WO2013190206A1 - Joining of manganese steel railway line components by direct welding - Google Patents

Joining of manganese steel railway line components by direct welding Download PDF

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Publication number
WO2013190206A1
WO2013190206A1 PCT/FR2013/051283 FR2013051283W WO2013190206A1 WO 2013190206 A1 WO2013190206 A1 WO 2013190206A1 FR 2013051283 W FR2013051283 W FR 2013051283W WO 2013190206 A1 WO2013190206 A1 WO 2013190206A1
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WIPO (PCT)
Prior art keywords
steel
content
direct
junction
rail
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PCT/FR2013/051283
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French (fr)
Inventor
Francesco Barresi
Original Assignee
Vossloh Cogifer (Société Anonyme)
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Priority to EA201301221A priority Critical patent/EA201301221A1/en
Publication of WO2013190206A1 publication Critical patent/WO2013190206A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
    • B23K35/3053—Fe as the principal constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K23/00—Alumino-thermic welding
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/26—Railway- or like rails

Definitions

  • the present invention relates to the field of manganese steel compositions and more particularly to the application of these compositions in methods of joining railroad track installations.
  • the junction of railway track elements and in particular the junction between, on the one hand, a high manganese alloy steel track core and, on the other hand, a rail involves the use of a part. intermediate made by a stainless steel insert.
  • the respective compositions of the steels which constitute each of the two elements of the junction prevent the realization of a direct weld of good quality.
  • the weld causes the formation of an alloy whose composition is different from that of the different base materials.
  • the combination of the carbon steel of the rail with the alloy of the channel core results in the formation in the melting zone of a steel alloy whose nature is difficult to control and whose properties of resistance to shocks and vibrations are relatively low with a high risk of rupture in this zone as well as in the thermally affected zone.
  • the present invention aims to overcome this drawback by proposing a railway junction allowing direct welding of a track core with a steel rail whose carbon content is not imperatively restricted, this rail junction having a improved strength at break as well as in some couples material a higher wear resistance.
  • the subject of the invention is thus a railway junction by direct welding between, on the one hand, a track core and, on the other hand, a rail, characterized in that at least one of the two joined elements is formed by a steel, the composition of which
  • the invention also relates to a direct welding process, characterized in that the method is implemented at a railway junction according to the invention.
  • FIG. 1 relates to a summary table of the examples of chemical composition of steel according to the invention
  • FIG. 2 relates to a table summarizing the mechanical properties of a steel according to one of the chemical compositions according to the invention
  • FIG. 3 relates to a graphical representation of the hardness of a direct solder junction as a function of the distance from the center of this junction
  • FIG. 4 relates to examples of flexural test according to the European standard three direct welds according to the invention operated by sparking.
  • railway refers to both dormant railroad rail elements and dormant railway track elements.
  • the present invention is based in particular on a railway junction by direct welding between, on the one hand, a track core and, on the other hand, a rail, characterized in that at least one of the two joined elements is formed by a steel whose composition presents:
  • Such a composition of one of the elements makes it possible, by virtue of its very low carbon content, to facilitate the welding of the element with a second where the composition of the steel does not have a carbon content that is too low and addition elements that promote a better weld.
  • the manganese content greater than 1 1% ensures a better wear resistance to deformation and hardening. This higher manganese content in the steel composition maintains its breaking strength while decreasing the carbon content.
  • the role of carbon in this steel is to obtain sufficient hardness of the steel mainly by strengthening solid solution.
  • a high carbon content leads to an increase in the amount of retained austenite, resulting in a reduction in hardness.
  • An increase in the carbon content will significantly improve the risk of embrittlement of the grain boundaries in these steels, due to the formation of carbide in the form of networks, on the one hand, in the as-manufactured state, and secondly, as a result of welding. Therefore, to maintain the delicate balance between the hardness and the risk of embrittlement, the carbon content must be between 0.01 and 0.12% for these steels (all compositions are given as a percentage of weight, unless indicated opposite).
  • the weldability is improved with a carbon content of less than 0.10, preferably less than 0.08.
  • the carbon content is at least 0.01% and preferably at least 0.02%. From a steel manufacturing point of view, a suitable minimum carbon content is of the order of 0.04%.
  • Manganese is an element promoting austenite. It stabilizes the austenite, for example by increasing the temperature range in which the austenite is formed.
  • a variation in the manganese content in the steels according to the invention has revealed that a maximum of hardness is obtained with a manganese content of at least 11%. At very high levels of manganese, for example at 15%, the hardness decreases to an insufficient level. The hardness shows an intimate correlation with the wear resistance. Wear resistance is a determining factor in the service life of most railway parts, including switches. A low wear rate means that the repair of the part is needed less frequently. The significant difference in wear resistance between steels with a manganese content of less than 11% and those with a content greater than 1% is attributed to differences in the microstructure.
