EP0538158A1 - Low alloy, resulfurized free-cutting steel - Google Patents

Low alloy, resulfurized free-cutting steel Download PDF

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Publication number
EP0538158A1
EP0538158A1 EP92420363A EP92420363A EP0538158A1 EP 0538158 A1 EP0538158 A1 EP 0538158A1 EP 92420363 A EP92420363 A EP 92420363A EP 92420363 A EP92420363 A EP 92420363A EP 0538158 A1 EP0538158 A1 EP 0538158A1
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cao
steel
steels
weight
mno
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German (de)
French (fr)
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EP0538158B1 (en
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André MALHERBE
Félix Pellicani
Régis Szezesny
Michel Tomczyk
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Vallourec SA
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Vallourec SA
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Definitions

  • the present invention relates to steels weakly alloyed with carbon-manganese and relates to steels of particular compositions which, in particular because of their sulfur content and of the composition of their oxidized inclusions, are particularly suitable for high speed machining in in particular by carbide or ceramic tools and by cutting at high cutting speed, in particular from tubes produced in said steels.
  • the search for the highest performance requires the combined addition of sulfur, tellurium (or selenium) and / or lead or bismuth.
  • These steels generally have a large amount of inclusions of oxides and sulfides and a high oxygen content greater than 0.0100% by weight.
  • steels with 0.30% by weight of sulfur have low mechanical tensile properties, close to that of A37 steel according to AFNOR standard. Nuances for heat treatment have been standardized, but their bar turning performance is therefore weaker.
  • the aim of the present invention is to propose a family of carbon-manganese steels which can be used in particular for mechanical construction having an excellent turning ability and giving excellent performance at high speed machining with carbide or ceramic tools. , performances superior to those obtained with steels with improved machinability cited above while retaining good mechanical characteristics and not having the drawbacks of free-cutting steels at 0.30% by weight of sulfur mentioned above.
  • the object of the invention is in particular to create a family of clean free-cutting steels, not requiring the use of toxic elements, covering a wide range of mechanical characteristics and having much better impact toughness characteristics than those free-cutting steel at 0.30% by weight of sulfur.
  • the non-metallic inclusions are located on the diagram of representation of the system Al 2 O3 - Si O2 - MnO / CaO in the domain of Anorthite or Gehlenite.
  • Such a representation diagram of the system Al 2 O3 - Si O2 - MnO / CaO can be found for example in "Phase diagrams for ceramists" Edited and Published by the American Ceramic Society 1964 figure 630 page 219.
  • MnO and CaO are oxides whose role is estimated to be similar.
  • the carbon content is limited to 0.22% by weight and the sum carbon content plus content in manganese / 6 at 0.48% by weight, ie C% + Mn% 6 ⁇ 0.48%.
  • the sulfur content is between 0.080% and 0.12% by weight.
  • composition described above makes it possible, while obtaining good mechanical properties under tension, to obtain a type of favorable inclusion of oxides and sulphides, distributed homogeneously in the metal and in a limited and controlled quantity.
  • This set of characteristics makes these steels suitable for bar turning in excellent conditions, this despite the relatively low sulfur content, in particular for bar turning using carbide or ceramic tools.
  • Such a process makes it possible to ensure the homogeneity of the metal, both in terms of the chemical composition and the distribution of the inclusions, over the entire length of casting.
  • compositions are as follows in percentages by weight: - Steel A according to: TU52b (AFNOR standard NFA 49310) VS : 0.178% Yes : 0.265% Mn : 1.270% S : 0.006% P : 0.014% Al : 0.024% It : 0.0015% 0 total : 0.0022%
  • the oxide inclusions consist of calcium aluminates Al2 O3 - CaO or spinels Al2 O3 - Mgo associated with mixed sulfides (Ca, Mn) S. There are also isolated inclusions of manganese sulfides MnS in small quantities.
  • - Steel B (steel version with improved machinability of steel A). according to TU 52 b q2 (AFNOR standard NFA 49310) VS : 0.180% Yes : 0.183% Mn : 1.340% S : 0.028% P : 0.016% Al : 0.022% It : 0.0016% 0 total : 0.0022%
  • oxide inclusions consist of Al2O3 - CaO calcium aluminates or Al2O3 - MgO spinels associated with mixed sulfides (Ca, Mn) S. Besides these inclusions, there are numerous inclusions of manganese sulfide.
  • This composition is located in the Gehlenite domain of the ternary diagram Al2 O3 - Si O2 - CaO cited above.
  • steel of the invention Steel at 0.30% sulfur weight according to NFA 35561 (grade S300). R ⁇ 0.2 539 MPa Rm 558 MPa A% 5.65 ⁇ S 11.4%
  • the steels according to the invention therefore have the advantage of having much better machinability properties than those of steels with improved machinability and of the same order of magnitude as those of free-cutting steels with 0.30% by weight of sulfur without having , especially in terms of mechanical characteristics and implementation of the drawbacks of these steels at 0.30% by weight of sulfur.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Shearing Machines (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Heat Treatment Of Steel (AREA)
  • Turning (AREA)

