EP0481844A1 - Steel with improved weldability - Google Patents

Steel with improved weldability Download PDF

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Publication number
EP0481844A1
EP0481844A1 EP91402670A EP91402670A EP0481844A1 EP 0481844 A1 EP0481844 A1 EP 0481844A1 EP 91402670 A EP91402670 A EP 91402670A EP 91402670 A EP91402670 A EP 91402670A EP 0481844 A1 EP0481844 A1 EP 0481844A1
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Prior art keywords
steel
improved weldability
silicon
nickel
titanium
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German (de)
French (fr)
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EP0481844B1 (en
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Thierry Maurickx
Pascal Verrier
Roland Taillard
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Sollac SA
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Sollac SA
Lorraine de Laminage Continu SA SOLLAC
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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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel

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  • the present invention relates to a structural steel with improved weldability.
  • the grades of steel for welded constructions must satisfy a high level of brittle tensile strength at low temperature, this temperature being a function of the stress conditions and the service temperature of the structure.
  • CTOD Chip Tip Opening Displacement
  • Fig. 1 represents the transition temperature for a resilience energy of 28 joules as a function of the cooling time from 700 ° to 300 ° C, for a steel of type 355 EMZ.
  • the resistance to cold cracking of such a steel can be assessed from the hardness-cooling criterion shown in FIG. 2.
  • the Vickers hardness is greater than 350Hv5. This is explained by the fact that the structure has 80 to 100% martensite.
  • the subject of the present invention is a steel with improved weldability having good resilience for high welding energies and not requiring preheating before welding.
  • the subject of the present invention is therefore a steel with improved weldability, characterized in that it contains silicon in a proportion of less than 0.15% and titanium in a proportion of between 0.005 and 0.020%.
  • Such a steel therefore has good resilience even at high welding energy.
  • the hardness-cooling criteria curve shown in Fig. 2 shows that the steel with improved weldability has a lower hardness than that of conventional steel 355 EMZ.
  • the Vickers hardness for cooling the area affected by heat from 700 ° to 300 ° C in 10s is only 280 HV5, against at least 350 HV5 for common steel.
  • the improved weldability steel according to the invention now has very little martensite, less than 20%.
  • the steel with improved weldability according to the invention makes it possible to guarantee the mechanical characteristics on a sheet of 50mm thickness as follows:
  • Such a steel therefore makes it possible, either to guarantee the same characteristics as the usual 355 EMZ steel but to weld with higher welding energies, or by retaining the same welding energy, to guarantee the mechanical characteristics of toughness at a service temperature. weaker allowing then to consider applications in a harsher environment.
  • the silicon content has an influence on the transition temperature at 28 Joules (TK 28J), therefore on the toughness of the area affected by heat.
  • the transition temperature at 28 Joules is of the order of -70 ° C.
  • this temperature below which an energy necessary for rupture at least equal to 28 Joules is guaranteed is no more than -50 ° C.
  • the improvement in the toughness of the welded joint involves the reduction of the volume fraction of austenite retained which is ensured by the reduction of the silicon content of the steel.
  • Steel with improved weldability can be obtained, for example, by ladle casting, continuous casting, production in an oven, production in an oxygen steelworks or aluminum quenching.
  • the description below relates to an example of a method for obtaining sheets 50mm thick with steel according to the present invention.
  • the steel with improved weldability according to the invention is obtained by continuous casting of a known type, taking the necessary precautions to combat segregation.
  • the steel undergoes heating at low temperature between the ferrite-austenite transformation temperature AC3 and 1100 ° C., followed by rolling.
  • the temperature at the end of rolling is between 850 ° and 720 ° C.
  • the steel is then subjected to accelerated cooling from the end of rolling temperature to 450 ° C at a speed of 3 to 10 ° C per second.

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Abstract

Steel with improved weldability, exhibiting a good resistance to cracking in the case of high welding energies, a good cold resilience and requiring no preheating before welding. <??>The weight composition of the steel is the following:   - from 0.07 to 0.11 % of carbon,   - from 1.40 to 1.70 % of manganese,   - from 0.20 to 0.55 % of nickel,   - from 0 to 0.30 % of copper,   - from 0 to 0.02 % of niobium,   - from 0.005 to 0.020 % of titanium,   - from 0.002 to 0.006 % of nitrogen,   - from 0 to 0.15 % of silicon, the remainder being iron.