  • the residual austenite levels become sufficiently high that the increase in the hardness of the martensitic phase is largely offset by the increasing proportion of the softer austenite, so that the Total hardness of steel decreases with wear resistance. Resistance to crack propagation is high and is associated with a very slow progression of breaks. With this, the possibility of detecting developing fatigue cracks is increased, and the affected part (s) can be removed or repaired before complete damage occurs.
  • the manganese content is preferably between at least 11% and at most 15%. Since manganese is also a costly alloying element, a maximum content of suitable manganese has been found at 14% or even 13%. A suitable minimum content of manganese was 1 1.5%.
  • the rail junction by direct welding is characterized in that at least one of the two elements of this junction is formed by a steel whose composition has:
  • Molybdenum is effective in increasing the impact resistance of steel. Moreover, due to the effect of purification (scavenging effect) of molybdenum for phosphorus, the phenomena of embrittlement of anger are prevented. At a level of 0.6% molybdenum, the increase in impact resistance is already noticeable, but a further increase is obtained with values above 0.6%. Increased levels of impact resistance peak at a value of 1.5%. Also, the addition of molybdenum in this steel must be between 0.6% and 2.95%, with a molybdenum content which is preferably at least 1.25%. A molybdenum content of 1.5% was found to be a suitable minimum value for stable values of impact resistance. A molarbdenum content of 1.90% was judged to be a maximum value adapted from a combined cost and a technical perspective since additions to values above 1.90% resulted only in a modest improvement.
  • silicon has little effect on the impact resistance and wear resistance of these steels, although it provides an increase in tensile strength and hardness by solution strengthening. solid. Silicon also serves as a deoxidizing agent (killing agent) during steel production. On this basis, a maximum value of Si of 0.5% is recommended. A suitable minimum content of 0.10 or even 0.15% and / or a suitable maximum level of 0.40 or even 0.35% have been determined.
  • Nickel (Ni), cobalt (Co) and copper (Cu) show a similar effect to that of manganese (Mn) through their ability to promote the formation of austenite. To some extent these elements can be added, or even replace, manganese.
  • the alloys according to the invention have been found to be easily machinable.
  • One or more additions of sulfur, calcium, tellurium, or selenium, or any other known element to improve machinability can be made to achieve these alloys if necessary.
  • the phosphorus content is generally kept below 0.02% to minimize the risk of hot cracking.
  • the steel according to the invention is preferentially deoxidized by silicon (silicon killed). Provided that the cleanliness of the steel remains in accordance with the specifications in terms of the maximum value of the inclusions of aluminum oxide, the steel can also be deoxidized by aluminum (killed aluminum) or by an association aluminum-silicon (aluminum-silicon killed)
  • the steel according to the invention has a hydrogen content of less than 5 ppm, preferably less than 3.5 ppm and ideally less than 2.5 ppm.
  • chromium is preferentially kept below an impurity level of 0.15%, chromium is not added deliberately. For some applications, chromium can be added up to a level of 0.3%.
  • the rail joint by direct welding is characterized in that the composition of the steel of at least one of the two elements of the junction comprises a silicon content of less than 0, 1%.
  • the composition of the steel of at least one of the two elements of the junction comprises an austenite content corresponding to at least 15% of the volume in its hot rolled state or in the element of the junction at room temperature.
  • the composition of the steel has a carbon content of less than 0.02%.
  • the composition of the steel has a chromium content of between 0.02% and 0.03%.
  • this railway junction by direct welding is characterized in that the track core is formed by a steel whose composition is defined according to the present document.
  • the present invention also relates to a direct welding process characterized in that it is implemented at a railway junction according to the invention.
  • the direct soldering method according to the invention involves a spark welding step.
  • the direct soldering method according to the invention involves an electric welding step.
  • the direct soldering method according to the invention involves a welding step by alumino thermie.
  • an advantage of the railway junction according to the invention represented by the results of FIG. 3 is a reduced variation of the hardness compared to a conventional railway junction.
  • the railway junction according to the invention allows a direct weld whose resistance to breakage and wear is greater and improved.
  • the combination of this breaking strength with the wear resistance is also confirmed by the results presented in FIG. 4, which show deformation tests of the direct welded rail junction according to the European standard EN 14587.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Arc Welding In General (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

Joining of manganese steel railway line components by direct welding. The subject matter of the present invention is a railway junction by direct welding between a railway frog and a rail, characterized in that at least one of the two components joined is made of a steel of which the composition has: - a carbon content of less than 0.12%, and - a manganese content greater than 11%.

Description

Jonction d'éléments de voie ferroviaire en acier manganèse  Junction of railroad elements of manganese steel
par soudure directe  by direct welding
La présente invention se rapporte au domaine des compositions d'acier manganèse et plus particulièrement à l'application de ces compositions dans des procédés de jonction d'installations de voie du domaine ferroviaire. The present invention relates to the field of manganese steel compositions and more particularly to the application of these compositions in methods of joining railroad track installations.
