EP1339880A1 - Method for making a strip or a workpiece cut out from a cold rolled maraging steel strip - Google Patents

Method for making a strip or a workpiece cut out from a cold rolled maraging steel strip

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Publication number
EP1339880A1
EP1339880A1 EP01996631A EP01996631A EP1339880A1 EP 1339880 A1 EP1339880 A1 EP 1339880A1 EP 01996631 A EP01996631 A EP 01996631A EP 01996631 A EP01996631 A EP 01996631A EP 1339880 A1 EP1339880 A1 EP 1339880A1
Authority
EP
European Patent Office
Prior art keywords
strip
heat treatment
steel
hardening
maraging steel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP01996631A
Other languages
German (de)
French (fr)
Other versions
EP1339880B1 (en
Inventor
Lucien Coutu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Aperam Alloys Imphy SAS
Original Assignee
Imphy Ugine Precision SA
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Filing date
Publication date
Application filed by Imphy Ugine Precision SA filed Critical Imphy Ugine Precision SA
Publication of EP1339880A1 publication Critical patent/EP1339880A1/en
Application granted granted Critical
Publication of EP1339880B1 publication Critical patent/EP1339880B1/en
Priority to CY20071101302T priority Critical patent/CY1106925T1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/02—Hardening by precipitation
    • 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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
    • C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2201/00—Treatment for obtaining particular effects
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing

