EP0164678A1 - Steel for the manufacture of large forgings and process for the treatment of this steel - Google Patents

Steel for the manufacture of large forgings and process for the treatment of this steel Download PDF

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Publication number
EP0164678A1
EP0164678A1 EP85106869A EP85106869A EP0164678A1 EP 0164678 A1 EP0164678 A1 EP 0164678A1 EP 85106869 A EP85106869 A EP 85106869A EP 85106869 A EP85106869 A EP 85106869A EP 0164678 A1 EP0164678 A1 EP 0164678A1
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Prior art keywords
steel
temperature
less
equivalent
chromium
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German (de)
French (fr)
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EP0164678B1 (en
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André Coulon
Chantal Loier
Jean-Pierre Badeau
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Alstom SA
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Alstom SA
Alsthom Atlantique SA
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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
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • 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
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78—Combined heat-treatments not provided for above

Definitions

  • the present invention relates to a steel for the manufacture of large forgings, in particular of turbine rotors.
  • the steel according to the invention improves the mechanical properties both at ambient and hot and can be used with steam at 600 ° C.
  • the invention relates to a composition of highly alloyed steel for large forgings for which the addition of Niobium, usual for a steel having hot high resistance to creep is limited correlatively with the addition of nitrogen, the whole ele addition elements which must achieve a balance in order to avoid the presence of residual ferrite in the structure.
  • an "unbalanced" composition can cause an excess of ferrite in the structure of large parts. We manage to exclude it by carefully dosing the contents of additives.
  • a fairly precise method for carrying out this assay is that of "equivalent chromium and nickel" allowing, by means of coefficients assigned to each element, to assess its aptitude for the formation of ferrite (element alphagenes) and the formation of austenite ( gamma elements).
  • alphagenic elements we find Si, Cr, Mo, W, V, Nb, Ti, Al.
  • gammagenic elements we find C, Mn, Ni, Co and Cu.
  • An alloy composition in accordance with the invention will have, on the basis of the above, a chromium equivalent of between 14.5 and 15.5 and more advantageously between 14.7 and 15.3 a nickel equivalent of between 9 and 10, 2, the optimum ratio between the chromium equivalent and the nickel equivalent should be between 1.49 and 1.65.
  • FIG. 1 represents a diagram where the chrome equivalent is plotted on the abscissa and the nickel equivalent is plotted on the ordinate.
  • the final structures obtained appear in Figure 1, the straight lines plotted cooventionally the passage from one structure to another (A being austenite, M martensite and ⁇ F delta-ferrite).
  • the rectangle a b c d represents the chemical analysis area limited by the extremes of the compositions used (7.25 ⁇ Ni eq ⁇ 11.72 and - 13.12 ⁇ Cr eq ⁇ 16.65)
  • the part in the alloy according to the invention is subjected after forging to a determined heat treatment.
  • the description which is given below relates to a forged part with a diameter of 1400 mm with a weight of approximately 30 tonnes.
  • this income may include several stages: a first temperature rise up to approximately 560 ° C. (540-600 ° C.) with maintenance for at least 25 h (up to 48 h).
  • a second tempering is carried out to complete the transformation of the possibly remaining austenite into martensite and give the desired characteristics to the part. This treatment is done at a temperature between 650 and 710 ° C (the optimum being around 685 ° C) for a time similar to the first tempering.
  • an expansion treatment will be carried out at a temperature approximately 30 ° C lower than the temperature second income with a maintenance of 25 to 48 hours.
  • compositions including the following compositions:
  • the 5d elongations at break are between 13.5 and 21%.
  • the necks at break are between 41 and 70%.

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Abstract

The present invention provides a steel containing, by mass: from 0.16% to 0.22% carbon (C) less than 0.3% silicon (Si) less than 0.5% manganese (Mn) from 0.6% to 0.9% nickel (Ni) from 10.7% to 12.3% chromium (Cr) from 0.8% to 1.1% molybdenum (Mo) from 0.2% to 0.35% vanadium (V) from 0.07% to 0.20% niobium (Nb) from 0.05% to 0.11% nitrogen (N2) less than 0.008% boron (B) and not more than the following residual percentages by mass: 0.020% sulfur, 0.020% phosphorous, 0.025% cobalt, 0.010% aluminum, 0.02% titanium, 0.02% tin, 0.10% copper, 0.015% tungsten, 0.020% arsenic, and 0.0025% antimony; the remainder of the alloy being iron; said steel having a nickel equivalent calculated using the formula: Ni eq=30C+0.5Mn+2Ni+25N2+40B, lying in the range 9 to 10.2; and a chromium equivalent calculated using the formula: Cr eq=Cr+2Si+1.5Mo+5V+1.75Nb lying in the range 14.5 to 15.5; the ratio between the chromium equivalent and the nickel equivalent lying in the range 1.49 to 1.65.