Actuellement, la jonction d'éléments de voie ferroviaire et notamment la jonction entre, d'une part, un cœur de voie en acier fortement allié au manganèse et, d'autre part, un rail, fait intervenir l'utilisation d'une pièce intermédiaire réalisée par un insert en acier inox. Lorsque la jonction des éléments est effectuée sans apport d'une pièce intermédiaire, les compositions respectives des aciers qui constituent chacun des deux éléments de la jonction empêchent la réalisation d'une soudure directe de bonne qualité. Ainsi, lorsqu'un rail en acier carbone est soudé à un cœur de voie en acier fortement allié, la soudure provoque la formation d'un alliage dont la composition est différente de celle des différents matériaux de base. La combinaison de l'acier carbone du rail avec l'alliage du cœur de voie aboutit à la formation dans la zone de fusion d'un alliage d'acier dont la nature est difficilement contrôlable et dont les propriétés de résistance aux chocs et aux vibrations sont relativement faibles avec un fort risque de rupture dans cette zone ainsi que dans la zone affectée thermiquement.  Currently, the junction of railway track elements and in particular the junction between, on the one hand, a high manganese alloy steel track core and, on the other hand, a rail, involves the use of a part. intermediate made by a stainless steel insert. When the joining of the elements is carried out without adding an intermediate part, the respective compositions of the steels which constitute each of the two elements of the junction prevent the realization of a direct weld of good quality. Thus, when a carbon steel rail is welded to a high alloy steel track core, the weld causes the formation of an alloy whose composition is different from that of the different base materials. The combination of the carbon steel of the rail with the alloy of the channel core results in the formation in the melting zone of a steel alloy whose nature is difficult to control and whose properties of resistance to shocks and vibrations are relatively low with a high risk of rupture in this zone as well as in the thermally affected zone.
Un exemple de jonction par soudure directe est illustré par la publication de la demande FR2840628 qui propose l'utilisation d'un tronçon de rail réalisé en acier bainitique dont la teneur en carbone est inférieure à 0,55% associé à un élément de voie dont la composition est celle d'un acier Hadfield contenant 12 à 14% de Manganèse. Cependant, une jonction avec des éléments d'une telle composition forme un arrangement qui présente comme inconvénient, d'une part, de ne pouvoir être appliqué qu'à des rails composés d'acier bainitique faiblement allié et, d'autre part, d'imposer une jonction rail/cœur de voie avec, au niveau de la soudure, une dureté élevée pouvant générer une rupture .  An example of direct solder junction is illustrated by the publication of the application FR2840628 which proposes the use of a rail section made of bainitic steel whose carbon content is less than 0.55% associated with a track element of which the composition is that of a Hadfield steel containing 12 to 14% of manganese. However, a junction with elements of such a composition forms an arrangement which has the disadvantage, on the one hand, of being able to be applied only to rails composed of low-alloy bainitic steel and, on the other hand, of impose a rail / track core junction with, at the weld, a high hardness that can cause a break.
La présente invention a pour but de pallier cet inconvénient en proposant une jonction ferroviaire autorisant une soudure directe d'un cœur de voie avec un rail en acier dont la teneur en carbone n'est pas impérativement restreinte, cette jonction ferroviaire présentant une résistance améliorée à la rupture ainsi que dans certains couples matière une résistance à l'usure plus élevée. The present invention aims to overcome this drawback by proposing a railway junction allowing direct welding of a track core with a steel rail whose carbon content is not imperatively restricted, this rail junction having a improved strength at break as well as in some couples material a higher wear resistance.
L'invention a ainsi pour objet une jonction ferroviaire par soudure directe entre, d'une part, un cœur de voie et, d'autre part, un rail, caractérisée en ce qu'au moins un des deux éléments joints est formé par un acier dont la composition présente :  The subject of the invention is thus a railway junction by direct welding between, on the one hand, a track core and, on the other hand, a rail, characterized in that at least one of the two joined elements is formed by a steel, the composition of which
- une teneur en carbone inférieure à 0,12%, et  - a carbon content of less than 0.12%, and
- une teneur en manganèse supérieure à 1 1%.  - a manganese content greater than 1 1%.
L'invention a également pour objet un procédé de soudure directe, caractérisé en ce que le procédé est mis en œuvre au niveau d'une jonction ferroviaire selon l'invention.  The invention also relates to a direct welding process, characterized in that the method is implemented at a railway junction according to the invention.
L'invention sera mieux comprise, grâce à la description ci- après, qui se rapporte à un mode de réalisation préféré, donné à titre d'exemple non limitatif, et expliqué avec référence aux dessins schématiques annexés, dans lesquels :  The invention will be better understood, thanks to the following description, which relates to a preferred embodiment, given by way of non-limiting example, and explained with reference to the attached schematic drawings, in which:
- la figure 1 se rapporte à un tableau récapitulatif des exemples de composition chimique d'acier selon l'invention,  FIG. 1 relates to a summary table of the examples of chemical composition of steel according to the invention,
- la figure 2 se rapporte à un tableau résumant les propriétés mécaniques d'un acier selon une des compositions chimiques selon l'invention,  FIG. 2 relates to a table summarizing the mechanical properties of a steel according to one of the chemical compositions according to the invention,
- la figure 3 se rapporte à une représentation graphique de la dureté d'une jonction par soudure directe en fonction de la distance par rapport au centre de cette jonction,  FIG. 3 relates to a graphical representation of the hardness of a direct solder junction as a function of the distance from the center of this junction,
- la figure 4 se rapporte à des exemples de test de flexion selon la norme européenne trois soudures directes selon l'invention opérées par étincelage.  - Figure 4 relates to examples of flexural test according to the European standard three direct welds according to the invention operated by sparking.
