EP0897018B1 - Acier inoxydable duplex présentant une amélioration de résistance mécanique et de résistance à la corrosion - Google Patents

Acier inoxydable duplex présentant une amélioration de résistance mécanique et de résistance à la corrosion Download PDF

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Publication number
EP0897018B1
EP0897018B1 EP19980890210 EP98890210A EP0897018B1 EP 0897018 B1 EP0897018 B1 EP 0897018B1 EP 19980890210 EP19980890210 EP 19980890210 EP 98890210 A EP98890210 A EP 98890210A EP 0897018 B1 EP0897018 B1 EP 0897018B1
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EP
European Patent Office
Prior art keywords
max
duplex
content
alloy according
austenite
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.)
Expired - Lifetime
Application number
EP19980890210
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German (de)
English (en)
Other versions
EP0897018A1 (fr
Inventor
Günter Dr. Hochörtler
Peter Dr. Uggowitzer
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.)
Voestalpine Boehler Edelstahl GmbH
Original Assignee
Boehler Edelstahl GmbH
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Publication date
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Publication of EP0897018A1 publication Critical patent/EP0897018A1/fr
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Anticipated expiration legal-status Critical
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Definitions

  • the invention relates to a duplex alloy for components subject to complex stress high corrosion resistance and high strength, which is essentially a heat-treated one Sigma-phase and nitride-free microstructure and a material strength RM of greater than 800 MPa, a 0.2 proof stress of at least 600 MPa and one Charpy V toughness greater than 125 joules
  • Duplex alloys are materials for complex components, which high mechanical values regarding the strength and toughness of the material have and a toughness transition temperature of below - 20 ° C if possible should have. Furthermore, the corrosion resistance of the duplex alloys of great importance because these, abbreviated to DSS (Duplex-Stainless-Steels), in corrosive media in the chemical industry and especially in the OFFSHORE TECHNOLOGY can be used for system components. A good Weldability while avoiding any cracks and maintaining the Corrosion resistance in the zone affected by welding are further requirements for such materials.
  • SDSS super duplex stainless steel
  • EP-455625-B An improved both in terms of corrosion behavior and in the mechanical and welding properties increased duplex alloy, a So-called SDSS (super duplex stainless steel) is disclosed in EP-455625-B. at an alloy composition of max. 0.04 C, 0.15-0.55 Si, 2.0-2.9 Mn, max. 0.025 P, max. 0.005 S, 23.0-27.0 Cr, 3.0-5.0 Mo, 5.6-8.0 Ni, 0.5-1.0 W, 0-0.5 Cu, 0.2-0.35 N, 0.04-0.25 V, 0-0.20 Nb / Ta, 0-0.04 Ca, 0-0.02 Mg, max, 0.06 Al. Rest Fe and accompanying elements and setting a Ni to Mn ratio value determined within limits and a structural phase factor, the properties are improved overall.
  • the invention is based on this prior art (EP-455 625-9) the task of creating a duplex alloy which can be used both in the corrosion and welding properties are improved - as well as higher mechanical material values and a material strength RM of greater than 800 MPa, a 0.2 proof stress of at least 600 MPa and one Charpy V toughness of higher than 125 joules.
  • a raw or component made from this alloy has one Heat treatment by solution annealing in the temperature range between 1180 ° C and 850 ° C with subsequent forced cooling a microstructure with one austenite content exceeding the ferrite content.
  • the advantages of the duplex alloy according to the invention are in particular that this improved corrosion resistance and increased mechanical Has properties of the material at the same time. Furthermore, the Temperature range for solution annealing before the increased cooling of raw or components expanded so that the heat treatment to adjust the desired austenite-ferrite structure in the structure less accuracy in their Execution requires or the generation security is significantly improved. It is namely with this new alloy through the total effect of the intended Elements in a wide solution annealing temperature range essentially constant and desired ratio of ferrite to austenite in this form Material before, which is an advantageous margin regarding the temperature control in the heat treatment. This gives another advantage to one Use of the alloy according to the invention that also with thick-walled parts a microstructure which is substantially uniform over the cross section are.
  • the composition of the duplex material according to the invention in each case within narrow limits.
  • Chromium, molybdenum, tungsten and nitrogen generally improve with increasing levels of corrosion resistance of the material, but indicate in their effect and mutual influence of the structural morphology pronounced limits.
  • the demanding Limits of 26.0, 5.0, 1.00 and 0.39 in% by weight for the above Elements have been found to promote the formation of the sigma phase and Nitrides excreted. As a result or exacerbate these excretions not only the mechanical properties and the weldability of the Material leaps and bounds, the corrosion resistance of it is also affected by a so-called phase limit depletion adversely affected.