Description

La présente invention a trait à un acier pour la fabrication de grosses pièces forgées en particulier de rotors de turbine.The present invention relates to a steel for the manufacture of large forgings, in particular of turbine rotors.

Les rotors de turbine classiques en acier Cr - Mo - V permettent des températures de vapeur de l'ordre de 550°C.Conventional turbine rotors in Cr - Mo - V steel allow steam temperatures of the order of 550 ° C.

Pour permettre une utilisation avec de la vapeur à plus haute température tout en conservant de bonnes propriétés mécaniques on a utilisé des aciers fortement alliés au chrome comme décrit par exemple dans le document FR-A-1 407 452.To allow use with steam at higher temperature while retaining good mechanical properties, steels highly alloyed with chromium were used as described for example in document FR-A-1 407 452.

L'acier selon l'invention permet d'améliorer les propriétés mécaniques tant à l'ambiante qu'à chaud et peut être utilisé avec de la vapeur à 600°C.The steel according to the invention improves the mechanical properties both at ambient and hot and can be used with steam at 600 ° C.

L'acier selon l'invention contient en masse

  • de 0,16 à 0,22% de carbone (C)
  • moins de 0,3% de silicium (Si)'
  • moins de 0,5% de manganèse (Mn)
  • de 0,6 à 0,9% de nickel (Ni)
  • de 10,7 à 12,3% de chrome (Cr)
  • de 0,8 à 1,1% de molybdène (Mo)
  • de 0,22 à 0,35% de vanadium (V)
  • de 0,07 à 0,20% de niobium (Nb)
  • de 0,05 à 0,11% d'azote (N2)
  • moins de 0,008% de bore (B)
  • et des quantités résiduelles maximales (en % en masse)
  • 0,020 pour le soufre, 0,020 pour le phosphore, 0,025 pour le cobalt, 0,010 pour l'aluminium, 0,02 pour le titane, 0,02 pour l'étain, 0,10 pour le cuivre, 0,015 pour le tungstène, 0,020 pour l'arsenic et 0,0025 pour l'antimoine, le complément étant en fer,
  • ledit acier ayant un nickel équivalent calculé selon la formule
  • Ni eq = 30 C + 0,5 Rm + 2 Ni + 25 N2 + 40 B,
  • compris entre 9 et 10,2
  • et un chrome équivalent calculé selon la formule
  • Cr eq = Cr + 2 Si + 1,5 Mo + 5 V + 1,75 Nb compris entre 14,5 et 15,5
  • le rapport entre le Cr eq et le Ni eq étant compris entre 1,49 et 1,65.
The steel according to the invention contains in mass
  • 0.16 to 0.22% carbon (C)
  • less than 0.3% silicon (Si) '
  • less than 0.5% manganese (Mn)
  • 0.6 to 0.9% nickel (Ni)
  • from 10.7 to 12.3% chromium (Cr)
  • 0.8 to 1.1% molybdenum (Mo)
  • from 0.22 to 0.35% vanadium (V)
  • from 0.07 to 0.20% niobium (Nb)
  • from 0.05 to 0.11% nitrogen (N 2 )
  • less than 0.008% boron (B)
  • and maximum residual quantities (in% by mass)
  • 0.020 for sulfur, 0.020 for phosphorus, 0.025 for cobalt, 0.010 for aluminum, 0.02 for titanium, 0.02 for tin, 0.10 for copper, 0.015 for tungsten, 0.020 for arsenic and 0.0025 for antimony, the balance being iron,
  • said steel having an equivalent nickel calculated according to the formula
  • Ni eq = 30 C + 0.5 Rm + 2 Ni + 25 N 2 + 40 B,
  • between 9 and 10.2
  • and an equivalent chromium calculated according to the formula
  • Cr eq = Cr + 2 Si + 1.5 Mo + 5 V + 1.75 Nb between 14.5 and 15.5
  • the ratio between Cr eq and Ni eq being between 1.49 and 1.65.