Il convient de comprendre que, dans le présent document, le terme « ferroviaire » se rapporte aussi bien à des éléments dormants de voie ferrée pour train qu'à des éléments dormants de voie ferrée pour tramway.  It should be understood that, in this document, the term "railway" refers to both dormant railroad rail elements and dormant railway track elements.
La présente invention repose notamment sur une jonction ferroviaire par soudure directe entre, d'une part, un cœur de voie et, d'autre part, un rail, caractérisée en ce qu'au moins un des deux éléments joints est formé par un acier dont la composition présente :  The present invention is based in particular on a railway junction by direct welding between, on the one hand, a track core and, on the other hand, a rail, characterized in that at least one of the two joined elements is formed by a steel whose composition presents:
- une teneur en carbone inférieure à 0,12%, et  - a carbon content of less than 0.12%, and
- une teneur en manganèse supérieure à 1 1%.  - a manganese content greater than 1 1%.
Une telle composition d'un des éléments permet, de par sa très faible teneur en carbone, une soudure facilitée de l'élément avec un second élément dont la composition de l'acier ne comporte pas une teneur imposée en carbone qui soit trop faible et des éléments d'addition favorisant une meilleure soudure. La teneur en manganèse supérieure à 1 1% assure une meilleure résistance à l'usure à la déformation et à l'écrouissage. Cette teneur plus élevée en manganèse dans la composition de l'acier permet de maintenir sa résistance à la rupture tout en diminuant la teneur en carbone. Such a composition of one of the elements makes it possible, by virtue of its very low carbon content, to facilitate the welding of the element with a second where the composition of the steel does not have a carbon content that is too low and addition elements that promote a better weld. The manganese content greater than 1 1% ensures a better wear resistance to deformation and hardening. This higher manganese content in the steel composition maintains its breaking strength while decreasing the carbon content.
Le rôle du carbone dans cet acier est d'obtenir une dureté suffisante de l'acier principalement par le renforcement de solution solide. D'autre part, une haute teneur en carbone conduit à une augmentation de la quantité d'austénite retenue, entraînant une réduction de la dureté. Une augmentation de la teneur en carbone améliorera de façon significative le risque de fragilisation des joints de grains dans ces aciers, en raison de la formation de carbure sous forme de réseaux, d'une part, dans l'état tel que manufacturé et, d'autre part, à la suite de soudage. Par conséquent, pour maintenir l'équilibre délicat entre la dureté et le risque de fragilisation, la teneur en carbone doit être comprise entre 0,01 et 0,12% pour ces aciers (toutes les compositions sont données en pourcentage de poids, sauf indication contraire). La soudabilité est améliorée avec une teneur en carbone inférieure à 0,10, préférablement inférieure à 0,08.  The role of carbon in this steel is to obtain sufficient hardness of the steel mainly by strengthening solid solution. On the other hand, a high carbon content leads to an increase in the amount of retained austenite, resulting in a reduction in hardness. An increase in the carbon content will significantly improve the risk of embrittlement of the grain boundaries in these steels, due to the formation of carbide in the form of networks, on the one hand, in the as-manufactured state, and secondly, as a result of welding. Therefore, to maintain the delicate balance between the hardness and the risk of embrittlement, the carbon content must be between 0.01 and 0.12% for these steels (all compositions are given as a percentage of weight, unless indicated opposite). The weldability is improved with a carbon content of less than 0.10, preferably less than 0.08.
Pour obtenir la micro structure souhaitée, la teneur en carbone est d'au moins 0,01% et de préférence au moins 0,02%. D'un point de vue de fabrication de l'acier, une teneur minimale appropriée de carbone est de l'ordre de 0,04%.  To obtain the desired micro structure, the carbon content is at least 0.01% and preferably at least 0.02%. From a steel manufacturing point of view, a suitable minimum carbon content is of the order of 0.04%.
Le manganèse est un élément favorisant l'austénite. Il stabilise l'austénite, par exemple en augmentant la plage de température dans laquelle l'austénite se forme.  Manganese is an element promoting austenite. It stabilizes the austenite, for example by increasing the temperature range in which the austenite is formed.
