EP0964071A1 - Ferritic stainless steel and exterior cover part for a watch made with such a steel - Google Patents
Ferritic stainless steel and exterior cover part for a watch made with such a steel Download PDFInfo
- Publication number
- EP0964071A1 EP0964071A1 EP98110813A EP98110813A EP0964071A1 EP 0964071 A1 EP0964071 A1 EP 0964071A1 EP 98110813 A EP98110813 A EP 98110813A EP 98110813 A EP98110813 A EP 98110813A EP 0964071 A1 EP0964071 A1 EP 0964071A1
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- EP
- European Patent Office
- Prior art keywords
- alloy
- steel
- ferritic
- weight
- watch
- 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.)
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- 229910000831 Steel Inorganic materials 0.000 title description 5
- 239000010959 steel Substances 0.000 title description 5
- 229910001220 stainless steel Inorganic materials 0.000 title description 2
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 38
- 239000000956 alloy Substances 0.000 claims abstract description 38
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 14
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 12
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 10
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000011572 manganese Substances 0.000 claims abstract description 10
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 9
- 239000011651 chromium Substances 0.000 claims abstract description 9
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 9
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910000851 Alloy steel Inorganic materials 0.000 claims abstract description 7
- 229910052742 iron Inorganic materials 0.000 claims abstract description 7
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 7
- 239000011733 molybdenum Substances 0.000 claims abstract description 7
- 239000000843 powder Substances 0.000 claims abstract description 6
- 239000012535 impurity Substances 0.000 claims abstract description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 26
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 22
- 230000005291 magnetic effect Effects 0.000 claims description 18
- 238000005272 metallurgy Methods 0.000 claims description 2
- 229910001256 stainless steel alloy Inorganic materials 0.000 claims description 2
- 238000010310 metallurgical process Methods 0.000 abstract 1
- 238000005260 corrosion Methods 0.000 description 14
- 230000007797 corrosion Effects 0.000 description 14
- 238000005245 sintering Methods 0.000 description 9
- 229910001566 austenite Inorganic materials 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000005275 alloying Methods 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 230000005415 magnetization Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000004663 powder metallurgy Methods 0.000 description 3
- 230000002009 allergenic effect Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 229910001004 magnetic alloy Inorganic materials 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001012 protector Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 210000004243 sweat Anatomy 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G04—HOROLOGY
- G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
- G04B37/00—Cases
- G04B37/22—Materials or processes of manufacturing pocket watch or wrist watch cases
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
- C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
- C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
Definitions
- the present invention relates to stainless steel ferritic nickel free, as well as an external part of clothing for watch.
- Iron the basic element of all steels, presents the disadvantage of being sensitive to corrosion.
- the essays of this type lead to a ferritic structure, in particular identifiable by the fact that the alloy thus obtained is ferromagnetic, that is, it is attracted to magnets.
- ferromagnetic that is, it is attracted to magnets.
- This structure is indeed known to have better properties than ferritic structure, particularly in terms of resistance to corrosion, and be non-magnetic.
- this technique requires a high sintering temperature to lead to parts dense, free of porosity.
- this temperature of sintering is usually very close, or even better, at the maximum allowable temperature to obtain a austenitic structure. It is thus difficult, even impossible, to obtain under industrial conditions, both porous and austenitic parts after sintering.
- experience shows that it is very difficult to reform the austenite on a structural part ferritic formed at high temperature.
- the object of the present invention is to remedy the problems and disadvantages above, by proposing a steel with no allergenic character, resistant well corrosion, and can be advantageously put shaped by powder metallurgy.
- the present invention relates to a stainless steel alloy with structure ferritic and magnetic, characterized in that it contains at least 0.4% by weight of nitrogen, and at most 0.5% by weight nickel, the balance being made up of iron and unavoidable impurities.
- the invention also relates to such a steel alloy produced by powder metallurgy.
- the invention finally relates to an external part of clothing for a watch made of such an alloy of steel.
- the present invention proposes to start from a ferritic structure free of nickel, whose corrosion resistance is known for be less good, and improve this resistance to corrosion in a completely original way, adding new alloying elements and retaining the structure ferritic.
- the alloy which is the subject of the present invention is a ferritic alloy based on iron, chromium, manganese and nitrogen.