Pour obtenir de bonnes propriétés mécaniques on soumet après forgeage les pièces en acier selon l'invention à un traitement comportant les étapes suivantes :

  • - homogénéisation de la pièce réalisée à une température comprise entre 1130° et 1170°C pendant un temps suffisant pour parachever la mise en solution suivie d'un refroidissestent lent au four
  • - austénitisation entre 1050°c et 1130°C suivie d'une trempe ramenant la température à 250°C
  • - revenu lui donnant les caractéristiques finales.
To obtain good mechanical properties, the steel parts according to the invention are subjected after forging to a treatment comprising the following stages:
  • - homogenization of the part produced at a temperature between 1130 ° and 1170 ° C for a time sufficient to complete the dissolution followed by slow cooling in the oven
  • - austenitization between 1050 ° C and 1130 ° C followed by quenching reducing the temperature to 250 ° C
  • - income giving it the final characteristics.

Selon une réalisation préférentielle le revenu comporte les étapes suivantes

  • - première montée en température jusqu'à une température θ1 comprise entre 540 et 600°C, de pvéférence 560°C, aveo maintien pendant un temps t au moins égal à 25 h.
  • - refroidissement lent jusqu'à l'ambiante
  • - seconde montée en température jusqu'à une température θ2 comprise entre 650°C et 710°C, de préférence égale à 685°C, avec maintien pendant le temps t moins égal à 25 h
  • - refroidissement lent jusqu'à l'ambiante. et est suivi d'un traitement de stabilisation à une température θ 3 = θ 2 - θo maintenu pendant un temps au moins égal à 25 h avec θo compris entre 30° et 50°C.
According to a preferred embodiment, the income comprises the following stages
  • - first temperature rise to a temperature θ 1 between 540 and 600 ° C, preferably 560 ° C, with maintenance for a time t at least equal to 25 h.
  • - slow cooling to ambient
  • - second rise in temperature to a temperature θ 2 of between 650 ° C and 710 ° C, preferably equal to 685 ° C, with maintenance for the time t minus 25 h
  • - slow cooling to ambient. and is followed by a stabilization treatment at a temperature θ 3 = θ 2 - θ o maintained for a time at least equal to 25 h with θ o between 30 ° and 50 ° C.

La présente invention sera mieux comprise à la lumière de la description qui va suivre dans laquelle

  • - la figure 1 représente dans le système d'axes Cr eq, Ni eq la place du domaine de composition des aciers selon l'invention
  • - la figure 2 représente dans le même système d'axe le domaine des aciers selon l'invention.
The present invention will be better understood in the light of the following description in which
  • - Figure 1 shows in the axis system Cr eq, Ni eq the place of the field of composition of steels according to the invention
  • - Figure 2 shows in the same axis system the field of steels according to the invention.

L'invention concerne une composition d'acier fortement allié pour grosses pièces de forge pour lesquelles l'addition de Niobium, habituelle pour un acier présentant à chaud une résistance élevée au fluage est limitée corrélativement avec l'addition d'azote, l'ensemble des élé ments d'addition devant réaliser un équilibre en vue d'éviter la présence de ferrite résiduelle dans la structure.The invention relates to a composition of highly alloyed steel for large forgings for which the addition of Niobium, usual for a steel having hot high resistance to creep is limited correlatively with the addition of nitrogen, the whole ele addition elements which must achieve a balance in order to avoid the presence of residual ferrite in the structure.