Abstract

Steels of particular compositions which, because of their sulphur contents and of the composition of the oxidised inclusions, are particularly suitable for screw-cutting and machining at high speed using carbide or ceramic tools. The steels contain, in weight %: C - 0.05 to 0.45 % Mn - 0.80 to 1.65 % Si - 0.10 to 0.35 % P - max. 0.030 % S - 0.050 to 0.12 % and the compositions of their oxidised inclusions are, in weight %: Al2O3 - 15 to 50 % SiO2 - 20 to 60 % CaO + MnO - 15 to 50 %. Despite the presence of sulphur, these steels retain good mechanical characteristics.

Description

La présente invention est relative aux aciers faiblement alliés au carbone-manganèse et a pour objet des aciers de compositions particulières qui du fait notamment de leur teneur en soufre et de la composition de leurs inclusions oxydées sont particulièrement aptes à l'usinage à grande vitesse en particulier par des outils en carbures ou en céramique et au décolletage à grande vitesse de coupe, notamment à partir de tubes réalisés dans lesdits aciers.The present invention relates to steels weakly alloyed with carbon-manganese and relates to steels of particular compositions which, in particular because of their sulfur content and of the composition of their oxidized inclusions, are particularly suitable for high speed machining in in particular by carbide or ceramic tools and by cutting at high cutting speed, in particular from tubes produced in said steels.

On connaît actuellement des aciers dont les caractéristiques d'usinabilité sont améliorées par la présence de soufre dans une gamme de teneur allant de 0,020 à 0,040 % en poids. Ces aciers ont toutefois des performances en usinage limitées qui ne permettent pas d'atteindre les grandes vitesses de coupe et/ou d'utiliser des outils de coupe en carbure ou en céramique dans de bonnes conditions. Par contre ces aciers à usinabilité améliorée gardent en général des caractéristiques mécaniques en particulier en traction voisines de celles correspondant à leur composition de base.Steels are currently known whose machinability characteristics are improved by the presence of sulfur in a content range from 0.020 to 0.040% by weight. However, these steels have limited machining performance which does not allow high cutting speeds to be achieved and / or the use of carbide or ceramic cutting tools under good conditions. On the other hand, these steels with improved machinability generally keep mechanical characteristics, in particular in traction, close to those corresponding to their basic composition.

On connaît également des aciers pour décolletage semi-calmés par des additions de silicium contenant de l'ordre de 0,3 % de soufre en poids. Ces aciers sont usinables à grande vitesse de coupe avec des outils de coupe en carbure ou en céramique.There are also known steels for bar turning semi-calmed by silicon additions containing about 0.3% sulfur by weight. These steels can be machined at high cutting speed with carbide or ceramic cutting tools.

Dans certains cas, même, la recherche des performances les plus élevées nécessite l'addition combinée de soufre, de Tellure (ou sélénium) et/ou de Plomb ou de Bismuth.In some cases, even, the search for the highest performance requires the combined addition of sulfur, tellurium (or selenium) and / or lead or bismuth.