Description

La présente invention concerne un acier de construction à soudabilité améliorée.The present invention relates to a structural steel with improved weldability.

L'utilisation d'acier dans des environnements sévères tels que les aciers pour application navale utilisés sur des navires, des méthaniers ou des brise-glaces par exemple, circulant en mer du nord ou dans l'océan arctique, des plates-formes de forage pétrolifère ou les aciers utilisés pour des réservoirs de stockage de gaz liquéfiés, impose le respect de cahiers des charges très restrictifs.The use of steel in severe environments such as steels for naval application used on ships, LNG carriers or icebreakers for example, circulating in the North Sea or in the Arctic Ocean, drilling platforms petroleum or steels used for liquefied gas storage tanks, requires compliance with very restrictive specifications.

Outre leurs caractéristiques de traction, les nuances d'aciers pour constructions soudées doivent satisfaire un niveau élevé de résistance à la rupture fragile à basse température, cette température étant fonction des conditions de sollicitation et de la température de service de la structure.In addition to their tensile characteristics, the grades of steel for welded constructions must satisfy a high level of brittle tensile strength at low temperature, this temperature being a function of the stress conditions and the service temperature of the structure.

Il est connu d'utiliser un acier référencé 355 EMZ dans la classification européenne et dont la composition pondérale est la suivante :

  • 0,11 % de carbone,
  • 1,45 % de manganèse,
  • 0,45 % de nickel,
  • 0,40 % de silicium,
  • 0,03 % de niobium,
  • 0,05 % d'azote, le reste étant du fer.
It is known to use a steel referenced 355 EMZ in the European classification and whose weight composition is as follows:
  • 0.11% carbon,
  • 1.45% manganese,
  • 0.45% nickel,
  • 0.40% silicon,
  • 0.03% niobium,
  • 0.05% nitrogen, the rest being iron.

Les caractéristiques mécaniques garanties par un tel acier sur une tôle de 50mm d'épaisseur sont les suivantes :

Figure imgb0001
The mechanical characteristics guaranteed by such steel on a sheet 50mm thick are as follows:
Figure imgb0001

Le CTOD (Crack Tip Opening Displacement) correspond à un essai normalisé de rupture (Norme BS 5762).The CTOD (Crack Tip Opening Displacement) corresponds to a standardized rupture test (Standard BS 5762).

La Fig. 1 représente la température de transition pour une énergie de résilience de 28 joules en fonction du temps de refroidissement de 700° à 300°C, pour un acier du type 355 EMZ.Fig. 1 represents the transition temperature for a resilience energy of 28 joules as a function of the cooling time from 700 ° to 300 ° C, for a steel of type 355 EMZ.

On constate que pour avoir une énergie de rupture supérieure à 28 J à - 40°C, il est nécessaire de souder avec une vitesse de refroidissement de 700° à 300°C inférieur à 50s. Il faut donc souder lentement ce qui signifie qu'il est nécessaire de faire plusieurs passes avec une faible énergie de soudage.It is noted that to have a breaking energy greater than 28 J at - 40 ° C, it is necessary to weld with a cooling rate of 700 ° to 300 ° C less than 50s. It is therefore necessary to weld slowly, which means that it is necessary to make several passes with low welding energy.

La résistance à la fissuration à froid d'un tel acier peut être appréciée à partir de la courbe dureté-critère de refroidissement représentée à la Fig. 2.The resistance to cold cracking of such a steel can be assessed from the hardness-cooling criterion shown in FIG. 2.

On constate que dans le cas d'un soudage manuel par électrode, correspondant à un temps de refroidissement entre 700° et 300°C d'environ 10s, la dureté Vickers est supérieure à 350Hv5. Ceci s'explique par le fait que la structure présente de 80 à 100% de martensite.It is noted that in the case of manual welding by electrode, corresponding to a cooling time between 700 ° and 300 ° C of approximately 10 s, the Vickers hardness is greater than 350Hv5. This is explained by the fact that the structure has 80 to 100% martensite.

