JP2012214881A - Ferritic stainless steel for biofuel supply system parts, and biofuel supply system parts - Google Patents
Ferritic stainless steel for biofuel supply system parts, and biofuel supply system parts Download PDFInfo
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- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 44
- 239000002551 biofuel Substances 0.000 title claims abstract description 41
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 22
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 20
- 150000001768 cations Chemical class 0.000 claims abstract description 19
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 16
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 15
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 229910052721 tungsten Inorganic materials 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 230000007797 corrosion Effects 0.000 abstract description 63
- 238000005260 corrosion Methods 0.000 abstract description 63
- 238000012360 testing method Methods 0.000 description 32
- 238000010438 heat treatment Methods 0.000 description 30
- 239000000446 fuel Substances 0.000 description 25
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 21
- 239000010935 stainless steel Substances 0.000 description 21
- 239000003502 gasoline Substances 0.000 description 20
- 230000000694 effects Effects 0.000 description 19
- 239000000463 material Substances 0.000 description 18
- 238000000034 method Methods 0.000 description 15
- 235000014113 dietary fatty acids Nutrition 0.000 description 14
- 229930195729 fatty acid Natural products 0.000 description 14
- 239000000194 fatty acid Substances 0.000 description 14
- 150000004665 fatty acids Chemical class 0.000 description 14
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 14
- 229910000831 Steel Inorganic materials 0.000 description 13
- 239000000203 mixture Substances 0.000 description 13
- 239000010959 steel Substances 0.000 description 13
- 229910052799 carbon Inorganic materials 0.000 description 11
- 229910052757 nitrogen Inorganic materials 0.000 description 11
- 238000005554 pickling Methods 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 238000005219 brazing Methods 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 9
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 7
- 238000000137 annealing Methods 0.000 description 7
- 235000019253 formic acid Nutrition 0.000 description 7
- 239000008346 aqueous phase Substances 0.000 description 6
- 238000009991 scouring Methods 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000003225 biodiesel Substances 0.000 description 5
- 239000010960 cold rolled steel Substances 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000005304 joining Methods 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 239000012141 concentrate Substances 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 230000004580 weight loss Effects 0.000 description 4
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 3
- 239000004148 curcumin Substances 0.000 description 3
- -1 first Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 238000010525 oxidative degradation reaction Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 235000019484 Rapeseed oil Nutrition 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 229910001651 emery Inorganic materials 0.000 description 2
- 235000019387 fatty acid methyl ester Nutrition 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 235000019198 oils Nutrition 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 238000005211 surface analysis Methods 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 240000002791 Brassica napus Species 0.000 description 1
- 235000004977 Brassica sinapistrum Nutrition 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 235000019482 Palm oil Nutrition 0.000 description 1
- 240000000111 Saccharum officinarum Species 0.000 description 1
- 235000007201 Saccharum officinarum Nutrition 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 235000011054 acetic acid Nutrition 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000000539 dimer Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000002828 fuel tank Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000004702 methyl esters Chemical class 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000002540 palm oil Substances 0.000 description 1
- 235000019260 propionic acid Nutrition 0.000 description 1
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 235000012424 soybean oil Nutrition 0.000 description 1
- 239000003549 soybean oil Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 235000015112 vegetable and seed oil Nutrition 0.000 description 1
- 239000008158 vegetable oil Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- Y02T10/16—
Landscapes
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
本発明は、バイオエタノールやバイオディーゼルといったバイオ燃料を供給する自動車燃料供給系部品用に好適なフェライト系ステンレス鋼、バイオ燃料供給系部品に関する。特に、燃料噴射系部品等、エンジンに近く高温になりやすいバイオ燃料供給系部品用に好適なフェライト系ステンレス鋼に関する。 The present invention relates to ferritic stainless steel and biofuel supply system parts suitable for automobile fuel supply system parts for supplying biofuel such as bioethanol and biodiesel. In particular, the present invention relates to a ferritic stainless steel suitable for biofuel supply system parts that are close to the engine and are likely to become high temperature, such as fuel injection system parts.
近年、自動車分野においては、環境問題に対する意識の高まりから、排ガス規制がより強化されると共に、炭酸ガス排出抑制に向けた取り組みが進められている。より一層の軽量化や、EGR、DPF、尿素SCRシステムといった排ガス処理装置を設置するといった取り組みに加え、バイオエタノールやバイオディーゼル燃料といった燃料面からの取り組みも実施されている。 In recent years, in the automotive field, exhaust gas regulations have been further strengthened due to increasing awareness of environmental issues, and efforts are being made to reduce carbon dioxide emissions. In addition to efforts to further reduce weight and install exhaust gas treatment devices such as EGR, DPF, and urea SCR systems, efforts from the fuel side such as bioethanol and biodiesel fuel are also being implemented.
バイオエタノールは、ガソリンエンジン用の燃料として、エタノールをガソリンに混合させた燃料である。バイオディーゼル燃料は、ディーゼルエンジン用の燃料として、脂肪酸メチルエステルを軽油に混合させたものである。ここで、エタノールは、とうもろこしやさとうきびを原料とし、脂肪酸メチルエステルは、菜種油、大豆油、やし油などの植物油や廃油を原料としてエステル化したものである。 Bioethanol is a fuel in which ethanol is mixed with gasoline as a fuel for a gasoline engine. Biodiesel fuel is obtained by mixing a fatty acid methyl ester with light oil as a fuel for a diesel engine. Here, ethanol is obtained by using corn and sugar cane as raw materials, and fatty acid methyl ester is obtained by esterifying vegetable oil and waste oil such as rapeseed oil, soybean oil, and palm oil as raw materials.
バイオエタノールやバイオディーゼル燃料などのバイオ燃料は、金属材料に対して従来よりも腐食性が高いとされている。これらを利用していくにあたって、事前に燃料系部品を構成する各種部材の使用性能に及ぼす影響が調べられてきたが、超長期寿命を保証するメーカーからは、より信頼性の高い素材を求めるニーズが寄せられ、ステンレス鋼が1つの候補とされている。 Biofuels such as bioethanol and biodiesel fuel are considered to be more corrosive than metal materials. In using these, the impact on the usage performance of various components that make up fuel system parts has been investigated in advance, but there is a need for a more reliable material from manufacturers that guarantee an ultra long life And stainless steel is one candidate.
燃料系部品のうち、燃料タンクや給油管にステンレス鋼を適用する従来技術として、以下が知られている。
特許文献1には、質量%で、C:≦0.015%、Si:≦0.5%、Cr:11.0〜25.0%、N:≦0.020%、Ti:0.05〜0.50%、Nb:0.10〜0.50%、B:≦0.0100%を含み、あるいは必要に応じてさらにMo:≦3.0%、Ni:≦2.0%、Cu:≦2.0%、Al:≦4.0%の1種以上を含み、破断伸びが30%以上、ランクフォード値が1.3以上のフェライト系ステンレス鋼板が開示されている。
Among the fuel system parts, the following is known as a prior art in which stainless steel is applied to a fuel tank and a fuel supply pipe.
In Patent Document 1, in mass%, C: ≦ 0.015%, Si: ≦ 0.5%, Cr: 11.0 to 25.0%, N: ≦ 0.020%, Ti: 0.05 -0.50%, Nb: 0.10-0.50%, B: ≤0.0100% included, or Mo: ≤3.0%, Ni: ≤2.0%, Cu if necessary A ferritic stainless steel sheet containing one or more of: ≦ 2.0% and Al: ≦ 4.0%, having an elongation at break of 30% or more and a Rankford value of 1.3 or more is disclosed.
特許文献2には、質量%で、C:≦0.01%、Si:≦1.0%、Mn:≦1.5%、P:≦0.06%、S:≦0.03%、Cr:11〜23%、Ni:≦2.0%、Mo:0.5〜3.0%、Al:≦1.0%、N:≦0.04%を含み、Cr+3.3Mo≧18の関係式を満足し、Nb:≦0.8%、Ti:≦1.0%の1種または2種を、18≦Nb/(C+N)+2Ti/(C+N)≦60の関係式を満足して含有し、フェライト結晶粒の粒度番号が6.0以上であり、平均r値が2.0以上であるフェライト系ステンレス鋼板が開示されている。 Patent Document 2 includes mass%, C: ≦ 0.01%, Si: ≦ 1.0%, Mn: ≦ 1.5%, P: ≦ 0.06%, S: ≦ 0.03%, Cr: 11 to 23%, Ni: ≦ 2.0%, Mo: 0.5 to 3.0%, Al: ≦ 1.0%, N: ≦ 0.04%, Cr + 3.3Mo ≧ 18 Satisfying the relational expression, satisfying the relational expression of Nb: ≦ 0.8%, Ti: ≦ 1.0%, 18 ≦ Nb / (C + N) + 2Ti / (C + N) ≦ 60 A ferritic stainless steel sheet containing a ferrite crystal grain number of 6.0 or more and an average r value of 2.0 or more is disclosed.
