after performing wet polishing by attaching a solid abrasive to a polishing flap wheel, buffing using a solid abrasive may be performed. Also, after applying a solid abrasive and performing wet polishing, using a polishing apparatus (air sander) attached with a nonwoven fabric, and manually polishing by a movement that combines eccentric motion and rotational motion, it is also possible to randomly A stainless steel pipe having polished eyes on the surface of the stainless steel pipe and having a colored oxide film and surface defects suppressed can be produced.
ステンレス鋼管の造管、形状修正を行い、装飾用研磨仕上げを行った。ステンレス鋼管は以下の２種類を用いた。組成（質量％）及び寸法は以下のとおりである。 We made stainless steel pipes, modified the shape, and finished the decorative polishing. The following two types of stainless steel pipes were used. The composition (mass%) and dimensions are as follows.
鋼種１（ＳＵＳ４４５Ｊ１） Ｃｒ：２２％、Ｍｏ：１．０５％、Ｔｉ：０．２％、Ｎｂ：０．２％、Ａｌ：０．０９％、残部Ｆｅ
鋼種２（ＳＵＳ３０４） Ｃｒ：１８％、Ｎｉ：８％、Ｓｉ：０．６％、Ｍｎ：０．８％、残部Ｆｅ
寸法：直径３４ｍｍ×厚み１．５ｍｍ×長さ４０００ｍｍ。
Steel type 1 (SUS445J1) Cr: 22%, Mo: 1.05%, Ti: 0.2%, Nb: 0.2%, Al: 0.09%, balance Fe
Steel type 2 (SUS304) Cr: 18%, Ni: 8%, Si: 0.6%, Mn: 0.8%, balance Fe
Dimensions: Diameter 34 mm x thickness 1.5 mm x length 4000 mm.
研磨は、以下のとおりライン１〜４で行った。また研磨条件は以下のとおりである。 Polishing was performed on lines 1 to 4 as follows. The polishing conditions are as follows.
ライン１は、５つのフラップホイール（＃２４０、＃２４０、＃２４０、＃４００、＃６００）が、鋼管表面の円周方向を研磨（円周方向の研磨目を付与）するように並んだラインである。
ライン２は、４つのフラップホイール（＃２４０、＃２４０、＃２４０、＃４００）が、鋼管表面の長手方向を研磨（長手方向の研磨目を付与）するように並んだラインである。
ライン３は、４つのフラップホイール（＃１５０、＃１５０、＃１５０、＃３２０）が、鋼管表面の長手方向を研磨（長手方向の研磨目を付与）するように並んだラインである。
ライン４は、鋼管表面の長手方向を研磨（長手方向の研磨目を付与）するように並んだ３つのフラップホイール（＃３２０、＃４００、＃６００）、及び鋼管表面の円周方向を研磨（円周方向の研磨目を付与）するように並んだ２つの綿バフ（＃４００、＃４００）からなるラインである。
ここで、ライン１及びライン４では固形研磨剤をフラップホイールに塗布した。一方、ライン２及びライン３では固形研磨剤を塗布しなかった。なお、「＃２４０」等はメッシュ粒度を示す。
Line 1 is a line in which five flap wheels (# 240, # 240, # 240, # 400, # 600) are lined up so as to polish the circumferential direction of the steel pipe surface (giving circumferential polishing marks). It is.
Line 2 is a line in which four flap wheels (# 240, # 240, # 240, # 400) are lined up so as to polish the longitudinal direction of the surface of the steel pipe (giving a polishing grain in the longitudinal direction).
Line 3 is a line in which four flap wheels (# 150, # 150, # 150, # 320) are lined up so as to polish the longitudinal direction of the surface of the steel pipe (giving a polishing grain in the longitudinal direction).
Line 4 comprises three flap wheels (# 320, # 400, # 600) arranged so as to polish the longitudinal direction of the surface of the steel pipe (giving longitudinal polishing marks) and the circumferential direction of the surface of the steel pipe ( It is a line composed of two cotton buffs (# 400, # 400) arranged so as to give a circumferential polishing line.
Here, in line 1 and line 4, a solid abrasive was applied to the flap wheel. On the other hand, no solid abrasive was applied in line 2 and line 3. “# 240” and the like indicate the mesh granularity.
