EP0120748A1 - High-resistance rod and its production method - Google Patents

High-resistance rod and its production method Download PDF

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Publication number
EP0120748A1
EP0120748A1 EP84400405A EP84400405A EP0120748A1 EP 0120748 A1 EP0120748 A1 EP 0120748A1 EP 84400405 A EP84400405 A EP 84400405A EP 84400405 A EP84400405 A EP 84400405A EP 0120748 A1 EP0120748 A1 EP 0120748A1
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EP
European Patent Office
Prior art keywords
approximately
bar
weight
grinding
bars
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EP84400405A
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German (de)
French (fr)
Inventor
Michel Thome
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Acieries Thome Cromback SA
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Acieries Thome Cromback SA
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Publication of EP0120748A1 publication Critical patent/EP0120748A1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/18—Details
    • B02C17/20—Disintegrating members
    • 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
    • C22C38/36—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.7% by weight of carbon
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4998—Combined manufacture including applying or shaping of fluent material
    • Y10T29/49988—Metal casting

Definitions

  • the grinding bodies are long bars (80 mm in diameter by a few meters in length), arranged in a cylindrical grinder approximately horizontally.
  • These grinding bars are used in fine or coarse grinding, dry or wet, and the products obtained are optionally further processed in ball mills.
  • These materials are made of low-alloy steel, with a carbon content less than or equal to 1.1% for, for example, a steel, according to AISI 52100 or 1095 with more or less manganese (Steel 50 MC 4 developed by CREUSOT LOIRE).
  • the bars are rough of rolling and dressing and, possibly, treated according to processes which preserve the straightness of the bar (U.S. Patent 3,255,053; communication from the CREUSOT LOIRE Company to the Abrasion Congress of 1979).
  • the treatment consists of an austenization heater, followed by cooling (quenching) to obtain an approximately martensitic structure of 55 to 60 RC.
  • Bimetallic bars have also been used, the core of which is made of mild steel and the surface of which is hard steel.
  • the present invention aims to provide grinding bars made of a material sufficiently loaded with carbon and alloy to produce quantities and types of carbides providing satisfactory resistance to wear.
  • the invention also aims to propose a method for manufacturing such bars which does not involve rolling.
  • the subject of the invention is a grinding bar made of ferrous metal, coming directly from directed solidification casting, characterized in that it has a fine-grained surface structure and a core with a dendritic structure oriented radially, and in that it comprises, in% by weight, between approximately 1.1 and 3% of carbon, between approximately 3 and 30% of chromium, between approximately 0.3 and 1.5% of manganese and between approximately 0.3 and 1% silicon.
  • these bars may also contain, in% by weight, from 0 to 1% of copper, from 0 to 5% of nickel, from 0 to 1% of molybdenum, from 0 to 1% of titanium , from 0 to 0.5% boron, from O to 2% of vanadium and from O to 2% of tungsten.
  • the invention also relates to a method of manufacturing such a grinding bar, characterized in that it is carried out by continuous casting of a ferrous metal of suitable composition, with directed solidification, to the exclusion of any phase rolling.
  • the grinding bars according to the present invention do not have fibers oriented in the longitudinal direction, that is to say parallel to the axis of the bar.
  • this structure will have to be thinner and thinner going from the core to the surface of the bar.
  • the grinding bars are subject to wear and corrosion from their surface, until they reach a certain diameter, where they are eliminated. It is therefore preferable that they break into small pieces, rather than bending and becoming entangled with the other bars.
  • the internal structure should preferably be coarse, case-sensitive.
  • the object of the present invention is to propose a grinding bar whose characteristics are much superior, thanks to the use of a different material and due to a particular structure obtained by an original process.
  • such a grinding bar is made of a steel having a high carbon content and a high percentage of carbide.
  • Table 1 below compares different types of grinding bars known in the art and those according to the invention.
  • the bar object of the invention has, on the surface, a homogeneous grain structure not oriented in the longitudinal direction; it is not a laminated structure with stretching of the fibers, elongation of inclusion, possible line, it is a clean structure resulting from the process.
  • this structure comprises a high percentage of carbide of the type M 3 C, M 7 C 3 , M 23 C 6 depending on the type of alloy, M denoting a compound iron-alloy.
  • the internal structure of the bar object of the invention has an orientation perpendicular to the cylindrical surface, in the form of a dendrite.
  • the hardness of carbides oriented in this direction is greater than their lateral hardness; the micro-hardness of the surface of the bar will therefore remain high even after reduction of the diameter by abrasion.
  • the radial dendrite structure ensures sufficient fragility of the metal to cause it to break into pieces below a certain diameter of the bar.
  • the bar according to the invention therefore has, on the surface, over a certain thickness, a fine-grained structure, while its core is of radial dendritic structure.
  • austenitic martensitic or bainitic, with hardnesses and constitutions of matrices and variable carbides.
  • Such a bar can only be produced by the method according to the invention, which will now be described in more detail.
  • the manufacture of the bar must also be eliminated by compacting sintered powder, an expensive process which gives a homogeneous structure in all directions without any particular advantage.
  • the bar according to the invention is produced by continuous horizontal casting, with a final diameter of 50 to 100 mm and at the required length, from 2 to 6 m and more. Directed solidification and the formation of the fine structure on the surface and dendritic at heart are obtained by appropriate adjustments of the conditions of extraction of the bar from the production ingot mold, either at a pitch of between 1 and 50 mm or a ratio P / D (length of step relative to the diameter of the bar) from 5/100 to 5/10.
  • the bar is cooled in a controlled manner to obtain the matrix and the morphology of the desired carbides.
  • This cooling can be a thermal cycle down in temperature, then up, followed by a bearing and cooling.
  • the process according to the invention provides a product which can be used directly in ordinary mills.
  • an additional or complementary heat treatment may be carried out.
  • the shredding bars In the event of a particularly high impact stress in very high power shredders, or of large shredder diameter, the shredding bars must have no surface defect, crack line, etc. These faults are well known in the state of the technique, are generally linked to the rolling process and to the possible segregations due to the ingot or the rough billet.
  • the bar which is the subject of the invention does not have any faults of this kind.
  • the constituent alloy of the bar and its manufacturing process there may be adherent calamines, surface reliefs or surface microsegregations on the product.
  • adherent calamines, surface reliefs or surface microsegregations on the product.
  • This bar has on the whole a diameter of 80 mm and is obtained by horizontal continuous casting in a machine with controlled extraction parameter giving a pitch of 10 mm.
  • the cooling of the bar between 1180 ° C temperature at the outlet of the mold and 400 ° C, will be done in 30 minutes.
  • the bar is cut in hot line to a length of 3.10 m.
  • Such a bar according to the invention has a hardness of 40 RC. Its surface structure is austenitic and has a fine grain layer over a thickness of 5 mm. The core of the bar has a hardness of 32 RC and its structure is dendritic.
  • the bars according to the invention therefore have a wear resistance much higher than the usual bars.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