特許文献3には、質量%で、C:≦0.01%、Si:≦1.0%、Mn:≦1.5%、P:≦0.06%、S:≦0.03%、Al:≦1.0%、Cr:11〜20%、Ni:≦2.0%、Mo:0.5〜3.0%、V:0.02〜1.0%、N:≦0.04%を含み、かつNb:0.01〜0.8%、Ti:0.01〜1.0%の1種または2種を含有し、一軸引張で25%変形させたときに発生する後半表面のうねり高さが50μm以下であるフェライト系ステンレス鋼板が開示されている。 In Patent Document 3, in mass%, C: ≦ 0.01%, Si: ≦ 1.0%, Mn: ≦ 1.5%, P: ≦ 0.06%, S: ≦ 0.03%, Al: ≦ 1.0%, Cr: 11-20%, Ni: ≦ 2.0%, Mo: 0.5-3.0%, V: 0.02-1.0%, N: ≦ 0. The latter half that occurs when it is deformed by 25% by uniaxial tension, including 04%, Nb: 0.01-0.8%, Ti: 0.01-1.0% A ferritic stainless steel sheet having a surface waviness height of 50 μm or less is disclosed.
しかしながら、前記特許文献は、通常のガソリンに対する耐食性を扱ったものである。後述するように、バイオ燃料の腐食性はガソリンの場合とは大きく異なることから、これらの技術ではバイオ燃料に対する腐食性は不十分であった。
また、従来、バイオ燃料のステンレス鋼に対する腐食性の詳細は必ずしも明瞭にされているとは言えず、種々のステンレス鋼種のバイオ燃料に対する耐食性についても必ずしも明らかにされているとは言いがたい。
However, the patent document deals with the corrosion resistance against ordinary gasoline. As will be described later, since the corrosivity of biofuels is significantly different from that of gasoline, these technologies are not sufficiently corrosive to biofuels.
Conventionally, the details of the corrosiveness of biofuels to stainless steel are not necessarily clarified, and it is difficult to say that the corrosion resistance of various stainless steel types to biofuels is necessarily clarified.
本発明は、このような従来の事情に鑑みて提案されたものであり、特にバイオ燃料に対する耐食性を備えたバイオ燃料供給系部品用フェライト系ステンレス鋼を提供することを目的とする。 The present invention has been proposed in view of such a conventional situation, and an object of the present invention is to provide a ferritic stainless steel for biofuel supply system parts having corrosion resistance to biofuel in particular.
上記課題を解決することを目的とした本発明の要旨は、以下のとおりである。
〔1〕 質量%で、C:0.03%以下、N:0.03%以下、Si:0.1%を超え、1%以下、Mn:0.02%以上、1.2%以下、Cr:15%以上、23%以下、Al:0.002%以上、0.5%以下、Nb、Tiの何れか1種または2種を含有し、以下に示す(式1)および(式2)を満たし、残部がFe及び不可避不純物からなり、表面に、Cr、Si、Nb、Ti、Alをカチオン分率の合計で30%以上含む酸化皮膜が形成されていることを特徴とするバイオ燃料供給系部品用フェライト系ステンレス鋼。
8(C+N)+0.03≦Nb+Ti≦0.6・・・(式1)
Si+Cr+Al+{Nb+Ti−8(C+N)}≧15.5・・・(式2)
(式1)および(式2)において、元素記号は、それぞれの元素の含有量(質量%)を表す。
The gist of the present invention aimed at solving the above problems is as follows.
[1] By mass%, C: 0.03% or less, N: 0.03% or less, Si: more than 0.1%, 1% or less, Mn: 0.02% or more, 1.2% or less, Cr: 15% or more, 23% or less, Al: 0.002% or more, 0.5% or less, containing one or two of Nb and Ti, shown below (Formula 1) and (Formula 2) ), The remainder is made of Fe and inevitable impurities, and the surface is formed with an oxide film containing Cr, Si, Nb, Ti, and Al with a total cation fraction of 30% or more. Ferritic stainless steel for supply system parts.
8 (C + N) + 0.03 ≦ Nb + Ti ≦ 0.6 (Formula 1)
Si + Cr + Al + {Nb + Ti-8 (C + N)} ≧ 15.5 (Formula 2)
In (Formula 1) and (Formula 2), an element symbol represents content (mass%) of each element.
〔2〕 更に、質量%で、Ni:2%以下、Cu:1.5%以下、Mo:3%以下、Sn:0.5%以下のうち何れか1種又は2種以上を含有することを特徴とする請求項1記載のバイオ燃料供給系部品用フェライト系ステンレス鋼。
〔3〕 更に、質量%で、V:1%以下、W:1%以下、B:0.005%以下、Zr:0.5%以下、Co:0.2%以下、Mg:0.002%以下、Ca:0.002%以下、REM:0.01%以下のうち何れか1種又は2種以上を含有することを特徴とする請求項1または2記載のバイオ燃料供給系部品用フェライト系ステンレス鋼。
[2] Further, by mass%, Ni: 2% or less, Cu: 1.5% or less, Mo: 3% or less, Sn: 0.5% or less, any one or two or more types The ferritic stainless steel for biofuel supply system parts according to claim 1.
[3] Further, in mass%, V: 1% or less, W: 1% or less, B: 0.005% or less, Zr: 0.5% or less, Co: 0.2% or less, Mg: 0.002 % Or less, Ca: 0.002% or less, REM: 0.01% or less, and one or more of them are contained. Ferrite for biofuel supply system parts according to claim 1 or 2 Stainless steel.
〔4〕 請求項1〜請求項3のいずれか一項に記載のバイオ燃料供給系部品用フェライト系ステンレス鋼からなることを特徴とするバイオ燃料供給系部品。 [4] A biofuel supply system component comprising the ferritic stainless steel for the biofuel supply system component according to any one of [1] to [3].
以上のように、本発明によれば、バイオ燃料に対する優れた耐食性を備えたフェライト系ステンレス鋼を提供することができる。このフェライト系ステンレス鋼は、バイオ燃料供給系部品用として好適に用いることが可能である。特に、このフェライト系ステンレス鋼は、噴射系部品等、エンジンに近く高温になりやすいバイオ燃料供給系部品用に好適である。 As described above, according to the present invention, it is possible to provide a ferritic stainless steel having excellent corrosion resistance against biofuel. This ferritic stainless steel can be suitably used for biofuel supply system parts. In particular, this ferritic stainless steel is suitable for biofuel supply system parts that are close to the engine and are likely to become high temperature, such as injection system parts.
以下、本発明の実施の形態について、詳細に説明する。
本発明者らは、ガソリンに北米で一般的に使用されているバイオエタノールをそれぞれ10%、22%混合したE10およびE22と、バイオエタノール100%のE100と、欧州で一般的に使用されているバイオディーゼル燃料である菜種油をメチルエステル化したRME(RapeSeed MethylEster)とを入手し、酸化劣化挙動やステンレス鋼に対する腐食性などについて、通常のガソリンと比較しながら詳細な調査解析を行った。
Hereinafter, embodiments of the present invention will be described in detail.
The present inventors are commonly used in Europe, E10 and E22 mixed with 10% and 22% of bioethanol commonly used in North America in gasoline, E100 of bioethanol 100%, and Europe. RME (RapeSeed Methyl Ester) obtained by methyl esterifying rapeseed oil, which is a biodiesel fuel, was obtained, and detailed investigation and analysis were performed with respect to oxidation deterioration behavior and corrosiveness to stainless steel in comparison with ordinary gasoline.
まず、ガソリンの酸化安定度の評価方法で用いられているJIS K2287に準じてE10、E22、E100、RMEの酸化安定度をガソリンの場合と比較した。オートクレーブ中にこれら燃料を封入し7気圧の酸素を導入した後100℃に昇温保定して、酸素が燃料の酸化に使用されて圧力が低下していく挙動を測定した。
その結果、E10、E100はガソリンよりも酸化劣化しにくい一方、E22、RMEはガソリンよりも酸化劣化し易く、なかでもRMEの酸化劣化の程度が最も大きいことが明らかとなった。
First, the oxidation stability of E10, E22, E100, and RME was compared with that of gasoline according to JIS K2287 used in the evaluation method of oxidation stability of gasoline. These fuels were sealed in an autoclave and oxygen at 7 atmospheres was introduced, and then the temperature was maintained at 100 ° C., and the behavior of the pressure decreasing as oxygen was used to oxidize the fuel was measured.
As a result, it became clear that E10 and E100 are less susceptible to oxidative degradation than gasoline, while E22 and RME are more susceptible to oxidative degradation than gasoline, and the degree of oxidative degradation of RME is the greatest.