En effet il est notoire que les aciers à 12% de chrome (10-14%) avec de fortes additions de niobium (0,2 à 0,5%) en plus du vanadium ont de bonnes propriétés vis-à-vis du fluage. Mais dans le cas de grosses pièces forgées la présence excessive de carbures de niobium à coeur peut entrainer des caractéristiques insuffisantes de la ductilité dans des directions perpendiculaires au sens de corroyage. La nécessaire réduction de la teneur en niobium peut corrélativement affecter les propriétés à chaud ce qui n'est pas le but recherché. Il importe donc de limiter au juste nécessaire les teneurs conjointes de niobium et d'azote pour obtenir dans toutes les directions une ductilité acceptable tout en cherchant à mettre totalement en solution les carbonitrures formés lors du traitement thermique. Le choix de la température d'austénitisation ainsi que le temps de maintien, seront ajustés pour un diamètre donné de pièce forgée, à la teneur précise en niobium dans la composition de l'acier de façon à utiliser toute l'efficacité de cette addition.Indeed it is known that steels with 12% chromium (10-14%) with strong additions of niobium (0.2 to 0.5%) in addition to vanadium have good properties with regard to creep . However, in the case of large forgings, the excessive presence of niobium carbides at the core can cause insufficient characteristics of the ductility in directions perpendicular to the direction of working. The necessary reduction of the niobium content can correlatively affect the hot properties which is not the aim sought. It is therefore important to limit to the necessary minimum the joint contents of niobium and nitrogen to obtain in all directions an acceptable ductility while seeking to completely dissolve the carbonitrides formed during the heat treatment. The choice of the austenitization temperature as well as the holding time, will be adjusted for a given diameter of forged part, to the precise niobium content in the composition of the steel so as to use all the efficiency of this addition.

D'autre part une composition "mal équilibrée" peut entrainer un excès de ferrite dans la structure de grosses pièces. On parvient à l'exclure en dosant soigneusement les teneurs en éléments d'addition. Une méthode assez précise pour réaliser ce dosage est celle des "chrome et nickel équivalents" permettant à l'aide de coefficients affectés à chaque élément d'apprécier son aptitude à la formation de ferrite (élément alphagènes) et à la formation d'austénite (éléments gammagènes). Parmi les éléments alphagènes on trouve Si, Cr, Mo, W, V, Nb, Ti, Al. Parmi les éléments gammagènes on trouve C, Mn, Ni, Co et Cu.On the other hand, an "unbalanced" composition can cause an excess of ferrite in the structure of large parts. We manage to exclude it by carefully dosing the contents of additives. A fairly precise method for carrying out this assay is that of "equivalent chromium and nickel" allowing, by means of coefficients assigned to each element, to assess its aptitude for the formation of ferrite (element alphagenes) and the formation of austenite ( gamma elements). Among the alphagenic elements we find Si, Cr, Mo, W, V, Nb, Ti, Al. Among the gammagenic elements we find C, Mn, Ni, Co and Cu.

La littérature existante fournit un choix de formules permettant le calcul des équivalents chrome et nickel. On peut citer les travaux de M. SCHNEIDER ou de MM. RICKETT, WHITE, WALTON et BUTLER. Le tableau ci-après donne une indication des coefficients d'aptitude à la formation de ferrite ou d'austénite pour chaque élément d'addition.

Figure imgb0001
The existing literature provides a choice of formulas allowing the calculation of chromium and nickel equivalents. We can cite the works of M. SCHNEIDER or MM. RICKETT, WHITE, WALTON and BUTLER. The table below gives an indication of the coefficients of aptitude for the formation of ferrite or austenite for each addition element.
Figure imgb0001

Les estimations se font en calculant les équations suivantes dans lesquelles les symboles correspondent en masse de l'élément dans 1'acier :

  • Wickel équivalent = 30 C + 0,5 Mn + 2 Ni + 25 N2 + 40 B
  • Chrome équivalent = Cr + 2 Si + 1,5 Mo + 5 V + 1,75 Nb
The estimates are made by calculating the following equations in which the symbols correspond in mass of the element in the steel:
  • Wickel equivalent = 30 C + 0.5 Mn + 2 Ni + 25 N 2 + 40 B
  • Chrome equivalent = Cr + 2 Si + 1.5 Mo + 5 V + 1.75 Nb

Une composition d'alliage conforme à l'invention aura, sur la base ce qui précède un équivalent chrome compris entre 14,5 et 15,5 et plus avantageusement entre 14,7 et 15,3 un équivalent nickel compris entre 9 et 10,2, le rapport optimm entre l'équivalent chrome et l'équivalent nickel devant être compris entre 1,49 et 1,65.An alloy composition in accordance with the invention will have, on the basis of the above, a chromium equivalent of between 14.5 and 15.5 and more advantageously between 14.7 and 15.3 a nickel equivalent of between 9 and 10, 2, the optimum ratio between the chromium equivalent and the nickel equivalent should be between 1.49 and 1.65.

