EP0795619A1 - Verfahren zur Herstellung rostfreies ferritisches Stahl mit erhöhte Korrosionsbeständigkeit, insbesondere Beständigkeit gegen interkristalline Korrosion und gegen Lochfrasskorrosion - Google Patents

Verfahren zur Herstellung rostfreies ferritisches Stahl mit erhöhte Korrosionsbeständigkeit, insbesondere Beständigkeit gegen interkristalline Korrosion und gegen Lochfrasskorrosion Download PDF

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Publication number
EP0795619A1
EP0795619A1 EP97400355A EP97400355A EP0795619A1 EP 0795619 A1 EP0795619 A1 EP 0795619A1 EP 97400355 A EP97400355 A EP 97400355A EP 97400355 A EP97400355 A EP 97400355A EP 0795619 A1 EP0795619 A1 EP 0795619A1
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EP
European Patent Office
Prior art keywords
steel
corrosion resistance
composition
less
nickel
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.)
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EP97400355A
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English (en)
French (fr)
Inventor
Jean-Michel Hauser
Pascale Haudrechy
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USINOR SA
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USINOR Sacilor SA
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Publication date
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Publication of EP0795619A1 publication Critical patent/EP0795619A1/de
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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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum

Definitions

  • the present invention relates to a method for producing a ferritic steel having improved corrosion resistance, and in particular resistance to intergranular and pitting corrosion.
  • NIPPON KOKAN a corrosion-resistant stainless steel ferritic, the composition of which is as follows: carbon less than 0.04%, silicon less than 1%, manganese less than 1 %, nickel less than 6%, chromium between 19 and 28%, molybdenum between 1 and 6%, nitrogen less than 0.03%, phosphorus less than 0.06%, sulfur less than 0.03%.
  • This steel may also contain niobium and or titanium.
  • This document presents a ferritic steel with high corrosion resistance, used to resist a mixture of phosphoric acid, sulfuric acid, chlorine and fluorine ions.
  • part of the aluminum can be replaced by doubling the amount of titanium, provided that there is at least 0.002% of aluminum.
  • the steel is preferably hot rolled or forged directly after continuous casting, without intermediate cooling.
  • the object of the invention is to improve the corrosion resistance of a ferritic steel, in particular the resistance to intergranular and pitting corrosion while retaining a transformation process compatible with the transformations of so-called 17% chromium ferritic steels. currents.
  • the subject of the invention is a method for producing a ferritic stainless steel having improved corrosion resistance, and in particular resistance to intergranular corrosion and to pitting corrosion, characterized in that the steel, in the form of slab, containing in its weight composition: 18% ⁇ chromium ⁇ 27% 1% ⁇ molybdenum ⁇ 3% 1% ⁇ nickel ⁇ 3% manganese ⁇ 1% silicon ⁇ 1% carbon ⁇ 0.030% nitrogen ⁇ 0.030% 0.075% ⁇ titanium ⁇ 0.20% 0.20% ⁇ niobium ⁇ 0.50% sulfur ⁇ 0.01% phosphorus ⁇ 0.1% the remainder being iron and impurities resulting from the melting of the materials necessary for the preparation, is subjected, in a first phase, to cooling at a speed of between 400 ° C and 600 ° C / hour up to the temperature of 900 ° C, then, in a second phase, rapid cooling at a speed between 1200 ° C and 1400 ° C / H.
  • the invention also relates to a ferritic stainless steel obtained by the process having improved corrosion resistance, and in particular resistance to inter-granular corrosion and by pitting, characterized in its weight composition: 18% ⁇ chromium ⁇ 27% 1% ⁇ molybdenum ⁇ 3% 1% ⁇ nickel ⁇ 3% manganese ⁇ 1% silicon ⁇ 1% carbon ⁇ 0.030% nitrogen ⁇ 0.030% 0.075% ⁇ titanium ⁇ 0.20% 0.20% ⁇ niobium ⁇ 0.50% sulfur ⁇ 0.01% phosphorus ⁇ 0.1% the remainder being iron and impurities resulting from the fusion of the materials necessary for the preparation.
  • the steel is characterized in its weight composition: 22% ⁇ chrome ⁇ 27% 1% ⁇ molybdenum ⁇ 3% 1% ⁇ nickel ⁇ 3% 0.3% ⁇ manganese ⁇ 0.5% 0.3 ⁇ silicon ⁇ 0.5% carbon ⁇ 0.030% nitrogen ⁇ 0.030% 0.075% ⁇ titanium ⁇ 0.20% 0.20% ⁇ niobium ⁇ 0.50% aluminum ⁇ 0.05% sulfur ⁇ 0.01% phosphorus ⁇ 0.1% the remainder being iron and impurities resulting from the fusion of the materials necessary for the preparation.
  • FIG. 1 shows three fragile - ductile transition curves for a steel of composition A (11721) according to the invention.
  • FIG. 2 shows two fragile - ductile transition curves for the steel of composition B (11722) according to the invention.
  • FIG. 3 shows fragile ductile transition curves after rapid cooling of the hot rolled steel strip.
  • FIG. 4 shows fragile ductile transition curves as a function of different nickel and molybdenum contents.
  • FIG. 5 presents comparative pitting corrosion test curves.
  • the invention relates to a method for producing a ferritic stainless steel having improved corrosion resistance, and in particular resistance to intergranular and pitting corrosion.