- the composition of the alloy according to the invention is similar to certain compositions of the prior art, its ferritic structure and magnetic is totally different, and results in extremely advantageous new properties.
- the alloy according to the invention is magnetic, that is, it is attracted by magnets. This property is particularly interesting when the invention is applied to boxes of watch. Indeed, watch movements are particularly sensitive to fields magnetic, and a case made of an alloy magnetic can provide shielding against fields magnetic exterior.
- Another advantage of the alloy according to the invention lies in the removal of the temperature constraint maximum treatment imposed on art alloys earlier, especially when the metallurgy of powders is used. Indeed, in accordance with the invention, to reach the ferritic structure you need a high temperature, perfectly compatible with the sintering temperature required for obtain dense parts, free of porosity.
- Another advantage of the alloy according to the invention is that the amount of nitrogen and added manganese can be reduced to the minimum necessary to obtain sufficient corrosion resistance for the application considered, while a concentration high is essential to obtain alloys with an austenitic structure. It is so possible to make alloys with a much better machinability than high alloys nitrogen and manganese content, elements which are known to significantly increase hardness, strength, and the toughness of the alloy.
- This powder is mixed with an organic binder to 60% by volume of powder for 40% by volume of binder, and injected according to the so-called "MIM" process (Metal Injection Molding).
- MIM Metal Injection Molding
- the parts thus obtained are freed from their binder by a thermochemical process said to be dewaxing, and sintered in an atmosphere of formiergaz comprising 8% hydrogen and 92% nitrogen, at one temperature of 1350 ° C for one hour. During the sintering, the nitrogen diffuses rapidly in the alloy, until its concentration reaches about 1% in weight, which is confirmed by the chemical analyzes carried out thereafter on the samples thus produced.
- the parts obtained are dense (only about 0.1% of porosities) and magnetic, indicating that their structure is ferritic.
- Ferritic parts obtained by means of the alloy according to the invention have been subjected to a corrosion test consisting of submerging them for seventy-two hours contact with a mist made from salt water, then putting them for seventy-two hours in a synthetic sweat solution. After the test, the parts show no trace of corrosion, indicating that unlike most other steels ferritic, their corrosion resistance is at least as good as a good stainless alloy austenitic. This is due to the presence of nitrogen and manganese which improve the properties of the phase ferritic.
- a mechanical watch movement has been set up in a watch case made by means of the alloy according to the invention.
- Standard watchmaking resistance tests to magnetic fields showed a shielding effect beneficial for movement in the presence of a field magnetic outside. No harmful influence of the magnetic alloy on the march of mechanical movement has not been observed even after subjecting the box to fields of five Tesla, a thousand times more powerful than magnetic fields normally used.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
La présente invention concerne un acier inoxydable ferritique sans nickel, ainsi qu'une pièce extérieure d'habillement pour montre.The present invention relates to stainless steel ferritic nickel free, as well as an external part of clothing for watch.
Le fer, élément de base de tous les aciers, présente l'inconvénient d'être sensible à la corrosion. Pour remédier à cet inconvénient, on sait depuis longtemps qu'il est possible de le rendre inoxydable en l'alliant avec une certaine quantité de chrome et, le cas échéant, de molybdène, ces éléments formant spontanément un film protecteur d'oxyde à la surface du métal. Les compositions de ce type conduisent à une structure ferritique, identifiable notamment au fait que l'alliage ainsi obtenu est ferromagnétique, c'est-à-dire qu'il est attiré par les aimants. Toutefois, on souhaite, le plus souvent, obtenir une structure austénitique. Cette structure est en effet connue pour avoir de meilleures propriétés que la structure ferritique, notamment en matière de résistance à la corrosion, et être non magnétique. Dans ce but, il est alors nécessaire d'ajouter un élément d'alliage supplémentaire, susceptible de stabiliser l'austénite. Dans la plupart des cas, cet élément est le nickel.Iron, the basic element of all steels, presents the disadvantage of being sensitive to corrosion. For remedy this drawback, we have known for a long time that it is possible to make it stainless by combining it with a certain amount of chromium and, if necessary, molybdenum, these elements spontaneously forming a film oxide protector on the metal surface. The essays of this type lead to a ferritic structure, in particular identifiable by the fact that the alloy thus obtained is ferromagnetic, that is, it is attracted to magnets. However, most often, we want to an austenitic structure. This structure is indeed known to have better properties than ferritic structure, particularly in terms of resistance to corrosion, and be non-magnetic. For this purpose, it is then necessary to add an alloying element additional, likely to stabilize the austenite. In most cases, this element is nickel.