L'invention concerne une barre de broyage en métal ferreux, issue directement d'une coulée à solidification dirigée, caractérisée en ce qu'elle présente une structure de surface à grain fin et un coeur à structure dendritique orientée radialement, en ce qu'elle comprend, en % en poids, entre environ 1,1 et 3% de carbone, entre environ 3 et 30% de chrome, entre environ 0,3 et 1,5% de manganèse et entre environ 0,3 et 1% de silicium, et en ce qu'elle comporte au moins 10% en volume de carbures.The invention relates to a grinding bar made of ferrous metal, coming directly from a directed solidification casting, characterized in that it has a fine-grained surface structure and a core with a dendritic structure oriented radially, in that it comprises, in% by weight, between approximately 1.1 and 3% of carbon, between approximately 3 and 30% of chromium, between approximately 0.3 and 1.5% of manganese and between approximately 0.3 and 1% of silicon , and in that it comprises at least 10% by volume of carbides.

Description

Pour le broyage de divers produits, on utilise une technique de broyage dans laquelle les corps broyants sont des barres longues (80 mm de diamètre par quelques mètres de longueur), disposées dans un broyeur cylindrique à peu près horizontalement.For the grinding of various products, a grinding technique is used in which the grinding bodies are long bars (80 mm in diameter by a few meters in length), arranged in a cylindrical grinder approximately horizontally.

Ces barres de broyage sont utilisées dans les broyages fins ou grossiers, à sec ou humide, et les produits obtenus sont éventuellement traités ensuite dans des broyeurs à boulets.These grinding bars are used in fine or coarse grinding, dry or wet, and the products obtained are optionally further processed in ball mills.