La figure 1 représente un diagramme où l' équivalent chrome est porté en abscisse et l'équivalent nickel est porté en ordonnée. Les structures finales obtenues apparaissent sur la figure 1, les droites tracées indiquant cooventionnellement le passage d'une structure à une autre (A étant l'austénite, M la martensite et δ F la delta-ferrite). Le rectangle a b c d représente la zone d'analyse chimique limitée par les extrêmes des coumpositions utilisées (7,25 < Ni eq < 11,72 et - 13,12 < Cr eq < 16,65)FIG. 1 represents a diagram where the chrome equivalent is plotted on the abscissa and the nickel equivalent is plotted on the ordinate. The final structures obtained appear in Figure 1, the straight lines plotted cooventionally the passage from one structure to another (A being austenite, M martensite and δ F delta-ferrite). The rectangle a b c d represents the chemical analysis area limited by the extremes of the compositions used (7.25 <Ni eq <11.72 and - 13.12 <Cr eq <16.65)

L'optimum est obtenu à l'intérieur du petit rectangle c f g h (voir figure 2) correspondant à 9 < Ni eq < 10,2 et 14,5 < Cr eq - 15,5 dans la zone 1 f j k h 1 de ce petit rectangle comprise entre les deux droites D et D' données par le rapport Cr éq/Ni éq égal à 1,49 et 1,65.The optimum is obtained inside the small rectangle cfgh (see figure 2) corresponding to 9 <Ni eq <10.2 and 14.5 <Cr eq - 15.5 in the area 1 fjkh 1 of this small rectangle included Between the two lines D and D 'given by the ratio Cr éq / Ni éq equal to 1.49 and 1.65.

Au-dessus de la droite D on peut trouver de l'austénite résiduelle. En dessous de la droite D' on peut trouver de la ferrite résiduelle. Dans la zone i f j k h 1 on a de la martensite exempte d'austénite et/ou de ferrite résiduelle.Above the right D we can find residual austenite. Below the right You can find residual ferrite. In the zone i f j k h 1 there is martensite free of austenite and / or residual ferrite.

Sur la figure 2 on a indiqué en pointillé le rectangle R donnant les limites des compositions préférentielles telles que décrites dans le document FR-A-1 407 452.In FIG. 2, the rectangle R giving the limits of the preferred compositions as indicated in document FR-A-1 407 452 indicates the dotted line.

Pour obtenir les caractéristiques à l'ambiante et aux températures élevées, on soumet après forgeage la pièce dans l'alliage suivant l'invention à un traitement thermique déterminé. La description qui est faite ci-après concerne une pièce forgée d'un diamètre de 1400 mm d'un poids de 30 tonnes environ.To obtain the characteristics at room temperature and at high temperatures, the part in the alloy according to the invention is subjected after forging to a determined heat treatment. The description which is given below relates to a forged part with a diameter of 1400 mm with a weight of approximately 30 tonnes.

Une homogénéisation de la pièce réalisée à une température comprise entre 1130 et 11700C pendant un temps suffisant pour parachever la mise en solution est suivie d'un refroidissement au four jusqu'à 700°C environ. Une austénitisation entre 1050 et 11300C est suivie d'une trempe (huile, brouillard d'eau ou air pulsé) de façon à ce que la vitesse de refroidissement au coeur de la pièce ne soit pas inférieure à 40°C. h-1 : il convient en effet d'éviter une transformation perlitique qui intervient à des vitesses faibles de refroidissement. La température de la pièce est ramenée à une température inférieure à 250°C, la transformation martensitique étant complète à cette température.Homogenization of the part carried out at a temperature between 1130 and 1170 0 C for a time sufficient to complete the dissolution is followed by cooling in the oven to approximately 700 ° C. Austenitization between 1050 and 1130 0 C is followed by quenching (oil, water mist or forced air) so that the cooling rate at the heart of the part is not less than 40 ° C. h-1: pearlitic transformation which occurs at low cooling rates should indeed be avoided. The room temperature is brought back to a temperature below 250 ° C, the martensitic transformation being complete at this temperature.