  • Concentrations below 24.0 wt% Cr, 4.0 wt% Mo, 0.51 wt% W and The corrosion resistance is reduced in particular below 0.351% by weight of N. and especially the strength of the alloy.
  • a comparatively high nitrogen content within narrow limits from 0.351 to 0.39 % By weight is important in the material according to the invention, because thereby how could surprisingly be found, an advantageously homogeneous Distribution of elements between austenite and ferrite in the structure is achieved with
  • chrome, tungsten and molybdenum are made by the high Compensating nitrogen contents from the usually alloyed ferrite in the alloyed austenite, which is a significant increase in Corrosion resistance and the tendency to excrete the SIGMA phase largely suppressed.
  • manganese in one Concentration range of 2.50 to 3.50 wt .-% is present because manganese on the one hand Nitrogen solubility increased and on the other hand has an austenite-forming function.
  • Mn Contents of more than 3.50% by weight of Mn increase the austenite content in the structure, however, reduce the corrosion resistance, and may also have an effect disadvantageous in terms of the achievable material strength and in particular safe setting of a desired ratio of ferrite to austenite in the Heat treatment of parts. Increase manganese contents lower than 2.50% by weight however, the activity of nitrogen in the steel and therefore the risk of Nitride deposits and also change the phase distribution of the structure in disadvantageously.
  • Ni contents higher than 7.50% by weight have an extraordinary effect in the alloy stabilizing, resulting in long thermal treatment times and unevenly high Austenite contents depending on the temperature, with lower ones Concentrations than 6.51 wt .-% of nickel higher ferrite contents with the result cause excretions.
  • Tungsten fractions of 0.51 to 1.00 wt .-% increase the corrosion resistance and reduce the tendency to form intermetallic phases in the Heat treatment of the material. At W contents below 0.51% by weight, these are mechanical material properties deteriorated, whereas the limit of W values exceeding 1.00% by weight can cause production disadvantages.
  • the alloy component vanadium as a strong nitride former is in the intended Limits in terms of fine microstructure and high homogeneity meaningful of the material. Vanadium contents higher than 0.202% by weight mask nitrogen and form harmful, especially row-shaped Nitrides, whereas lower levels of vanadium are no longer effective are, so that Grobkom can arise disadvantageously. This also applies to the in this regard, partially substitutable elements Ti and Nb / Ta.
  • Silicon contents in the range between 0.21 and 0.82 wt .-% are with regard to the Material quality is important. Lower concentrations of Si can increase Oxygen levels and a poor degree of purity of the material cause. High values above a content of 0.82% by weight influence due to the ferrite-forming and nitride-forming effects of Si Phase formation disadvantageous. Another disadvantage of higher Si contents is that these favor the formation of intermetallic phases or precipitations
  • Aluminum contents of 0.003 to 0.062% by weight are provided in the alloy. Higher Al contents again promote nitride formation and thereby Reduction of the proportion of dissolved nitrogen with all of the above Disadvantages and smaller aluminum values increase the tendency to form coarse grains.
  • the austenite is compared to the ferrite Phase with the lower hardness and strength, it is for components from the alloy according to the invention important that the volume fraction of austenite is greater than that of the ferrite is present in the structure. On the one hand, this increases the tendency formation of chromium nitride, which worsens the Usage properties of the part causes, reduced, on the other hand, the Austenite phase due to the dissolved nitrogen with regard to the mechanical Properties improved.
  • the new duplex steel according to the invention in specialist circles HDSS (Hyper-Duplex-Stainless- Steel) connects the lowest differences in corrosion potential between alpha and gamma or maximum corrosion resistance and optimal Phase formation kinetics with largely homogeneous distribution of elements between Ferrite and austenite and is therefore concerning the chemical attack that Weldability and the strength properties of the generic Superior materials according to the state of the art.
  • HDSS Hydro-Duplex-Stainless- Steel
  • the PREN factor calculated from the current alloy composition a value between 44.6 and 49.5, preferably between 45.5 and 48.0, exhibits the highest corrosion resistance of the duplex material become.
  • the heat treatment uses a ratio of ferrite to austenite in the structure between 0 , 42 and 0.8, preferably between 0.60 and 0.69, is set, the proportion of the sigma phase and the nitride proportion and the proportion of carbides being less than 5% by weight, preferably less than 0.5% by weight is.
  • the good weldability of the material is further improved, with practically none in particular in the zones of the base material which are affected by the heat Impairment of the properties are caused.
  • Tab. 1 shows the chemical composition and the PREN factor achieved of examined melts or samples.
  • Table 2 shows the heat treatment and the test results.