Bien des produits et des procédés ont été expérimentés comme barre de broyage, à commencer par des rails laminés rebutés, simplement coupés en longueur et utilisés en l'état.Many products and processes have been tested as a grinding bar, starting with discarded laminated rails, simply cut in length and used as is.

On a ainsi utilisé des barres réalisées en matériaux laminés à partir d'une ébauche (lingot ou billette), ce qui oriente les fibres du métal en long,par la déformation du métal à chaud, sous la pression de cylindre ou de marteau de frappe. Les fibres du métal sont alors orientées très fortement dans le sens longitudinal de la barre (voir par exemple le brevet U.S. 3 170 641).We thus used bars made of laminated materials from a blank (ingot or billet), which directs the fibers of the metal lengthwise, by the deformation of the hot metal, under the pressure of a cylinder or hammer . The metal fibers are then oriented very strongly in the longitudinal direction of the bar (see, for example, U.S. Patent 3,170,641).

Ces matériaux,pour être facilement laminables,sont en acier faiblement allié,avec une teneur en carbone inférieure ou égale à 1, 1% pour, par exemple,un acier ,selon AISI 52100 ou 1095 avec plus ou moins de manganèse (Acier 50 MC 4 développé par la Société CREUSOT LOIRE).These materials, to be easily laminable, are made of low-alloy steel, with a carbon content less than or equal to 1.1% for, for example, a steel, according to AISI 52100 or 1095 with more or less manganese (Steel 50 MC 4 developed by CREUSOT LOIRE).

Les barres sont brutes de laminage et dressage et, éventuellement, traitées selon des procédés qui conservent la rectitude de la barre (brevet U.S. 3 255 053 ; communication de la Société CREUSOT LOIRE au Congrès Abrasion de 1979). Le traitement consiste en une chauffe d'austénisation, suivie d'un refroidissement (trempe) pour obtenir une structure à peu près martensitique de 55 à 60 RC. On a également utilisé des barres bimétalliques, dont le noyau est en acier doux et la surface en acier dur.The bars are rough of rolling and dressing and, possibly, treated according to processes which preserve the straightness of the bar (U.S. Patent 3,255,053; communication from the CREUSOT LOIRE Company to the Abrasion Congress of 1979). The treatment consists of an austenization heater, followed by cooling (quenching) to obtain an approximately martensitic structure of 55 to 60 RC. Bimetallic bars have also been used, the core of which is made of mild steel and the surface of which is hard steel.

Tous ces matériaux utilisés sont laminables à un coût raisonnable ce sont donc des matériaux à teneur limitée en carbone et en alliage.Cependant,pour cette raison, leur usure est élevée, du fait d'une quantité insuffisante de carbure et d'alliage pour résister à la corrosion.All these materials used can be laminated at a reasonable cost, so they are materials with limited carbon and alloy content, however, their wear is high, due to an insufficient quantity of carbide and alloy to resist corrosion.

La présente invention vise à proposer des barres de broyage en un matériau suffisamment chargé en carbone et en alliage pour produire des quantités et types de carbures procurant une résistance satisfaisante à l'usure.The present invention aims to provide grinding bars made of a material sufficiently loaded with carbon and alloy to produce quantities and types of carbides providing satisfactory resistance to wear.

L'invention vise également à proposer un procédé de fabrication de telles barres ne faisant pas intervenir de laminage.The invention also aims to propose a method for manufacturing such bars which does not involve rolling.

A cet effet, l'invention a pour objet une barre de broyage en métal ferreux, issue directement de coulée à solidification dirigée, caractérisée en ce qu'elle présente une structure de surface à grain fin et un coeur à structure dendritique orientée radialement, et en ce qu'elle comprend, en % en poids, entre environ 1,1 et 3 % de carbone, entre environ 3 et 30 % de chrome, entre environ 0,3 et 1,5 % de manganèse et entre environ 0,3 et 1 % de silicium.To this end, the subject of the invention is a grinding bar made of ferrous metal, coming directly from directed solidification casting, characterized in that it has a fine-grained surface structure and a core with a dendritic structure oriented radially, and in that it comprises, in% by weight, between approximately 1.1 and 3% of carbon, between approximately 3 and 30% of chromium, between approximately 0.3 and 1.5% of manganese and between approximately 0.3 and 1% silicon.