Ensuite la pièce subit un revenu qui lui donnera les caractéristiques finales. En fait ce revenu pourra comporter plusieurs stades : une première montée en température jusqu'à 560°C environ (540-6000C) avec maintien pendant 25 h au moins (jusqu'à 48 h). Après refroidissement lent jusqu'à l'ambiante, on procède à un deuxième revenu pour parachever la transformation de l'austénite éventuellement restante, en martensite et donner les caractéristiques désirées à la pièce. Ce traitement se fait à une température comprise entre 650 et 710°C (l'optimum se situant vers 685°C) pendant un temps similaire au premier revenu. Après un refroidissement au four jusqu'à l'ambiante, on procèdera à un traitement de détente à une température inférieure de 30°C environ à la température du deuxième revenu avec un maintien de 25 à 48 h.Then the coin undergoes an income which will give it the final characteristics. In fact, this income may include several stages: a first temperature rise up to approximately 560 ° C. (540-600 ° C.) with maintenance for at least 25 h (up to 48 h). After slow cooling to room temperature, a second tempering is carried out to complete the transformation of the possibly remaining austenite into martensite and give the desired characteristics to the part. This treatment is done at a temperature between 650 and 710 ° C (the optimum being around 685 ° C) for a time similar to the first tempering. After cooling in the oven to ambient, an expansion treatment will be carried out at a temperature approximately 30 ° C lower than the temperature second income with a maintenance of 25 to 48 hours.

On a effectué de nombreux essais avec plusieurs compositions dont les compositions suivantes :

Figure imgb0002
Numerous tests have been carried out with several compositions, including the following compositions:
Figure imgb0002

Les traitement thermiques ont été les suivants :

  • Homogénéisation 1150°C
  • Austénitisatieo 1080°C
  • trempe brouillard d'eau
  • Revenus 560°C et 685°C
The heat treatments were as follows:
  • Homogenization 1150 ° C
  • Austenitisatieo 1080 ° C
  • water mist quenching
  • Income 560 ° C and 685 ° C

Les rémltate de rupture instantanée à 550°C sont

  • pour ces aciers : Ra mini 535 HPa R 0,002 mini 460 MPa
  • Rm maxi 600 MPa R 0,002 maxi 530 MPa
The instant breaking values at 550 ° C are
  • for these steels: Ra mini 535 HPa R 0,002 mini 460 MPa
  • Rm max 600 MPa R 0.002 max 530 MPa

Les essais de fluage - extrapolation Larson et Miller à 550°C (paramètre TK (25 + log t) 10-3)

  • 10 4 h : 282 MPa ± 28
  • 105h : 185 MPa ± 14
Creep tests - Larson and Miller extrapolation at 550 ° C (parameter TK (25 + log t) 10- 3 )
  • 10 4 h: 282 MPa ± 28
  • 10 5 h: 185 MPa ± 14

Les allongements 5d à rupture sont compris entre 13,5 et 21% Les strictions à rupture sont comprises entre 41 et 70%.The 5d elongations at break are between 13.5 and 21%. The necks at break are between 41 and 70%.

Claims (8)