Néanmoins, lorsque ces alliages sont utilisés pour fabriquer des objets tels que, par exemple, des pièces d'habillement pour montres, qui peuvent être en contact prolongé avec la peau, la présence du nickel pose un problème en raison de ses effets allergènes bien connus. Pour ces applications, on a donc cherché à remplacer le nickel par un autre élément d'alliage également apte à stabiliser l'austénite. Différents auteurs ont proposé de remplacer le nickel par de l'azote. La solubilité de l'azote dans le fer est toutefois insuffisante pour obtenir l'austénisation, c'est-à-dire la stabilisation de l'austénite recherchée. Il est tout de même possible d'augmenter cette solubilité en ajoutant une certaine quantité de manganèse à l'alliage, qui peut alors devenir austénitique.However, when these alloys are used for manufacture objects such as, for example, coins of clothing for watches, which may be in contact prolonged with the skin, the presence of nickel poses a problem due to its well-known allergenic effects. For these applications, we therefore sought to replace the nickel by another alloying element also suitable for stabilize the austenite. Different authors have proposed replace nickel with nitrogen. The solubility of however, the nitrogen in the iron is insufficient for obtain austenization, i.e. stabilization of the austenite sought. It is still possible to increase this solubility by adding some amount of manganese to the alloy, which can then become austenitic.
A titre d'exemple, on connaít le brevet DE 195 13 407 dans lequel Uggowitzer et al. proposent un alliage inoxydable austénitique, non magnétique, et ne contenant pas de nickel. Cet alliage est basé sur le système Fe-Cr-N-Mn. Un tel alliage ne peut toutefois être obtenu que si l'on effectue un traitement thermique dans un domaine étroit de température. En effet, si la température de traitement est trop faible, des précipités de nitrure de chrome se forment, qui détruisent les propriétés de résistance à la corrosion de l'alliage. Inversement, si la température de traitement est trop élevée, la structure austénitique recherchée ne se forme pas. Cette dernière contrainte est particulièrement gênante lorsque ces alliages sont mis en forme par métallurgie des poudres, technique de plus en plus utilisée pour la fabrication de petites pièces de formes complexes, telles que des boítes de montre. En effet, cette technique requiert une température de frittage élevée pour conduire à des pièces denses, exemptes de porosité. Or, cette température de frittage est généralement très proche, ou même supérieure, à la température maximale admissible pour obtenir une structure austénitique. Il est ainsi difficile, voire impossible, d'obtenir dans des conditions industrielles, des pièces à la fois peu poreuses et austénitiques après frittage. On pourrait, éventuellement, envisager d'effectuer d'abord un frittage à haute température, pour obtenir des pièces peu poreuses, puis un traitement thermique ultérieur à une température plus faible, pour former la structure austénitique. Néanmoins, outre les coûts supplémentaires qui résulteraient de ce double traitement, l'expérience montre qu'il est très difficile de reformer l'austénite sur une pièce de structure ferritique formée à haute température.For example, we know the patent DE 195 13 407 in which Uggowitzer et al. offer an alloy austenitic stainless, not magnetic, and does not contain no nickel. This alloy is based on the system Fe-Cr-N-Mn. However, such an alloy cannot be obtained. that if one performs a heat treatment in a narrow temperature range. Indeed, if the temperature too low, nitride precipitates of chromium are formed, which destroy the properties of corrosion resistance of the alloy. Conversely, if the processing temperature is too high, the structure austenitic sought does not form. This last constraint is particularly troublesome when these alloys are shaped by powder metallurgy, technique increasingly used for the manufacture of small parts with complex shapes, such as boxes of watch. Indeed, this technique requires a high sintering temperature to lead to parts dense, free of porosity. Now, this temperature of sintering is usually very close, or even better, at the maximum allowable temperature to obtain a austenitic structure. It is thus difficult, even impossible, to obtain under industrial conditions, both porous and austenitic parts after sintering. We could possibly consider first perform a high temperature sintering, to obtain slightly porous parts, then a treatment subsequent thermal at a lower temperature, for form the austenitic structure. However, in addition to additional costs that would result from this double treatment, experience shows that it is very difficult to reform the austenite on a structural part ferritic formed at high temperature.