Or, la martensite étant sensible à l'hydrogène, une telle soudure présente une faible résitance à la fissuration à froid.However, martensite being sensitive to hydrogen, such a weld has a low resistance to cold cracking.

Par conséquent, un tel acier connu, du type 355 EMZ présente une mauvaise résilience pour de fortes énergies de soudage, et nécéssite un préchauffage avant soudage pour éviter la fissuration à froid.Consequently, such a known steel, of the 355 EMZ type, exhibits poor resilience for high welding energies, and requires preheating before welding to avoid cold cracking.

La présente invention a pour objet un acier à soudabilité améliorée présentant une bonne résilience pour les fortes énergies de soudage et ne nécessitant pas de préchauffage avant soudage.The subject of the present invention is a steel with improved weldability having good resilience for high welding energies and not requiring preheating before welding.

La présente invention a donc pour objet un acier à soudabilité améliorée, caractérisé en ce qu'il contient du silicium dans une proportion inférieure à 0,15% et du titane dans une proportion comprise entre 0,005 et 0,020%.The subject of the present invention is therefore a steel with improved weldability, characterized in that it contains silicon in a proportion of less than 0.15% and titanium in a proportion of between 0.005 and 0.020%.

Selon une autre caractéristique, la composition pondérale de l'acier à soudabilité améliorée selon l'invention est la suivante :

  • de 0,07 à 0,11% de carbone,
  • de 1,40 à 1,70% de manganèse,
  • de 0,20 à 0,55% de nickel,
  • de 0 à 0,30% de cuivre,
  • de 0 à 0,02% de niobium,
  • de 0,005 à 0,020% de titane,
  • de 0,002 à 0,006% d'azote,
  • de 0 à 0,15% de silicium,
le reste étant du fer.According to another characteristic, the weight composition of the steel with improved weldability according to the invention is as follows:
  • from 0.07 to 0.11% carbon,
  • from 1.40 to 1.70% manganese,
  • from 0.20 to 0.55% nickel,
  • from 0 to 0.30% copper,
  • from 0 to 0.02% niobium,
  • from 0.005 to 0.020% of titanium,
  • from 0.002 to 0.006% nitrogen,
  • from 0 to 0.15% silicon,
the rest being iron.

De préférence, la composition pondérale de l'acier à soudabilité améliorée selon l'invention est la suivante :

  • 0,08% de carbone,
  • 1,50% de manganèse,
  • 0,45% de nickel,
  • 0,20% de cuivre,
  • 0,01% de titane,
  • 0,004% d'azote,
  • 0,09% de silicium,
le reste étant du fer.Preferably, the weight composition of the steel with improved weldability according to the invention is as follows:
  • 0.08% carbon,
  • 1.50% manganese,
  • 0.45% nickel,
  • 0.20% copper,
  • 0.01% titanium,
  • 0.004% nitrogen,
  • 0.09% silicon,
the rest being iron.

Un tel acier peut être obtenu par exemple par :

  • un réchauffage à basse température entre la température de transformation ferrite-austénite AC3 et 1100°C,
  • un laminage entre 850° et 720°C,
  • un refroidissement accéléré de 750° à 450°C entre 3 et 10° par seconde.
Such steel can be obtained for example by:
  • reheating at low temperature between the ferrite-austenite transformation temperature AC3 and 1100 ° C.,
  • rolling between 850 ° and 720 ° C,
  • accelerated cooling from 750 ° to 450 ° C between 3 and 10 ° per second.

D'autres caractéristiques et avantages apparaîtront au cours de la description qui va suivre, donnée uniquement à titre d'exemple, faite en référence aux dessins annexés, dans lesquels :