Une variation de la teneur en manganèse dans les aciers selon l'invention a révélé qu'un maximum de dureté est obtenu avec une teneur en manganèse d'au moins 1 1%. A des niveaux très élevés de manganèse, par exemple à 15%, la dureté diminue à un niveau insuffisant. La dureté montre une intime corrélation avec la résistance à l'usure. La résistance à l'usure est un facteur déterminant pour la durée de vie de la plupart des pièces de chemins de fer, y compris des appareils de voie. Un faible taux d'usure signifie que la réparation de la pièce est nécessaire moins fréquemment. La différence significative de la résistance d'usure entre les aciers ayant une teneur en manganèse inférieure à 1 1% et ceux avec une teneur supérieure à 1 1% est attribuée à des différences dans la microstructure. Les niveaux de manganèse inférieurs à 1 1% ont entièrement abouti à des micro structure s martensitiques, alors que les niveaux supérieurs à 1 1% ont présenté des micro structure s mixtes d'austénite, de ε-martensite (arrangement condensé hexagonale, ou hep martensite) et de martensite. La résistance à l'usure des aciers ayant des micro structure s martensitiques complètes apparaît être plus pauvres que celle des micro structure s mixtes contenant martensite et austénite. Cependant, l'augmentation de la teneur en manganèse entraîne également une augmentation de l'austénite retenue. Pour les teneurs en manganèse de plus de 15%, les niveaux d'austénite résiduelle devient suffisamment élevée pour que l'augmentation de la dureté de la phase martensitique soit largement compensée par la proportion croissante de l'austénite plus molle, de sorte que la dureté totale de l'acier diminue avec la résistance à l'usure. La résistance à la propagation des fissures est élevée et est associée à une progression très lente des cassures. Grâce à cela, la possibilité de détection des fissures de fatigue en développement est accrue, et la ou les parties touchées peuvent être retirées ou réparées avant qu'un dommage complet ne se produise. Sur la base de ce raisonnement, la teneur en manganèse est préférentiellement comprise entre au moins 1 1% et au plus 15%. Comme le manganèse est également un élément d'alliage coûteux, une teneur maximale de manganèse approprié a été trouvée à 14%, voire même 13%. Une teneur appropriée minimale de manganèse a été de 1 1,5%. La valeur maximale de dureté et de résistance à l'usure a été atteinte lorsque la teneur en manganèse est comprise entre 12 et 13% de Mn. À ces niveaux les quantités, d'une part, d'austénite retenue et de ε-martensite et, d'autre part, de martensite dure sont en proportion sensiblement équivalente, fournissant ainsi une combinaison satisfaisante de résistance au choc et la dureté. A variation in the manganese content in the steels according to the invention has revealed that a maximum of hardness is obtained with a manganese content of at least 11%. At very high levels of manganese, for example at 15%, the hardness decreases to an insufficient level. The hardness shows an intimate correlation with the wear resistance. Wear resistance is a determining factor in the service life of most railway parts, including switches. A low wear rate means that the repair of the part is needed less frequently. The significant difference in wear resistance between steels with a manganese content of less than 11% and those with a content greater than 1% is attributed to differences in the microstructure. Levels of less than 11% have resulted in martensitic micro-structures, while levels greater than 1% have shown mixed micro-structures of austenite, ε-martensite (hexagonal condensed arrangement, or hep martensite) and of martensite. The wear resistance of steels with complete martensitic micro-structures appears to be poorer than that of mixed micro-structures containing martensite and austenite. However, the increase in manganese content also results in an increase in retained austenite. For manganese contents of more than 15%, the residual austenite levels become sufficiently high that the increase in the hardness of the martensitic phase is largely offset by the increasing proportion of the softer austenite, so that the Total hardness of steel decreases with wear resistance. Resistance to crack propagation is high and is associated with a very slow progression of breaks. With this, the possibility of detecting developing fatigue cracks is increased, and the affected part (s) can be removed or repaired before complete damage occurs. On the basis of this reasoning, the manganese content is preferably between at least 11% and at most 15%. Since manganese is also a costly alloying element, a maximum content of suitable manganese has been found at 14% or even 13%. A suitable minimum content of manganese was 1 1.5%. The maximum value of hardness and wear resistance has been reached when the manganese content is between 12 and 13% of Mn. At these levels the amounts of retained austenite and ε-martensite on the one hand and hard martensite on the other hand are in substantially equivalent proportion, thus providing a satisfactory combination of impact strength and hardness.
Selon une particularité de réalisation, la jonction ferroviaire par soudure directe est caractérisée en ce qu'au moins un des deux éléments de cette jonction est formé par un acier dont la composition présente :  According to a particular embodiment, the rail junction by direct welding is characterized in that at least one of the two elements of this junction is formed by a steel whose composition has:
- une teneur en carbone comprise entre 0,01 et 0,12%,  a carbon content of between 0.01 and 0.12%,
- une teneur en manganèse comprise entre 1 1% et 15%,  a manganese content of between 11% and 15%,
- une teneur en silicium inférieure à 0,5%,  a silicon content of less than 0.5%,
- une teneur en molybdène comprise entre 1,6% et 2,95%.  a molybdenum content of between 1.6% and 2.95%.