La présente invention a pour but de remédier aux problèmes et inconvénients ci-dessus, en proposant un acier ne présentant aucun caractère allergène, résistant bien à la corrosion, et pouvant être avantageusement mis en forme par métallurgie des poudres.The object of the present invention is to remedy the problems and disadvantages above, by proposing a steel with no allergenic character, resistant well corrosion, and can be advantageously put shaped by powder metallurgy.
A cet effet, la présente invention concerne un alliage d'acier inoxydable présentant une structure ferritique et magnétique, caractérisé en ce qu'il contient au moins 0,4% en poids d'azote, et au plus 0,5% en poids de nickel, le solde étant constitué par du fer et les impuretés inévitables.To this end, the present invention relates to a stainless steel alloy with structure ferritic and magnetic, characterized in that it contains at least 0.4% by weight of nitrogen, and at most 0.5% by weight nickel, the balance being made up of iron and unavoidable impurities.
Avantageusement, les alliages d'acier choisis auront une composition comprise dans les limites suivantes :
- entre 10 et 35% en poids pour le total de chrome et de molybdène, et
- entre 5 et 20% en poids de manganèse.
- between 10 and 35% by weight for the total of chromium and molybdenum, and
- between 5 and 20% by weight of manganese.
L'invention a aussi pour objet un tel alliage d'acier réalisé par métallurgie des poudres.The invention also relates to such a steel alloy produced by powder metallurgy.
L'invention a enfin pour objet une pièce extérieure d'habillement pour montre réalisée en un tel alliage d' acier.The invention finally relates to an external part of clothing for a watch made of such an alloy of steel.
Pour bien comprendre les caractéristiques de la présente invention, il faut rappeler les conditions qui ont présidées à sa mise en oeuvre. En effet, au lieu de partir d'un acier inoxydable austénitique résistant bien à la corrosion, et de remplacer le nickel par un autre élément stabilisant l'austénite, la présente invention propose de partir d'une structure ferritique exempte de nickel, dont la résistance à la corrosion est connue pour être moins bonne, et d'améliorer cette résistance à la corrosion de manière tout à fait originale, en ajoutant de nouveaux éléments d'alliage et en conservant la structure ferritique.To fully understand the characteristics of the present invention, it is necessary to recall the conditions which have presided over its implementation. Indeed, instead of from an austenitic stainless steel resistant to corrosion, and replace nickel with another austenite stabilizing element, the present invention proposes to start from a ferritic structure free of nickel, whose corrosion resistance is known for be less good, and improve this resistance to corrosion in a completely original way, adding new alloying elements and retaining the structure ferritic.
Il est connu qu'il n'est guère possible d'augmenter la résistance à la corrosion d'une structure ferritique simplement en augmentant le pourcentage de chrome et de molybdène dans l'alliage. En effet, des taux plus élevés que ceux utilisés habituellement (plus de 25% en poids de chrome ou plus de 10% en poids de molybdène) conduisent rapidement à la formation de phases intermétalliques qui produisent des alliages aux propriétés mécaniques et à l'usinabilité extrêmement mauvaises.It is known that it is hardly possible to increase the corrosion resistance of a ferritic structure simply by increasing the percentage of chromium and molybdenum in the alloy. Indeed higher rates than those usually used (more than 25% by weight of chromium or more than 10% by weight of molybdenum) lead quickly to the formation of intermetallic phases which produce alloys with mechanical properties and extremely poor machinability.
Parmi les éléments susceptibles d'améliorer la résistance des alliages ferritiques à la corrosion, le demandeur a constaté qu'un élément efficace pour atteindre ce but était l'azote.Among the elements likely to improve the resistance of ferritic alloys to corrosion, Applicant has found that an effective element to achieve that goal was nitrogen.