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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)

Claims (6)

  1. Alliage duplex pour composants soumis à des sollicitations complexes, possédant une grande résistance à la corrosion et une grande résistance mécanique et présentant la composition chimique suivante, exprimée en pourcentages pondéraux :
    carbone 0,04 maxi
    silicium 0,21 à 0,82
    manganèse 2,50 à 3,50
    phosphore 0,03 maxi
    soufre 0,005 maxi
    chrome 24,0 à 26,0
    molybdène 4,0 à 5,0
    nickel 6,51 à 7,50
    tungstène 0,51 à 1,00
    cuivre 0,8 maxi
    azote 0,351 à 0,39
    vanadium 0,021 à 0,202
    niobium/tantale 0 à 0,1
    calcium 0 à 0,05
    magnésium 0 à 0,025
    aluminium 0,003 à 0,062
    bore 0,003 maxi
    pour le reste, du fer et des impuretés liées à la fabrication, l'indice PREN de résistance à la corrosion par piqûre de l'alliage, calculé selon la formule (%Cr + 3,3 x %Mo + 20 x %N), présentant une valeur comprise entre 44,5 et 50 et ledit alliage possédant, après traitement thermique, une structure mixte sensiblement exempte de phase sigma et de nitrures et une résistance à la traction RM supérieure à 800 MPa, une limite d'élasticité Rp 0,2 % supérieure ou égale à 600 MPa et une résilience Charpy (entaille en V) supérieure à 125 Joules.
  2. Alliage duplex selon la revendication 1, caractérisé en ce qu'il présente, après traitement thermique par recuit de mise en solution dans une plage de températures comprise entre 1180°C et 850°C suivi d'un refroidissement forcé, une microstructure dont la teneur en austénite est supérieure à la teneur en ferrite.
  3. Alliage duplex selon la revendication 1 ou 2, caractérisé en ce qu'il présente la composition chimique suivante, exprimée en pourcentages pondéraux :
    carbone 0,028 maxi
    silicium 0,30 à 0,62
    manganèse 2,92 à 3,38
    phosphore 0,028 maxi
    soufre 0,004 maxi
    chrome 24,8 à 25,8
    molybdène 4,1 à 4,7
    nickel 6,9 à 7,4
    tungstène 0,6 à 0,8
    cuivre 0,5 maxi
    azote 0,352 à 0,385
    vanadium 0,05 à 0,1
    aluminium 0,005 à 0,009
    pour le reste, du fer et des impuretés liées à la fabrication.
  4. Alliage duplex selon l'une des revendications 1 à 3, caractérisé en ce que l'indice PREN de résistance à la corrosion par piqûre calculé présente une valeur comprise entre 44,5 et 49,5, et de préférence entre 45,5 et 48,0.
  5. Alliage duplex selon l'une des revendications 1 à 4, caractérisé en ce que le rapport ferrite:austénite dans la structure est réglé par traitement thermique pour être compris entre 0,42 et 0,8 et de préférence entre 0,60 et 0,69, la teneur en phase sigma, la teneur en nitrures et la teneur en carbures étant inférieures à 5 % en poids, et de préférence inférieures à 0,5 % en poids.
  6. Alliage duplex selon l'une des revendications 1 à 5, caractérisé en ce qu'une pièce façonnée réalisée dans ledit alliage présente un degré de déformation supérieur ou égal à 2,5, en particulier supérieur ou égal à 3,8, étant précisé que par degré de déformation, l'on entend la somme des réductions de section.
EP19980890210 1997-08-13 1998-07-17 Acier inoxydable duplex présentant une amélioration de résistance mécanique et de résistance à la corrosion Expired - Lifetime EP0897018B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AT136597A AT405297B (de) 1997-08-13 1997-08-13 Duplexlegierung für komplex beanspruchte bauteile
AT1365/97 1997-08-13
AT136597 1997-08-13

