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EP0991789A1 - Tool steel composition - Google Patents

Tool steel composition

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Publication number
EP0991789A1
EP0991789A1 EP99910459A EP99910459A EP0991789A1 EP 0991789 A1 EP0991789 A1 EP 0991789A1 EP 99910459 A EP99910459 A EP 99910459A EP 99910459 A EP99910459 A EP 99910459A EP 0991789 A1 EP0991789 A1 EP 0991789A1
Authority
EP
European Patent Office
Prior art keywords
composition
weight
steel
tool
temperatures
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.)
Granted
Application number
EP99910459A
Other languages
German (de)
French (fr)
Other versions
EP0991789B1 (en
Inventor
André GRELLIER
Michel Siaut
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.)
Aubert and Duval SA
Original Assignee
Aubert and Duval SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Aubert and Duval SA filed Critical Aubert and Duval SA
Publication of EP0991789A1 publication Critical patent/EP0991789A1/en
Application granted granted Critical
Publication of EP0991789B1 publication Critical patent/EP0991789B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening

Definitions

  • the present invention relates to a steel of the family known as 3% to 5% by weight of chromium used for the manufacture of tools resistant to heat and working under high stresses such as stamping and forging dies, tools dies and molds for static casting or die casting of various alloys such as aluminum, copper or titanium alloys.
  • Such steels are alloyed with chromium, molybdenum and vanadium, elements which give them the required heat resistance properties.
  • compositions comprising, expressed by weight, the following alloying elements: * 5% of chromium, 1, 3% of molybdenum, 0.5% to 1, 3% of vanadium approximately, or
  • the surface of the tools is brought into contact with materials heated to high temperature, for example liquid aluminum at 600 ° C / 750 ° C or steel intended to be forged and preheated to 1200X .
  • the surface of the tool is itself brought to high temperature: it follows that a thermal regime is established in the tool between the working part subjected to heating and the rest of the part cooled by conditions natural or forced. 2
  • the present invention firstly relates to a steel composition allowing good performance in service under said severe conditions.
  • composition which is the subject of the invention comprises, expressed in percentages by weight:
  • the composition is within the following limits:
  • composition which is the subject of the invention comprises contents of P, Sb, Sn and As, expressed in percentages by weight, which satisfy the relationships:
  • the set of alloying elements whose actions complement each other is balanced to give sufficient quenchability necessary for obtaining homogeneous properties in the thickness of large parts.
  • Carbon is the basic hardening element, its level is adjusted to obtain sufficient mechanical resistance, while avoiding by excess concentration the formation of eutectic carbides at the solidification. Its content in the alloy according to the invention is 0.3-0.4% by weight, preferably 0.33-0.37% by weight.
  • Chromium and molybdenum contribute to quenchability and hardening after quenching and tempering by the formation of alloyed carbides during thermal tempering treatments.
  • the content of these elements should not be excessive so as not to favor excessively the formation of chromium-molybdenum carbides to the detriment of vanadium and tungsten carbides.
  • the chromium content in the alloy according to the invention is 2.0-4.0% by weight, preferably 2.50-3.50% by weight, as for that of molybdenum it is 0.8- 3.0% by weight, preferably 1.20-2.20% by weight.
  • Vanadium contributes to hardening during tempering treatments by the formation of specific carbides, which makes it possible to increase the structural resistance to heating, therefore to shift upwards the higher temperatures admissible in service. An excess of this element would be detrimental to the toughness by the formation of eutectic carbides on solidification and by the segregating nature of this element.
  • Its content in the alloy according to the invention is 0.4-1.0% by weight, preferably 0.6-0.9% by weight.
  • Tungsten in the same way, supplements the action of vanadium by the same types of mechanisms and contributes in the same way to the raising of the compatible temperatures of use and, in the same way, an excess would be detrimental to the toughness and the structural homogeneity. Its content in the alloy according to the invention is 1.5-3.0% by weight, preferably 1.8-2.6% by weight.
  • Cobalt improves mechanical resistance when hot. Its content in the alloy according to the invention is 1.0-5.0% by weight, preferably 1.5-5.0% by weight.
  • the contents of silicon and manganese in the alloy according to the invention are each 0-1.0% by weight, preferably 0.20-0.50% by weight.
  • the content of nickel in the alloy according to the invention is 0-1.0% by weight, preferably 0-0.30% by weight. More generally, although it is not desired to be bound by any theory, it is therefore believed that obtaining good characteristics for such steels depends on the balance of the alloying elements; it results from the individual properties of each of the elements, but also from their interaction. w The effect of tungsten results from the formation of carbides, in the composition of which this element intervenes. It competes with chromium and molybdenum, knowing that a predominance of chromium carbides is harmful for stability in service. However: 15 - the crystallographic nature of carbides formed according to steels is still poorly understood today,
  • the subject of the invention is also a process for the preparation of tool steel having the composition defined above, in which, according to a particular embodiment, an appropriate annealing treatment is carried out, before heat treatment for use, to result in a metallographic structure 5 showing fine and well distributed carbides.