1/ Acier contenant en masse de 0,16 à 0,22% de carbone (C) moins de 0,3% de silicium (Si) moins de 0,5% de manganèse (Mn) de 0,6 à 0,9% de nickel (Mi) de 10,7 à 12,3% de chrome (Cr) de 0,8 à 1,1% de molybdène (Mo) de 0,22 à 0,35% de vanadium (V) de 0,07 à 0,20% de niobium (Nb) de 0,05 à 0,11% d'azote (N2) moins de 0,008% de bore (B) et des quantités résiduelles maximales (en % du poids) 0,020 pour le soufre, 0,020 pour le phosphore, 0,025 pour le cobalt, 0,010 pour l'aluminium, 0,02 pour le titane, 0,02 pour l'étain, 0,10 pour le cuivre, 0,015 pour le tungstène, 0,020 pour l'arsenic et 0,0025 pour l'antimoine, le complément étant en fer. ledit acier ayant un nickel équivalent calculé selon la formule Ni eq = 30 C + 0,5 Mn + 2 Ni + 25 N2 + 40 B compris entre 9 et 10,2 et un chrome équivalent calculé selon la formule Cr eq = Cr + 2 Si + 1,5 Mo 4. 5 V + 1,75 Nb compris entre 14,5 et 15,5 le rapport entre le Cr eq et le Ni eq étant compris entre 1,49 et 1,65. 1 / Steel containing by mass from 0.16 to 0.22% of carbon (C) less than 0.3% silicon (Si) less than 0.5% manganese (Mn) 0.6 to 0.9% nickel (Mi) from 10.7 to 12.3% chromium (Cr) 0.8 to 1.1% molybdenum (Mo) from 0.22 to 0.35% vanadium (V) from 0.07 to 0.20% niobium (Nb) from 0.05 to 0.11% nitrogen (N 2 ) less than 0.008% boron (B) and maximum residual quantities (in% of weight) 0.020 for sulfur, 0.020 for phosphorus, 0.025 for cobalt, 0.010 for aluminum, 0.02 for titanium, 0.02 for tin, 0.10 for copper, 0.015 for tungsten, 0.020 for arsenic and 0.0025 for antimony, the balance being iron. said steel having an equivalent nickel calculated according to the formula Ni eq = 30 C + 0.5 Mn + 2 Ni + 25 N 2 + 40 B between 9 and 10.2 and an equivalent chromium calculated according to the formula Cr eq = Cr + 2 Si + 1.5 Mo 4. 5 V + 1.75 Nb between 14.5 and 15.5 the ratio between Cr eq and Ni eq being between 1.49 and 1.65. 2/ Acier selon la revendication 1, caractérisé en ce que le chrome équivalent est compris entre 14,7 et 15,3.2 / Steel according to claim 1, characterized in that the equivalent chromium is between 14.7 and 15.3. 3/ Acier selon l'une des revendications précédentes, caractérisé en ce qu'il contient en poids moins de 0,1% de silicium.3 / Steel according to one of the preceding claims, characterized in that it contains by weight less than 0.1% of silicon. 4/ Acier selon l'une des revendications précédentes caractérisé en ce qu'il contient moins de 0,3% de manganèse.4 / Steel according to one of the preceding claims, characterized in that it contains less than 0.3% of manganese. 5/ Acier selon l'une des revendications précédentes caractérisé en ce qu'il comporte 0,005% de bore.5 / Steel according to one of the preceding claims characterized in that it comprises 0.005% boron. 6/ Procédé de traitement après forgeage d'une pièce en acier selon l'une des revendications précédentes, caractérisé en ce qu'il comporte les étapes suivantes : - homogénéisation de la pièce réalisée à une température comprise entre 1130 et 1170°C pendant un temps suffisant pour parachever la mise en solution suivie d'un refroidissement lent au four jusqu'à 700°C environ - austénitisation entre 1058°C et 1130°C suivie d'une trempe ramenant la température à 250°C - revenu lui donnant les caractéristiques finales. 6 / A method of treatment after forging a steel part according to one of the preceding claims, characterized in that it comprises the following steps: - homogenization of the part produced at a temperature between 1130 and 1170 ° C for a time sufficient to complete the dissolution followed by slow cooling in the oven to about 700 ° C - austenitization between 1058 ° C and 1130 ° C followed by quenching reducing the temperature to 250 ° C - income giving it the final characteristics. 7/ Procédé de traitement selon la revendication 6, caractérisé en ce que le revenu comporte les stades suivants - première montée en température jusqu'à une température θ1 comprise entre 540 et 600°C, de préférence 560°C, avec maintien pendant un temps t au moins égal à 25 h. - refroidissement lent jusqu'à l'ambiante - seconde montée en température jusqu'à une température θ2 comprise entre 650°C et 710°C, de préférence égale à 685°C, avec maintien pendant le temps t - refroidissement lent jusqu'à l'ambiante 7 / treatment method according to claim 6, characterized in that the income includes the following stages - first temperature rise to a temperature θ 1 between 540 and 600 ° C, preferably 560 ° C, with maintenance for a time t at least equal to 25 h. - slow cooling to ambient - second temperature rise to a temperature θ 2 of between 650 ° C and 710 ° C, preferably equal to 685 ° C, with maintenance for time t - slow cooling to ambient 8/ Procédé de traitement selon la revendication 7, caractérisé en ce que le revenu est suivi d'un traitement de détente à une température θ 3 = θ 2 - θ o maintenu pendant un temps au moins égal à 25 h, avec θ o compris entre 30°C et 50°C.8 / A treatment method according to claim 7, characterized in that the income is followed by an expansion treatment at a temperature θ 3 = θ 2 - θ o maintained for a time at least equal to 25 h, with θ o included between 30 ° C and 50 ° C.
EP85106869A 1984-06-05 1985-06-04 Steel for the manufacture of large forgings and process for the treatment of this steel Expired EP0164678B1 (en)

Priority Applications (1)

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AT85106869T ATE42347T1 (en) 1984-06-05 1985-06-04 STEEL FOR THE PRODUCTION OF LARGE FORGINGS AND METHOD OF TREATMENT OF SUCH STEEL.