Suivant les applications envisagées pour ces barres, elles pourront en outre contenir, en % en poids, de 0 à 1 % de cuivre, de 0 à 5 % de nickel, de 0 à 1 % de molybdène, de O à 1 % de titane, de 0 à 0,5 % de bore, de O à 2 % de vanadium et de O à 2 % de tungstène.Depending on the applications envisaged for these bars, they may also contain, in% by weight, from 0 to 1% of copper, from 0 to 5% of nickel, from 0 to 1% of molybdenum, from 0 to 1% of titanium , from 0 to 0.5% boron, from O to 2% of vanadium and from O to 2% of tungsten.

Ces barres contiendront au moins 10 % en volume de carbures.These bars will contain at least 10% by volume of carbides.

L'invention a également pour objet un procédé de fabrication d'une telle barre de broyage, caractérisé en ce qu'on la réalise par coulée continue d'un métal ferreux de composition convenable, avec solidification dirigée, à l'exclusion de toute phase de laminage.The invention also relates to a method of manufacturing such a grinding bar, characterized in that it is carried out by continuous casting of a ferrous metal of suitable composition, with directed solidification, to the exclusion of any phase rolling.

Du fait de ce procédé, contrairement aux barres de la technique antérieure, les barres de broyage conformes à la présente invention ne présentent pas de fibres orientées dans le sens longitudinal, c'est-à-dire parallèlement à l'axe de la barre.Due to this process, unlike the bars of the prior art, the grinding bars according to the present invention do not have fibers oriented in the longitudinal direction, that is to say parallel to the axis of the bar.

Il est bien connu quepour améliorer les performances d'usure et de résistance à la corrosion, cette structure devra être de plus en plus fine en allant du coeur vers la surface de la barre. En effet, les barres de broyage sont soumises à une usure et une corrosion à partir de leur surface, jusqu'à ce qu'elles atteignent un certain diamètre, où elles sont éliminées. Il est alors préférable qu'elles cassent en petits morceaux,plutôt que de fléchir et s'entremêler avec les autres barres. De ce fait, la structure interne devra, de préférence, être grossière, sensible à la casse.It is well known that in order to improve the wear and corrosion resistance performance, this structure will have to be thinner and thinner going from the core to the surface of the bar. Indeed, the grinding bars are subject to wear and corrosion from their surface, until they reach a certain diameter, where they are eliminated. It is therefore preferable that they break into small pieces, rather than bending and becoming entangled with the other bars. As a result, the internal structure should preferably be coarse, case-sensitive.

Les barres de broyage connues dans la technique présentent deux types de structure :

  • 1) Brutes de laminage structure perlitique, avec un grain identique sur toute la section.
  • 2) Laminées avec traitement : structure martensitique en surface, avec un grain fin ; structure perlitique à coeur,avec conservation du grain du laminage initial.
Grinding bars known in the art have two types of structure:
  • 1) Raw laminate pearlitic structure, with an identical grain over the entire section.
  • 2) Laminates with treatment: martensitic structure on the surface, with a fine grain; pearlitic structure at heart, with conservation of the grain of the initial rolling.

Ces barres connues, en acier faiblement alliée avec une teneur en carbone inférieure ou égale à 1,1 %,sont conçues pour avoir une couche externe résistante à l'usure et un noyau interne doux et résilient, afin d'assurer le meilleur compromis entre résistance à l'usure et fragilité. Elles n'ont pas,pour ce faire,une trempabilité suffisante pour être martensitiques à coeur pour un diamètre de 80 à 100 mm.These known bars, made of low-alloy steel with a carbon content of 1.1% or less, are designed to have a wear-resistant outer layer and a soft and resilient inner core, in order to ensure the best compromise between wear resistance and brittleness. To do this, they do not have sufficient quenchability to be martensitic at heart for a diameter of 80 to 100 mm.

Le but de la présente invention est de proposer une barre de broyage dont les caractéristiques sont bien supérieures, grâce à l'emploi d'un matériau différent et du fait d'une structure particulière obtenue par un procédé originaleThe object of the present invention is to propose a grinding bar whose characteristics are much superior, thanks to the use of a different material and due to a particular structure obtained by an original process.

Ainsi qu'il a été indiqué ci-dessus, une telle barre de broyage est réalisée en un acier présentant une forte teneur en carbone et un pourcentage élevé de carbure.As indicated above, such a grinding bar is made of a steel having a high carbon content and a high percentage of carbide.