  • la Fig. 1 représente l'évolution de la température de transition pour une énergie de rupture de 28 joules (TK 28J) en fonction de la vitesse de refroidissement de la soudure pour un acier usuel 355 EMZ et pour l'acier à soudabilité améliorée selon l'invention,
  • la Fig. 2 représente la courbe dureté-critère de refroidissement pour un acier usuel 355 EMZ et pour l'acier à soudabilité améliorée selon l'invention.
  • la Fig. 3 représente l'influence de la teneur en silicium, d'une part sur la température de transition à 28 Joules (TK 28J) et, d'autre part, sur la fraction volumique d'austénite retenue ( γ r),
  • la Fig. 4 représente l'évolution de la fraction volumique d'austénite retenue ( γ r) en fonction du critère de refroidissement et de la teneur en silicium de l'acier.
Other characteristics and advantages will become apparent during the description which follows, given solely by way of example, made with reference to the appended drawings, in which:
  • Fig. 1 represents the evolution of the transition temperature for a breaking energy of 28 joules (TK 28J) as a function of the cooling rate of the weld for a conventional steel 355 EMZ and for the steel with improved weldability according to the invention ,
  • Fig. 2 shows the hardness-cooling criteria curve for a conventional steel 355 EMZ and for steel with improved weldability according to the invention.
  • Fig. 3 represents the influence of the silicon content, on the one hand on the transition temperature at 28 Joules (TK 28J) and, on the other hand, on the volume fraction of austenite retained (γ r),
  • Fig. 4 represents the evolution of the volume fraction of austenite retained (γ r) as a function of the cooling criterion and of the silicon content of the steel.

La composition pondérale de l'acier à soudabilité améliorée selon l'invention est :

  • de 0,07 à 0,11% de carbone,
  • de 1,40 à 1,70% de manganèse,
  • de 0,20 à 0,55% de nickel,
  • de 0 à 0,30% de cuivre,
  • de 0 à 0,02% de niobium
  • de 0,005 à 0,020% de titane,
  • de 0,002 à 0,006% d'azote,
  • de 0 à 0,15% de silicium,
le reste étant du fer.The weight composition of the steel with improved weldability according to the invention is:
  • from 0.07 to 0.11% carbon,
  • from 1.40 to 1.70% manganese,
  • from 0.20 to 0.55% nickel,
  • from 0 to 0.30% copper,
  • 0 to 0.02% niobium
  • from 0.005 to 0.020% of titanium,
  • from 0.002 to 0.006% nitrogen,
  • from 0 to 0.15% silicon,
the rest being iron.

De préférence, la composition pondérale de l'acier à soudabilité améliorée selon l'invention comprend :

  • 0,08% de carbone,
  • 1,50% de manganèse,
  • 0,45% de nickel,
  • 0,20% de cuivre,
  • 0,01% de titane,
  • 0,004% d'azote,
  • 0,09% de silicium
le reste étant de fer.Preferably, the weight composition of the steel with improved weldability according to the invention comprises:
  • 0.08% carbon,
  • 1.50% manganese,
  • 0.45% nickel,
  • 0.20% copper,
  • 0.01% titanium,
  • 0.004% nitrogen,
  • 0.09% silicon
the rest being iron.

Lorsqu'on compare la courbe température de transition à 28J en fonction de la vitesse de refroidissement de la soudure de l'acier usuel 355 EMZ et de l'acier à soudabilité améliorée selon l'invention (Fig. 1), on constate que quelle soit l'énergie de soudage, c'est à dire quelle que soit la vitesse de refroidissement de la soudure, la résilience de l'acier selon l'invention est toujours garantie jusqu'à -60°C.When comparing the transition temperature curve at 28J as a function of the cooling rate of the weld of the usual 355 EMZ steel and of the steel with improved weldability according to the invention (FIG. 1), it can be seen that or the welding energy, that is to say whatever the cooling rate of the weld, the resilience of the steel according to the invention is always guaranteed up to -60 ° C.

Un tel acier a donc une bonne résilience même à forte énergie de soudage.Such a steel therefore has good resilience even at high welding energy.

La courbe dureté-critère de refroidissement représentée Fig. 2 montre que l'acier à soudabilité améliorée présente une dureté inférieure à celle de l'acier usuel 355 EMZ.The hardness-cooling criteria curve shown in Fig. 2 shows that the steel with improved weldability has a lower hardness than that of conventional steel 355 EMZ.

En effet, la dureté Vickers pour un refroidissement de la zone affectée par la chaleur de 700° à 300°C en 10s n'est que de 280 HV5, contre au moins 350 HV5 pour l'acier usuel.Indeed, the Vickers hardness for cooling the area affected by heat from 700 ° to 300 ° C in 10s is only 280 HV5, against at least 350 HV5 for common steel.