  • the quenching is carried out by heating the part to a temperature between 1020 ° C and 1100 ° C, preferably between 1040 ° C and 1070 ° C, then by cooling in a stepped quench at 250 ° C / 320 ° C by any suitable means.
  • the desired properties are obtained after carrying out two tempering treatments, after quenching, the first tempering being carried out in the temperature range 550 ° C / 580 ° C, and the second in the range 580 ° C / 680 ° C adjusted according to the hardness of use sought.
  • Example 3 Stress rupture tests These tests were carried out on steel A according to the invention, as well as on another steel grade with 5% chromium, 1.2% molybdenum and 0.5% of vanadium and aimed to determine the stress necessary to obtain a rupture of the test pieces in 100 hours. The results are collated in Table 3 below.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Heat Treatment Of Steel (AREA)
  • Lubricants (AREA)
  • Heat Treatment Of Articles (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)

Abstract

The invention relates to a tool steel composition comprising, expressed in weight percentage:C 0.3%-0.4%Cr 2.0%-4.0%Mo 0.8%-3.0%V 0.4%-1.0%W 1.5%-3.0%Co 1.0%-5.0%Si 0 %-1.0%Mn 0 %-1.0%Ni 0 %-1.0%the balance being mainly constituted by iron and inevitable impurities, and also to a method of preparing the composition.

Description

Composition d'acier à outilsTool steel composition
La présente invention concerne un acier de la famille dite de 3% à 5% en poids de chrome utilisée pour la fabrication d'outillages résistant à la chaleur et travaillant sous de fortes contraintes tels que les matrices d'estampage et de forgeage, les outils de filières et les moules de coulée statique ou coulée sous pression d'alliages divers comme les alliages d'aluminium, de cuivre ou de titane.The present invention relates to a steel of the family known as 3% to 5% by weight of chromium used for the manufacture of tools resistant to heat and working under high stresses such as stamping and forging dies, tools dies and molds for static casting or die casting of various alloys such as aluminum, copper or titanium alloys.
De tels aciers sont alliés en chrome, molybdène et vanadium, éléments qui leur confèrent les propriétés de résistance à chaud requises.Such steels are alloyed with chromium, molybdenum and vanadium, elements which give them the required heat resistance properties.
Plus précisément, ils se répartissent en trois familles de compositions dont les propriétés sont voisines, de sorte que ces trois familles sont mises en oeuvre pour les mêmes applications. Il s'agit de compositions comprenant, exprimés en poids, les éléments d'alliages suivants : * 5% de chrome, 1 ,3% de molybdène, 0,5% à 1 ,3% de vanadium environ, ouMore precisely, they are divided into three families of compositions whose properties are similar, so that these three families are used for the same applications. These are compositions comprising, expressed by weight, the following alloying elements: * 5% of chromium, 1, 3% of molybdenum, 0.5% to 1, 3% of vanadium approximately, or
* 3% de chrome, 3% de molybdène, 0,5% de vanadium environ, ou enfin* 3% chromium, 3% molybdenum, 0.5% vanadium approximately, or finally
* 5% de chrome, 3% de molybdène, 0,8% de vanadium environ.* 5% chromium, 3% molybdenum, 0.8% vanadium approximately.
Certains de ces aciers sont désignés dans la nomenclature des Etats-Unis d'Amérique AISI sous les dénominations H11 , H12, H13, dans la nomenclature allemande DIN sous les dénominations W1.2343, W1.2606 et W1.2344, et sont cités dans la norme française NF A 35-590.Some of these steels are designated in the United States of America AISI nomenclature under the names H11, H12, H13, in the German DIN nomenclature under the names W1.2343, W1.2606 and W1.2344, and are cited in French standard NF A 35-590.
Lors de l'utilisation, la surface des outillages est mise en contact avec des matériaux chauffés à haute température, par exemple de l'aluminium liquide à 600°C / 750°C ou de l'acier destiné à être forgé et préchauffé à 1200X.During use, the surface of the tools is brought into contact with materials heated to high temperature, for example liquid aluminum at 600 ° C / 750 ° C or steel intended to be forged and preheated to 1200X .