Le molybdène est efficace pour augmenter la résistance de l'acier aux chocs. De plus, en raison de l'effet d'épuration (scavenging effect) du molybdène pour le phosphore, les phénomènes de fragilisation de colère sont empêchés. À un niveau de 0,6% de molybdène, l'augmentation de la résistance aux chocs est déjà notable, mais une augmentation supplémentaire est obtenue avec des valeurs supérieures à 0,6%. L'augmentation des niveaux de résistance aux impacts plafonne à partir d'une valeur de 1,5%. Aussi, l'addition de molybdène dans cet acier doit être comprise entre 0,6% et 2,95%, avec une teneur en molybdène qui est préférentiellement d'au moins 1,25%. Une teneur en molybdène de 1,5% a été trouvée pour être une valeur minimum convenable pour des valeurs stables de résistance aux chocs. Une teneur en molybdène de 1,90% a été jugée comme étant une valeur maximale adaptée à partir d'un coût combiné et d'une perspective technique puisque des additions à des valeurs au-delà de 1 ,90% aboutissent uniquement à une modeste amélioration. Molybdenum is effective in increasing the impact resistance of steel. Moreover, due to the effect of purification (scavenging effect) of molybdenum for phosphorus, the phenomena of embrittlement of anger are prevented. At a level of 0.6% molybdenum, the increase in impact resistance is already noticeable, but a further increase is obtained with values above 0.6%. Increased levels of impact resistance peak at a value of 1.5%. Also, the addition of molybdenum in this steel must be between 0.6% and 2.95%, with a molybdenum content which is preferably at least 1.25%. A molybdenum content of 1.5% was found to be a suitable minimum value for stable values of impact resistance. A molarbdenum content of 1.90% was judged to be a maximum value adapted from a combined cost and a technical perspective since additions to values above 1.90% resulted only in a modest improvement.
Il a été constaté que le silicium a peu d'effet sur la résistance aux chocs et la résistance à l'usure de ces aciers, bien qu'il fournisse une augmentation de la résistance à la traction et à la dureté par le renforcement de solution solide. Le silicium sert également en tant qu'agent désoxydant (killing agent) au cours de la production d'acier. Sur cette base, une valeur maximale de Si de 0,5% est recommandée. Une teneur minimale appropriée de 0,10, voire 0,15%, et/ou une teneur maximale appropriée de 0,40 ou même 0,35%, ont été déterminées.  It has been found that silicon has little effect on the impact resistance and wear resistance of these steels, although it provides an increase in tensile strength and hardness by solution strengthening. solid. Silicon also serves as a deoxidizing agent (killing agent) during steel production. On this basis, a maximum value of Si of 0.5% is recommended. A suitable minimum content of 0.10 or even 0.15% and / or a suitable maximum level of 0.40 or even 0.35% have been determined.
Le nickel (Ni), le cobalt (Co) et le cuivre (Cu) montrent un effet similaire à celui du manganèse (Mn) par l'intermédiaire de leurs capacités à favoriser la formation de l'austénite. Dans une certaine mesure ces éléments peuvent être ajoutés, voire remplacer, le manganèse.  Nickel (Ni), cobalt (Co) and copper (Cu) show a similar effect to that of manganese (Mn) through their ability to promote the formation of austenite. To some extent these elements can be added, or even replace, manganese.
Les alliages selon l'invention se sont révélés être facilement usinable. Un ou plusieurs ajouts de soufre, de calcium, de tellure, ou de sélénium, ou de tout autre élément connu permettant d'améliorer l'usinabilité peuvent être réalisés pour aboutir à ces alliages si nécessaire.  The alloys according to the invention have been found to be easily machinable. One or more additions of sulfur, calcium, tellurium, or selenium, or any other known element to improve machinability can be made to achieve these alloys if necessary.
La teneur en phosphore est généralement maintenue en dessous de 0,02% pour minimiser les risques de fissuration à chaud.  The phosphorus content is generally kept below 0.02% to minimize the risk of hot cracking.
L'acier selon l'invention est préférentiellement désoxydé par le silicium (silicon killed). Pourvu que la propreté de l'acier reste en conformité avec les spécifications en termes de valeur maximale des inclusions d'oxyde d'aluminium, l'acier peut également être désoxydé par l'aluminium (aluminium killed) ou par une association aluminium-silicium (aluminium-silicon killed). L'acier selon l'invention présente une teneur en hydrogène inférieure à 5 ppm, préférentiellement inférieure à 3,5 ppm et idéalement inférieure à 2,5 ppm. The steel according to the invention is preferentially deoxidized by silicon (silicon killed). Provided that the cleanliness of the steel remains in accordance with the specifications in terms of the maximum value of the inclusions of aluminum oxide, the steel can also be deoxidized by aluminum (killed aluminum) or by an association aluminum-silicon (aluminum-silicon killed) The steel according to the invention has a hydrogen content of less than 5 ppm, preferably less than 3.5 ppm and ideally less than 2.5 ppm.