Ces aciers présentent en général une grande quantité d'inclusions d'oxydes et de sulfures et une teneur en oxygène élevée supérieure à 0,0100 % en poids.These steels generally have a large amount of inclusions of oxides and sulfides and a high oxygen content greater than 0.0100% by weight.

Ces aciers dont la caractéristique essentielle sinon exclusive est de présenter des propriétés aussi élevées que possible au décolletage ont par ailleurs une résilience très médiocre et il est impossible de les assembler par soudage à l'arc. On peut également souligner les problèmes de toxicité liés à la manipulation notamment au stade de l'élaboration du métal liquide des éléments Tellure, Sélénium, Plomb, Bismuth ainsi que lors du recyclage des ferrailles et copeaux.These steels, the essential characteristic of which, if not exclusive, is that they have properties that are as high as possible in bar turning, have, moreover, very poor resilience and it is impossible to assemble them by arc welding. We can also highlight the toxicity problems associated with handling, especially at the the elaboration of the liquid metal of the Tellurium, Selenium, Lead, Bismuth elements as well as during the recycling of scrap and chips

De plus les aciers avec 0,30 % en poids de soufre ont des caractéristiques mécaniques à la traction basses, voisines de celle d'un acier A37 selon norme AFNOR. Des nuances pour traitement thermique ont été normalisées mais leurs performances au décolletage sont alors plus faibles.In addition, steels with 0.30% by weight of sulfur have low mechanical tensile properties, close to that of A37 steel according to AFNOR standard. Nuances for heat treatment have been standardized, but their bar turning performance is therefore weaker.

Le but de la présente invention est de proposer une famille d'aciers au carbone-manganèse utilisables notamment pour la construction mécanique ayant une excellente aptitude au décolletage et donnant d'excellentes performances à l'usinage à grande vitesse par des outils en carbure ou céramique, performances supérieures à celles obtenues avec des aciers à usinabilité améliorée cités ci-dessus tout en gardant de bonnes caractéristiques mécaniques et ne présentant pas les inconvénients des aciers de décolletage à 0,30 % en poids de soufre cités plus haut.The aim of the present invention is to propose a family of carbon-manganese steels which can be used in particular for mechanical construction having an excellent turning ability and giving excellent performance at high speed machining with carbide or ceramic tools. , performances superior to those obtained with steels with improved machinability cited above while retaining good mechanical characteristics and not having the drawbacks of free-cutting steels at 0.30% by weight of sulfur mentioned above.

L'invention a en particulier pour but la création d'une famille d'aciers de décolletage propres, ne nécessitant pas la mise en oeuvre d'éléments toxiques, couvrant une large gamme de caractéristiques mécaniques et présentant des caractéristiques de résilience bien meilleures que celles de l'acier de décolletage à 0,30 % en poids de soufre.The object of the invention is in particular to create a family of clean free-cutting steels, not requiring the use of toxic elements, covering a wide range of mechanical characteristics and having much better impact toughness characteristics than those free-cutting steel at 0.30% by weight of sulfur.

Les aciers au carbone-manganèse aptes au décolletage de la famille de l'invention ont la composition suivante exprimée en pourcentages pondéraux :

Carbone
- 0,05 à 0,45 %
Manganèse
- 0,80 à 1,65 %
Silicium
- 0,10 à 0,35 %
Phosphore
- inférieur à 0,030 %

ainsi que les impuretés habituelles.The carbon-manganese steels suitable for bar turning of the family of the invention have the following composition expressed in weight percentages:
Carbon
- 0.05 to 0.45%
Manganese
- 0.80 to 1.65%
Silicon
- 0.10 to 0.35%
Phosphorus
- less than 0.030%

as well as the usual impurities.

Ils contiennent également :

Soufre
- 0,050 à 0,12 %
Calcium
- 0,001 à 0,010 %

l'aluminium étant entièrement sous forme oxydée, et les inclusions non métalliques d'oxydes comprennent en pourcentage pondéraux :
Al ₂ O₃
15 à 50 %
Si O₂
20 à 60 %
CaO + MnO
15 à 50 %

la teneur totale en oxygène étant comprise entre 0,0015 et 0,0080 %.They also contain:
Sulfur
- 0.050 to 0.12%
Calcium
- 0.001 to 0.010%

aluminum being entirely in oxidized form, and the non-metallic inclusions of oxides comprise in percentage by weight:
Al ₂ WHERE
15 to 50%
If where
20 to 60%
CaO + MnO
15 to 50%

the total oxygen content being between 0.0015 and 0.0080%.

