EP0480461B1 - Acier inoxydable ferritique, contenant de l'aluminium et possédant une excellente résistance contre l'oxydation à haute température et une tenacité élevée - Google Patents

Acier inoxydable ferritique, contenant de l'aluminium et possédant une excellente résistance contre l'oxydation à haute température et une tenacité élevée Download PDF

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Publication number
EP0480461B1
EP0480461B1 EP91117384A EP91117384A EP0480461B1 EP 0480461 B1 EP0480461 B1 EP 0480461B1 EP 91117384 A EP91117384 A EP 91117384A EP 91117384 A EP91117384 A EP 91117384A EP 0480461 B1 EP0480461 B1 EP 0480461B1
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EP
European Patent Office
Prior art keywords
high temperature
oxidation resistance
content
steel
temperature oxidation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Revoked
Application number
EP91117384A
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German (de)
English (en)
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EP0480461A1 (fr
Inventor
Hiramatsu Nisshin-Seiko-Kabushikikaisha Naoto
Uematsu Nisshin-Seiko-Kabushikikaisha Yoshihiro
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Nisshin Co Ltd
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Nisshin Steel Co Ltd
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Publication date
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium

Definitions

  • the present invention relates to an aluminum (Al)-containing ferritic stainless steel for use in automobile exhaust-gas-treating apparatuses, heating apparatuses and the like.
  • Al-containing ferritic stainless steels have excellent high temperature oxidation resistance and thus are widely used for parts of heating apparatuses such as stove chimneys, electric heating means, etc.
  • the substrate of metallic catalytic converters is formed of metal foil having a thickness of around 50 micrometers.
  • This substrate is used in an exhaust gas atmosphere, in which catalytic reaction takes place and, therefore, has to have excellent high temperature oxidation resistance.
  • high-Al ferritic stainless steels essentially comprising 20Cr-5Al and containing rare earth metals (REM), yttrium (Y), etc. are used for this purpose.
  • REM rare earth metals
  • Y yttrium
  • the present invention is intended to provide a Fe-Cr-Al-REM, Y ferritic stainless steel for metallic catalytic converters having sufficient high temperature oxidation resistance, excellent toughness and good manufacturability, wherein the Al2O3 formed on the surface thereof does not suffer abnormal oxidation.
  • manganese (Mn) oxide compounds penetrate into the Al2O3 formed on the surface of the steel immediately before the abnormal oxidation occurs.
  • the present invention provides a ferritic stainless steel which comprises by weight: C: not more than 0.03 % Si: less than 0.25 % Mn: less than 0.25 % P: not more than 0.03 % S: less than 0.001 % N: not more than 0.03 % Cr: 15 - 25 % Al: 3 - 6 % at least one of REM, Y and alkaline earth metals: 0 01 - 0.2 % and optionally at least one of Nb, V and Ti: 0.05 - 1 %, balance of FE and inevitable incidental impurities.
  • the Mn content is preferably 0.21 % or less and more preferably 0.13 % or less.
  • the Si content is preferably 0.22 % or less and more preferably 0.17 % or less.
  • the reason for defining the composition of the steel of the present invention as above is generally as follows.
  • Si content is the most significant factor in the steel of the present invention. Generally, it is considered that Si is effective for high temperature oxidation resistance. In the case of high-Al-containing ferritic steels, however, the high temperature oxidation resistance thereof is markedly improved by reducing the Si content. We found that the high temperature oxidation resistance of high-Al-containing ferritic stainless steels is markedly improved by reducing both the Si content and the Mn content simultaneously. Also, the toughness of the high-Al-containing ferritic stainless steel can be markedly improved by reducing the Si content. We found that the above-described effects are brought about if the Si content is reduced to less than 0.25 %.
  • Mn In the present invention, the Mn content is significant. Generally Mn is effective for improving hot-workability. In the case of the present invention, however, Mn has a deleterious effect on high temperature oxidation resistance. We found that the high temperature oxidation resistance of high-Al-containing ferritic stainless steels is markedly improved by reducing the Mn content and further by increased addition of Cr, Al, REM, Y, etc. The toughness of the steel of the present invention is also remarkably improved by reduction of the Mn content and the effect is achieved by reducing the Mn content to less than 0.25 %. That is, the lower the Mn content, the better the effect and thus the Mn content is defined as less than 0.25 %.