燃料が酸化すると、ギ酸、酢酸、プロピオン酸といった脂肪酸が生成するが、脂肪酸の腐食性を知るために、まず酸化させたRMEとガソリンにステンレス冷延鋼板を浸漬して腐食の有無を調べた。すると、いずれの場合にも腐食は認められなかった。
これは、酸化生成物である脂肪酸が、燃料媒体中では二量体として存在するためである。脂肪酸が腐食性を発現するためには、解離して水素イオンを放出する必要があり、そのためには水の存在が不可欠であると考えた。実際の環境において、水は空気中水分が凝結して生成するので、水相の共存を考慮することは極めて重要である。
When the fuel is oxidized, fatty acids such as formic acid, acetic acid, and propionic acid are produced. In order to know the corrosiveness of the fatty acids, first, stainless steel cold-rolled steel sheets were immersed in oxidized RME and gasoline to examine the presence or absence of corrosion. Then, corrosion was not recognized in any case.
This is because the fatty acid that is an oxidation product exists as a dimer in the fuel medium. In order for fatty acids to develop corrosive properties, they must dissociate and release hydrogen ions, and for this purpose, the existence of water was considered indispensable. In an actual environment, water is generated by condensation of moisture in the air, so it is extremely important to consider the coexistence of the aqueous phase.
そこで、酸化処理したRMEとガソリンに、それぞれ10vol%の水を加えてステンレス冷延鋼板を曝したところ、RME,ガソリンいずれの場合においても腐食が生じていた。
このことから、酸化劣化燃料が腐食性を発現するには水の共存が不可欠であり、燃料中の脂肪酸が水相に分配されて始めて腐食性が発現されることが確認された。水相中の腐食性物質は水素イオンであるから、その腐食性は、水素イオン濃度で表されることになる。水中の水素イオン濃度は、主に、酸化燃料中の脂肪酸種と脂肪酸濃度、脂肪酸の燃料―水相間の分配挙動に依存する。このうち、脂肪酸の分配挙動は温度が影響し、温度が高いほど脂肪酸は燃料中から水相に分配され易い。
Accordingly, when 10 vol% water was added to each of the oxidized RME and gasoline and the stainless cold-rolled steel sheet was exposed, corrosion occurred in both cases of RME and gasoline.
From this, it was confirmed that the coexistence of water is indispensable for the oxidation-degraded fuel to exhibit corrosivity, and the corrosivity is manifested only after the fatty acid in the fuel is distributed to the aqueous phase. Since the corrosive substance in the aqueous phase is hydrogen ions, the corrosiveness is expressed by the hydrogen ion concentration. The hydrogen ion concentration in water mainly depends on the fatty acid species and the fatty acid concentration in the oxidized fuel and the distribution behavior of the fatty acid between the fuel and the water phase. Among these, fatty acid distribution behavior is affected by temperature, and the higher the temperature, the easier the fatty acid is distributed from the fuel to the water phase.
また、このときの水相のpHは、RMEの場合pH2.1、ガソリンの場合pH3.0と両者には0.9の違いがあるが、この差異を脂肪酸濃度に換算すると約100倍の違いに相当する。従来、酸化劣化ガソリンに対する腐食試験は、水中のギ酸+酢酸の濃度を100〜1000ppm程度として行っているが、RMEをはじめとするバイオ燃料については、ギ酸+酢酸の濃度をガソリンの約100倍の濃度に相当する1%〜10%まで高める必要があることがわかった。 In addition, the pH of the aqueous phase at this time has a difference of 0.9 between R2.1 for pH and pH 3.0 for gasoline, both of which differ by about 100 times when converted to fatty acid concentration. It corresponds to. Conventionally, corrosion tests on oxidatively deteriorated gasoline have been conducted with a concentration of formic acid + acetic acid in water of about 100 to 1000 ppm, but for biofuels such as RME, the concentration of formic acid + acetic acid is about 100 times that of gasoline It was found that it was necessary to increase to 1% to 10% corresponding to the concentration.
また、エンジンに近い燃料噴射系などについては90〜100℃程度まで温度が上昇し、温度そのものと共に脂肪酸が燃料中から水相に分配されやすくなって腐食環境が苛酷になる。酸化劣化ガソリンに対する腐食試験温度40〜50℃に比べて苛酷な条件である。
さらに、燃料中のバイオエタノールは水相に移動して、水相部分を拡大させるとともに、特にステンレス鋼において不働態を維持するのを阻害する要因となる。
Further, the temperature of the fuel injection system close to the engine rises to about 90 to 100 ° C., and the fatty acid is easily distributed from the fuel to the water phase together with the temperature itself, and the corrosive environment becomes severe. This is a severe condition as compared to a corrosion test temperature of 40 to 50 ° C. for oxidized and deteriorated gasoline.
Furthermore, the bioethanol in the fuel moves to the aqueous phase and enlarges the aqueous phase, and becomes a factor that hinders maintaining a passive state particularly in stainless steel.
このように、通常のガソリンに比べ、バイオ燃料の腐食性は高いため、バイオ燃料供給系部品に使用する材料にはより優れた耐食性が要求される。
そこで、本発明者らは高温酸性脂肪酸環境中での耐食性について鋭意検討した。その結果、ステンレス鋼の表面に安定な酸化皮膜を形成することで、不働態を維持して腐食の発生を抑えることが最も重要であり、表面に、Cr、Si、Nb、Ti、Alをカチオン分率((Cr+Si+Nb+Ti+Al)/全カチオン)の合計で30%以上含む酸化皮膜を形成させた場合に、高温酸性脂肪酸環境において優れた耐食性を示すことを知見した。
As described above, since the corrosiveness of biofuel is higher than that of ordinary gasoline, the material used for the biofuel supply system parts is required to have better corrosion resistance.
Therefore, the present inventors diligently investigated the corrosion resistance in a high-temperature acidic fatty acid environment. As a result, it is most important to maintain a passive state and suppress the occurrence of corrosion by forming a stable oxide film on the surface of stainless steel, and Cr, Si, Nb, Ti, and Al are cations on the surface. It was found that when an oxide film containing 30% or more in total ((Cr + Si + Nb + Ti + Al) / total cations) was formed, excellent corrosion resistance was exhibited in a high-temperature acidic fatty acid environment.
このような酸化皮膜を形成するには、まず、鋼材の化学組成として以下に示す(式2)を満たす必要がある。
Si+Cr+Al+{Nb+Ti−8(C+N)}≧15.5・・・(式2)
(式2)において、元素記号は、それぞれの元素の含有量(質量%)を表す。
In order to form such an oxide film, first, it is necessary to satisfy (Equation 2) shown below as the chemical composition of the steel material.
Si + Cr + Al + {Nb + Ti-8 (C + N)} ≧ 15.5 (Formula 2)
In (Formula 2), an element symbol represents content (mass%) of each element.
なお、ステンレス鋼に含まれるNbおよび/またはTiは、全量が固溶状態として存在するのではなく、一部がC、Nに固定された状態で存在する。そして、ステンレス鋼に含まれるNbおよび/またはTiのうち、C、Nに固定されない固溶状態のNbおよび/またはTiが、熱処理によって不働態皮膜中に濃化し、熱処理後に形成される酸化皮膜における腐食防止作用に寄与する。ステンレス鋼に含まれるNbおよび/またはTiのうち、C、Nに固定されて固溶状態とならないNbおよび/またはTi量は、Nbの原子量93と、Cの原子量12、Nの原子量14との比から、CとNの合計(C+N)量の概ね8倍と考えられる。したがって、腐食の発生を抑制する上記の酸化皮膜を形成するためには、ステンレス鋼に含まれるSiとCrとAlと{Nb+Ti−8(C+N)}の合計の含有量を15.5%以上とする必要があり、17.5%以上とすることがより好ましい。 It should be noted that Nb and / or Ti contained in the stainless steel does not exist in the form of a solid solution, but exists in a state in which a part thereof is fixed to C and N. And among Nb and / or Ti contained in stainless steel, Nb and / or Ti in a solid solution state not fixed to C and N is concentrated in the passive film by heat treatment, and in the oxide film formed after heat treatment Contributes to corrosion prevention. Among Nb and / or Ti contained in stainless steel, the amount of Nb and / or Ti that is fixed to C and N and does not enter into a solid solution state is Nb atomic weight 93, C atomic weight 12, N atomic weight 14 From the ratio, it is considered that the total amount of C and N (C + N) is approximately 8 times. Therefore, in order to form the above oxide film that suppresses the occurrence of corrosion, the total content of Si, Cr, Al, and {Nb + Ti-8 (C + N)} contained in the stainless steel is 15.5% or more. It is necessary to make it 17.5% or more.