De préférence les inclusions non métalliques se situent sur le diagramme de représentation du système Al ₂ O₃ - Si O₂ - MnO/CaO dans le domaine de l'Anorthite ou de la Gehlenite. Un tel diagramme de représentation du système Al ₂ O₃ - Si O₂ - MnO/CaO se trouve par exemple dans "Phase diagrams for ceramists" Edited and Published by the American Ceramic Society 1964 figure 630 page 219. MnO et CaO sont des oxydes dont le role est estimé similaire. Dans la mesure où le pourcentage de MnO est faible (inférieur à 10 '/.) on peut donc cumuler CaO + MnO pour se rapporter au diagramme du système Al ₂ O₃ - Si O₂ - CaO où seul CaO est représenté et prendre la valeur de CaO + MnO pour une valeur de CaO.Preferably the non-metallic inclusions are located on the diagram of representation of the system Al ₂ O₃ - Si O₂ - MnO / CaO in the domain of Anorthite or Gehlenite. Such a representation diagram of the system Al ₂ O₃ - Si O₂ - MnO / CaO can be found for example in "Phase diagrams for ceramists" Edited and Published by the American Ceramic Society 1964 figure 630 page 219. MnO and CaO are oxides whose role is estimated to be similar. Insofar as the percentage of MnO is low (less than 10 '/.) We can therefore cumulate CaO + MnO to refer to the diagram of the system Al ₂ O₃ - Si O₂ - CaO where only CaO is represented and take the value of CaO + MnO for a value of CaO.

De façon avantageuse pour la mise en oeuvre de l'acier par soudage par un procédé de soudage à l'arc électrique avec métal d'apport on limite la teneur en carbone à 0,22 % en poids et la somme teneur en carbone plus teneur en manganèse/6 à 0,48 % en poids soit C % + Mn % 6 ≦ 0,48 %.

Figure imgb0001
Advantageously for the implementation of steel by welding by an electric arc welding process with filler metal, the carbon content is limited to 0.22% by weight and the sum carbon content plus content in manganese / 6 at 0.48% by weight, ie C% + Mn% 6 ≦ 0.48%.
Figure imgb0001

Avantageusement également la teneur en soufre est comprise entre 0,080% et 0,12 % en poids.Advantageously also the sulfur content is between 0.080% and 0.12% by weight.

La composition ci-dessus décrite permet, tout en obtenant de bonnes caractéristiques mécaniques à la traction, d'obtenir un type d'inclusions d'oxydes et de sulfures favorables, réparties de manière homogène dans le métal et en quantité limitée et contrôlée. Cet ensemble de caractéristiques rend ces aciers aptes au décolletage dans d'excellentes conditions, ceci malgré la teneur relativement basse en soufre, en particulier pour le décolletage utilisant les outils carbure ou céramique.The composition described above makes it possible, while obtaining good mechanical properties under tension, to obtain a type of favorable inclusion of oxides and sulphides, distributed homogeneously in the metal and in a limited and controlled quantity. This set of characteristics makes these steels suitable for bar turning in excellent conditions, this despite the relatively low sulfur content, in particular for bar turning using carbide or ceramic tools.

Il est particulièrement intéressant pour fabriquer l'acier d'utiliser le procédé de coulée continue rotative, en soit connu.It is particularly advantageous for manufacturing steel to use the rotary continuous casting process, as is known.

Ce procédé est par exemple décrit dans l'article de la Revue de métallurgie CIT, Février 1981 pages 119-135.This process is for example described in the article of the CIT metallurgical review, February 1981 pages 119-135.

Un tel procédé permet d'assurer l'homogénéité du métal, tant au niveau de la composition chimique que de la répartition des inclusions, sur toute la longueur coulée.Such a process makes it possible to ensure the homogeneity of the metal, both in terms of the chemical composition and the distribution of the inclusions, over the entire length of casting.