En conséquence, la surface de l'outillage est elle-même portée à haute température : il en résulte qu'un régime thermique s'établit dans l'outillage entre la partie travaillante soumise à échauffement et le reste de la pièce refroidie par des conditions naturelles ou forcées. 2Consequently, the surface of the tool is itself brought to high temperature: it follows that a thermal regime is established in the tool between the working part subjected to heating and the rest of the part cooled by conditions natural or forced. 2
Dans des conditions d'utilisation sévères mettant en jeu des températures de surface élevées et des contraintes mécaniques fortes, la destruction de l'outil devient rapide selon deux principes :Under severe conditions of use involving high surface temperatures and strong mechanical constraints, the destruction of the tool becomes rapid according to two principles:
- la résistance mécanique du matériau décroît régulièrement lorsque la température s'élève,- the mechanical resistance of the material decreases regularly when the temperature rises,
- le matériau perd ses propriétés initiales qui avaient été conférées par le traitement thermique préliminaire du fait que des transformations métallurgiques se produisent sous l'effet combiné des contraintes et de la température et provoquent l'abaissement, puis l'effondrement de la résistance mécanique. On observe ainsi des détériorations rapides voire catastrophiques de ces outillages employés dans des conditions sévères, par adoucissement, fluage, déformation plastique et fatigue thermique de la surface travaillante. La présente invention a pour premier objet une composition d'acier permettant une bonne tenue en service dans lesdites conditions sévères.- The material loses its initial properties which had been conferred by the preliminary heat treatment due to the fact that metallurgical transformations occur under the combined effect of stresses and temperature and cause the lowering, then the collapse of the mechanical resistance. We thus observe rapid or even catastrophic deterioration of these tools used under severe conditions, by softening, creep, plastic deformation and thermal fatigue of the working surface. The present invention firstly relates to a steel composition allowing good performance in service under said severe conditions.
La composition objet de l'invention comprend, exprimés en pourcentages en poids :The composition which is the subject of the invention comprises, expressed in percentages by weight:
C 0,3 - 0,4%C 0.3 - 0.4%
Cr 2,0 - 4,0%Cr 2.0 - 4.0%
Mo 0,8 - 3,0%MB 0.8 - 3.0%
V 0,4 - 1 ,0%V 0.4 - 1.0%
W 1 ,5 - 3,0%W 1.5, 3.0%
Co 1 ,0 - 5,0%Co 1.0, 5.0%
Si 0 - 1 ,0%If 0 - 1.0%
Mn 0 - 1 ,0% Ni 0 - 1 ,0% le complément étant principalement constitué de fer et d'impuretés inévitables. De préférence, la composition se situe dans les limites suivantes :Mn 0 - 1.0% Ni 0 - 1, 0% the complement being mainly made up of iron and unavoidable impurities. Preferably, the composition is within the following limits:
C 0,33 - 0,37%C 0.33 - 0.37%
Cr 2,58 - 3,50%Cr 2.58 - 3.50%
Mo 1,20 - 2,20%MB 1.20 - 2.20%
V 0,6 - 0,9%V 0.6 - 0.9%
W 1 ,8 - 2,6%W 1.8, 2.6%
Co 1 ,5 - 3,0%Co 1.5, 3.0%
Si 0,2 - 0,5%If 0.2 - 0.5%
Mn 0,2 - 0,5% Ni 0 - 0,3%Mn 0.2 - 0.5% Ni 0 - 0.3%
De façon plus particulièrement préférée, la composition objet de l'invention comprend des teneurs en P, Sb, Sn et As, exprimées en pourcentages en poids, qui satisfont aux relations :More particularly preferably, the composition which is the subject of the invention comprises contents of P, Sb, Sn and As, expressed in percentages by weight, which satisfy the relationships:
P < 0,008%P <0.008%
Sb ≤ 0,002%Sb ≤ 0.002%
Sn < 0,003%Sn <0.003%
As < 0,005% tandis que la valeur exprimée par la relation de BruscatoAs <0.005% while the value expressed by the Bruscato relation
B = (10 P + 5 Sb + 4 Sn + As) x 0,01B = (10 P + 5 Sb + 4 Sn + As) x 0.01
est au plus égale à 0, 10%.is at most equal to 0.10%.
L'ensemble des éléments d'alliages dont les actions se complètent est équilibré pour donner une trempabilité suffisante nécessaire pour l'obtention de propriétés homogènes dans l'épaisseur de pièces de forte taille.The set of alloying elements whose actions complement each other is balanced to give sufficient quenchability necessary for obtaining homogeneous properties in the thickness of large parts.
Le carbone est l'élément durcissant de base, son niveau est ajusté pour obtenir une résistance mécanique suffisante, tout en évitant par un excès de concentration la formation de carbures eutectiques à la solidification. Sa teneur dans l'alliage selon l'invention est de 0,3-0,4% en poids, de préférence 0,33-0,37% en poids.Carbon is the basic hardening element, its level is adjusted to obtain sufficient mechanical resistance, while avoiding by excess concentration the formation of eutectic carbides at the solidification. Its content in the alloy according to the invention is 0.3-0.4% by weight, preferably 0.33-0.37% by weight.