（研磨条件）
ライン速度：１．８ｍ／ｍｉｎ
管の回転数：３８０ｒｐｍ
ホイール回転数：１５００ｒｐｍ
ホイール直径：４００ｍｍ
(Polishing conditions)
Line speed: 1.8m / min
Tube rotation speed: 380 rpm
Wheel rotation speed: 1500rpm
Wheel diameter: 400mm
（固形研磨剤）
固形研磨剤は、ＳｉＯ２含有量が７５質量％であり、脂肪酸であるステアリン酸の含有量が１６質量％であり、鉱物性油脂であるパルチミン酸の含有量が３．８質量％であった。
(Solid abrasive)
The solid abrasive had a SiO 2 content of 75 mass%, a fatty acid stearic acid content of 16 mass%, and a mineral oil fat palmitic acid content of 3.8 mass%. .
（実施例１）
鋼種１について、ライン１（固形研磨剤塗布あり）で研磨を行った。
Example 1
About the steel type 1, it grind | polished by the line 1 (with solid abrasive | polishing agent application | coating).
（実施例２）
鋼種１について、ライン３（固形研磨剤塗布なし）で研磨を行ったのちに、ライン４（固形研磨剤塗布あり）で研磨を行った。その後、不織布（＃８０）を取り付けた研磨装置（エアーサンダー）を用い、固形研磨剤を塗布せずに、偏心運動と回転運動をあわせた動きにより、ランダムな研磨目を均一につける研磨を手作業で行った。
(Example 2)
About the steel type 1, after grinding | polishing by the line 3 (without solid abrasive | polishing agent application | coating), it grind | polished by the line 4 (with solid abrasive | polishing agent application | coating). Then, using a polishing device (air sander) with a non-woven fabric (# 80) attached, it was possible to polish evenly with random polishing eyes by applying a combination of eccentric motion and rotational motion without applying a solid abrasive. Done by work.
（比較例１）
鋼種１について、ライン２（固形研磨剤塗布なし）で研磨を行った。
(Comparative Example 1)
About the steel type 1, it grind | polished by the line 2 (no solid abrasive application | coating).
（比較例２）
鋼種２について、ライン２（固形研磨剤塗布なし）で研磨を行った。
(Comparative Example 2)
About the steel type 2, it grind | polished by the line 2 (no solid abrasive application | coating).
（参考例１）
鋼種２について、ライン１（固形研磨剤塗布あり）で研磨を行った。
(Reference Example 1)
About the steel type 2, it grind | polished by the line 1 (with solid abrasive | polishing agent application | coating).
（表面欠陥）
光学顕微鏡を用いて研磨されたステンレス鋼管表面を２００倍に拡大し、１００μｍ×１００μｍ（０．０１ｍｍ２）の範囲を観察した。５μｍ以上の金属素地の被さりを有する表面欠陥が５個以内の場合には表面欠陥が抑制された状態として「○」と評価し、５個より多い場合には表面欠陥が抑制された状態として「×」と評価した（表１参照）。
(Surface defect)
The surface of the polished stainless steel tube was magnified 200 times using an optical microscope, and a range of 100 μm × 100 μm (0.01 mm 2 ) was observed. When the number of surface defects having a metal substrate covering of 5 μm or more is 5 or less, it is evaluated as “◯” as a state in which the surface defects are suppressed. X "(refer to Table 1).
表１に示すとおり、実施例１のステンレス鋼管表面は、図１（ａ）のとおり表面欠陥がなかった。一方、比較例１のステンレス鋼管表面は、図１（ｂ）のとおり表面欠陥が少なくとも９つあり、表面欠陥が抑制された状態ではなかった。また、比較例２のステンレス鋼管表面は、図４のとおり表面欠陥が少なくとも６個以上あり、表面欠陥が抑制された状態ではなかった。なお、参考例１は図５のとおり表面欠陥がなかった。 As shown in Table 1, the surface of the stainless steel pipe of Example 1 was free from surface defects as shown in FIG. On the other hand, the surface of the stainless steel pipe of Comparative Example 1 had at least nine surface defects as shown in FIG. 1B and was not in a state in which the surface defects were suppressed. Further, the surface of the stainless steel pipe of Comparative Example 2 had at least 6 surface defects as shown in FIG. 4 and was not in a state in which the surface defects were suppressed. Reference Example 1 had no surface defects as shown in FIG.