L'élaboration de l'acier coulé ensuite en continu qui est faite avantageusement en poche après fusion en four électrique à l'arc sera exécutée avec soin de façon à conserver toujours le métal homogène et à l'abri de l'oxydation, le métal étant, dans sa phase finale traité au Calcium, par exemple par l'introduction dans la poche de métal liquide d'un fil fourré tel que décrit dans le brevet européen n° 87 420052.0 à base de silico-calcium.The production of steel which is then continuously cast, which is advantageously made in a ladle after fusion in an electric arc furnace, will be carried out with care so as to always keep the metal homogeneous and protected from oxidation, the metal being, in its final phase treated with Calcium, for example by the introduction into the pocket of liquid metal of a cored wire as described in European patent n ° 87 420052.0 based on silico-calcium.

Il est particulièrement intéressant d'utiliser l'acier selon l'invention sous forme de tube, par exemple de tubes étirés, ceci réduisant les temps de décolletage par suppression de l'opération de perçage du trou intérieur.It is particularly advantageous to use the steel according to the invention in the form of a tube, for example of drawn tubes, this reducing the turning times by eliminating the drilling operation of the internal hole.

En utilisant un tube, on est également certain d'éviter les ségrégations centrales qui pourraient se trouver au coeur des barres, ségrégations qui, on l'a déjà expliqué ci-dessus, sont très réduites si on utilise le procédé de coulée continue rotative.By using a tube, one is also certain to avoid the central segregations which could be found at the heart of the bars, segregations which, as already explained above, are very reduced if the rotary continuous casting process is used.

De la sorte l'utilisation de tubes au lieu de barres est une garantie complémentaire pour le produit destiné au décolletage.In this way the use of tubes instead of bars is an additional guarantee for the product intended for bar turning.

A titre d'exemple, non limitatif, on a comparé les résultats d'un acier selon l'invention à des aciers normalisés préexistants.By way of non-limiting example, the results of a steel according to the invention have been compared with pre-existing standardized steels.

Les compositions sont les suivantes en pourcentages pondéraux :
   - Acier A selon :
    TU52b (norme AFNOR NFA 49310) C : 0,178 % Si : 0,265 % Mn : 1,270 % S : 0,006 % P : 0,014 % Al : 0,024 % Ca : 0,0015 % 0 total : 0,0022 % The compositions are as follows in percentages by weight:
- Steel A according to:
TU52b (AFNOR standard NFA 49310) VS : 0.178% Yes : 0.265% Mn : 1.270% S : 0.006% P : 0.014% Al : 0.024% It : 0.0015% 0 total : 0.0022%

Les inclusions d'oxydes sont constituées d'aluminates de calcium Al₂ O₃ - CaO ou de spinelles Al₂ O₃ - Mgo associés à des sulfures mixtes (Ca, Mn)S. On trouve en outre des inclusions isolées de sulfures de manganèse MnS en faible quantité.
   - Acier B (version acier à usinabilité améliorée de l'acier A).
selon
   TU 52 b q2 (norme AFNOR NFA 49310) C : 0,180 % Si : 0,183 % Mn : 1,340 % S : 0,028 % P : 0,016 % Al : 0,022 % Ca : 0,0016 % 0 total : 0,0022 % The oxide inclusions consist of calcium aluminates Al₂ O₃ - CaO or spinels Al₂ O₃ - Mgo associated with mixed sulfides (Ca, Mn) S. There are also isolated inclusions of manganese sulfides MnS in small quantities.
- Steel B (steel version with improved machinability of steel A).
according to
TU 52 b q2 (AFNOR standard NFA 49310) VS : 0.180% Yes : 0.183% Mn : 1.340% S : 0.028% P : 0.016% Al : 0.022% It : 0.0016% 0 total : 0.0022%

Ici les inclusions d'oxydes sont constituées d'aluminates de calcium Al₂O₃ - CaO ou de spinelles Al₂O₃ - MgO associés à des sulfures mixtes (Ca, Mn)S. On trouve en dehors de ces inclusions de nombreuses inclusions de sulfure de manganèse.Here the oxide inclusions consist of Al₂O₃ - CaO calcium aluminates or Al₂O₃ - MgO spinels associated with mixed sulfides (Ca, Mn) S. Besides these inclusions, there are numerous inclusions of manganese sulfide.