  • P is an element which is deleterious to high temperature oxidation resistance as well as toughness of steels and, therefore, the lower the P content, the better the steel properties in general. In the case of the present invention, the P content should be not more than 0.03 %.
  • S forms compounds with REM, Y, etc. which degrade the surface properties as non-metallic inclusions. Also S consumes metallic REM, Y etc., which are effective for high temperature oxidation resistance. These adverse effects are great when the content is 0.001% or more. That is, the high temperature oxidation resistance is improved by reducing the S content to less than 0.001 %. In the present invention, the S content is defined as less than 0.001 %.
  • N reduces toughness of steels of the kind contemplated by the present invention. Also, it forms AlN consuming Al, which is effective for providing the steel with high temperature oxidation resistance, and thus inducing abnormal oxidation.
  • the N content is defined as not more than 0.03 %.
  • Cr is a fundamental element that provides the steel with high temperature oxidation resistance. At least 15 % of Cr is required in order to exhibit its effect. On the other hand, Cr in excess of 25 % deteriorates the toughness of slabs and hot coils, causing difficulty in manufacturing. Thus the Cr content is defined as 15 - 25 %.
  • Al is an essential element as well as Cr for providing the steel with high temperature oxidation resistance.
  • Cr Cr
  • abnormal oxidation readily occurs.
  • addition of not less than 3 % of Al is necessary.
  • the Al content need not be excessively high. Rather, Al in excess of 6 % deteriorates the toughness of slabs and hot coils. Thus the Al content is defined as 3 - 6 %.
  • REM, Y and alkaline earth metals are important elements which improve the high temperature oxidation resistance of Fe-Cr-Al alloys. They greatly improve the protecting effect of the formed oxide film, well inhibit abnormal oxidation, which easily develops in very thin materials, and improve adherence of the produced oxide film to the substrate. With a content of less than 0.01 %, the effect is not exhibited. To the contrary, at a content in excess of 0.2 %, they adversely affect hot-workability, making manufacture difficult, and form non-metallic inclusions impairing the surface properties. Thus the content of these elements is defined as 0.01 - 0.2 %.
  • Nb, V and Ti When contained in suitable amounts, these elements combine with C and N in the steel and greatly improve the toughness of the steel.
  • the steel of the present invention is used in severe high temperature environments and thus is required to be provided with excellent high temperature strength. Addition of these elements is very effective for this purpose. Addition of 0.05 % or more is required. The maximum amount is limited to 1 % since addition of excessive amount hardens the steel.
  • the high temperature oxidation resistance of high-Al-containing ferritic steels is provided by the Al2O3 which forms on the surface of the steel. Therefore, it is considered that the high temperature oxidation resistance will be improved as the Al content is increased.
  • Test specimens of the compositions indicated in Table 1 respectively having a thickness of 50 micrometers were subjected to an oxidation test at 1150 °C and the time until abnormal oxidation occurred was measured. The results are also indicated in Table 1. From these results, it is apparent that with increase in the contents of Cr and Al and addition of REM, high temperature oxidation resistance is improved and the steel becomes less susceptible to abnormal oxidation.
  • Respectively 30 kg heats of the steels of the compositions indicated in Table 4 were melted and casted and the ingots were forged, machined, hot-rolled and, thereafter, made into 30 micrometers thick sheets by repeating annealing and cold rolling. These samples were subjected to an oxidation test at 1150 °C and the time upto the occurrence of the abnormal oxidation was measured. The results are also shown in Table 4. The results show that for the steels of the present invention the time required for the occurrence of abnormal oxidation was remarkably prolonged in comparison with conventional steels, that is, the oxidation resistance of the steel of the present invention is greatly improved.
  • the present invention provides an inexpensive steel material having excellent high temperature oxidation resistance and excellent toughness without adding unnecessarily large amounts of Cr, Al, REM and Y.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Claims (5)