L'acier à soudabilité améliorée selon l'invention ne présente plus que très peu de martensite, moins de 20%.The improved weldability steel according to the invention now has very little martensite, less than 20%.

La résilience est donc fortement améliorée à froid et un tel acier ne nécessite pas de préchauffage avant soudage.Resilience is therefore greatly improved at cold and such steel does not require preheating before welding.

L'acier à soudabilité améliorée selon l'invention permet de garantir les caractéristiques mécaniques sur une tôle de 50mm d'épaisseur suivantes :

Figure imgb0002
The steel with improved weldability according to the invention makes it possible to guarantee the mechanical characteristics on a sheet of 50mm thickness as follows:
Figure imgb0002

Un tel acier permet donc, soit de garantir les mêmes caractéristiques que l'acier usuel 355 EMZ mais souder avec de plus fortes énergies de soudage, soit en conservant la même énergie de soudage, de garantir les caractéristiques mécaniques de tenacité à une température de service plus faible laissant envisager alors des applications dans un environnement plus sévère.Such a steel therefore makes it possible, either to guarantee the same characteristics as the usual 355 EMZ steel but to weld with higher welding energies, or by retaining the same welding energy, to guarantee the mechanical characteristics of toughness at a service temperature. weaker allowing then to consider applications in a harsher environment.

Comme on le voit à la Fig. 3, la teneur en silicium a une influence sur la température de transition à 28 Joules (TK 28J), donc sur la ténacité de la zone affectée par la chaleur.As seen in Fig. 3, the silicon content has an influence on the transition temperature at 28 Joules (TK 28J), therefore on the toughness of the area affected by heat.

En effet, on constate que pour une teneur en silicium de 0,05% la température de transition à 28 Joules est de l'ordre de -70°C. Or, pour une teneur en silicium de 0,5%, cette température en deça de laquelle on garantit une énergie nécessaire à la rupture au moins égale à 28 Joules n'est plus que de -50°C.Indeed, it is found that for a silicon content of 0.05% the transition temperature at 28 Joules is of the order of -70 ° C. However, for a silicon content of 0.5%, this temperature below which an energy necessary for rupture at least equal to 28 Joules is guaranteed is no more than -50 ° C.

On constate également sur les Figs. 3 et 4 que la fraction d'austénite retenue en zone affectée par la chaleur est fonction de la teneur en silicium de l'acier. Ce phénomne est à associer à une décomposition favorisée de l'austénite en ferrite et carbures pendant le refroidissement après soudage.We also see in Figs. 3 and 4 that the austenite fraction retained in the zone affected by heat is a function of the silicon content of the steel. This phenomenon is to be associated with a favored decomposition of the austenite into ferrite and carbides during cooling after welding.

Ainsi, sur la Fig. 4, on voit que pour une teneur en silicium de 0,05% le taux d'austénite retenue lors de fortes énergies de soudage est d'environ 1% alors que pour ces mêmes énergies avec une teneur en silicium de 0,5%, il est de 5%.Thus, in FIG. 4, it can be seen that for a silicon content of 0.05% the austenite rate retained during high welding energies is around 1% whereas for these same energies with a silicon content of 0.5%, it is 5%.

Par conséquent, l'amélioration de la ténacité du joint soudé passe par la réduction de la fraction volumique d'austénite retenue qui est assurée par la diminution de la teneur en silicium de l'acier.Consequently, the improvement in the toughness of the welded joint involves the reduction of the volume fraction of austenite retained which is ensured by the reduction of the silicon content of the steel.

L'acier à soudabilité améliorée peut être obtenu par exemple par coulée en poche, coulée continue, élaboration en four, élaboration en aciérie à oxygène ou calmage aluminium.Steel with improved weldability can be obtained, for example, by ladle casting, continuous casting, production in an oven, production in an oxygen steelworks or aluminum quenching.

La description ci-après concerne un exemple de procédé d'obtention de tôles de 50mm d'épaisseur avec un acier selon la présente invention.The description below relates to an example of a method for obtaining sheets 50mm thick with steel according to the present invention.