Le Tableau 1 ci-après compare différents types de barres de broyage connues dans la technique et celles conformes à l'invention.

Figure imgb0001
Table 1 below compares different types of grinding bars known in the art and those according to the invention.
Figure imgb0001

La barre objet de l'invention a, en surface, une structure à grain homogène non orienté dans le sens longitudinal ; ce n'est pas une structure laminée avec étirement des fibres, allongement d'inclusion, ligne possible, c'est une structure propre issue du procédé. Avec une teneur en carbone supérieure ou égale à 1,2 % en poids, cette structure comporte un fort pourcentage de carbure du type M3C, M7C3, M23 C6 suivant le type d'alliage, M désignant un composé fer-alliage.The bar object of the invention has, on the surface, a homogeneous grain structure not oriented in the longitudinal direction; it is not a laminated structure with stretching of the fibers, elongation of inclusion, possible line, it is a clean structure resulting from the process. With a carbon content greater than or equal to 1.2% by weight, this structure comprises a high percentage of carbide of the type M 3 C, M 7 C 3 , M 23 C 6 depending on the type of alloy, M denoting a compound iron-alloy.

La structure interne de la barre objet de l'invention présente une orientation perpendiculaire à la surface cylindrique, en forme de dendrite. De ce fait, la dureté des carbures orientés dans ce sens est supérieure à leur dureté latérale ; la micro-dureté de la surface de la barre restera donc élevée même après réduction du diamètre par l'abrasion.The internal structure of the bar object of the invention has an orientation perpendicular to the cylindrical surface, in the form of a dendrite. As a result, the hardness of carbides oriented in this direction is greater than their lateral hardness; the micro-hardness of the surface of the bar will therefore remain high even after reduction of the diameter by abrasion.

D'autre part, la structure en dendrite radiale assure une fragilité suffisante du métal pour entraîner sa casse en morceaux en dessous d'un'certain diamètre de la barre.On the other hand, the radial dendrite structure ensures sufficient fragility of the metal to cause it to break into pieces below a certain diameter of the bar.

La barre conforme à l'invention a donc,en surface, sur une certaine épaisseur, une structure à grain fin, tandis que son coeur est à structure dendritique radiale.The bar according to the invention therefore has, on the surface, over a certain thickness, a fine-grained structure, while its core is of radial dendritic structure.

En fonction des applications à un broyage sec, humide, plus ou moins acide et plus ou moins abrasif, différentes constitutions pourront être retenues : austénitique, martensitique ou bainitique, avec des duretés et des constitutions de matrices et de carbures variables.Depending on the applications to dry, wet, more or less acidic and more or less abrasive grinding, different constitutions may be adopted: austenitic, martensitic or bainitic, with hardnesses and constitutions of matrices and variable carbides.

Une telle barre ne peut être réalisée que par le procédé conforme à l'invention , que l'on va maintenant décrire plus en détail.Such a bar can only be produced by the method according to the invention, which will now be described in more detail.

Il est nécessaire d'utiliser un procédé d'un coût économique donnant directement la barre objet de l'invention, car elle ne peut être laminée économiquement. Par ailleurs, un laminage, même coûteux, détruirait la structure favorable aux caractéristiques de résistance à l'usure.It is necessary to use a method of economic cost directly giving the bar object of the invention, because it cannot be laminated economically. Furthermore, rolling, even expensive, would destroy the structure favorable to the characteristics of wear resistance.

On doit éliminer également la fabrication de la barre par compactage de poudre frittée, procédé coûteux et qui donne une structure homogène dans toutes les directions sans avantage particulier.The manufacture of the bar must also be eliminated by compacting sintered powder, an expensive process which gives a homogeneous structure in all directions without any particular advantage.

La barre selon l'invention est réalisée par coulée continue horizontale, en diamètre final de 50 à 100 mm et à la longueur nécessaire, de 2 à 6 m et plus. La solidification dirigée et la formation de la structure fine eh surface et dendritique à coeur sont obtenues par des réglages appropriés des conditions d'extraction de la barre de la lingotière de production, soit selon un pas compris entre 1 et 50 mm ou un ratio P/D (longueur du pas rapportée au diamètre de la barre) de 5/100 à 5/10.The bar according to the invention is produced by continuous horizontal casting, with a final diameter of 50 to 100 mm and at the required length, from 2 to 6 m and more. Directed solidification and the formation of the fine structure on the surface and dendritic at heart are obtained by appropriate adjustments of the conditions of extraction of the bar from the production ingot mold, either at a pitch of between 1 and 50 mm or a ratio P / D (length of step relative to the diameter of the bar) from 5/100 to 5/10.