Ainsi, l'alliage objet de la présente invention est un alliage ferritique à base de fer, de chrome, de manganèse et d'azote. On remarquera que si la composition de l'alliage selon l'invention est semblable à certaines compositions de l'art antérieur, sa structure ferritique et magnétique est totalement différente, et se traduit par des propriétés nouvelles extrêmement avantageuses. En particulier, on constate que, contrairement aux alliages austénitiques de l'art antérieur, l'alliage selon l'invention est magnétique, c'est-à-dire qu'il est attiré par les aimants. Cette propriété est particulièrement intéressante lorsque l'invention est appliquée aux boítes de montre. En effet, les mouvements d'horlogerie mécaniques sont particulièrement sensibles aux champs magnétiques, et un boítier réalisé dans un alliage magnétique peut constituer un blindage contre les champs magnétiques extérieurs. Il est toutefois impératif que ce magnétisme soit totalement doux, ce qui signifie qu'aucune aimantation résiduelle ne doit persister dans l'alliage lorsqu'il n'est plus soumis à un champ magnétique extérieur. On a vérifié que l'alliage selon l'invention ne présente aucune aimantation résiduelle, même après avoir été soumis de nombreuses fois à un champ magnétique de cinq Tesla, mille fois plus puissant que les champs magnétiques utilisés d'ordinaire pour tester les mouvements d'horlogerie. Contrairement aux autres alliages magnétiques susceptibles de présenter une légère aimantation résiduelle et qui, pour cette raison, ne sont pas utilisés en horlogerie, le caractère magnétique de l'alliage selon l'invention constitue donc un avantage pour les applications horlogères. Thus, the alloy which is the subject of the present invention is a ferritic alloy based on iron, chromium, manganese and nitrogen. Note that if the composition of the alloy according to the invention is similar to certain compositions of the prior art, its ferritic structure and magnetic is totally different, and results in extremely advantageous new properties. In particular, we note that, unlike alloys austenitics of the prior art, the alloy according to the invention is magnetic, that is, it is attracted by magnets. This property is particularly interesting when the invention is applied to boxes of watch. Indeed, watch movements are particularly sensitive to fields magnetic, and a case made of an alloy magnetic can provide shielding against fields magnetic exterior. It is however imperative that this magnetism is completely soft, which means that no residual magnetization must not persist in the alloy when it is no longer subjected to a magnetic field outside. It has been verified that the alloy according to the invention does not has no residual magnetization, even after been subjected many times to a magnetic field of five Tesla, a thousand times more powerful than the fields usually used to test watch movements. Unlike other alloys magnetic likely to present a slight residual magnetization and which, for this reason, are not not used in watchmaking, the magnetic character of the alloy according to the invention therefore constitutes an advantage for watchmaking applications.
Un autre avantage de l'alliage selon l'invention réside dans la suppression de la contrainte de température de traitement maximale imposée aux alliages de l'art antérieur, en particulier lorsque la métallurgie des poudres est utilisée. En effet, conformément à l'invention, pour atteindre la structure ferritique recherchée, il faut une température élevée, parfaitement compatible avec la température de frittage nécessaire pour obtenir des pièces denses, exemptes de porosité.Another advantage of the alloy according to the invention lies in the removal of the temperature constraint maximum treatment imposed on art alloys earlier, especially when the metallurgy of powders is used. Indeed, in accordance with the invention, to reach the ferritic structure you need a high temperature, perfectly compatible with the sintering temperature required for obtain dense parts, free of porosity.
Un autre avantage de l'alliage selon l'invention réside dans le fait que la quantité d'azote et de manganèse ajoutée peut être réduite au minimum nécessaire pour obtenir une résistance à la corrosion suffisante pour l'application considérée, alors qu'une concentration élevée est indispensable pour obtenir des alliages présentant une structure austénitique. Il est ainsi possible de réaliser des alliages présentant une usinabilité bien meilleure que celle des alliages à haute teneur en azote et en manganèse, éléments qui sont connus pour augmenter considérablement la dureté, la résistance, et la ténacité de l'alliage.Another advantage of the alloy according to the invention is that the amount of nitrogen and added manganese can be reduced to the minimum necessary to obtain sufficient corrosion resistance for the application considered, while a concentration high is essential to obtain alloys with an austenitic structure. It is so possible to make alloys with a much better machinability than high alloys nitrogen and manganese content, elements which are known to significantly increase hardness, strength, and the toughness of the alloy.