L'acier à soudabilité améliorée selon l'invention est obtenu par coulée continue de type connue en prenant les précautions nécessaires pour lutter contre la ségrégation.The steel with improved weldability according to the invention is obtained by continuous casting of a known type, taking the necessary precautions to combat segregation.

A la sortie de la coulée, l'acier subit un réchauffage à basse température entre la température de transformation ferrite-austénite AC3 et 1100°C, suivi par un laminage.At the outlet of the casting, the steel undergoes heating at low temperature between the ferrite-austenite transformation temperature AC3 and 1100 ° C., followed by rolling.

La température en fin de laminage se situe entre 850° et 720°C.The temperature at the end of rolling is between 850 ° and 720 ° C.

L'acier subit alors un refroidissement accéléré depuis la température de fin de laminage jusqu'à 450°C à une vitesse de 3 à 10°C par seconde.The steel is then subjected to accelerated cooling from the end of rolling temperature to 450 ° C at a speed of 3 to 10 ° C per second.

L'acier à soudabilité améliorée utilisé pour établir les courbes représentées aux Figs. 1 et 2 est un acier dont la composition est celle donnée préférentiellement dans la description et obtenu selon le procédé suivant :

  • réchauffage homogène à 950°C pendant 3 heures,
  • laminage entre 760° et 740°C,
  • refroidissement jusqu'à 550°C à une vitesse de 6°C par seconde.
The improved weldability steel used to establish the curves shown in Figs. 1 and 2 is a steel whose composition is that given preferentially in the description and obtained according to the following process:
  • homogeneous reheating at 950 ° C for 3 hours,
  • rolling between 760 ° and 740 ° C,
  • cooling to 550 ° C at a rate of 6 ° C per second.

Claims (5)

Acier à soudabilité améliorée caractérisé en ce qu'il contient du silicium dans une proportion inférieure à 0,15% et du titane dans une proportion comprise entre 0,005 et 0,020%.Steel with improved weldability characterized in that it contains silicon in a proportion of less than 0.15% and titanium in a proportion of between 0.005 and 0.020%. Acier selon la revendication 1, caractérisé en ce que sa composition pondérale est la suivante : - de 0,07 à 0,11% de carbone, - de 1,40 à 1,70% de manganèse, - de 0,20 à 0,55% de nickel, - de 0 à 0,30% de cuivre, - de 0 à 0,02% de niobium, - de 0,005 à 0,020% de titane, - de 0,002 à 0,006% d'azote, - de 0 à 0,15% de silicium, le reste étant du fer.Steel according to claim 1, characterized in that its weight composition is as follows: - from 0.07 to 0.11% carbon, - from 1.40 to 1.70% manganese, - from 0.20 to 0.55% nickel, - from 0 to 0.30% copper, - from 0 to 0.02% niobium, - from 0.005 to 0.020% of titanium, - from 0.002 to 0.006% nitrogen, - from 0 to 0.15% of silicon, the rest being iron. Acier selon la revendication 2, caractérisé en ce que sa composition pondérale est de préférence la suivante : - 0,08% de carbone, - 1,50% de manganèse, - 0,45% de nickel, - 0,20% de cuivre, - 0,01% de titane, - 0,004% d'azote, - 0,09% de silicium, le reste étant de fer.Steel according to claim 2, characterized in that its weight composition is preferably as follows: - 0.08% carbon, - 1.50% manganese, - 0.45% nickel, - 0.20% copper, - 0.01% titanium, - 0.004% nitrogen, - 0.09% silicon, the rest being iron. Procédé d'obtention d'un acier selon l'une quelconque des revendications précédentes, caractérisé en ce que : - on réchauffe à basse température entre la température de transformation ferrite-auténite AC3 et 1100°C, - on lamine entre 850° et 720°C, - on pratique un refroidissement accéléré de 750° à 450°C à une vitesse de 3 à 10° par seconde. Process for obtaining a steel according to any one of the preceding claims, characterized in that: - reheating at low temperature between the ferrite-autenite transformation temperature AC3 and 1100 ° C, - laminated between 850 ° and 720 ° C, - accelerated cooling from 750 ° to 450 ° C is carried out at a speed of 3 to 10 ° per second. Procédé selon la revendicaion 4, caractérisé en ce que : - on réchauffe à 950°C pendant 3 heures, - on lamine entre 760° et 740°C, - on refroidit jusqu'à 550°C à une vitesse de 6°par seconde. Method according to claim 4, characterized in that: - reheated to 950 ° C for 3 hours, - laminated between 760 ° and 740 ° C, - cooled to 550 ° C at a speed of 6 ° per second.
EP91402670A 1990-10-18 1991-10-07 Steel with improved weldability Revoked EP0481844B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9012916 1990-10-18
FR9012916A FR2668169B1 (en) 1990-10-18 1990-10-18 IMPROVED WELDING STEEL.