Publications (2)

Publication Number Publication Date
EP0897018A1 EP0897018A1 (fr) 1999-02-17
EP0897018B1 true EP0897018B1 (fr) 2003-09-03

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EP19980890210 Expired - Lifetime EP0897018B1 (fr) 1997-08-13 1998-07-17 Acier inoxydable duplex présentant une amélioration de résistance mécanique et de résistance à la corrosion

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EP (1) EP0897018B1 (fr)
AT (1) AT405297B (fr)
DE (1) DE59809467D1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2735179C2 (ru) * 2015-01-20 2020-10-28 Нуово Пиньоне Текнолоджи С.Р.Л. Коррозионностойкое изделие и способ его изготовления

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6187045B1 (en) 1999-02-10 2001-02-13 Thomas K. Fehring Enhanced biocompatible implants and alloys
SE524952C2 (sv) * 2001-09-02 2004-10-26 Sandvik Ab Duplex rostfri stållegering
SE524951C2 (sv) * 2001-09-02 2004-10-26 Sandvik Ab Användning av en duplex rostfri stållegering
SE527178C2 (sv) * 2003-03-02 2006-01-17 Sandvik Intellectual Property Användning av en duplex rostfri stållegering
SE527175C2 (sv) * 2003-03-02 2006-01-17 Sandvik Intellectual Property Duplex rostfri ställegering och dess användning
CN104919072B (zh) * 2013-01-15 2017-07-14 株式会社神户制钢所 双相不锈钢钢材和双相不锈钢钢管
CN113584377A (zh) * 2021-06-22 2021-11-02 济源市瑞麦特金属材料有限公司 一种含氮不锈钢及制备方法
CN118253937A (zh) * 2024-03-25 2024-06-28 中国第一汽车股份有限公司 金属零件及其制备方法和发动机

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT397515B (de) * 1990-05-03 1994-04-25 Boehler Edelstahl Hochfeste korrosionsbeständige duplex-legierung
JP2500162B2 (ja) * 1991-11-11 1996-05-29 住友金属工業株式会社 耐食性に優れた高強度二相ステンレス鋼
SE501321C2 (sv) * 1993-06-21 1995-01-16 Sandvik Ab Ferrit-austenitiskt rostfritt stål samt användning av stålet
EP0683241B1 (fr) * 1994-05-21 2000-08-16 Yong Soo Park Acier inoxydable duplex présentant une amélioration de la résistance à la corrosion

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2735179C2 (ru) * 2015-01-20 2020-10-28 Нуово Пиньоне Текнолоджи С.Р.Л. Коррозионностойкое изделие и способ его изготовления

Also Published As

Publication number Publication date
ATA136597A (de) 1998-11-15
DE59809467D1 (de) 2003-10-09
AT405297B (de) 1999-06-25
EP0897018A1 (fr) 1999-02-17

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