（酸化皮膜）
ステンレス鋼管の表面を光学顕微鏡で４００倍の倍率で観察し、茶褐色のシミ状物質である酸化皮膜が５０μｍ四方において面積比率でどの程度存在しているかを算出した。残存酸化皮膜の面積比率が３％以上５％未満である場合は、着色を有する酸化皮膜が存在しないとして「○」、残存酸化皮膜の面積比率が３％未満であるより好ましい状態の場合は「◎」と評価し、面積比率が５％以上の場合は着色を有する酸化皮膜が存在するとして「×」と評価した（表１参照）。
(Oxide film)
The surface of the stainless steel tube was observed with an optical microscope at a magnification of 400 times, and it was calculated how much the oxide film, which is a brownish brown stain-like substance, was present in an area ratio of 50 μm square. When the area ratio of the remaining oxide film is 3% or more and less than 5%, “O” indicates that there is no colored oxide film, and when the area ratio of the remaining oxide film is less than 3%, “ When the area ratio was 5% or more, it was evaluated as “x” because there was a colored oxide film (see Table 1).
表１に示すとおり、実施例１においては酸化皮膜の面積比率が１％以下であり、実施例２においては酸化皮膜の面積比率が３％であり、着色を有する酸化皮膜が存在しなかった。一方、比較例１及び２においては酸化皮膜の面積比率が１５％、２０％、であり、着色を有する酸化皮膜が存在するステンレス鋼管表面であった。なお、参考例１は酸化皮膜の面積比率が２％であり、着色を有する酸化皮膜が存在しなかった。 As shown in Table 1, in Example 1, the area ratio of the oxide film was 1% or less, and in Example 2, the area ratio of the oxide film was 3%, and there was no colored oxide film. On the other hand, in Comparative Examples 1 and 2, the area ratio of the oxide film was 15% and 20%, and the surface of the stainless steel pipe had a colored oxide film. In Reference Example 1, the area ratio of the oxide film was 2%, and there was no colored oxide film.
（耐食性試験）
実施例１、２、比較例１、２及び参考例１のステンレス鋼管について、以下の条件で耐食性試験（塩乾湿複合サイクル試験（ＣＣＴ試験））を行った。
条件：（１）塩水噴霧（３５℃、５％ＮａＣｌ、１５分）
（２）乾燥 （６０℃、３０％ＲＨ、６０分）
（３）湿潤 （５０℃、９５％ＲＨ、３時間）
上記条件（１）〜（３）を１サイクルとして、３０サイクル繰り返した。
評価：試験後の発銹面積が、鋼管表面全体の５％以内のときに耐食性が良好として「○」と評価し、５％より大きく１５％以下の場合は「△」、１５％より大きい場合は耐食性が不良として「×」と評価した（表１参照）。
(Corrosion resistance test)
The stainless steel pipes of Examples 1 and 2, Comparative Examples 1 and 2 and Reference Example 1 were subjected to a corrosion resistance test (salt-dry moisture combined cycle test (CCT test)) under the following conditions.
Conditions: (1) Salt spray (35 ° C., 5% NaCl, 15 minutes)
(2) Drying (60 ° C., 30% RH, 60 minutes)
(3) Wet (50 ° C., 95% RH, 3 hours)
The above conditions (1) to (3) were set as one cycle, and 30 cycles were repeated.
Evaluation: When the area after the test is within 5% of the entire surface of the steel pipe, the corrosion resistance is evaluated as “Good”, and when it is larger than 5% but not larger than 15%, “△” is larger than 15%. Was evaluated as “x” because of its poor corrosion resistance (see Table 1).
実施例１、比較例１のＣＣＴ試験後の表面写真を図６に示す。実施例１においては、図６（ａ）のとおりＣＣＴ試験後も表面に発銹が生じておらず、耐食性に優れていることを示した。一方、比較例１においては図６（ｂ）のとおりＣＣＴ試験後に表面に発銹が生じており、耐食性に劣っていた。なお、参考例１は、母材そのものの耐食性レベルが低いため、耐食性が△となった。海塩粒子の影響を受けるウォーターフロント環境における母材耐食レベルは、耐孔食指数（ＰＩ）が２４以上であることが好ましい。 The surface photograph after the CCT test of Example 1 and Comparative Example 1 is shown in FIG. In Example 1, as shown in FIG. 6 (a), no wrinkles were generated on the surface even after the CCT test, indicating excellent corrosion resistance. On the other hand, in Comparative Example 1, the surface was wrinkled after the CCT test as shown in FIG. 6B, and the corrosion resistance was poor. In Reference Example 1, since the corrosion resistance level of the base material itself was low, the corrosion resistance was Δ. As for the base material corrosion resistance level in the waterfront environment affected by sea salt particles, the pitting corrosion resistance index (PI) is preferably 24 or more.