Si la quantité d'azote que l'alliage est susceptible de contenir en solution est trop faible pour améliorer suffisamment la résistance à la corrosion, on peut l'augmenter en ajoutant du manganèse qui, comme dans le cas des structures austénitiques, permet également d'améliorer la solubilité de l'azote dans la structure ferritique de l'alliage recherché.If the amount of nitrogen that the alloy is likely to contain in solution is too weak to improve enough corrosion resistance, we can increase it by adding manganese which, as in the case of austenitic structures, also allows improve the solubility of nitrogen in the structure ferritic of the desired alloy.
Un exemple d'alliage selon l'invention et de son mode de réalisation va maintenant être décrit en référence à une fine poudre constituée de 16,91% en poids de chrome, 3,61% en poids de molybdène, 11,92% en poids de manganèse, 0,37% en poids de silicium, 0,03% en poids de nickel et la balance de fer.An example of an alloy according to the invention and its mode of realization will now be described with reference to a fine powder consisting of 16.91% by weight of chromium, 3.61% by weight of molybdenum, 11.92% by weight of manganese, 0.37% by weight of silicon, 0.03% by weight of nickel and the iron balance.
Cette poudre est mélangée à un liant organique à raison de 60% en volume de poudre pour 40% en volume de liant, et injectée selon le procédé dit "MIM" (Metal Injection Moulding). Les pièces ainsi obtenues sont débarrassées de leur liant par un procédé thermochimique dit de décirage, et frittées dans une atmosphère de formiergaz comprenant 8% d'hydrogène et 92% d'azote, à une température de 1350°C pendant une heure. Au cours du frittage, l'azote diffuse rapidement dans l'alliage, jusqu'à ce que sa concentration atteigne environ 1% en poids, ce que confirment les analyses chimiques effectuées par la suite sur les échantillons ainsi réalisés. Les pièces obtenues sont denses (seulement environ 0,1% de porosités) et magnétiques, indiquant que leur structure est ferritique. Pour réaliser une structure austénitique, non magnétique, avec la même composition, il faudrait utiliser une température de frittage de 1275°C au maximum. Dans ces conditions, la porosité des pièces obtenues est de 1%, et même de 4% pour une température de frittage de 1265°C. Cette porosité serait inacceptable pour la réalisation d'une boíte de montre, et une telle sensibilité à la température de frittage serait difficilement compatible avec des conditions de production industrielles.This powder is mixed with an organic binder to 60% by volume of powder for 40% by volume of binder, and injected according to the so-called "MIM" process (Metal Injection Molding). The parts thus obtained are freed from their binder by a thermochemical process said to be dewaxing, and sintered in an atmosphere of formiergaz comprising 8% hydrogen and 92% nitrogen, at one temperature of 1350 ° C for one hour. During the sintering, the nitrogen diffuses rapidly in the alloy, until its concentration reaches about 1% in weight, which is confirmed by the chemical analyzes carried out thereafter on the samples thus produced. The parts obtained are dense (only about 0.1% of porosities) and magnetic, indicating that their structure is ferritic. To achieve an austenitic structure, non magnetic, with the same composition, use a sintering temperature of 1275 ° C maximum. Under these conditions, the porosity of the parts obtained is by 1%, and even by 4% for a sintering temperature of 1265 ° C. This porosity would be unacceptable for the realization of a watch case, and such sensitivity to sintering temperature would hardly compatible with production conditions industrial.
Les pièces ferritiques obtenues au moyen de l'alliage selon l'invention ont été soumises à un test de corrosion consistant à les plonger pendant soixante-douze heures en contact avec un brouillard réalisé à partir d'eau salée, puis en les mettant pendant soixante-douze heures dans une solution de sueur synthétique. Après le test, les pièces ne présentent pas la moindre trace de corrosion, indiquant que, contrairement à la plupart des autres aciers ferritiques, leur résistance à la corrosion est au moins aussi bonne que celle d'un bon alliage inoxydable austénitique. Ceci est dû à la présence d'azote et de manganèse qui améliorent les propriétés de la phase ferritique.Ferritic parts obtained by means of the alloy according to the invention have been subjected to a corrosion test consisting of submerging them for seventy-two hours contact with a mist made from salt water, then putting them for seventy-two hours in a synthetic sweat solution. After the test, the parts show no trace of corrosion, indicating that unlike most other steels ferritic, their corrosion resistance is at least as good as a good stainless alloy austenitic. This is due to the presence of nitrogen and manganese which improve the properties of the phase ferritic.