さらに、熱処理、酸洗等のプロセス条件を加味して上記組成の酸化皮膜を形成させる。
上記化学組成の鋼材の表面に、上記のカチオン分率の酸化皮膜を形成する熱処理としては、部品となる部材をろう付け接合する時の熱処理が挙げられる。例えば、デリバリーチューブやコモンレールのように燃料噴射系部品の中には部材がろう付け接合されてなる部品がある。このような部品を製造するためのろう付け接合時の熱処理条件として、N2を含む環境で、800〜1200℃、10−2〜1torrの真空雰囲気もしくはH2雰囲気において、0.5〜30分間保持することで、好適に所望の組成の酸化皮膜が形成できる。ここで、単に10−2torr以下の真空中で熱処理するだけでは、形成された酸化皮膜のCr、Si、Nb、Ti、Alのカチオン分率の合計が、上記所望のカチオン分率には到達しない。たとえば、10−2torr以下の真空に引いた後、N2を導入して10−2〜1torrとして熱処理することで所望の組成の酸化皮膜を得ることができる。一方、H2雰囲気においては、N2を導入してもよいが、特にN2を導入する必要はなく、雰囲気内に残存しているN2でも所望の組成の酸化皮膜を得ることができる。
Furthermore, an oxide film having the above composition is formed in consideration of process conditions such as heat treatment and pickling.
An example of the heat treatment for forming the oxide film having the above cation fraction on the surface of the steel material having the above chemical composition is a heat treatment for brazing and joining members to be parts. For example, some fuel injection system parts such as delivery tubes and common rails are parts in which members are brazed and joined. As heat treatment conditions during brazing and joining for manufacturing such a component, in an environment containing N 2 , in a vacuum atmosphere of 800 to 1200 ° C. and 10 −2 to 1 torr or an H 2 atmosphere, 0.5 to 30 minutes. By holding, an oxide film having a desired composition can be suitably formed. Here, simply by heat-treating in a vacuum of 10 −2 torr or less, the total cation fraction of Cr, Si, Nb, Ti, and Al in the formed oxide film reaches the desired cation fraction. do not do. For example, after pulling a vacuum of 10 −2 torr or less, N 2 is introduced and heat treatment is performed at 10 −2 to 1 torr, whereby an oxide film having a desired composition can be obtained. On the other hand, N 2 may be introduced in the H 2 atmosphere, but it is not particularly necessary to introduce N 2, and an oxide film having a desired composition can be obtained even with N 2 remaining in the atmosphere.
この理由については、定かではないが、N2を含む環境で熱処理することにより鋼材の表面には(Nb、Ti)の炭窒化物が生成しており、これによりFe酸化物の還元が促進された可能性がある。
熱処理の雰囲気中におけるN2の含有量は、0.001〜0.2%が好ましく、0.005〜0.1%がより好ましい。
熱処理条件としては、カチオン分率の合計で30%以上のCr、Si、Nb、Ti、Alが濃化した酸化皮膜を形成するために、1000〜1200℃にて5〜30分間保持することが好ましい。保持温度としては1050〜1150℃、保持時間としては10〜20分間がより好ましい。
The reason for this is not clear, but (Nb, Ti) carbonitrides are formed on the surface of the steel material by heat treatment in an environment containing N 2 , which promotes the reduction of Fe oxide. There is a possibility.
The content of N 2 in the heat treatment atmosphere is preferably 0.001 to 0.2%, and more preferably 0.005 to 0.1%.
As heat treatment conditions, in order to form an oxide film in which Cr, Si, Nb, Ti, and Al having a total cation fraction of 30% or more are concentrated, holding at 1000 to 1200 ° C. for 5 to 30 minutes is possible. preferable. The holding temperature is preferably 1050 to 1150 ° C., and the holding time is more preferably 10 to 20 minutes.
このように、上記化学組成の鋼材からなる部材をろう付け接合する際における熱処理により、上記カチオン分率の酸化皮膜を形成できる。したがって、上記カチオン分率の酸化皮膜を形成するための熱処理工程は、上記化学組成の鋼材からなる部材をろう付け接合する工程を兼ねることができる。
なお、ろう付け接合されていない部品を製造する場合には、上記カチオン分率の酸化皮膜を形成するために、N2を含む環境で、800〜1200℃、10−2〜1torrにおいて、0.5〜30分間保持する熱処理工程を行ってもよいし、製造工程を簡略化して生産性を向上させるために、上記の熱処理工程を追加せず、鋼材や部品の製造課程において、酸化皮膜の形成される熱処理の条件と酸化皮膜の除去される酸洗の条件とを適切に調整することにより所望のカチオン分率の酸化皮膜としてもよい。
As described above, the oxide film having the cation fraction can be formed by heat treatment in brazing and joining the members made of steel having the chemical composition. Therefore, the heat treatment step for forming the oxide film having the cation fraction can also serve as a step of brazing and joining a member made of a steel material having the above chemical composition.
In the case of manufacturing a part that is not brazed, in order to form the oxide film having the above cation fraction, in an environment containing N 2 , at a temperature of 800 ° C. to 1200 ° C. and 10 −2 to 1 torr. A heat treatment process may be performed for 5 to 30 minutes. In order to simplify the manufacturing process and improve productivity, the above heat treatment process is not added, and an oxide film is formed in the manufacturing process of steel materials and parts. It is good also as an oxide film of a desired cation fraction by adjusting suitably the conditions of the heat processing performed, and the conditions of the pickling from which an oxide film is removed.
鋼材や部品の製造課程において、上記カチオン分率の酸化皮膜を形成する場合、具体的には、例えば、鋼材の製造課程の最終仕上焼鈍において、露点−45〜−75℃のN2−H2混合ガス雰囲気中で、800〜1100℃にて0.5〜5分保持する方法が挙げられる。この場合、後工程の酸洗は省略される。 When forming the oxide film having the cation fraction in the manufacturing process of steel materials and parts, specifically, for example, in the final finishing annealing of the manufacturing process of steel materials, N 2 —H 2 having a dew point of −45 to −75 ° C. The method of hold | maintaining at 800-1100 degreeC for 0.5 to 5 minutes in mixed gas atmosphere is mentioned. In this case, the subsequent pickling is omitted.
なお、ここで、より一層優れた耐食性を得るためには、Cr、Si、Nb、Ti、Alをカチオン分率の合計で40%以上含むことが好ましく、Cr、Si、Nb、Ti、Alのなかで最も重要なCrについては20%以上含有することが好ましい。さらに好ましくはCr、Si、Nb、Ti、Alをカチオン分率の合計で50%以上である。
また、酸化皮膜の膜厚は15nm以下とすることが好ましく、10nm以下がより好ましい。膜厚の増加は単位体積あたりに占めるCr、Si、Nb、Ti、Alといったカチオン分率の低下につながり、耐食性の低下を招く。N2を含む環境で熱処理することにより生成した(Nb、Ti)の炭窒化物が、膜厚の増加を抑制している可能性がある。
Here, in order to obtain even more excellent corrosion resistance, it is preferable to contain Cr, Si, Nb, Ti, Al in a total of 40% or more of the cation fraction, and Cr, Si, Nb, Ti, Al Of these, the most important Cr is preferably 20% or more. More preferably, Cr, Si, Nb, Ti, and Al have a total cation fraction of 50% or more.
Moreover, it is preferable that the film thickness of an oxide film shall be 15 nm or less, and 10 nm or less is more preferable. The increase in film thickness leads to a decrease in the fraction of cations such as Cr, Si, Nb, Ti, and Al occupied per unit volume, leading to a decrease in corrosion resistance. There is a possibility that the carbonitride of (Nb, Ti) generated by heat treatment in an environment containing N 2 suppresses an increase in film thickness.
本発明は、上記知見に加え、バイオ燃料供給系部品の材料として必要な加工性を考慮してなされ、バイオ燃料に対して優れた耐食性を備えた燃料供給系部品用フェライト系ステンレス鋼を提供するものであり、その要旨とするところは、特許請求の範囲に記載した通りの内容である。 In addition to the above knowledge, the present invention provides a ferritic stainless steel for fuel supply system parts that is made in consideration of workability required as a material for biofuel supply system parts and has excellent corrosion resistance against biofuels. The gist of the present invention is as described in the claims.
以下、バイオ燃料供給系部品用フェライト系ステンレス鋼の各組成を限定した理由について説明する。なお、以下の説明では、特に断らない限り、各成分の%は、質量%を表すものとする。 Hereinafter, the reason why each composition of ferritic stainless steel for biofuel supply system parts is limited will be described. In the following description, unless otherwise specified,% of each component represents mass%.