Après solidification, on procède au refroidissement contrôlé de la barre pour obtenir la matrice et la morphologie des carbures désirées.Ce refroidissement peut être un cycle thermique descente en température,puis remontée, suivie d'un palier et refroidissement. De cette manière, le procédé conforme à l'invention fournit un produit directement utilisable dans les broyeurs ordinaires. Dans certains cas particuliers, il pourra être procédé à un traitement thermique additionnel ou complémentaire.After solidification, the bar is cooled in a controlled manner to obtain the matrix and the morphology of the desired carbides. This cooling can be a thermal cycle down in temperature, then up, followed by a bearing and cooling. In this way, the process according to the invention provides a product which can be used directly in ordinary mills. In certain specific cases, an additional or complementary heat treatment may be carried out.

En cas de sollicitation de choc particulièrement élevée dans les broyeurs de très forte puissance, ou de diamètre important du broyeur,les barresde broyage ne doivent présenter aucun défaut de surface, ligne de fissure, etc... Ces défauts bien connus dans l'état de la technique, sont généralement liés au procédé de laminage et aux ségrégations possibles dus au lingot ou à la billette d'ébauche.In the event of a particularly high impact stress in very high power shredders, or of large shredder diameter, the shredding bars must have no surface defect, crack line, etc. These faults are well known in the state of the technique, are generally linked to the rolling process and to the possible segregations due to the ingot or the rough billet.

La barre faisant l'objet de l'invention ne comporte pas de défauts de cette sorte. Cependant, compte tenu de l'alliage constitutif de la barre et de son procédé de fabrication, il peut y avoir des calamines adhérentes, des reliefs de surface ou des microségrégations de surface sur le produit. Pour éliminer les concentrations possibles de contrainte sous les efforts et les zones de fragilité potentielle prématurées, on procèdera si nécessaire à la régénération de l'état de cette surface par l'un des moyens suivants.The bar which is the subject of the invention does not have any faults of this kind. However, taking into account the constituent alloy of the bar and its manufacturing process, there may be adherent calamines, surface reliefs or surface microsegregations on the product. To eliminate the possible concentrations of stress under the stresses and the zones of premature potential brittleness, one will proceed if necessary to the regeneration of the state of this surface by one of the following means.

Il a déjà été proposé de procéder à l'élimination d'une couche superficielle, par meulage et usinage avec enlèvement de matière, mais une telle solution est coûteuse. Selon l'invention, il est préférable d'avoir recours à des moyens qui transforment localement la surface pour la régénérer -sur barre chaude ou froide- par refusion, plasma, laser ou induction à haute fréquence. Une autre solution peut consister à écraser les micro- reliefs et les ségrégations locales de surface engendrées par la coulée continue horizontale. A cet effet, on peut grenailler ou marteler la surface par des dispositifs circulaires au défilé.It has already been proposed to remove a surface layer by grinding and machining with removal of material, but such a solution is expensive. According to the invention, it is preferable to use means which locally transform the surface to regenerate it - on hot or cold bar - by reflow, plasma, laser or high frequency induction. Another solution can consist in crushing the micro-reliefs and the local surface segregations generated by the horizontal continuous casting. To this end, the surface can be shot blasted or hammered by circular devices.

Dans une forme de mise en oeuvre préférée de l'invention, la barre de broyage est réalisée en métal ferreux présentant l'analyse suivante, en % en poids :

  • - carbone : 1,4 à 1,6 %,
  • - chrome : 11 à 12 %,
  • - molybdène : 0,4 à 0,6 %,
  • - vanadium : 0,3 à 0,5 %,
  • - silicium : 0,5 à 0,7 %,
  • - manganèse : 0,5 à 0,8 %.
In a preferred embodiment of the invention, the grinding bar is made of ferrous metal having the following analysis, in% by weight:
  • - carbon: 1.4 to 1.6%,
  • - chromium: 11 to 12%,
  • - molybdenum: 0.4 to 0.6%,
  • - vanadium: 0.3 to 0.5%,
  • - silicon: 0.5 to 0.7%,
  • - manganese: 0.5 to 0.8%.