Un mouvement d'horlogerie mécanique a été monté dans une boíte de montre réalisée au moyen de l'alliage selon l'invention. Les test horlogers standards de résistance aux champs magnétiques ont montré un effet de blindage bénéfique pour le mouvement en présence d'un champ magnétique extérieur. Aucune influence néfaste de l'alliage magnétique sur la marche du mouvement mécanique n'a été observée, même après avoir soumis la boíte à des champs de cinq Tesla, mille fois plus puissants que les champs magnétiques utilisés normalement.A mechanical watch movement has been set up in a watch case made by means of the alloy according to the invention. Standard watchmaking resistance tests to magnetic fields showed a shielding effect beneficial for movement in the presence of a field magnetic outside. No harmful influence of the magnetic alloy on the march of mechanical movement has not been observed even after subjecting the box to fields of five Tesla, a thousand times more powerful than magnetic fields normally used.
Il va de soi que diverses variantes et modifications simples entrent dans le cadre de la présente invention.It goes without saying that various variants and modifications simple fall within the scope of the present invention.
Claims (5)
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP98110813A EP0964071A1 (en) | 1998-06-12 | 1998-06-12 | Ferritic stainless steel and exterior cover part for a watch made with such a steel |
| JP11162265A JP2000017403A (en) | 1998-06-12 | 1999-06-09 | Ferritic stainless steel and external parts for clock made of ferritic stainless steel |
| US09/329,793 US6093233A (en) | 1998-06-12 | 1999-06-10 | Ferritic stainless steel and external part for a watch made thereof |
| CN99109480.8A CN1239153A (en) | 1998-06-12 | 1999-06-11 | Ferritic stainless steel and external part for watch made thereof |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH128098 | 1998-06-12 | ||
| EP98110813A EP0964071A1 (en) | 1998-06-12 | 1998-06-12 | Ferritic stainless steel and exterior cover part for a watch made with such a steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0964071A1 true EP0964071A1 (en) | 1999-12-15 |
Family
ID=25687196
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP98110813A Withdrawn EP0964071A1 (en) | 1998-06-12 | 1998-06-12 | Ferritic stainless steel and exterior cover part for a watch made with such a steel |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US6093233A (en) |
| EP (1) | EP0964071A1 (en) |
| JP (1) | JP2000017403A (en) |
| CN (1) | CN1239153A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2728028A1 (en) | 2012-11-02 | 2014-05-07 | The Swatch Group Research and Development Ltd. | Edelstahllegierung ohne Nickel |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH694401A5 (en) * | 1999-05-26 | 2004-12-31 | Basf Ag | Low-nickel, low-molybdenum, biocompatible, non-allergenic, corrosion-resistant austenitic steel. |
| WO2001000897A1 (en) * | 1999-06-24 | 2001-01-04 | Basf Aktiengesellschaft | Nickel-poor austenitic steel |
| US8158057B2 (en) * | 2005-06-15 | 2012-04-17 | Ati Properties, Inc. | Interconnects for solid oxide fuel cells and ferritic stainless steels adapted for use with solid oxide fuel cells |
| US7842434B2 (en) * | 2005-06-15 | 2010-11-30 | Ati Properties, Inc. | Interconnects for solid oxide fuel cells and ferritic stainless steels adapted for use with solid oxide fuel cells |
| US7981561B2 (en) * | 2005-06-15 | 2011-07-19 | Ati Properties, Inc. | Interconnects for solid oxide fuel cells and ferritic stainless steels adapted for use with solid oxide fuel cells |
| JP2005536631A (en) * | 2002-07-02 | 2005-12-02 | フィルト・アクチェンゲゼルシャフト | Steel alloy |