(C:0.03%以下)
Cは、耐粒界腐食性、加工性を低下させるため、その含有量を低く抑える必要がある。このため、Cの含有量を0.03%以下とした。しかしながら、過度に低めることは精練コストを上昇させるため、Cの含有量を0.002%以上とすることが好ましい。より好ましくは0.002〜0.02%である。
(C: 0.03% or less)
Since C reduces intergranular corrosion resistance and workability, it is necessary to keep the content low. Therefore, the C content is set to 0.03% or less. However, since excessively reducing the scouring cost, the C content is preferably 0.002% or more. More preferably, it is 0.002 to 0.02%.
(N:0.03%以下)
Nは、耐孔食性に有用な元素であるが、耐粒界腐食性、加工性を低下させるため、その含有量を低く抑える必要がある。このため、Nの含有量を0.03%以下とした。しかしながら、過度に低めることは精練コストを上昇させるため、Nの含有量を0.002%以上とすることが好ましい。より好ましくは0.002〜0.02%である。
また、炭窒化物により熱処理時の結晶粒粗大化を抑制して、強度低下を抑制するという観点から、CとNの合計含有量を0.015%以上とすることが好ましい。
(N: 0.03% or less)
N is an element useful for pitting corrosion resistance, but its content needs to be kept low in order to reduce intergranular corrosion resistance and workability. Therefore, the N content is set to 0.03% or less. However, since excessively reducing the scouring cost, the N content is preferably 0.002% or more. More preferably, it is 0.002 to 0.02%.
Moreover, it is preferable to make the total content of C and N 0.015% or more from the viewpoint of suppressing crystal grain coarsening during heat treatment by carbonitride and suppressing strength reduction.
(Si:0.1%超、1%以下)
Siは、熱処理後に表面皮膜に濃化してステンレス鋼の耐食性向上に寄与するためには、少なくとも0.1%超必要である。また、Siは、脱酸元素として有用である。しかしながら、過剰な添加は加工性を低下させるため、Siの含有量を1%以下とする。好ましくは0.1%超〜0.5%である。
(Si: more than 0.1%, 1% or less)
Si needs to be at least more than 0.1% in order to concentrate in the surface film after heat treatment and contribute to improving the corrosion resistance of stainless steel. Si is useful as a deoxidizing element. However, excessive addition reduces workability, so the Si content is 1% or less. Preferably it is more than 0.1% to 0.5%.
(Mn:0.02%以上、1.2%以下)
Mnは、脱酸元素として有用な元素であり、少なくとも0.02%以上含有させることが必要である。しかしながら、過剰に含有させると耐食性を劣化させるので、Mnの含有量を1.2%以下とする。好ましくは、0.05〜1%である。
(Mn: 0.02% or more, 1.2% or less)
Mn is an element useful as a deoxidizing element, and it is necessary to contain at least 0.02% or more. However, if it is excessively contained, the corrosion resistance is deteriorated, so the Mn content is set to 1.2% or less. Preferably, it is 0.05 to 1%.
(Cr:15%以上、23%以下)
Crは、バイオ燃料中での耐食性を確保する上で基本となる元素であり、少なくとも15%以上含有させることが必要である。Crの含有量を増加させるほど耐食性を向上させることができるが、過剰な添加は加工性、製造性を低下させるため、Crの含有量を23%以下とした。好ましくは17〜20.5%である。
(Cr: 15% or more, 23% or less)
Cr is an element that is fundamental for ensuring corrosion resistance in biofuel, and it is necessary to contain at least 15% or more. The corrosion resistance can be improved as the Cr content is increased. However, excessive addition reduces workability and manufacturability, so the Cr content is 23% or less. Preferably it is 17 to 20.5%.
8(C+N)+0.03≦Nb+Ti≦0.6・・・(式1)
なお(式1)において、元素記号は、それぞれの元素の含有量(質量%)を表す。
Nb、Tiは、C、Nを固定し、溶接部の耐粒界腐食性を向上させる上で有用な元素であるため、NbとTiとの合計(Nb+Ti)で、(C+N)量の8倍以上含有させる必要がある。また、熱処理後にステンレス鋼の表面皮膜に濃化して耐食性向上に寄与するためには、C、Nに固定されない固溶状態のNbおよび/またはTiとして少なくとも0.03%以上含有させる必要がある。したがって、Nb+Tiの下限を8(C+N)+0.03%とした。しかしながら、Nbおよび/またはTiの過剰の添加は、加工性、製造性を低下させるため、Nb+Tiの含有量の上限を0.6%とした。Nb+Tiの含有量は、好ましくは10(C+N)+0.03〜0.6%である。
8 (C + N) + 0.03 ≦ Nb + Ti ≦ 0.6 (Formula 1)
In addition, in (Formula 1), an element symbol represents content (mass%) of each element.
Nb and Ti are elements useful for fixing C and N and improving the intergranular corrosion resistance of the weld. Therefore, the total of Nb and Ti (Nb + Ti) is 8 times the (C + N) amount. It is necessary to contain above. Further, in order to concentrate on the surface film of stainless steel after heat treatment and contribute to the improvement of corrosion resistance, it is necessary to contain at least 0.03% or more as Nb and / or Ti in a solid solution state not fixed to C and N. Therefore, the lower limit of Nb + Ti is set to 8 (C + N) + 0.03%. However, excessive addition of Nb and / or Ti reduces workability and manufacturability, so the upper limit of the content of Nb + Ti is set to 0.6%. The content of Nb + Ti is preferably 10 (C + N) +0.03 to 0.6%.
ここで、Nb、Tiのうち、Tiにはステンレス鋼の表面皮膜に濃化して耐食性向上に寄与する反面、ろう付け性を阻害する作用がある。ろう付け構造のバイオ燃料供給系部品を製造する場合に良好なろう付け性を得るためには、Ti−3Nの値が0.03%以下になるようにTi量を制限するのが好ましい。 Here, among Nb and Ti, Ti concentrates on the surface film of stainless steel and contributes to the improvement of corrosion resistance, but has the effect of inhibiting brazing. In order to obtain good brazing properties when producing a brazing structure biofuel supply system part, it is preferable to limit the amount of Ti so that the value of Ti-3N is 0.03% or less.
(Al:0.002%以上、0.5%以下)
Alは、熱処理後にステンレス鋼の表面皮膜に濃化して耐食性向上に寄与するためには、0.002%以上含有させることが必要である。また、Alは、脱酸効果等を有するので精練上有用な元素であり、成形性を向上させる効果もある。しかしながら、過剰の添加は靭性を劣化させるため、Alの含有量を0.002〜0.5%とした。好ましくは0.005〜0.1%である。
(Al: 0.002% or more, 0.5% or less)
Al is required to be contained in an amount of 0.002% or more in order to concentrate on the surface film of stainless steel after heat treatment and contribute to the improvement of corrosion resistance. Al is an element useful for scouring because it has a deoxidizing effect and the like, and has an effect of improving moldability. However, since excessive addition deteriorates toughness, the Al content is set to 0.002 to 0.5%. Preferably it is 0.005 to 0.1%.
(Ni:2%以下)
Niは、耐食性を向上させるために、必要に応じて2%以下含有させることができる。安定した効果が得られるNiの含有量は0.2%以上である。Niは、その含有量を増加させるほど耐食性を向上させることができるが、多量の添加は、硬質化させ加工性を低下させると共に、高価であるためコストアップにつながる。したがって、Niは0.2〜2%含有させることが好ましい。より好ましくは0.2〜1.2%である。
(Ni: 2% or less)
Ni can be contained in an amount of 2% or less as required in order to improve the corrosion resistance. The Ni content that provides a stable effect is 0.2% or more. Ni can improve the corrosion resistance as the content is increased, but the addition of a large amount makes it harder and lowers the workability and increases the cost because it is expensive. Therefore, it is preferable to contain 0.2 to 2% of Ni. More preferably, it is 0.2 to 1.2%.
(Cu:1.5%以下)
Cuは、耐食性を向上させるために、必要に応じて1.5%以下含有させることができる。安定した効果が得られるCuの含有量は0.2%以上である。Cuは、その含有量を増加させるほど耐食性を向上させることができるが、多量の添加は、硬質化させ加工性を低下させる。したがって、Cuは0.2〜1.5%含有させることが好ましい。より好ましくは0.2〜0.8%である。
(Cu: 1.5% or less)
Cu can be contained in an amount of 1.5% or less as required in order to improve the corrosion resistance. The Cu content that provides a stable effect is 0.2% or more. Although Cu can improve corrosion resistance, so that the content increases, addition of a large amount hardens and reduces workability. Therefore, it is preferable to contain 0.2 to 1.5% of Cu. More preferably, it is 0.2 to 0.8%.