Le chrome et le molybdène contribuent à la trempabilité et au durcissement après trempe et revenu par formation de carbures alliés lors des traitements thermiques de revenu. La teneur en ces éléments ne doit pas être excessive pour ne pas favoriser exagérément la formation de carbures de chrome-molybdène au détriment des carbures de vanadium et tungstène. La teneur en chrome dans l'alliage selon l'invention est de 2,0- 4,0% en poids, de préférence 2,50-3,50% en poids, quant à celle du molybdène elle est de 0,8-3,0% en poids, de préférence 1 ,20-2,20% en poids.Chromium and molybdenum contribute to quenchability and hardening after quenching and tempering by the formation of alloyed carbides during thermal tempering treatments. The content of these elements should not be excessive so as not to favor excessively the formation of chromium-molybdenum carbides to the detriment of vanadium and tungsten carbides. The chromium content in the alloy according to the invention is 2.0-4.0% by weight, preferably 2.50-3.50% by weight, as for that of molybdenum it is 0.8- 3.0% by weight, preferably 1.20-2.20% by weight.
Le vanadium contribue au durcissement lors des traitements de revenu par formation de carbures spécifiques, ce qui permet d'augmenter la résistance structurale à réchauffement, donc de décaler vers le haut les températures supérieures admissibles en service. Un excès de cet élément serait préjudiciable à la ténacité par formation de carbures eutectiques à la solidification et par le caractère ségrégant de cet élément. Sa teneur dans l'alliage selon l'invention est de 0,4-1 ,0% en poids, de préférence 0,6-0,9% en poids. Le tungstène, de la même manière, complète l'action du vanadium par les mêmes types de mécanismes et contribue de même au relèvement des températures compatibles d'emploi et, de la même manière, un excès serait préjudiciable à la ténacité et à l'homogénéité structurale. Sa teneur dans l'alliage selon l'invention est de 1 ,5-3,0% en poids, de préférence 1 ,8- 2,6% en poids.Vanadium contributes to hardening during tempering treatments by the formation of specific carbides, which makes it possible to increase the structural resistance to heating, therefore to shift upwards the higher temperatures admissible in service. An excess of this element would be detrimental to the toughness by the formation of eutectic carbides on solidification and by the segregating nature of this element. Its content in the alloy according to the invention is 0.4-1.0% by weight, preferably 0.6-0.9% by weight. Tungsten, in the same way, supplements the action of vanadium by the same types of mechanisms and contributes in the same way to the raising of the compatible temperatures of use and, in the same way, an excess would be detrimental to the toughness and the structural homogeneity. Its content in the alloy according to the invention is 1.5-3.0% by weight, preferably 1.8-2.6% by weight.
Ce sont les actions complémentaires et convenablement équilibrées de ces quatre éléments carburigènes Cr, Mo, V et W qui confèrent à l'acier de l'invention des propriétés nouvelles.It is the complementary and suitably balanced actions of these four carburetogenic elements Cr, Mo, V and W which give the steel of the invention new properties.
Le cobalt améliore la résistance mécanique à chaud. Sa teneur dans l'alliage selon l'invention est de 1 ,0-5,0% en poids, de préférence 1 ,5-3,0% en poids. Les teneurs du silicium et du manganèse dans l'alliage selon l'invention sont chacune de 0-1 ,0% en poids, de préférence 0,20-0,50% en poids. La teneur du nickel dans l'alliage selon l'invention est de 0-1 ,0% en poids, de préférence 0-0,30% en poids. 5 De manière plus générale, bien que l'on ne souhaite pas être lié par une quelconque théorie, on estime ainsi que l'obtention de bonnes caractéristiques pour de tels aciers dépend de l'équilibrage des éléments d'alliage ; elle résulte des propriétés individuelles de chacun des éléments, mais aussi de leur interaction. w L'effet du tungstène découle de la formation de carbures, dans la composition desquels cet élément intervient. Il est en compétition avec le chrome et le molybdène, sachant qu'une présominance des carbures de chrome est néfaste pour la stabilité en service. Cependant : 15 - la nature cristallographique des carbures formés selon les aciers est encore mal connue de nos jours,Cobalt improves mechanical resistance when hot. Its content in the alloy according to the invention is 1.0-5.0% by weight, preferably 1.5-5.0% by weight. The contents of silicon and manganese in the alloy according to the invention are each 0-1.0% by weight, preferably 0.20-0.50% by weight. The content of nickel in the alloy according to the invention is 0-1.0% by weight, preferably 0-0.30% by weight. More generally, although it is not desired to be bound by any theory, it is therefore believed that obtaining good characteristics for such steels depends on the balance of the alloying elements; it results from the individual properties of each of the elements, but also from their interaction. w The effect of tungsten results from the formation of carbides, in the composition of which this element intervenes. It competes with chromium and molybdenum, knowing that a predominance of chromium carbides is harmful for stability in service. However: 15 - the crystallographic nature of carbides formed according to steels is still poorly understood today,
- l'effet de ces carbures sur les propriétés et la stabilité structurale ne sont connus que dans les grandes lignes. L'acier de l'invention est fabriqué selon les procédés applicables aux 20 matériaux usuels cités en référence.- The effect of these carbides on the properties and the structural stability are only known in broad outline. The steel of the invention is manufactured according to the methods applicable to the usual materials cited in reference.