  • the family of steels with more than 18% chromium includes steels whose transformation presents difficulties linked to the high proportion of chromium they contain. However, the high chromium contents have the effect of increasing the resistance to corrosion, compared with ferritic steels known as 17% chromium.
  • the aluminum and zirconium introduced into the composition in residual quantity enter the proportion of impurities due to the production.
  • Molybdenum improves resistance to general corrosion in an acid environment and to pitting corrosion. It must however be limited in concentration to avoid problems in the field of hot resilience.
  • Nickel improves resistance to corrosion in an acid medium, but a maximum limit is imposed because too much nickel weakens the steel.
  • the steel according to the invention in the form of a slab, undergoes a particular heat treatment to reduce its embrittlement, in particular when the steel is highly stabilized.
  • a slab of the steel is subjected to core cooling at a speed of between 400 and 600 ° C / hour up to the temperature of 900 ° C.
  • the slab is then subjected to rapid cooling to the core at a speed of between 1200 and 1400 ° C / hour, for example by immersing the slab in a swimming pool until it reaches a temperature of approximately 550 ° C.
  • the slab is subjected to cooling in a swimming pool for a period of less than 10 minutes.
  • the cooling at the heart of the slab takes place at a speed of the order of 600 ° C./H, then at a speed of 1300 ° C./H during the passage in swimming pool and that until at least a temperature of approximately 550 ° C.
  • Figure 1 shows three fragile - ductile transition curves for steel A (11721).
  • Curves 1 and 2 are the brittle - ductile transition characteristics of steel A, according to the invention, steel A having undergone rapid cooling in the swimming pool, respectively 10 and 5 min.
  • Curve 3 presents the brittle - ductile transition characteristic of steel A which has not undergone rapid cooling.
  • the cooling according to the invention avoids the precipitation of embrittling intermetallic compounds of the Fe 2 Nb type enriched in Mo.
  • FIG. 2 shows two characteristic curves of brittle-ductile transition for steel B (11722) compared to a resilience characteristic of steel A. It is noted that the cooling provides a ductile-brittle transition temperature of 124 ° C. and values of resilience when hot at temperatures between 180 ° C and 260 ° C of the order of 160 J / cm 2 .
  • the strip obtained is subjected to rapid cooling and then wound at a temperature below 600 ° C and preferably at a temperature in the region of 550 ° C.
  • the heat treatment according to the invention makes it possible to obtain, for a steel with more than 18% chromium, characteristics comparable to those of steels known as 17% chromium. It significantly improves its resilience properties, in particular by lowering the brittle ductile transition temperatures.
  • the carbon and nitrogen contents of the steel according to the invention are limited in order to reduce the phenomena of intergranular corrosion.
  • FIG. 4 shows a characteristic ductile-brittle transition curve of a steel C according to the invention containing 2% molybdenum and 2% nickel, characteristic, on the one hand, compared to that of a steel of the same general composition and containing 3.2% molybdenum and 2% nickel, and, on the other hand, that of a steel of the same general composition and containing 2% molybdenum and 4% nickel.
  • the resistance to intergranular corrosion is evaluated by the Strauss test applied to samples on which a TIG fusion line is drawn.
  • FIG. 5 presents characteristics of pitting corrosion on polished samples, air-aged then subjected to polarization under a sweep of 100 mV min -1 , in an aqueous solution of sodium chloride at 0.5 M and having a pH equal to 6.6 and a temperature of 70 ° C.
  • steels E and F have a resistance to pitting corrosion higher than steels taken as reference such as steels 316 L and F 18 MT.
  • steel C (11519) and steel D (11694) were compared with a reference steel 316L.
  • Steel C has higher titanium and niobium contents than steel D. It appears that these elements have no significant influence on the behavior of steel in cavernous corrosion.
  • ⁇ Nb 0.040% is considered as a minimum value to ensure resistance to intergranular corrosion.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Steel (AREA)
EP97400355A 1996-03-15 1997-02-18 Verfahren zur Herstellung rostfreies ferritisches Stahl mit erhöhte Korrosionsbeständigkeit, insbesondere Beständigkeit gegen interkristalline Korrosion und gegen Lochfrasskorrosion Withdrawn EP0795619A1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9603258 1996-03-15
FR9603258A FR2746114B1 (fr) 1996-03-15 1996-03-15 Procede d'elaboration d'un acier inoxydable ferritique presentant une resistance a la corrosion amelioree, et notamment une resistance a la corrosion intergranulaire et par piqure
US08/819,371 US5779820A (en) 1996-03-15 1997-03-17 Process for producing a ferritic stainless steel having an improved corrosion resistance, especially resistance to intergranular and pitting corrosion