Cette barre a dans l'ensemble un diamètre de 80 mm et est obtenue par coulée continue horizontale dans une machine à paramètre d'extraction contrôlée donnant un pas de 10 mm.This bar has on the whole a diameter of 80 mm and is obtained by horizontal continuous casting in a machine with controlled extraction parameter giving a pitch of 10 mm.

Le refroidissement de la barre entre 1180°C de température à la sortie de la lingotière et 400°C, se fera en 30 minutes. La barre est tronçonnée en ligne à chaud à une longueur de 3,10 m.The cooling of the bar between 1180 ° C temperature at the outlet of the mold and 400 ° C, will be done in 30 minutes. The bar is cut in hot line to a length of 3.10 m.

Une telle barre conforme à l'invention a une dureté de 40 RC. Sa structure de surface est austénitique et présente une couche à grain fin sur une épaisseur de 5 mm. Le coeur de la barre a une dureté de 32 RC et sa structure est dendritique.Such a bar according to the invention has a hardness of 40 RC. Its surface structure is austenitic and has a fine grain layer over a thickness of 5 mm. The core of the bar has a hardness of 32 RC and its structure is dendritic.

Une telle barre,tombant d'une hauteur de 4 m sur un appui rigide en son milieune casse pas.Such a bar, falling from a height of 4 m on a rigid support in the middle does not break.

Un lot de telles barres a été essayé dans un broyeur de 2 m de diamètre utilisé pour broyer du minerai d'uranium.A batch of such bars was tested in a 2 m diameter mill used to grind uranium ore.

Les usures relevées par comparaison avec un acier traité en surface ont été les suivantes (en microns par heure), au cours de deux mesures 1 et 2 successives :

Figure imgb0002
The wear recorded by comparison with a steel treated on the surface was as follows (in microns per hour), during two successive measurements 1 and 2:
Figure imgb0002

Les barres selon l'invention présentent donc une résistance à l'usure très supérieure aux barres usuelles.The bars according to the invention therefore have a wear resistance much higher than the usual bars.

Claims (7)

1.- Barre de broyage en métal ferreux, issue directement d'une coulée à solidification dirigée, caractérisée en ce qu'elle présente une structure de surface à grain fin et un coeur à structure dendritique orientée radialement, en ce qu'elle comprend, en % en poids, entre environ 1,1 et 3 % de carbone, entre environ 3 et 30 % de chrome, entre environ 0,3 et 1,5% de manganèse et entre environ 0,3 et 1 % de silicium, et en ce qu'elle comporte au moins 10 % en volume de carbures..1.- Ferrous metal grinding bar, coming directly from a directed solidification casting, characterized in that it has a fine-grained surface structure and a core with a dendritic structure oriented radially, in that it comprises, in% by weight, between approximately 1.1 and 3% of carbon, between approximately 3 and 30% of chromium, between approximately 0.3 and 1.5% of manganese and between approximately 0.3 and 1% of silicon, and in that it comprises at least 10% by volume of carbides. 2.- Barre de broyage selon la revendication 1, caractérisée en ce qu'elle contient en outre, en % en poids, de O à 1 % de cuivre, de O à 5 % de nickel, de 0 à 1 % de molybdène, de O à 1 % de titane, de 0 à 0,5% de bore, de O à 2 % de vanadium et de O à 2 % de tungstène.2. Grinding bar according to claim 1, characterized in that it also contains, in% by weight, from O to 1% of copper, from O to 5% of nickel, from 0 to 1% of molybdenum, from O to 1% of titanium, from 0 to 0.5% of boron, from O to 2% of vanadium and from O to 2% of tungsten. 3.- Barre de broyage selon la revendication 2, caractérisée en ce qu'elle contient, en % en poids, de 1,4 à 1,6 % de carbone, de 11 à 12 % en poids de chrome, de 0,4 à 0,6 % de molybdène, de 0,3 à 0,5 % de vanadium, de 0,5 à 0,7 % de silicium, et de 0,5 à 0,8 % de manganèse.3.- Grinding bar according to claim 2, characterized in that it contains, in% by weight, from 1.4 to 1.6% of carbon, from 11 to 12% by weight of chromium, from 0.4 0.6% molybdenum, 0.3-0.5% vanadium, 0.5-0.7% silicon, and 0.5-0.8% manganese. 4.- Procédé de fabrication d'une barre de broyage selon l'une des revendications 1 à 3, caractérisé en ce qu'on la réalise par coulée continue d'un métal ferreux de la composition convenable, avec solidification dirigée, à l'exclusion de toute phase de laminage.4.- Method of manufacturing a grinding bar according to one of claims 1 to 3, characterized in that it is carried out by continuous casting of a ferrous metal of the suitable composition, with directed solidification, with exclusion of any rolling phase. 5.- Procédé selon la revendication 4, caractérisé en ce que la phase de solidification dirigée est suivie d'un refroidissement contrôlé en vue d'obtenir le type de matrice et de carbures désirés.5.- Method according to claim 4, characterized in that the directed solidification phase is followed by controlled cooling in order to obtain the desired type of matrix and carbides. 6.- Procédé selon la revendication 5, caractérisé en ce que la phase de refroidissement est constituée par un cycle thermique comprenant une descente en température suivie d'une remontée et d'un palier de température, puis d'un refroidissement.6.- Method according to claim 5, characterized in that the cooling phase is constituted by a thermal cycle comprising a drop in temperature followed by a rise and a temperature plateau, then cooling. 7.- Procédé selon l'une des revendications 5 et 6, caractérisé en ce que la phase de refroidissement contrôlée est suivie d'un traitement de régénération de l'état de surface de la barre.7.- Method according to one of claims 5 and 6, characterized in that the controlled cooling phase is followed by a regeneration treatment of the surface condition of the bar.
EP84400405A 1983-03-01 1984-02-29 High-resistance rod and its production method Withdrawn EP0120748A1 (en)