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EP0481844A1 true EP0481844A1 (en) 1992-04-22
EP0481844B1 EP0481844B1 (en) 1995-08-02

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US (1) US5183633A (en)
EP (1) EP0481844B1 (en)
JP (1) JPH04297549A (en)
KR (1) KR940004033B1 (en)
AT (1) ATE125878T1 (en)
CA (1) CA2053197C (en)
DE (1) DE69111744T2 (en)
ES (1) ES2076490T3 (en)
FI (1) FI100340B (en)
FR (1) FR2668169B1 (en)
NO (1) NO178796C (en)

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FR2728591A1 (en) * 1994-12-27 1996-06-28 Lorraine Laminage Low alloy steel mfr.

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TW444109B (en) * 1997-06-20 2001-07-01 Exxon Production Research Co LNG fuel storage and delivery systems for natural gas powered vehicles
DZ2527A1 (en) * 1997-12-19 2003-02-01 Exxon Production Research Co Container parts and processing lines capable of containing and transporting fluids at cryogenic temperatures.
JP3524790B2 (en) 1998-09-30 2004-05-10 株式会社神戸製鋼所 Coating steel excellent in coating film durability and method for producing the same
JP2003124783A (en) * 2001-10-10 2003-04-25 Mitsubishi Electric Corp Gm-C FILTER
CA2468163A1 (en) 2001-11-27 2003-06-05 Exxonmobil Upstream Research Company Cng fuel storage and delivery systems for natural gas powered vehicles
US6852175B2 (en) * 2001-11-27 2005-02-08 Exxonmobil Upstream Research Company High strength marine structures

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FR2212434A1 (en) * 1972-12-31 1974-07-26 Nippon Steel Corp
DE2436419A1 (en) * 1973-07-31 1975-02-20 Nippon Steel Corp PROCESS FOR IMPROVING THE WELDABILITY OF A STEEL
DE2517164A1 (en) * 1975-04-18 1976-10-21 Rheinstahl Giesserei Ag Weldable strong steel alloy for thick castings - cooled from soln annealing at controlled rate and isothermally hardened
FR2500482A1 (en) * 1981-02-26 1982-08-27 Nippon Kokan Kk STEEL FOR WELDING WITH ENERGY HIGH CURRENT
EP0080809A1 (en) * 1981-10-31 1983-06-08 Nippon Steel Corporation A method of making wrought high tension steel having superior low temperature toughness

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2728591A1 (en) * 1994-12-27 1996-06-28 Lorraine Laminage Low alloy steel mfr.

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FI100340B (en) 1997-11-14
DE69111744T2 (en) 1996-01-18
NO914055L (en) 1992-04-21
CA2053197C (en) 1997-09-09
FR2668169B1 (en) 1993-01-22
FR2668169A1 (en) 1992-04-24
DE69111744D1 (en) 1995-09-07
NO178796C (en) 1996-06-05
NO914055D0 (en) 1991-10-16
ATE125878T1 (en) 1995-08-15
NO178796B (en) 1996-02-26
FI914907A (en) 1992-04-19
US5183633A (en) 1993-02-02
JPH04297549A (en) 1992-10-21
EP0481844B1 (en) 1995-08-02
KR940004033B1 (en) 1994-05-11
ES2076490T3 (en) 1995-11-01
KR920008204A (en) 1992-05-27
FI914907A0 (en) 1991-10-17
CA2053197A1 (en) 1992-04-19

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