Acier C selon l'invention. C : 0,172 % Si : 0,191 % Mn : 1,430 % P : 0,018 % S : 0,090 % Al : ≦ à 0,005 % Ca : 0,0014 % 0 total : 0,0026 %
ayant des inclusions d'oxydes dont la composition moyenne est la suivante en pourcentages pondéraux : Al ₂ O₃ : 34 % Si O₂ : 30 % CaO : 36 % Steel C according to the invention. VS : 0.172% Yes : 0.191% Mn : 1.430% P : 0.018% S : 0.090% Al : ≦ 0.005% It : 0.0014% 0 total : 0.0026%
having inclusions of oxides the average composition of which is as follows in percentages by weight: Al ₂ WHERE : 34% If where : 30 % CaO : 36%

Cette composition se situe dans le domaine de la Gehlenite du diagramme ternaire Al₂ O₃ - Si O₂ - CaO cité antérieurement.This composition is located in the Gehlenite domain of the ternary diagram Al₂ O₃ - Si O₂ - CaO cited above.

Dans cet acier C le soufre est essentiellement combiné sous forme de sulfures MnS.In this steel C the sulfur is essentially combined in the form of MnS sulphides.

Ces trois aciers ont été soumis à un test de chariotage sur tube étiré écrouté avec outil carbure, référencé SAFETY TPMR 16 n° 030476S4 de la Société SAFETY, non revêtu et sans lubrifiant.These three steels were subjected to a turning test on a drawn-out tube with a carbide tool, referenced SAFETY TPMR 16 n ° 030476S4 from the company SAFETY, uncoated and without lubricant.

On a comparé :

  • la durée pour créer une usure de 0,4 mm de l'arête de l'outil à une vitesse de coupe de 180 m/min (durée de vie)
    et
  • la vitesse de coupe en m/min donnant une usure de 0,4 mm de l'arête de l'outil en 20 minutes (VB 20-0,4).
We compared:
  • time to create 0.4 mm wear on the tool edge at a cutting speed of 180 m / min (lifetime)
    and
  • the cutting speed in m / min giving a wear of 0.4 mm of the tool edge in 20 minutes (VB 20-0.4).

Les résultats sont les suivants :

Figure imgb0002
The results are as follows:
Figure imgb0002

On voit que l'acier selon l'invention (acier C) présente des résultats très supérieurs à ceux obtenus avec l'acier à usinabilité améliorée existant (acier B) et sans commune mesure avec l'acier non destiné à l'usinage (acier A).It can be seen that the steel according to the invention (steel C) presents results far superior to those obtained with the existing improved machinability steel (steel B) and without common measure with the steel not intended for machining (steel AT).

On a par ailleurs comparé par un essai de productivité avec outils carbure avec des critères identiques un acier de décolletage à 0,30 % en poids de soufre avec l'acier C de l'invention.We also compared by a productivity test with carbide tools with identical criteria a free-cutting steel at 0.30% by weight of sulfur with the steel C of the invention.

En 6 heures on a trouvé une production quasiment identique pour les deux aciers, ceci malgré les différences de caractéristiques mécaniques défavorables pour l'acier C, acier de l'invention :
   Acier à 0,30 % poids de soufre selon NFA 35561 (nuance S300). R ρ 0,2 539 MPa Rm 558 MPa A % 5,65 √S 11,4 % In 6 hours, almost identical production was found for the two steels, this despite the differences in unfavorable mechanical characteristics for the steel C, steel of the invention:
Steel at 0.30% sulfur weight according to NFA 35561 (grade S300). R ρ 0.2 539 MPa Rm 558 MPa A% 5.65 √S 11.4%

Acier C de l'invention R ρ 0,2 704 MPa Rm 765 MPa A % 5,65 √S 8,4 % Steel C of the invention R ρ 0.2 704 MPa Rm 765 MPa A% 5.65 √S 8.4%

Ceci montre clairement que l'acier selon l'invention est particulièrement approprié au décolletage à grande vitesse avec des outils carbure ou céramique.This clearly shows that the steel according to the invention is particularly suitable for high-speed turning with carbide or ceramic tools.