Publications (1)

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EP0795619A1 true EP0795619A1 (de) 1997-09-17

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EP97400355A Withdrawn EP0795619A1 (de) 1996-03-15 1997-02-18 Verfahren zur Herstellung rostfreies ferritisches Stahl mit erhöhte Korrosionsbeständigkeit, insbesondere Beständigkeit gegen interkristalline Korrosion und gegen Lochfrasskorrosion

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US (1) US5779820A (de)
EP (1) EP0795619A1 (de)
CA (1) CA2199916A1 (de)
FR (1) FR2746114B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102443683A (zh) * 2011-12-09 2012-05-09 浙江中达特钢股份有限公司 一种小容量aod炉冶炼不锈钢添加硼、铈的方法

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6956210B2 (en) * 2003-10-15 2005-10-18 Micron Tchnology, Inc. Methods for preparing samples for atom probe analysis
UA111115C2 (uk) 2012-04-02 2016-03-25 Ейкей Стіл Пропертіс, Інк. Рентабельна феритна нержавіюча сталь
CN104480387B (zh) * 2014-10-16 2016-08-24 太原理工大学 高韧性Laves相NbFe2基高温结构材料及其制备方法
US11261512B2 (en) * 2016-09-02 2022-03-01 Jfe Steel Corporation Ferritic stainless steel
JP6420893B1 (ja) * 2017-12-26 2018-11-07 日新製鋼株式会社 フェライト系ステンレス鋼

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2348275A1 (fr) * 1976-04-13 1977-11-10 Mannesmann Ag Procede de fabrication d'objets resistant a un gaz acide
FR2349659A1 (fr) * 1976-04-27 1977-11-25 Crucible Inc Articles soudes en acier inoxydable
DE3221087A1 (de) 1982-06-04 1983-12-08 Thyssen Edelstahlwerke AG, 4000 Düsseldorf Verfahren zur erzeugung und verarbeitung hochlegierter nichtrostender ferritischer chrom-molybdaen-nickel-staehle
EP0478790A1 (de) * 1990-03-24 1992-04-08 Nisshin Steel Co., Ltd. Hitzebeständiger ferritischer nichtrostender stahl mit hervorragenden eigenschaften für zähigkeit bei tiefen temperaturen, schweissbarkeit und hitzebeständigkeit

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5302214A (en) * 1990-03-24 1994-04-12 Nisshin Steel Co., Ltd. Heat resisting ferritic stainless steel excellent in low temperature toughness, weldability and heat resistance

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2348275A1 (fr) * 1976-04-13 1977-11-10 Mannesmann Ag Procede de fabrication d'objets resistant a un gaz acide
FR2349659A1 (fr) * 1976-04-27 1977-11-25 Crucible Inc Articles soudes en acier inoxydable
DE3221087A1 (de) 1982-06-04 1983-12-08 Thyssen Edelstahlwerke AG, 4000 Düsseldorf Verfahren zur erzeugung und verarbeitung hochlegierter nichtrostender ferritischer chrom-molybdaen-nickel-staehle
EP0478790A1 (de) * 1990-03-24 1992-04-08 Nisshin Steel Co., Ltd. Hitzebeständiger ferritischer nichtrostender stahl mit hervorragenden eigenschaften für zähigkeit bei tiefen temperaturen, schweissbarkeit und hitzebeständigkeit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102443683A (zh) * 2011-12-09 2012-05-09 浙江中达特钢股份有限公司 一种小容量aod炉冶炼不锈钢添加硼、铈的方法
CN102443683B (zh) * 2011-12-09 2013-07-03 浙江中达特钢股份有限公司 一种小容量aod炉冶炼不锈钢添加硼、铈的方法

Also Published As

Publication number Publication date
CA2199916A1 (fr) 1997-09-15
FR2746114A1 (fr) 1997-09-19
US5779820A (en) 1998-07-14
FR2746114B1 (fr) 1998-04-24

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