L'invention a également pour objet un procédé pour la préparation d'acier à outils ayant la composition définie ci-dessus, dans lequel, selon un mode de réalisation particulier, un traitement de recuit approprié est pratiqué, avant traitement thermique d'emploi, pour aboutir à une structure 5 métallographique montrant des carbures fins et bien répartis.The subject of the invention is also a process for the preparation of tool steel having the composition defined above, in which, according to a particular embodiment, an appropriate annealing treatment is carried out, before heat treatment for use, to result in a metallographic structure 5 showing fine and well distributed carbides.
Dans un mode de réalisation particulier, on réalise la trempe en chauffant la pièce à une température comprise entre 1020°C et 1100°C, de préférence entre 1040°C et 1070°C, puis en refroidissant selon une trempe étagée à 250°C / 320°C par tout moyen adapté. 30 Dans un mode de réalisation particulier, les propriétés recherchées sont obtenues après réalisation de deux traitements de revenu, après trempe, le premier revenu étant effectué dans l'intervalle de températures 550°C / 580°C, et le second dans l'intervalle 580°C / 680°C ajusté en fonction de la dureté d'emploi recherchée.In a particular embodiment, the quenching is carried out by heating the part to a temperature between 1020 ° C and 1100 ° C, preferably between 1040 ° C and 1070 ° C, then by cooling in a stepped quench at 250 ° C / 320 ° C by any suitable means. In a particular embodiment, the desired properties are obtained after carrying out two tempering treatments, after quenching, the first tempering being carried out in the temperature range 550 ° C / 580 ° C, and the second in the range 580 ° C / 680 ° C adjusted according to the hardness of use sought.
Dans un autre mode particulier de réalisation du procédé selon l'invention, on réalise, à partir du métal produit par un procédé d'aciérie conventionnel, une refusion par électrode consommable sous vide ou par électrode consommable sous laitier conférant au matériau une propreté inclusionnaire améliorée et une meilleure homogénéité chimique, ce qui a pour effet d'augmenter les propriétés de ténacité et par voie de conséquence de tenue en service. L'invention va à présent être illustrée au moyen des exemples qui suivent. EXEMPLESIn another particular embodiment of the method according to the invention, there is produced, from the metal produced by a conventional steelmaking process, remelting by consumable electrode under vacuum or by consumable electrode under slag giving the material improved inclusional cleanliness and better chemical homogeneity, which has the effect of increasing the toughness properties and consequently of the service life. The invention will now be illustrated by means of the following examples. EXAMPLES
Une coulée d'essai d'un acier A selon l'invention, dont la composition est donnée dans le tableau ci-dessous, a été réalisée afin de procéder aux différents essais :A test casting of a steel A according to the invention, the composition of which is given in the table below, was carried out in order to carry out the various tests:
C 0,354 %C 0.354%
Cr 3,09 %Cr 3.09%
Mo 1 ,36 %MB 1.36%
V 0,81 %V 0.81%
W 2,26 %W 2.26%
Co 2,00 %Co 2.00%
Si 0,31 %If 0.31%
Mn 0,30 %Mn 0.30%
Ni 0,08 %Ni 0.08%
P 0,007 % le complément étant constitué de fer et d'impuretés inévitables.P 0.007% the remainder consisting of iron and unavoidable impurities.