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FR8408785A FR2565251B1 (en) 1984-06-05 1984-06-05 STEEL FOR THE MANUFACTURE OF LARGE FORGED PARTS AND PROCESS FOR TREATING THE SAME
FR8408785 1984-06-05

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EP0164678A1 true EP0164678A1 (en) 1985-12-18
EP0164678B1 EP0164678B1 (en) 1989-04-19

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EP (1) EP0164678B1 (en)
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KR (1) KR930003604B1 (en)
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CS (1) CS274262B2 (en)
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FR (1) FR2565251B1 (en)

Cited By (2)

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WO1992000158A1 (en) * 1990-06-28 1992-01-09 Abb Powdermet Ab METHOD OF POWDERMETALLURGICALLY MANUFACTURING FULLY DENSE BODIES FROM HIGH TEMPERATURE MARTENSITIC Cr STEEL
EP0796685A1 (en) * 1996-03-22 1997-09-24 Usinor Sacilor Process and apparatus for continuously casting a strand of inoxidable austenitic steel on a moving wall or in between two moving walls whose surfaces are grooved

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JPS62222027A (en) * 1986-03-25 1987-09-30 Nippon Chiyuutankou Kk Manufacture of heat resisting rotor
JPH0621323B2 (en) * 1989-03-06 1994-03-23 住友金属工業株式会社 High strength and high chrome steel with excellent corrosion resistance and oxidation resistance
KR20040012227A (en) * 2002-08-01 2004-02-11 서명원 a operation and suction device of sewing machine
US7591909B2 (en) * 2007-08-23 2009-09-22 Transportation Technology Center, Inc. Railroad wheel steels having improved resistance to rolling contact fatigue
KR101444750B1 (en) * 2012-08-31 2014-09-26 한국원자력연구원 the Ni-Cr-Mo low alloy steel improved resistance of temper embrittleness and the manufacturing method thereof
CN103774061B (en) * 2014-01-07 2015-11-18 无锡市派克重型铸锻有限公司 Leaf joint forging and manufacture craft thereof

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FR1407452A (en) * 1964-09-10 1965-07-30 Gen Electric Alloy for the manufacture of large forgings with good properties at room temperature and at high temperature

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GB833240A (en) * 1956-07-18 1960-04-21 Firth Vickers Stainless Steels Ltd Improvements relating to ferritic alloy steels
FR1407452A (en) * 1964-09-10 1965-07-30 Gen Electric Alloy for the manufacture of large forgings with good properties at room temperature and at high temperature

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992000158A1 (en) * 1990-06-28 1992-01-09 Abb Powdermet Ab METHOD OF POWDERMETALLURGICALLY MANUFACTURING FULLY DENSE BODIES FROM HIGH TEMPERATURE MARTENSITIC Cr STEEL
EP0796685A1 (en) * 1996-03-22 1997-09-24 Usinor Sacilor Process and apparatus for continuously casting a strand of inoxidable austenitic steel on a moving wall or in between two moving walls whose surfaces are grooved
FR2746333A1 (en) * 1996-03-22 1997-09-26 Usinor Sacilor CONTINUOUS CASTING PROCESS OF AN AUSTENITIC STAINLESS STEEL STRIP ON ONE OR BETWEEN TWO MOVABLE WALLS WHOSE SURFACES ARE PROVIDED WITH DIMENSIONS, AND CASTING PLANT FOR ITS IMPLEMENTATION
US5807444A (en) * 1996-03-22 1998-09-15 Usinor Sacilor Process for the continuous casting of an austenitic stainless steel strip onto one or between two moving walls with dimpled surfaces, and casting plant for its implementation
CN1067306C (en) * 1996-03-22 2001-06-20 犹齐诺-萨西洛公司 Process for continuous casting of austenitic stainless steel strip onto one or between two moving walls with dimpled surfaces, and casting plant for its implementation

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US4689095A (en) 1987-08-25
KR930003604B1 (en) 1993-05-08
EP0164678B1 (en) 1989-04-19
DE3569576D1 (en) 1989-05-24
KR860000400A (en) 1986-01-28
FR2565251A1 (en) 1985-12-06
ATE42347T1 (en) 1989-05-15
FR2565251B1 (en) 1987-12-31
CS274262B2 (en) 1991-04-11
JPS61566A (en) 1986-01-06
CS402885A2 (en) 1990-09-12

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