Les aciers selon l'invention présentent donc l'avantage d'avoir des propriétés d'usinabilité bien meilleures que celles des aciers à usinabilité améliorée et du même ordre de grandeur que celles des aciers de décolletage à 0,30 % poids de soufre sans présenter, notamment sur le plan des caractéristiques mécaniques et de la mise en oeuvre les inconvénients de ces aciers à 0,30 % poids de soufre.The steels according to the invention therefore have the advantage of having much better machinability properties than those of steels with improved machinability and of the same order of magnitude as those of free-cutting steels with 0.30% by weight of sulfur without having , especially in terms of mechanical characteristics and implementation of the drawbacks of these steels at 0.30% by weight of sulfur.

Claims (6)

1) Acier au carbone-manganèse apte au décolletage à grande vitesse de coupe caractérisé par le fait qu'il contient en pourcentages pondéraux, 0,05 à 0,45 % de carbone, 0,80 à 1,65 % de manganèse , 0,10 à 0,35 % de silicium, au plus 0,030 % de phosphore et les impuretés habituelles ainsi que 0,050 à 0,12 % de soufre et 0,001 à 0,010 % de calcium et dans lequel les inclusions non métalliques d'oxydes comprennent en pourcentages pondéraux 15 à 50 % d'Al₂ O₃, 20 à 60 % de SiO₂ et 15 à 50 % de CaO + MnO, la teneur totale en oxygène étant comprise entre 0,0015 à 0,0080 % et l'aluminium étant entièrement sous forme oxydée. 1) Carbon-manganese steel suitable for free cutting at high cutting speed, characterized in that it contains in weight percentages, 0.05 to 0.45% of carbon, 0.80 to 1.65% of manganese, 0 , 10 to 0.35% of silicon, at most 0.030% of phosphorus and the usual impurities as well as 0.050 to 0.12% of sulfur and 0.001 to 0.010% of calcium and in which the non-metallic inclusions of oxides comprise in percentages by weight 15 to 50% of Al₂ O₃, 20 to 60% of SiO₂ and 15 to 50% of CaO + MnO, the total oxygen content being between 0.0015 to 0.0080% and the aluminum being entirely in the form oxidized. 2) Acier selon la revendication 1 caractérisé en ce que les inclusions non métalliques se situent sur le diagramme du système Al₂ O₃ - Si O₂ - CaO/MnO dans le domaine de l'Anorthite ou de la Gehlenite, la teneur en CaO + MnO étant traitée comme étant du CaO. 2) Steel according to claim 1 characterized in that the non-metallic inclusions are located on the diagram of the system Al₂ O système - Si O₂ - CaO / MnO in the field of Anorthite or Gehlenite, the CaO + MnO content being treated as CaO. 3) Acier selon la revendication 1 ou 2 caractérisé en ce que la teneur en soufre est de 0,080 à 0,12 %. 3) Steel according to claim 1 or 2 characterized in that the sulfur content is 0.080 to 0.12%. 4) Acier selon l'une des revendications 1 à 3 caractérisé par le fait que dans le but d'avoir une bonne soudabilité à l'arc électrique avec métal d'apport on limite la teneur en Carbone à 0,22 % et la somme C % + Mn % 6 à 0,48 %.
Figure imgb0003
 4) Steel according to one of claims 1 to 3 characterized in that in order to have good weldability with an electric arc with filler metal, the carbon content is limited to 0.22% and the sum C% + Mn% 6 at 0.48%.
Figure imgb0003
 5) Acier selon l'une quelconque des revendications 1 à 4 caractérisé par le fait qu'il est coulé par le procédé de coulée continue rotative. 5) Steel according to any one of claims 1 to 4 characterized in that it is cast by the rotary continuous casting process. 6) Tube d'acier pour décolletage caractérisé par le fait que sa composition est conforme à l'une quelconque des revendications 1 à 4. 6) Steel tube for free cutting characterized in that its composition is in accordance with any one of claims 1 to 4.
EP92420363A 1991-10-17 1992-10-15 Low alloy, resulfurized free-cutting steel Expired - Lifetime EP0538158B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9113059 1991-10-17
FR919113059A FR2682686B1 (en) 1991-10-17 1991-10-17 CARBON-MANGANESE STEEL, ESPECIALLY FOR TURNING.