Les différents matériaux de référence utilisés pour ces essais sont des aciers à 5% de chrome contenant des quantités variables de molybdène et de vanadium. Les symboles utilisés dans la suite ont les significations suivantes :The different reference materials used for these tests are 5% chromium steels containing varying amounts of molybdenum and vanadium. The symbols used in the following have the following meanings:
Rm : résistance maximumR m : maximum resistance
Rpo,2 : limite élastique conventionnelle à 0,2% HRC : dureté Rockwell Exemple 1 - Essais de traction à chaudR p o, 2 : conventional elastic limit at 0.2% HRC: Rockwell hardness Example 1 - Hot tensile tests
Ces essais ont été réalisés à différentes températures sur l'acier A selon l'invention, ainsi que sur trois autres nuances classiques d'aciers à 5% de chrome contenant du molybdène et du vanadium. Les résultats sont rassemblés dans le tableau 1 suivant.These tests were carried out at different temperatures on steel A according to the invention, as well as on three other conventional grades of steel with 5% chromium containing molybdenum and vanadium. The results are collated in Table 1 below.
Tableau 1Table 1
Température Rm Rp0,2 Visée deTemperature Rm Rp0,2 Aim of
Matériaux d'essai (MPa) (MPa) traitementTest materials (MPa) (MPa) processing
(°C) (HRC)(° C) (HRC)
A 1092 916A 1092 916
520 46 5Cr 1.3Mo 0.5V 1088 851520 46 5Cr 1.3Mo 0.5V 1088 851
A 918 753A 918 753
5Cr 1.3Mo 0.5V 916 7095Cr 1.3Mo 0.5V 916 709
550 42 5Cr 3Mo 0.5V 842 664 5Cr 1.5Mo 1V 901 702550 42 5Cr 3Mo 0.5V 842 664 5Cr 1.5Mo 1V 901 702
A 1028 830A 1028 830
560 46 5CM.3Mo 0.5V 979 710560 46 5CM.3Mo 0.5V 979 710
A 955 745A 955 745
600 46 5Cr 1.3Mo 0.5V 796 552 600 46 5Cr 1.3Mo 0.5V 796 552
Comparativement aux matériaux de référence, on observe que la résistance à chaud décrite par l'essai de traction est améliorée, en particulier dès que la température d'emploi dépasse 550°C.Compared to the reference materials, it is observed that the hot resistance described by the tensile test is improved, in particular as soon as the temperature of use exceeds 550 ° C.
Exemple 2 - Essais de traction à chaud après maintien à la températureEXAMPLE 2 Hot Tensile Tests After Maintaining the Temperature
Ces essais ont été réalisés à la température de 550°C, après un maintien à 550°C pendant 50 heures, sur l'acier A selon l'invention ainsi que sur les trois autres nuances précédemment décrites dans l'exemple 1. Les résultats sont rassemblés dans le tableau 2 suivant. Tableau 2These tests were carried out at a temperature of 550 ° C., after being kept at 550 ° C. for 50 hours, on steel A according to the invention as well as on the three other grades previously described in example 1. The results are collated in the following table 2. Table 2
Température ΔRm ΔRpo,2 Visée deTemperature ΔR m ΔR p o, 2 Aim of
Matériaux d'essai (MPa) (MPa) traitement (X) (HRC)Test materials (MPa) (MPa) treatment (X) (HRC)
A -15 -13 42A -15 -13 42
5Cr 1.3Mo 0.5V -50 -40 425Cr 1.3Mo 0.5V -50 -40 42
550550
5Cr 3Mo 0.5V -18 -41 425Cr 3Mo 0.5V -18 -41 42
5Cr 1.5Mo 1V -101 -104 42 5Cr 1.5Mo 1V -101 -104 42
De la même manière, on observe que la résistance à chaud décrite par l'essai de traction est moins altérée par un maintien prolongé pendant 50 heures à la température d'emploi pour l'acier selon l'invention que pour les aciers de référence.In the same way, it is observed that the hot resistance described by the tensile test is less altered by a prolonged maintenance for 50 hours at the temperature of use for the steel according to the invention than for the reference steels.
Exemple 3 - Essais de rupture sous contrainte Ces essais ont été réalisés sur l'acier A selon l'invention, ainsi que sur une autre nuance d'acier à 5% de chrome, 1 ,2% de molybdène et 0,5% de vanadium et avaient pour but de déterminer la contrainte nécessaire pour obtenir une rupture des eprouvettes en 100 heures. Les résultats sont rassemblés dans le tableau 3 suivant. Example 3 - Stress rupture tests These tests were carried out on steel A according to the invention, as well as on another steel grade with 5% chromium, 1.2% molybdenum and 0.5% of vanadium and aimed to determine the stress necessary to obtain a rupture of the test pieces in 100 hours. The results are collated in Table 3 below.