(Mo:3%以下)
Moは、耐食性を向上させるために、必要に応じて3%以下含有させることができる。安定した効果が得られるMoの含有量は0.3%以上である。Moは、その含有量を増加させるほど耐食性を向上させることができるが、多量の添加は、硬質化させ加工性を低下させると共に、高価であるためコストアップにつながる。したがって、Moは0.3〜3%含有させることが好ましい。より好ましく1は0.5〜2.0%である。
(Mo: 3% or less)
Mo can be contained in an amount of 3% or less as required in order to improve the corrosion resistance. The Mo content that provides a stable effect is 0.3% or more. Mo can improve the corrosion resistance as the content is increased, but the addition of a large amount makes it harder and lowers workability and is expensive, leading to an increase in cost. Therefore, it is preferable to contain 0.3 to 3% of Mo. More preferably, 1 is 0.5 to 2.0%.
(Sn:0.5%以下)
Snは、耐食性を向上させるために、必要に応じて0.5%以下含有させることができる。安定した効果が得られるSnの含有量は0.01%以上である。Snは、その含有量を増加させるほど耐食性を向上させることができるが、多量の添加は、硬質化させ加工性を低下させる。したがって、Snは0.01〜0.5%含有させることが好ましい。より好ましくは0.05〜0.4%である。
(Sn: 0.5% or less)
Sn can be contained in an amount of 0.5% or less as required in order to improve the corrosion resistance. The Sn content that provides a stable effect is 0.01% or more. Sn can improve the corrosion resistance as the content is increased, but addition of a large amount makes it harder and lowers the workability. Therefore, it is preferable to contain Sn 0.01 to 0.5%. More preferably, it is 0.05 to 0.4%.
(V:1%以下)
Vは、耐食性を向上させるために、必要に応じて1%以下含有させることができる。安定した効果が得られるVの含有量は0.05%以上である。しかしながら、Vの過剰の添加は、加工性を劣化させると共に、高価であるためコストアップにつながる。したがって、Vは0.05〜1%含有させることが好ましい。
(V: 1% or less)
V can be contained in an amount of 1% or less as required in order to improve the corrosion resistance. The content of V that provides a stable effect is 0.05% or more. However, excessive addition of V deteriorates processability and increases the cost because it is expensive. Therefore, V is preferably contained in an amount of 0.05 to 1%.
(W:1%以下)
Wは、耐食性を向上させるために、必要に応じて1%以下含有させることができる。安定した効果が得られるWの含有量は0.3%以上である。しかしながら、Wの過剰の添加は、加工性を劣化させると共に、高価であるためコストアップにつながる。したがって、Wは0.3〜1%含有させることが好ましい。
(W: 1% or less)
In order to improve corrosion resistance, W can be contained in an amount of 1% or less as necessary. The W content that provides a stable effect is 0.3% or more. However, excessive addition of W deteriorates workability and is expensive, leading to an increase in cost. Therefore, it is preferable to contain 0.3 to 1% of W.
(B:0.005%以下)
Bは、加工性、特に二次加工性を向上させるために、必要に応じて0.005%以下含有させることができる。安定した効果を得るには、Bを0.0001%以上含有させることが望ましい。より好ましくは0.0002〜0.001%である。
(B: 0.005% or less)
B can be contained in an amount of 0.005% or less as required in order to improve workability, particularly secondary workability. In order to obtain a stable effect, it is preferable to contain 0.0001% or more of B. More preferably, it is 0.0002 to 0.001%.
(Zr:0.5%以下)
Zrは、耐食性を向上させる上で、必要に応じて0.5%以下含有させることができる。安定した効果が得られるには、Zrを0.05%以上含有させることが好ましい。
(Zr: 0.5% or less)
Zr can be contained in an amount of 0.5% or less as required in order to improve the corrosion resistance. In order to obtain a stable effect, it is preferable to contain 0.05% or more of Zr.
(Co:0.2%以下)
Coは、二次加工性と靭性を向上させる上で、必要に応じて0.2%以下含有させることができる。安定した効果が得られるには、Coを0.02%以上含有させることが好ましい。
(Co: 0.2% or less)
Co can be contained in an amount of 0.2% or less as required in order to improve secondary workability and toughness. In order to obtain a stable effect, it is preferable to contain 0.02% or more of Co.
(Mg:0.002%以下)
Mgは、脱酸効果等を有するので精練上有用な元素であり、組織を微細化し加工性や靭性の向上にも効果があることから、必要に応じて0.002%以下含有させることができる。安定した効果が得られるには、Mgを0.0002%以上含有させることが好ましい。
(Mg: 0.002% or less)
Mg is an element useful for scouring because it has a deoxidizing effect and the like, and it is effective in improving the workability and toughness by refining the structure. Therefore, it can be contained in an amount of 0.002% or less as necessary. . In order to obtain a stable effect, it is preferable to contain 0.0002% or more of Mg.
(Ca:0.002%以下)
Caは、脱酸効果等を有するので精練上有用な元素であり、必要に応じて0.002%以下含有させることができる。安定した効果が得られるには、Caを0.0002%以上含有させることが好ましい。
(Ca: 0.002% or less)
Ca is an element useful for scouring because it has a deoxidizing effect and the like, and can be contained in an amount of 0.002% or less as required. In order to obtain a stable effect, it is preferable to contain 0.0002% or more of Ca.
(REM:0.01%以下)
REMは、脱酸効果等を有するので精練上有用な元素であり、必要に応じて0.01%以下含有させることができる。安定した効果が得られるには、REMを0.001%以上含有させることが好ましい。
(REM: 0.01% or less)
Since REM has a deoxidizing effect and the like, it is an element useful for scouring, and can be contained in an amount of 0.01% or less as required. In order to obtain a stable effect, it is preferable to contain REM 0.001% or more.
なお、不可避不純物のうち、Pについては、溶接性の観点から0.04%以下とすることが好ましく、より好ましくは0.035%以下である。また、Sについては、耐食性の観点から0.02%以下とすることが好ましく、より好ましくは0.01%以下である。 Of the inevitable impurities, P is preferably 0.04% or less, more preferably 0.035% or less from the viewpoint of weldability. Moreover, about S, it is preferable to set it as 0.02% or less from a viewpoint of corrosion resistance, More preferably, it is 0.01% or less.
本発明のステンレス鋼は、例えば、転炉又は電気炉で上記の化学組成を有する溶鋼とし、AOD炉やVOD炉などで精練して、連続鋳造法又は造塊法で鋼片とした後、熱間圧延−焼鈍−酸洗−冷間圧延−仕上焼鈍−酸洗の工程を行い、その後に、N2を含む10−2〜1torrの真空雰囲気もしくはN2を含むH2雰囲気中、800℃〜1200℃の温度で0.5〜30分保持する熱処理工程を行うことにより上記カチオン分率の酸化皮膜を形成する方法によって製造される。必要に応じて、熱延板の焼鈍を省略してもよいし、冷間圧延−仕上焼鈍−酸洗を繰り返し行ってもよい。製品の形態としては、板、管、棒、線が挙げられる。
なお、本発明のステンレス鋼は、上述したように、冷間圧延−仕上焼鈍−酸洗の工程を経た後に上記の熱処理工程を行うことによって製造してもよいが、熱処理工程を製造工程の他の段階で行う方法によって製造してもよい。
The stainless steel of the present invention is, for example, a molten steel having the above chemical composition in a converter or electric furnace, scoured in an AOD furnace, a VOD furnace, or the like, and made into a steel piece by a continuous casting method or an ingot forming method, during rolling - annealing - pickling - cold rolling - recrystallization annealing - performs pickling step, after which H 2 atmosphere containing 10 -2 ~1torr vacuum atmosphere or N 2, including N 2, 800 ° C. ~ It is manufactured by a method of forming an oxide film having the above cation fraction by performing a heat treatment step of holding at a temperature of 1200 ° C. for 0.5 to 30 minutes. If necessary, annealing of the hot-rolled sheet may be omitted, or cold rolling-finish annealing-pickling may be repeated. Examples of product forms include plates, tubes, bars, and wires.
In addition, as above-mentioned, the stainless steel of this invention may be manufactured by performing said heat processing process, after passing through the process of cold rolling-finish annealing-pickling, but heat processing processes are other than a manufacturing process. You may manufacture by the method performed in the step.
次に、本発明のバイオ燃料供給系部品について説明する。本発明のバイオ燃料供給系部品は、本発明のステンレス鋼からなるものである。
本発明のバイオ燃料供給系部品は、上記の化学組成を有する部材を形成する工程と、上記の熱処理工程とを行うことによって製造することが好ましい。本発明のバイオ燃料供給系部品の製造方法における熱処理工程は、部品としての形状に加工する前に行っても良いし、部品としての形状に加工した後に行っても良い。部品としての形状に加工した後に熱処理工程を行う場合、形状を加工することによって、表面の酸化皮膜が除去されて耐食性が低下する恐れがなく、好ましい。
また、熱処理工程は、部材をろう付け接合する工程を兼ねることが好ましい。この場合、熱処理工程とろう付け接合する工程とを別々に行う場合と比較して、効率よくバイオ燃料供給系部品を製造できる。
なお、本発明のバイオ燃料供給系部品は、本発明のステンレス鋼からなるものであればよく、ろう付け接合されたものに限定されない。
Next, the biofuel supply system component of the present invention will be described. The biofuel supply system component of the present invention is made of the stainless steel of the present invention.