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EP0538158A1 true EP0538158A1 (en) 1993-04-21
EP0538158B1 EP0538158B1 (en) 1997-01-29

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AT (1) ATE148505T1 (en)
DE (2) DE69217153T2 (en)
ES (1) ES2096739T3 (en)
FR (1) FR2682686B1 (en)
IT (1) IT1255537B (en)
SE (1) SE9203015L (en)

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EP1784519A2 (en) * 2004-08-26 2007-05-16 von Moos Stahl AG Case-hardened steel and method for production thereof by fusion treatment

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2088862A5 (en) * 1970-04-18 1972-01-07 Nippon Kokan Kk Free cutting steel
DE2323623A1 (en) * 1972-05-10 1973-11-22 Kobe Steel Ltd AUTOMATIC STEEL
US4115111A (en) * 1973-11-13 1978-09-19 Daido Tokushuko Kabushiki Kaisha Free-cutting structural steel for machines
DE2839637A1 (en) * 1977-09-15 1979-03-22 British Steel Corp PROCESS FOR PRODUCING SULFURIZED STEEL
FR2456785A1 (en) * 1979-05-17 1980-12-12 Daido Steel Co Ltd DECOLLETING STEEL CONTAINING DETERMINED INCLUSIONS AND A PROCESS FOR THE PREPARATION THEREOF
DD265530A3 (en) * 1985-06-13 1989-03-08 Maxhuette Unterwellenborn Bfn METHOD FOR PRODUCING A FORMATABLE AUTOMATIC STEEL WITH DEFINED FUELS
EP0371840A1 (en) * 1988-12-01 1990-06-06 UNIMETAL Société Française des Aciers Longs Free cutting mild steel and process for manufacturing same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2088862A5 (en) * 1970-04-18 1972-01-07 Nippon Kokan Kk Free cutting steel
DE2323623A1 (en) * 1972-05-10 1973-11-22 Kobe Steel Ltd AUTOMATIC STEEL
US4115111A (en) * 1973-11-13 1978-09-19 Daido Tokushuko Kabushiki Kaisha Free-cutting structural steel for machines
DE2839637A1 (en) * 1977-09-15 1979-03-22 British Steel Corp PROCESS FOR PRODUCING SULFURIZED STEEL
FR2456785A1 (en) * 1979-05-17 1980-12-12 Daido Steel Co Ltd DECOLLETING STEEL CONTAINING DETERMINED INCLUSIONS AND A PROCESS FOR THE PREPARATION THEREOF
DD265530A3 (en) * 1985-06-13 1989-03-08 Maxhuette Unterwellenborn Bfn METHOD FOR PRODUCING A FORMATABLE AUTOMATIC STEEL WITH DEFINED FUELS
EP0371840A1 (en) * 1988-12-01 1990-06-06 UNIMETAL Société Française des Aciers Longs Free cutting mild steel and process for manufacturing same

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ES2096739T3 (en) 1997-03-16
ITMI922319A0 (en) 1992-10-08
SE9203015L (en) 1993-04-18
DE69217153T2 (en) 1997-06-05
SE9203015D0 (en) 1992-10-14
DE4235002A1 (en) 1993-04-22
FR2682686A1 (en) 1993-04-23
IT1255537B (en) 1995-11-09
DE69217153D1 (en) 1997-03-13
FR2682686B1 (en) 1994-07-01
ATE148505T1 (en) 1997-02-15
EP0538158B1 (en) 1997-01-29
ITMI922319A1 (en) 1994-04-08

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