１〜９・・・表面欠陥
Ａ、Ｂ・・・電流密度の変化領域
1-9 ... Surface defects A, B ... Current density change region
Claims (3)
着色を有する酸化皮膜が前記表面上に存在せず、
前記表面上における５μｍ以上の金属素地の被さりを含む表面欠陥の平均個数が０．０１ｍｍ２当たり５個以内に抑制されている、耐食性に優れたステンレス鋼管。 Has an anti-glare polishing surface on the surface of the stainless steel pipe,
There is no colored oxide film on the surface,
A stainless steel pipe excellent in corrosion resistance, in which the average number of surface defects including a metal substrate covering of 5 μm or more on the surface is suppressed to 5 or less per 0.01 mm 2 .
The manufacturing method according to claim 2, wherein in the polishing step, the surface of the stainless steel pipe is polished by attaching the solid abrasive to a polishing flap wheel.
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| JP2015197977A JP6138209B2 (en) | 2015-10-05 | 2015-10-05 | Stainless steel pipe excellent in corrosion resistance and manufacturing method thereof |
| PCT/JP2016/076142 WO2017061215A1 (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof |
| ES16853369T ES2927025T3 (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe with excellent resistance to corrosion and its manufacturing process |
| EP16853369.3A EP3360643B1 (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof |
| CN201680058079.0A CN108136562A (en) | 2015-10-05 | 2016-09-06 | The stainless steel tube and its manufacturing method of excellent corrosion resistance |
| SG11201802748QA SG11201802748QA (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof |
| MYPI2018000469A MY182694A (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe wth excellent corrosion resistance and manufacturing method thereof |
| CA3000608A CA3000608C (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof |
| US15/765,031 US20180304433A1 (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof |
| KR1020187012900A KR102067916B1 (en) | 2015-10-05 | 2016-09-06 | Stainless steel pipe with excellent corrosion resistance and manufacturing method |
| TW105131854A TWI698517B (en) | 2015-10-05 | 2016-10-03 | Stainless steel pipe with excellent corrosion resistance and its manufacturing method (1) |
| PH12018500734A PH12018500734A1 (en) | 2015-10-05 | 2018-04-03 | Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof |
| HK18110007.0A HK1250687A1 (en) | 2015-10-05 | 2018-08-03 | Stainless steel pipe with excellent corrosion resistance and manufacturing method thereof |
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| JP2003025209A (en) * | 2001-07-23 | 2003-01-29 | Nisshin Steel Co Ltd | Polishing method for stainless steel |
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| ES2584253T3 (en) * | 2011-03-31 | 2016-09-26 | Nisshin Steel Co., Ltd. | Stainless steel sheet and method for manufacturing |
| KR101686721B1 (en) * | 2012-03-08 | 2016-12-14 | 제이에프이 스틸 가부시키가이샤 | Seawater-resistant stainless clad steel |
| CN103072067A (en) * | 2013-01-25 | 2013-05-01 | 汪正友 | Polishing wheel type selection and configuration for improving surface polishing quality of stainless steel composite pipe |
| AU2014100218A4 (en) * | 2014-03-09 | 2014-04-10 | Termsteel Pty Ltd | Method for improving the corrosion resistance of stainless steel mesh used to protect buildings from concealed termite entry |
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Also Published As
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|---|---|
| KR20180066158A (en) | 2018-06-18 |
| CA3000608A1 (en) | 2017-04-13 |
| CA3000608C (en) | 2020-05-05 |
| HK1250687A1 (en) | 2019-01-11 |
| TW201726882A (en) | 2017-08-01 |
| PH12018500734A1 (en) | 2018-10-15 |
| US20180304433A1 (en) | 2018-10-25 |
| MY182694A (en) | 2021-02-01 |
| JP2017071004A (en) | 2017-04-13 |
| ES2927025T3 (en) | 2022-11-02 |
| EP3360643A1 (en) | 2018-08-15 |
| EP3360643A4 (en) | 2018-10-31 |
| EP3360643B1 (en) | 2022-08-10 |
| WO2017061215A1 (en) | 2017-04-13 |
| SG11201802748QA (en) | 2018-05-30 |
| CN108136562A (en) | 2018-06-08 |
| TWI698517B (en) | 2020-07-11 |
| KR102067916B1 (en) | 2020-01-17 |
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