Tableau 3Table 3
Température Contrainte TraitéTemperature Constraint Processed
Matériaux d'essai (MPa) pourTest materials (MPa) for
(X) (HRC)(X) (HRC)
520 695520,695
A 560 555 42A 560 555 42
600 360600 360
520 795520,795
A 560 610 46A 560 610 46
600 400600 400
520 670520,670
5Cr 1.2Mo 0.5V 560 420 465Cr 1.2Mo 0.5V 560 420 46
600 195600 195
520 795520,795
5Cr 1.2Mo 0.5V 560 425 505Cr 1.2Mo 0.5V 560 425 50
600 188 600 188
De la même manière que précédemment, on observe que la tenue en fluage exprimée par la contrainte conduisant à la rupture en 100 heures, est supérieure pour l'acier selon l'invention.In the same way as above, it is observed that the creep behavior expressed by the stress leading to rupture in 100 hours, is higher for the steel according to the invention.
Exemple 4 - Essais de déformation sous contrainteEXAMPLE 4 Stress Deformation Tests
Ces essais ont été réalisés sur l'acier A selon l'invention, ainsi que sur la même nuance d'acier que celle utilisée dans l'exemple 3 et avaient pour but de déterminer la contrainte nécessaire pour obtenir une déformation de 1% des eprouvettes en 100 heures. Les résultats sont rassemblés dans le tableau 4 suivant. 10These tests were carried out on steel A according to the invention, as well as on the same steel grade as that used in Example 3 and were intended to determine the stress necessary to obtain a deformation of 1% of the test pieces in 100 hours. The results are collated in Table 4 below. 10
Tableau 4Table 4
Température Contrainte TraitéTemperature Constraint Processed
Matériaux d'essai (MPa) pourTest materials (MPa) for
(X) (HRC)(X) (HRC)
A 560 500 42A 560 500 42
A 560 640 46A 560 640 46
5Cr 1.2Mo 0.5V 560 350 465Cr 1.2Mo 0.5V 560 350 46
5Cr 1.2Mo 0.5V 560 370 50 5Cr 1.2Mo 0.5V 560 370 50
De la même manière que précédemment, on observe que la tenue en fluage exprimée par la contrainte conduisant à 1% de déformation en 100 heures, est supérieure pour l'acier selon l'invention.In the same way as above, it is observed that the creep behavior expressed by the stress leading to 1% deformation in 100 hours, is greater for the steel according to the invention.
Il va de soi que les formes de réalisation de la composition d'acier à outils selon l'invention qui ont été décrites ci-dessus ont été données à titre purement indicatif et nullement limitatif, et que de nombreuses modifications peuvent être facilement apportées par l'homme de l'art sans pour autant sortir du cadre de l'invention. It goes without saying that the embodiments of the tool steel composition according to the invention which have been described above have been given for information only and are in no way limitative, and that numerous modifications can be easily made by 'skilled in the art without departing from the scope of the invention.

Claims

11REVENDICATIONS 11 CLAIMS
1. Composition d'acier à outil comprenant, exprimés en pourcentages en poids :1. Composition of tool steel comprising, expressed in percentages by weight:
C 0,3 - 0,4%C 0.3 - 0.4%
Cr 2,0 - 4,0%Cr 2.0 - 4.0%
Mo 0,8 - 3,0%MB 0.8 - 3.0%
V 0,4 - 1 ,0%V 0.4 - 1.0%
W 1,5-3,0%W 1.5-3.0%
Co 1,0-5,0%Co 1.0-5.0%
Si 0-1,0%If 0-1.0%
Mn 0-1,0% Ni 0 - 1 ,0% le complément étant principalement constitué de fer et d'impuretés inévitables.Mn 0-1.0% Ni 0 - 1, 0% the complement being mainly made up of iron and unavoidable impurities.
2. Composition d'acier à outils selon la revendication 1 comprenant, exprimés en pourcentages en poids :2. A composition of tool steel according to claim 1 comprising, expressed in percentages by weight:
C 0,33 - 0,37%C 0.33 - 0.37%
Cr 2,58 - 3,50%Cr 2.58 - 3.50%
Mo 1,20-2,20%MB 1.20-2.20%
V 0,60 - 0,90%V 0.60 - 0.90%
3. Composition d'aciers à outils selon la revendication 1 ou 2, caractérisée en ce que les teneurs de cette composition en P, Sb, Sn et As, exprimées en pourcentages en poids, satisfont aux relations3. Composition of tool steels according to claim 1 or 2, characterized in that the contents of this composition in P, Sb, Sn and As, expressed in percentages by weight, satisfy the relationships
P < 0,008%P <0.008%
Sb < 0,002% 12Sb <0.002% 12
Sn < 0,003%Sn <0.003%
As < 0,005% tandis que la valeur exprimée par la relation de BruscatoAs <0.005% while the value expressed by the Bruscato relation
B = (10 P + 5 Sb + 4 Sn + As) x 0,01B = (10 P + 5 Sb + 4 Sn + As) x 0.01
est au plus égale à 0,10%.is at most equal to 0.10%.