Bien que le chrome soit préférentiellement maintenu en dessous d'un niveau d'impureté de 0,15%, le chrome n'est pas ajouté délibérément. Pour certaines applications, le chrome peut être ajouté jusqu'à un niveau de 0,3%.  Although chromium is preferentially kept below an impurity level of 0.15%, chromium is not added deliberately. For some applications, chromium can be added up to a level of 0.3%.
Selon une particularité de réalisation non-limitative de l'invention, la jonction ferroviaire par soudure directe est caractérisée en ce que la composition de l'acier d'au moins un des deux éléments de la jonction comprend une teneur en silicium inférieure à 0,1%.  According to a non-limiting embodiment of the invention, the rail joint by direct welding is characterized in that the composition of the steel of at least one of the two elements of the junction comprises a silicon content of less than 0, 1%.
Selon une particularité complémentaire de réalisation de l'invention, la composition de l'acier d'au moins un des deux éléments de la jonction comprend une teneur en austénite correspondant à au moins 15% du volume dans son état laminé à chaud ou dans l'élément de la jonction à la température ambiante.  According to an additional embodiment of the invention, the composition of the steel of at least one of the two elements of the junction comprises an austenite content corresponding to at least 15% of the volume in its hot rolled state or in the element of the junction at room temperature.
Selon une autre particularité complémentaire de réalisation de l'invention, la composition de l'acier présente une teneur en carbone inférieure à 0,02%.  According to another additional embodiment of the invention, the composition of the steel has a carbon content of less than 0.02%.
Selon une autre particularité complémentaire de réalisation de l'invention, la composition de l'acier présente une teneur en chrome comprise entre 0,02% et 0,03%.  According to another additional embodiment of the invention, the composition of the steel has a chromium content of between 0.02% and 0.03%.
Selon un mode de réalisation préférée de la jonction ferroviaire de l'invention, cette jonction ferroviaire par soudure directe est caractérisée en ce que le cœur de voie est formé par un acier dont la composition est définie selon le présent document.  According to a preferred embodiment of the railway junction of the invention, this railway junction by direct welding is characterized in that the track core is formed by a steel whose composition is defined according to the present document.
La présente invention se rapporte également à un procédé de soudure directe caractérisé en ce qu'il est mis en œuvre au niveau d'une jonction ferroviaire selon l'invention.  The present invention also relates to a direct welding process characterized in that it is implemented at a railway junction according to the invention.
Selon une première variante de réalisation, le procédé de soudure directe selon l'invention fait intervenir une étape de soudure par étincelage.  According to a first variant embodiment, the direct soldering method according to the invention involves a spark welding step.
Selon une seconde variante de réalisation, le procédé de soudure directe selon l'invention fait intervenir une étape de soudure électrique. Selon une troisième variante de réalisation, le procédé de soudure directe selon l'invention fait intervenir une étape de soudure par alumino thermie. According to a second variant embodiment, the direct soldering method according to the invention involves an electric welding step. According to a third variant embodiment, the direct soldering method according to the invention involves a welding step by alumino thermie.
Grâce à un durcissement en voie de l'acier allié au manganèse permettant d'obtenir une dureté de l'ordre de 550 HB, un avantage de la jonction ferroviaire selon l'invention représenté par les résultats de la figure 3 est une variation réduite de la dureté par rapport à une jonction ferroviaire classique. Ainsi la jonction ferroviaire selon l'invention permet une soudure directe dont la résistance à la cassure et à l'usure est plus importante et améliorée. La combinaison de cette résistance à la cassure avec la résistance à l'usure se trouve également confirmée par les résultats présentés par la figure 4 qui présentent des tests de déformation de la jonction ferroviaire par soudure directe selon la norme européenne EN 14587.  Thanks to a hardening of the manganese-alloy steel to obtain a hardness of the order of 550 HB, an advantage of the railway junction according to the invention represented by the results of FIG. 3 is a reduced variation of the hardness compared to a conventional railway junction. Thus the railway junction according to the invention allows a direct weld whose resistance to breakage and wear is greater and improved. The combination of this breaking strength with the wear resistance is also confirmed by the results presented in FIG. 4, which show deformation tests of the direct welded rail junction according to the European standard EN 14587.
Bien entendu, l'invention n'est pas limitée au mode de réalisation décrit et représenté aux dessins annexés. Des modifications restent possibles, notamment du point de vue de la constitution des divers éléments ou par substitution d'équivalents techniques, sans sortir pour autant du domaine de protection de l'invention.  Of course, the invention is not limited to the embodiment described and shown in the accompanying drawings. Modifications are possible, particularly from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

EVENDICATIONS EVENDICATIONS
1. Jonction ferroviaire par soudure directe entre, d'une part, un cœur de voie et, d'autre part, un rail, caractérisée en ce qu'au moins un des deux éléments joints est formé par un acier dont la composition présente : 1. Rail junction by direct welding between, on the one hand, a track core and, on the other hand, a rail, characterized in that at least one of the two joined elements is formed by a steel whose composition has:
- une teneur en carbone inférieure à 0,12%, et  - a carbon content of less than 0.12%, and
- une teneur en manganèse supérieure à 1 1%.  - a manganese content greater than 1 1%.