  1. Acier inoxydable ferritique qui comprend, en poids,
    C : pas plus de 0,03 %,
    Si : moins de 0,25 %,
    Mn : moins de 0,25 %,
    P : pas plus de 0,03 %,
    S : moins de 0,001 %,
    N : pas plus de 0,03 %,
    Cr : 15 à 25 %,
    Al : 3 à 6 %, et
    au moins l'un parmi métaux de terres rare, Y et métaux alcalino-terreux : 0,01 à 0,2 %,
    et facultativement au moins l'un parmi Nb, V et Ti : 0,05 à 1 %,
    et le reste étant du Fe et d'inévitables impuretés accidentelles.
  2. Acier selon la Revendication 1, dans lequel la teneur en Mn n'est pas plus de 0,21 %.
  3. Acier selon la Revendication 2, dans lequel la teneur en Mn n'est pas plus de 0,13 %.
  4. Acier selon la Revendication 1, dans lequel la teneur en Si n'est pas plus de 0,21 %.
  5. Acier selon la Revendication 4, dans lequel la teneur en Si n'est pas plus de 0,17 %.
EP91117384A 1990-10-11 1991-10-11 Acier inoxydable ferritique, contenant de l'aluminium et possédant une excellente résistance contre l'oxydation à haute température et une tenacité élevée Revoked EP0480461B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2270521A JPH04147945A (ja) 1990-10-11 1990-10-11 耐高温酸化性および靭性に優れた高Ａｌ含有フェライト系ステンレス鋼
JP270521/90 1990-10-11

Publications (2)

Publication Number Publication Date
EP0480461A1 EP0480461A1 (fr) 1992-04-15
EP0480461B1 true EP0480461B1 (fr) 1995-08-16

Family

ID=17487384

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91117384A Revoked EP0480461B1 (fr) 1990-10-11 1991-10-11 Acier inoxydable ferritique, contenant de l'aluminium et possédant une excellente résistance contre l'oxydation à haute température et une tenacité élevée

Country Status (5)

Country Link
EP (1) EP0480461B1 (fr)
JP (1) JPH04147945A (fr)
KR (1) KR100196984B1 (fr)
CA (1) CA2053175A1 (fr)
DE (1) DE69112165T2 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3176403B2 (ja) * 1991-12-20 2001-06-18 新日本製鐵株式会社 波付け加工用高強度ステンレス鋼箔およびその製造方法
JP2689208B2 (ja) * 1992-12-11 1997-12-10 新日本製鐵株式会社 湿潤耐食性および加工性の優れた内燃機関排気系用鋼
US5480608A (en) * 1993-03-19 1996-01-02 Nippon Yakin Kogyo Co., Ltd. Ferritic stainless steel having an excellent oxidation resistance
JPH08117614A (ja) * 1994-10-20 1996-05-14 Matsushita Electric Ind Co Ltd 触媒体およびその製造方法
FR2732360B1 (fr) * 1995-03-29 1998-03-20 Ugine Savoie Sa Acier inoxydable ferritique utilisable, notamment pour des supports de catalyseurs
US6652830B2 (en) * 2001-02-16 2003-11-25 Battelle Memorial Institute Catalysts reactors and methods of producing hydrogen via the water-gas shift reaction
DE10261207A1 (de) * 2002-12-20 2004-07-15 Mk Metallfolien Gmbh Eisenlegierung, insbesondere zur Verwendung in einer Abgasreinigungseinheit

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3171737A (en) * 1961-04-28 1965-03-02 Hoskins Mfg Company Electrical resistance alloy
SU552369A1 (ru) * 1975-12-12 1977-03-30 Предприятие П/Я Р-2120 Жаростойка сталь
EP0033203A3 (fr) * 1980-01-28 1981-08-26 Allegheny Ludlum Steel Corporation Support pour catalyseur et acier ferritique inoxydable, utilisé pour sa fabrication
GB2079065B (en) * 1980-06-27 1983-09-07 Sharetree Ltd Linear differential transformer
DE3780082T2 (de) * 1986-04-21 1993-01-14 Kawasaki Steel Co Rostfreier chrom-aluminium-stahl mit hoher bestaendigkeit gegen oxydation und abblaetterung und folien aus chrom-aluminium-stahl fuer katalysatortraeger in katalytischen konvertern.

Also Published As

Publication number Publication date
DE69112165T2 (de) 1996-03-21
EP0480461A1 (fr) 1992-04-15
DE69112165D1 (de) 1995-09-21
JPH04147945A (ja) 1992-05-21
KR100196984B1 (ko) 1999-06-15
CA2053175A1 (fr) 1992-04-12
KR920008206A (ko) 1992-05-27

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