| US20060130938A1 (en) * | 2002-10-04 | 2006-06-22 | Firth Ag | Ferritic steel alloy |
| US7467346B2 (en) * | 2005-08-18 | 2008-12-16 | Hitachi Global Storage Technologies Netherlands, B.V. | Decoding error correction codes using a modular single recursion implementation |
| JP4321506B2 (en) * | 2005-09-08 | 2009-08-26 | オムロン株式会社 | Method for manufacturing photoelectric sensor |
| JP2007248397A (en) * | 2006-03-17 | 2007-09-27 | Seiko Epson Corp | Ornaments and watches |
| JP5212602B2 (en) * | 2007-09-14 | 2013-06-19 | セイコーエプソン株式会社 | Device and housing material manufacturing method |
| EP2488675B1 (en) | 2009-10-16 | 2021-03-10 | Höganäs Ab (publ) | Nitrogen containing, low nickel sintered stainless steel |
| EP2813906A1 (en) * | 2013-06-12 | 2014-12-17 | Nivarox-FAR S.A. | Part for clockwork |
| EP3176653B1 (en) * | 2015-12-03 | 2018-09-26 | Cartier International AG | Clock component having a magnetic shielding function and comprising a steel alloy |
| JP7459495B2 (en) * | 2019-12-13 | 2024-04-02 | セイコーエプソン株式会社 | Austenitized ferritic stainless steel, watch parts, and electronic watches |
| EP3835438A1 (en) * | 2019-12-13 | 2021-06-16 | The Swatch Group Research and Development Ltd | Paramagnetic hard stainless steel and method for manufacturing same |
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| US4340432A (en) * | 1980-05-13 | 1982-07-20 | Asea Aktiebolag | Method of manufacturing stainless ferritic-austenitic steel |
| EP0379061A1 (en) * | 1989-01-18 | 1990-07-25 | Eta SA Fabriques d'Ebauches | Exterior cover part for a watch, and method for manufacturing the same |
| EP0640695A1 (en) * | 1992-07-07 | 1995-03-01 | BÖHLER Edelstahl GmbH | Corrosion resistant alloy, useful as material for parts in contact with living beings |
| DE19513407C1 (en) * | 1995-04-08 | 1996-10-10 | Vsg En & Schmiedetechnik Gmbh | Steel alloy used for jewellery implants and dental applications |
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| US4340424A (en) * | 1974-04-23 | 1982-07-20 | Daido Tokushuko Kabushiki Kaisha | Ferritic stainless steel having excellent machinability and local corrosion resistance |
| JPS5360814A (en) * | 1976-11-12 | 1978-05-31 | Sumitomo Metal Ind Ltd | Heat resisting ferritic stainless steel with excellent weldability |
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1998
- 1998-06-12 EP EP98110813A patent/EP0964071A1/en not_active Withdrawn
-
1999
- 1999-06-09 JP JP11162265A patent/JP2000017403A/en active Pending
- 1999-06-10 US US09/329,793 patent/US6093233A/en not_active Expired - Fee Related
- 1999-06-11 CN CN99109480.8A patent/CN1239153A/en active Pending
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|---|---|---|---|---|
| US4340432A (en) * | 1980-05-13 | 1982-07-20 | Asea Aktiebolag | Method of manufacturing stainless ferritic-austenitic steel |
| EP0379061A1 (en) * | 1989-01-18 | 1990-07-25 | Eta SA Fabriques d'Ebauches | Exterior cover part for a watch, and method for manufacturing the same |
| EP0640695A1 (en) * | 1992-07-07 | 1995-03-01 | BÖHLER Edelstahl GmbH | Corrosion resistant alloy, useful as material for parts in contact with living beings |
| DE19513407C1 (en) * | 1995-04-08 | 1996-10-10 | Vsg En & Schmiedetechnik Gmbh | Steel alloy used for jewellery implants and dental applications |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2728028A1 (en) | 2012-11-02 | 2014-05-07 | The Swatch Group Research and Development Ltd. | Edelstahllegierung ohne Nickel |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000017403A (en) | 2000-01-18 |
| CN1239153A (en) | 1999-12-22 |
| US6093233A (en) | 2000-07-25 |
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