2. Jonction ferroviaire par soudure directe selon la revendication 1, caractérisée en ce qu'au moins un des deux éléments de cette jonction est formé par un acier dont la composition présente :  2. soldered railway junction according to claim 1, characterized in that at least one of the two elements of this junction is formed by a steel whose composition has:
- une teneur en carbone comprise entre 0,01 et 0,12%,  a carbon content of between 0.01 and 0.12%,
- une teneur en manganèse comprise entre 1 1% et 15%, a manganese content of between 11% and 15%,
- une teneur en silicium inférieure à 0,5%, a silicon content of less than 0.5%,
- une teneur en molybdène comprise entre 1,6% et 2,95%.  a molybdenum content of between 1.6% and 2.95%.
3. Jonction ferroviaire par soudure directe selon une des revendications précédentes, caractérisée en ce que la composition d'acier comprend une teneur en silicium d'au moins 0,1%.  3. Direct weld rail junction according to one of the preceding claims, characterized in that the steel composition comprises a silicon content of at least 0.1%.
4. Jonction ferroviaire par soudure directe selon une des revendications précédentes, caractérisée la composition d'acier comprend une teneur en austénite correspondant à au moins 15% du volume dans son état laminé à chaud ou dans l'élément de la jonction.  The direct welded rail joint according to one of the preceding claims, characterized in that the steel composition comprises an austenite content of at least 15% by volume in its hot-rolled state or in the joint element.
5. Jonction ferroviaire par soudure directe selon une des revendications précédentes, caractérisée en ce que la composition d'acier présente une teneur en carbone d'au moins 0,02%.  Direct soldering rail junction according to one of the preceding claims, characterized in that the steel composition has a carbon content of at least 0.02%.
6. Jonction ferroviaire par soudure directe selon une des revendications précédentes, caractérisée en ce que l'acier présente une teneur en chrome comprise entre 0,02% et 0,03%.  6. Direct weld rail junction according to one of the preceding claims, characterized in that the steel has a chromium content of between 0.02% and 0.03%.
7. Jonction ferroviaire par soudure directe selon une des revendications précédentes, caractérisée en ce que le cœur de voie est formé par un acier dont la composition est définie par une des revendications précédentes.  7. Railway junction by direct welding according to one of the preceding claims, characterized in that the channel core is formed by a steel whose composition is defined by one of the preceding claims.
8. Procédé de soudure directe, caractérisé en ce que le procédé est mis en œuvre au niveau d'une jonction ferroviaire selon une des revendications 1 à 7. 8. Direct welding process, characterized in that the method is implemented at a railway junction according to one of claims 1 to 7.
9. Procédé de soudure directe selon la revendication 8, caractérisé en ce que le procédé fait intervenir une étape de soudure par étincelage. 9. Direct soldering method according to claim 8, characterized in that the method involves a sparking welding step.
10. Procédé de soudure directe selon la revendication 8, caractérisé en ce que le procédé fait intervenir une étape de soudure électrique.  10. Direct soldering method according to claim 8, characterized in that the method involves an electric welding step.
1 1. Procédé de soudure directe selon la revendication 8, caractérisé en ce que le procédé fait intervenir une étape de soudure par alumino thermie .  1 1. Direct soldering method according to claim 8, characterized in that the method involves a welding step by alumino thermie.
PCT/FR2013/051283 2012-06-21 2013-06-06 Joining of manganese steel railway line components by direct welding WO2013190206A1 (en)

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EA201301221A EA201301221A1 (en) 2012-06-21 2013-06-06 CONNECTION OF ELEMENTS OF RAILWAY RAILWAYS FROM MANGANESE STEEL BY A WELDING METHOD WITHOUT ADDITIVE METAL

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FR1255859 2012-06-21
FR1255859A FR2992334B1 (en) 2012-06-21 2012-06-21 JOINING RAILWAY ELEMENTS IN STEEL MANGANESE BY DIRECT WELDING

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FR2864117A1 (en) * 2003-12-17 2005-06-24 Didier Pierre Rene Dages Renovation of a worn rail track component of high manganese austenitic steel by electric arc weld recharging of the worn zones and machining or grinding to original dimensions
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GB1134527A (en) * 1966-06-18 1968-11-27 Allen Edgar Eng Improvements in or relating to railway points and crossings of manganese steel
GB2007257A (en) * 1977-11-03 1979-05-16 Creusot Loire Austenitic manganese steel for railway frogs
EP0838552A1 (en) * 1996-04-29 1998-04-29 Jez Sistemas Ferroviarios, S.l. Acute crossing of railway tongue
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FR3069255A1 (en) * 2017-07-20 2019-01-25 Vossloh Cogifer HEART OF CROSSING FOR TRACK APPARATUS

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