The biofuel supply system component of the present invention is preferably manufactured by performing the step of forming a member having the above chemical composition and the above heat treatment step. The heat treatment step in the method for producing a biofuel supply system component of the present invention may be performed before being processed into a shape as a component, or may be performed after being processed into a shape as a component. When the heat treatment step is performed after being processed into a shape as a part, it is preferable that the shape is processed without removing the oxide film on the surface and reducing the corrosion resistance.
Moreover, it is preferable that the heat treatment process also serves as a process of brazing and joining the members. In this case, compared with the case where the heat treatment step and the brazing step are performed separately, the biofuel supply system component can be efficiently manufactured.
In addition, the biofuel supply system component of the present invention may be made of the stainless steel of the present invention, and is not limited to a brazed joint.
以下、実施例により本発明の効果をより明らかなものとする。なお、本発明は、以下の実施例に限定されるものではなく、その要旨を変更しない範囲で適宜変更して実施することができる。 Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.
表1および表2に示す組成の溶鋼を150kg真空溶解炉で溶製し、50kg鋼塊に鋳造し、鋼片とした後、加熱温度1200℃にて板厚4mmまで熱延した。その後850〜950℃にて熱延板焼鈍を行い、ショットと硝ふっ酸溶液中での酸洗によりスケールを除去して、まず板厚2mmまで冷延した。再度同一温度範囲で中間焼鈍を行った後、同一酸洗方法でスケールを除去して板厚0.8mmまで冷延した。これを880〜1000℃にて仕上焼鈍を行い、素材No.A〜Nの冷延鋼板とした。 Molten steel having the composition shown in Tables 1 and 2 was melted in a 150 kg vacuum melting furnace, cast into a 50 kg steel ingot, formed into a steel piece, and hot rolled to a plate thickness of 4 mm at a heating temperature of 1200 ° C. Thereafter, hot-rolled sheet annealing was performed at 850 to 950 ° C., the scale was removed by pickling and pickling in a nitric hydrofluoric acid solution, and first cold-rolled to a sheet thickness of 2 mm. After performing intermediate annealing again in the same temperature range, the scale was removed by the same pickling method and cold rolled to a plate thickness of 0.8 mm. This was subjected to finish annealing at 880 to 1000 ° C., and material No. A to N cold-rolled steel sheets were used.
(腐食試験1)
素材No.A〜Nの冷延鋼板より、それぞれ25W×100Lの試験片を切り出し、エメリー紙にて全面を#320まで湿式研磨した。
続いて、素材No.A〜Nの試験片に対して、次に示す条件1にて熱処理を行ない、表3のNo.1〜10、101〜103、106、201〜203の試験片とした。10−3torrで真空引き後、N2を導入して10−1〜10−2torrに調製した。その後昇温し、1100℃にて10分保持後、炉内で常温まで冷却した。なお、昇温中ならびに1100℃保持中も10−1〜10−2torrに保持した。また、素材No.D、FおよびJの試験片に対して、露点−65℃の100%H2中、1100℃にて10分保持の熱処理を行った。この熱処理条件を条件2とし、表3のNo.11〜13の試験片とした。
(Corrosion test 1)
Material No. From the cold rolled steel sheets A to N, test pieces of 25 W × 100 L were cut out, and the entire surface was wet-polished to # 320 with emery paper.
Subsequently, the material No. The test pieces A to N were subjected to heat treatment under the following condition 1, and Nos. Test pieces of 1 to 10, 101 to 103, 106, 201 to 203 were used. After evacuation at 10 −3 torr, N 2 was introduced to prepare 10 −1 to 10 −2 torr. Thereafter, the temperature was raised, held at 1100 ° C. for 10 minutes, and then cooled to room temperature in the furnace. In addition, it hold | maintained at 10 < -1 > -10 <-2 > torr also during temperature rising and 1100 degreeC holding | maintenance. In addition, the material No. The D, F, and J test pieces were heat-treated at 1100 ° C. for 10 minutes in 100% H 2 with a dew point of −65 ° C. This heat treatment condition was defined as condition 2, and No. 1 in Table 3 was obtained. It was set as the test piece of 11-13.
さらに、比較のため、素材No.DとFの試験片については、別の条件での熱処理も行った。素材No.Dの試験片については、10−3torrで真空引き後昇温し、1100℃にて10分保持後、炉内で常温まで冷却(条件3)し、表3のNo.104の試験片とした。素材No.Fの試験片については、大気中で700℃、30分保持後、常温まで空冷(条件4)し、表3のNo.105の試験片とした。 For comparison, the material No. About the test piece of D and F, the heat processing on another condition was also performed. Material No. For the test piece of D, the temperature was raised after evacuation at 10 −3 torr, held at 1100 ° C. for 10 minutes, then cooled to room temperature in the furnace (condition 3). 104 test pieces were obtained. Material No. About the test piece of F, after hold | maintaining at 700 degreeC and 30 minute (s) in air | atmosphere, it air-cools to normal temperature (condition 4). 105 test pieces were obtained.
表3のNo.1〜13、101〜106、201〜203の試験片に対して、表3に示す条件で腐食試験を行った。
No.1〜13、101〜106では、試験液として、ギ酸と酢酸の合計濃度が1%〜10%でClイオン濃度が100ppmになるようにNaClを溶解させた水溶液を用いた。試験温度は95℃とし、試験時間は168hrとした。なお、No.201〜203では、参考のため、ギ酸+酢酸の合計濃度が1%未満で、温度45℃とした、従来ガソリンに相当する条件についても試験を行った。これら以外の試験条件については、JASO−M611−92−Aに準じた。
No. in Table 3 Corrosion tests were performed on the test pieces 1 to 101, 101 to 106, and 201 to 203 under the conditions shown in Table 3.
No. In Nos. 1 to 13 and 101 to 106, an aqueous solution in which NaCl was dissolved so that the total concentration of formic acid and acetic acid was 1% to 10% and the Cl ion concentration was 100 ppm was used as the test solution. The test temperature was 95 ° C. and the test time was 168 hr. In addition, No. In 201-203, the test was also conducted for the conditions corresponding to the conventional gasoline in which the total concentration of formic acid + acetic acid was less than 1% and the temperature was 45 ° C. for reference. About test conditions other than these, it applied to JASO-M611-92-A.
腐食試験後の試験片は、硝酸を用いて脱錆処理を施した後、腐食減量測定、局部腐食有無の観察に供した。腐食減量は、試験前後の試験片の質量を0.0001gまで測定可能な直示天秤を用いて測定し、その変化量から算出される質量減少を試験前の試験片表面積で除して算出した。局部腐食の観察は、気相、液相、気相/液相境界を問わず試験片全面を対象に倍率200倍の光学顕微鏡を用いて行った。 The test piece after the corrosion test was subjected to derusting treatment using nitric acid, and then subjected to corrosion weight loss measurement and observation of local corrosion. Corrosion weight loss was calculated by measuring the mass of the test piece before and after the test using a direct balance capable of measuring up to 0.0001 g, and dividing the mass loss calculated from the change amount by the surface area of the test piece before the test. . The local corrosion was observed using an optical microscope with a magnification of 200 times on the entire surface of the test piece regardless of the gas phase, liquid phase, or gas phase / liquid phase boundary.
腐食減量が検出限界相当の0.5g・m−2以上、もしくは焦点深度法による腐食深さ測定値の検出限界10μm超える腐食痕が検出された場合を「局部腐食あり」と定義して不合格(×)とし、腐食減量が0.5g・m−2未満で局部腐食が認められなかった場合を合格(○)とした。その結果を表3に示す。 A case where corrosion weight loss of 0.5 g · m -2 or more equivalent to the detection limit or a corrosion mark exceeding the detection limit of 10 μm by the depth of focus method is detected is defined as “local corrosion” and is rejected. The case where the corrosion weight loss was less than 0.5 g · m −2 and local corrosion was not observed was determined to be acceptable (◯). The results are shown in Table 3.