4. Composition d'aciers à outils selon la revendication 1 , caractérisée en ce qu'elle comprend de 1 ,8% à 2,6% en poids de tungstène.4. Composition of tool steels according to claim 1, characterized in that it comprises from 1.8% to 2.6% by weight of tungsten.
5. Composition d'aciers à outils selon la revendication 1 , caractérisée en ce qu'elle comprend de 1 ,5% à 3,0% en poids de cobalt. 5. Composition of tool steels according to claim 1, characterized in that it comprises from 1.5% to 3.0% by weight of cobalt.
6. Composition d'aciers à outils selon la revendication 1 , caractérisée en ce qu'elle comprend de 0,20 % à 0,50% en poids de silicium.6. Composition of tool steels according to claim 1, characterized in that it comprises from 0.20% to 0.50% by weight of silicon.
7. Composition d'aciers à outils selon la revendication 1 , caractérisée en ce qu'elle comprend de 0,20 % à 0,50% en poids de manganèse.7. Composition of tool steels according to claim 1, characterized in that it comprises from 0.20% to 0.50% by weight of manganese.
8. Composition d'aciers à outils selon la revendication 1 , caractérisée en ce qu'elle comprend moins de 0,30% en poids de nickel.8. Composition of tool steels according to claim 1, characterized in that it comprises less than 0.30% by weight of nickel.
9. Procédé de préparation d'acier à outils de composition selon l'une quelconque des revendications 1 à 8, caractérisé en ce qu'il comporte une trempe comprenant :9. A process for the preparation of composition tool steel according to any one of claims 1 to 8, characterized in that it comprises a quenching comprising:
- un chauffage de l'acier à des températures comprises entre 1020X et HOOX et- heating the steel to temperatures between 1020X and HOOX and
- une trempe étagée à des températures comprises entre 250X et 320X.- stepped quenching at temperatures between 250X and 320X.
10. Procédé selon la revendication 9, caractérisé en ce qu'il comporte une trempe comprenant : - un chauffage de l'acier à des températures comprises entre 1040X et 1070X et10. Method according to claim 9, characterized in that it comprises a quenching comprising: - a heating of the steel to temperatures between 1040X and 1070X and
- une trempe étagée à des températures comprises entre 250X et 320X. 13- stepped quenching at temperatures between 250X and 320X. 13
11. Procédé selon la revendication 9 ou 10, caractérisé en ce que l'acier est soumis à un revenu à des températures comprises entre 550X et 580X, à l'issue de l'opération de trempe.11. Method according to claim 9 or 10, characterized in that the steel is subjected to tempering at temperatures between 550X and 580X, at the end of the quenching operation.
12. Procédé selon la revendication 11 , caractérisé en ce que l'acier est soumis à un deuxième revenu à des températures comprises entre12. Method according to claim 11, characterized in that the steel is subjected to a second tempering at temperatures between
580X et 680X, à l'issue du premier revenu.580X and 680X, after the first income.
13. Procédé de préparation d'acier à outils de composition selon l'une quelconque des revendications 1 à 8, caractérisé en ce qu'il comporte une refusion par électrode consommable sous vide ou par électrode consommable sous laitier. 13. A process for the preparation of compositional tool steel according to any one of claims 1 to 8, characterized in that it comprises a remelting by electrode consumable under vacuum or by electrode consumable under slag.
EP99910459A 1998-04-02 1999-03-30 Tool steel composition Expired - Lifetime EP0991789B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9804122A FR2777023B1 (en) 1998-04-02 1998-04-02 COMPOSITION OF TOOL STEEL
FR9804122 1998-04-02
PCT/FR1999/000735 WO1999051788A1 (en) 1998-04-02 1999-03-30 Tool steel composition

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EP0991789B1 EP0991789B1 (en) 2003-05-02

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US7700210B2 (en) * 2005-05-10 2010-04-20 Bloom Energy Corporation Increasing thermal dissipation of fuel cell stacks under partial electrical load
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SE364997B (en) * 1972-07-17 1974-03-11 Bofors Ab
JPS5436893B2 (en) * 1973-11-28 1979-11-12
JPS516117A (en) * 1974-07-06 1976-01-19 Daido Steel Co Ltd TAINETSUSHOGEKISEIOKAIRYOSHITA KOJINSEITEITANKABUTSUKEINETSUKANKOGUKO
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BR9906337A (en) 2000-10-03
CA2292742A1 (en) 1999-10-14
FR2777023A1 (en) 1999-10-08
DE991789T1 (en) 2001-01-11
EP0991789B1 (en) 2003-05-02
DE69907358D1 (en) 2003-06-05
US6280685B1 (en) 2001-08-28
FR2777023B1 (en) 2000-06-16

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