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FR8303327 1983-03-01
FR8303327A FR2541910B1 (en) 1983-03-01 1983-03-01 HIGH STRENGTH CRUSHING BAR AND MANUFACTURING METHOD THEREOF

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WO1995028506A1 (en) * 1994-04-18 1995-10-26 Magotteaux International S.A. High carbon content steel, method of manufacture thereof, and use as wear parts made of such steel
WO2000043555A1 (en) * 1999-01-19 2000-07-27 Magotteaux International S.A. Process of the production of high-carbon cast steels intended for wearing parts
US6221184B1 (en) 1998-01-19 2001-04-24 Magotteaux International S.A. Process of the production of high-carbon cast steels intended for wearing parts

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US5865385A (en) * 1997-02-21 1999-02-02 Arnett; Charles R. Comminuting media comprising martensitic/austenitic steel containing retained work-transformable austenite
DE10055449A1 (en) * 2000-11-09 2002-05-23 Schwaebische Huettenwerke Gmbh Gradient material molded body
CN101392354B (en) * 2008-10-24 2010-09-08 宁波禾顺新材料有限公司 High alloy cold-work die steel

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GB1112882A (en) * 1965-05-17 1968-05-08 United States Steel Corp Casting steel ingots
FR1533841A (en) * 1966-08-12 1968-07-19 Process and plant for continuous metal casting
FR2089166A5 (en) * 1970-04-03 1972-01-07 Philips Nv
FR2405749A1 (en) * 1977-10-14 1979-05-11 Thome Cromback Acieries NEW FORGED CRUSHING BODIES, ESPECIALLY CRUSHING BALLS, AND THEIR MANUFACTURING PROCESS
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Publication number Priority date Publication date Assignee Title
WO1995028506A1 (en) * 1994-04-18 1995-10-26 Magotteaux International S.A. High carbon content steel, method of manufacture thereof, and use as wear parts made of such steel
US5855701A (en) * 1994-04-18 1999-01-05 Magotteaux International S.A. Method of manufacture high carbon content steel
US6221184B1 (en) 1998-01-19 2001-04-24 Magotteaux International S.A. Process of the production of high-carbon cast steels intended for wearing parts
WO2000043555A1 (en) * 1999-01-19 2000-07-27 Magotteaux International S.A. Process of the production of high-carbon cast steels intended for wearing parts

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ES8504485A1 (en) 1985-05-01
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FR2541910A1 (en) 1984-09-07
CA1208613A (en) 1986-07-29
JPS59162956A (en) 1984-09-13
US4602416A (en) 1986-07-29
ES530173A0 (en) 1985-05-01
FR2541910B1 (en) 1985-06-28
ZA84976B (en) 1984-09-26

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