(腐食試験2)
表1および表2の素材No.A〜Nの冷延鋼板を切り出しエメリー紙にて全面を#320まで湿式研磨後、内径50mm、深さ35mmのカップに成形した。次に、これを上記条件1〜条件4で腐食試験1と同様にして熱処理を行った。熱処理後のカップの一つにRMEを45mL、もう一つにE22を45mL入れ、予めギ酸+酢酸および塩素イオンを表3の濃度で溶解させた水5mLを2つのカップに加えて封入し、95℃の恒温槽内に168時間放置した(表3のNo.1〜13、101〜106)。尚、一部の試験はガソリン条件に相当する45℃の恒温槽内にて実施した(表3のNo.201〜203)。試験終了後、腐食液を排出しカップ内部をアセトン洗浄した後、腐食痕の有無を目視観察した。その結果を表3に示す。
(Corrosion test 2)
In Table 1 and Table 2, the material No. A to N cold-rolled steel sheets were cut out and the entire surface was wet-polished to # 320 with emery paper, and then formed into a cup having an inner diameter of 50 mm and a depth of 35 mm. Next, this was heat-treated in the same manner as in corrosion test 1 under the above conditions 1 to 4. 45 mL of RME is put in one of the cups after the heat treatment, 45 mL of E22 is put in the other, and 5 mL of water in which formic acid + acetic acid and chloride ions are dissolved in the concentrations shown in Table 3 are added to the two cups and sealed. It was left to stand in a constant temperature bath at 168 hours (Nos. 1 to 13, 101 to 106 in Table 3). In addition, some tests were implemented in a 45 degreeC thermostat corresponding to gasoline conditions (No. 201-203 of Table 3). After completion of the test, the corrosive liquid was discharged and the inside of the cup was washed with acetone, and then the presence or absence of corrosion marks was visually observed. The results are shown in Table 3.
(表面分析)
表3のNo.1〜13、101〜106、201〜203の腐食試験片の熱処理時に、表面分析用の試料も並行して熱処理を行い、X線光電子分光法(XPS)により、表面の酸化皮膜を分析し、酸化皮膜中のカチオン分率(A値)を算出した。XPSはアルバック・ファイ社製で、X線源にmono−AlKα線を用い、X線ビーム径約100μm、取り出し角45度の条件で測定した。その結果を表3に示す。
(Surface analysis)
No. in Table 3 During the heat treatment of the corrosion test specimens 1 to 13, 101 to 106, 201 to 203, the sample for surface analysis is also heat treated in parallel, and the oxide film on the surface is analyzed by X-ray photoelectron spectroscopy (XPS). The cation fraction (A value) in the oxide film was calculated. XPS was manufactured by ULVAC-PHI, Inc., using a mono-AlKα ray as an X-ray source, and measured under the conditions of an X-ray beam diameter of about 100 μm and an extraction angle of 45 degrees. The results are shown in Table 3.
表3に示す試験結果から、No.1〜13は、本発明範囲内にあるため、優れた耐食性を示した。
一方、比較例No.101〜103は、Cr含有量ならびにSi+Cr+Al+{Nb+Ti−8(C+N)}の値が本発明範囲外にあるため、満足すべき耐食性が得られていない。また、比較例No.106は、Si+Cr+Al+{Nb+Ti−8(C+N)}の値が本発明範囲外にあるため、満足すべき耐食性が得られていない。
From the test results shown in Table 3, no. Since 1-13 is in the range of the present invention, it showed excellent corrosion resistance.
On the other hand, Comparative Example No. In 101 to 103, since the Cr content and the value of Si + Cr + Al + {Nb + Ti-8 (C + N)} are outside the range of the present invention, satisfactory corrosion resistance is not obtained. Comparative Example No. No. 106 has a value of Si + Cr + Al + {Nb + Ti-8 (C + N)} outside the range of the present invention, so that satisfactory corrosion resistance is not obtained.
また、参考例No.201〜203は、Cr含有量が本発明の条件を満たしていないにもかかわらず、ギ酸+酢酸の合計濃度が1%未満で、温度が45℃とマイルドな条件であったため、良好な耐食性を示した。 Reference Example No. 201-203 was a mild condition with a total concentration of formic acid and acetic acid of less than 1% and a temperature of 45 ° C., despite the Cr content not satisfying the conditions of the present invention. Indicated.
また、N2を導入せずに真空中でのみ熱処理されたNo.104のA値は0.22、大気中で熱処理されたNo.105のA値は0.17となり、組成が本発明範囲であるのにA値が本発明範囲を満足せず耐食性に劣る。 In addition, No. 2 was heat-treated only in a vacuum without introducing N 2 . 104 has an A value of 0.22 and No. 104 heat-treated in air. The A value of 105 is 0.17, and although the composition is within the range of the present invention, the A value does not satisfy the range of the present invention and the corrosion resistance is poor.
バイオ燃料に対して優れた耐食性を備えた本発明のフェライト系ステンレス鋼は、燃料供給系部品、なかでも燃料噴射系のようにエンジンに近く高温になりやすい部位の部品に好適である。 The ferritic stainless steel of the present invention having excellent corrosion resistance against biofuel is suitable for fuel supply system parts, particularly parts in parts that are likely to be close to the engine and become hot like a fuel injection system.
Claims (4)
C:0.03%以下、
N:0.03%以下、
Si:0.1%を超え、1%以下、
Mn:0.02%以上、1.2%以下、
Cr:15%以上、23%以下、
Al:0.002%以上、0.5%以下、
Nb、Tiの何れか1種または2種を含有し、
以下に示す(式1)および(式2)を満たし、残部がFe及び不可避不純物からなり、表面に、Cr、Si、Nb、Ti、Alをカチオン分率の合計で30%以上含む酸化皮膜が形成されていることを特徴とするバイオ燃料供給系部品用フェライト系ステンレス鋼。
8(C+N)+0.03≦Nb+Ti≦0.6・・・(式1)
Si+Cr+Al+{Nb+Ti−8(C+N)}≧15.5・・・(式2)
(式1)および(式2)において、元素記号は、それぞれの元素の含有量(質量%)を表す。 % By mass
C: 0.03% or less,
N: 0.03% or less,
Si: more than 0.1%, 1% or less,
Mn: 0.02% or more, 1.2% or less,
Cr: 15% or more, 23% or less,
Al: 0.002% or more, 0.5% or less,
Contains one or two of Nb and Ti,
An oxide film satisfying (Equation 1) and (Equation 2) shown below, the balance being Fe and inevitable impurities, and containing Cr, Si, Nb, Ti, Al on the surface in a total of 30% or more of the cation fraction Ferritic stainless steel for biofuel supply system parts characterized by being formed.
8 (C + N) + 0.03 ≦ Nb + Ti ≦ 0.6 (Formula 1)
Si + Cr + Al + {Nb + Ti-8 (C + N)} ≧ 15.5 (Formula 2)
In (Formula 1) and (Formula 2), an element symbol represents content (mass%) of each element.
Ni:2%以下、Cu:1.5%以下、Mo:3%以下、Sn:0.5%以下のうち何れか1種又は2種以上を含有することを特徴とする請求項1記載のバイオ燃料供給系部品用フェライト系ステンレス鋼。 Furthermore, in mass%,
It contains any one or more of Ni: 2% or less, Cu: 1.5% or less, Mo: 3% or less, and Sn: 0.5% or less. Ferritic stainless steel for biofuel supply system parts.
V:1%以下、W:1%以下、B:0.005%以下、Zr:0.5%以下、Co:0.2%以下、Mg:0.002%以下、Ca:0.002%以下、REM:0.01%以下のうち何れか1種又は2種以上を含有することを特徴とする請求項1または2記載のバイオ燃料供給系部品用フェライト系ステンレス鋼。 Furthermore, in mass%,
V: 1% or less, W: 1% or less, B: 0.005% or less, Zr: 0.5% or less, Co: 0.2% or less, Mg: 0.002% or less, Ca: 0.002% The ferritic stainless steel for biofuel supply system parts according to claim 1 or 2, wherein one or more of REM: 0.01% or less are contained.
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CN201510761562.2A CN105296860B (en) | 2011-03-29 | 2012-03-28 | Bio-fuel feed system part ferrite-group stainless steel and bio-fuel feed system part |
CN201280015457.9A CN103459636B (en) | 2011-03-29 | 2012-03-28 | Biofuel plenum system parts ferrite-group stainless steel, biofuel plenum system parts, heat extraction withdrawer ferrite-group stainless steel and heat extraction withdrawer |
US14/007,807 US9611525B2 (en) | 2011-03-29 | 2012-03-28 | Ferritic stainless steel for biofuel supply system part, biofuel supply system part, ferritic stainless steel for exhaust heat recovery unit, and exhaust heat recovery unit |
KR1020137024892A KR20130125823A (en) | 2011-03-29 | 2012-03-28 | Ferritic stainless steel for biofuel supply system part, biofuel supply system part, ferritic stainless steel for exhaust heat recovery unit, and exhaust heat recovery unit |
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