Definitions

  • the present invention relates to a maraging steel particularly suitable for the manufacture of parts requiring very good resistance to fatigue.
  • Many parts are made from maraging steel strips containing, in% by weight, about 18% of nickel, 9% of cobalt, 5% of molybdenum, 0.5% of titanium and 0.1% of aluminum, treated to have an elastic limit greater than 1800 MPa. These strips are obtained by hot rolling and cold rolling. The strips or the pieces cut from the strips are then hardened by a heat treatment to harden around 500 ° C.
  • the parts are optionally nitrided on the surface to improve their resistance to fatigue. However, the fatigue strength of these parts is insufficient.
  • maraging steels having different chemical compositions and mechanical characteristics, such as maraging steels containing 18% of nickel, 12% of cobalt, 4% of molybdenum, 1.6% titanium and 0.2% aluminum, or maraging steels containing 18% nickel, 3% molybdenum, 1.4% titanium and 0.1% aluminum, or maraging steels containing 13% chromium, 8% nickel, 2% molybdenum and 1% aluminum.
  • maraging steels having different chemical compositions and mechanical characteristics, such as maraging steels containing 18% of nickel, 12% of cobalt, 4% of molybdenum, 1.6% titanium and 0.2% aluminum, or maraging steels containing 18% nickel, 3% molybdenum, 1.4% titanium and 0.1% aluminum, or maraging steels containing 13% chromium, 8% nickel, 2% molybdenum and 1% aluminum.
  • the object of the present invention is to remedy this drawback and to propose a band or a piece of maraging steel having improved resistance to fatigue.
  • the subject of the invention is a method for manufacturing a strip or a part cut from a cold rolled maraging steel strip. According to this method, before carrying out the hardening heat treatment, the strip or the part is subjected to cold plastic deformation with a rate of work hardening greater than 30% and the strip or the part is subjected to annealing. recrystallization so as to obtain a fine grain of ASTM index greater than 8.
  • the chemical composition of the steel comprises, by weight:
  • the strip or the part is subjected to cold rolling with a reduction rate of between 1% and 10%.
  • the maraging steel is remelted under vacuum by the VAR process or remelted a first time under vacuum by the VAR process or under electroconductive slag by the process ESR and remelted a second time under vacuum by the VAR process.
  • the invention also relates to a strip or part, of thickness less than 1 mm, made of maraging steel having a fine grain of ASTM index greater than 8 and a yield strength after hardening greater than 1850 MPa.
  • the strip or the part thus obtained can be used for the manufacture of parts such as belts. These parts are hardened by a hardening treatment between 450 and 550 ° C for 1 to 10 hours which can be followed by nitriding on the surface.
  • a cold rolled strip of maraging steel is produced by targeting a carbon of less than 0.005% and then by deoxidizing with aluminum.
  • the steel thus produced is cast in the form of reflow electrodes.
  • These electrodes are either remelted under vacuum (VAR process, “Vacuum Arc Remelting” known in itself) to form ingots or slabs, or remelted a first time under vacuum (VAR) or under electroconductive slag (ESR process, “Electro Slag Remelting ", known in itself) to form second electrodes which are themselves remelted under vacuum (VAR) to form ingots or slabs.
  • VAR process remelted under vacuum
  • ESR process electroconductive slag Remelting
  • the ingots or slabs are then hot rolled after reheating to around 1200 ° C, and for example between 1150 ° C and 1250 ° C to obtain hot rolled strips a few millimeters thick, and for example about 4 , 5 mm thick.
  • the hot-rolled strips are pickled and then cold-rolled with one or more recrystallization anneals to obtain cold-rolled strips of thickness less than 1 mm, for example 0.4 mm or 0.2 mm thick .
  • the last intermediate recrystallization annealing treatment is carried out at a thickness such that the cold-rolled strip has a work hardening rate greater than 30% and better still greater than 40%.
  • the strip thus hardened is annealed, for example in a passage oven, to obtain a fine grain of ASTM index greater than 8 (corresponding to an average grain diameter less than 20 microns), and better still greater than 10 (corresponding to a diameter grain size less than 10 microns); the grain size being determined according to ASTM E112.
  • the annealing treatment intended to obtain a fine grain is carried out under a protective atmosphere by suitably adjusting the temperature and duration parameters. These parameters depend on the particular conditions for carrying out the heat treatment and those skilled in the art know how to determine these parameters in each particular case.
  • the duration that is to say the residence time of any point of the strip in the oven
  • the setpoint temperature oven is between 900 ° C and 1100 ° C
  • the atmosphere of the oven can be argon with a dew temperature preferably below -50 ° C.
  • the strip In order to improve the flatness of the strip and, if necessary, to perfect the martensitic transformation, the strip can, moreover, be subjected to a light cold rolling with a reduction rate of between 1% and 10%, which leads to a work hardening rate of the same value.
  • the hardening treatment can also be carried out in a passage oven at a temperature between 600 ° C and 700 ° C for a time between 30 seconds and 3 minutes.
  • the part can be hardened on the surface by a nitriding treatment carried out by keeping it for a few hours at around 500 ° C. in a reactive gas mixture rich in nitrogen.
  • blanks of parts can be cut from cold-rolled strips of thickness greater than the final thickness desired for the parts. These blanks are shaped, possibly welded, then cold-rolled to the final thickness so as to have a work hardening rate greater than 30% or better still greater than 40%.
  • the parts are then annealed under the same conditions as what has just been described, so as to obtain a fine grain of ASTM index greater than 8, or better still greater than 10, then subjected to a hardening treatment as indicated above. above.
  • the yield strength obtained is high and the resistance to fatigue is excellent.
  • Parts can also be produced by cutting, for example by chemical cutting, from hardened strips. The entire process, including the hardening heat treatment, is then applied to the strip.
  • These parts are, for example, integrated circuit support grids.
  • the maraging steel which it is preferable to use to obtain very good fatigue properties and an elastic limit greater than 1850 MPa, contains mainly, in% by weight:
  • the nickel and molybdenum contents must be such that 20% ⁇ Ni + Mo ⁇ 27%, and preferably such that 22% ⁇ Ni + Mo ⁇ 25%.
  • the cobalt and molybdenum contents In order to obtain an elastic limit, after thermal hardening treatment, greater than 1850 MPa, the cobalt and molybdenum contents must be such that Co x Mo> 50, and preferably such that Co x Mo> 70. Indeed , the higher this product, the higher the elastic limit. However, in order to obtain sufficient ductility, the cobalt and molybdenum contents must be such that Co x Mo ⁇ 200, and preferably such that Co x Mo ⁇ 120. These values correspond respectively to elastic limits less than around 3000 MPa and 2500 MPa. Molybdenum has a favorable effect on hardening by surface nitriding. To obtain good curing, the molybdenum content should preferably be greater than 4%, and better still greater than 6%. However, it is preferable for it to remain below 8% to limit the problems of segregation and to facilitate the hot transformation operations as well as to improve the ductility of the final product. Two preferred ranges of molybdenum contents can
  • the following preferential composition domains can be defined for the main elements: 1) in order to obtain a yield strength greater than 1850 MPa and an average suitability for hardening by nitriding:
  • the minimum content can be 0% or traces.
  • the nitrogen and titanium contents must be such that: Ti x N ⁇ 2 x 10 "4 , or better, ⁇ 1 x 10 " 4 .
  • maraging steel strips of composition have been produced:
  • a first strip A given by way of example, was annealed in a hydrogen oven at 1020 ° C for 1 minute to obtain a fine grain of ASTM 11 index and then hardened by maintaining at 490 ° C for 3 hours.
  • a second strip B given for comparison, was annealed in a passage oven at 1150 ° C for 1 minute to obtain a coarse grain of index ASTM 7 and then hardened by maintaining at 490 ° C for 3 hours. Comparative fatigue resistance tests were carried out with bands A and B by wavy traction, at 25 hertz, with a maximum stress of 750 MPa and a minimum stress of 75 MPa.
  • the fatigue limit was greater than 8 ⁇ 10 8 cycles, while for band B, the fatigue limit was equal to 5 ⁇ 10 8 cycles.
  • a strip of maraging steel was also produced containing 18% nickel, 9% cobalt, 5% molybdenum, 0.5% titanium and 0.1% aluminum. This strip was manufactured by the method according to the invention, the grain had an ASTM index of 10 and the elastic limit was 1910 MPa. The fatigue limit measured under the same test conditions as in the previous case was 2 x 10 8 cycles.
  • These bands can advantageously be used to manufacture belts or any other product, such as grids supporting integrated circuits.
  • transmission belts for internal combustion engines are made up of jumpers held by rings made up of narrow bands according to the invention and the two ends of which are welded. These belts have a lifespan more than ten times longer than the lifespan of identical belts but manufactured with strips of maraging steel in accordance with the prior art.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Manufacturing Of Steel Electrode Plates (AREA)
  • Soft Magnetic Materials (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

The invention concerns a method for making a strip or a workpiece cut out from a cold rolled maraging steel strip and hardened by a hardening heat treatment, which consists, prior to the heat treatment, in subjecting the strip or the workpiece to cold plastic deformation with a rate of strain hardening more than 30 % and in subjecting the strip or the workpiece to a recrystallization annealing so as to obtain a fine grain of ASTM index more than 8. The maraging steel composition comprises, by weight: 12 % ≤ Ni ≤ 24.5 %; 2.5 % ≤ Mo ≤ 12 %; 4.17 % ≤ Co ≤ 20 %; Al ≤ 0.15 %; Ti ≤ 0.1 %; N ≤ 0.003 %; Si ≤ 0.1 %; Mn ≤ 0.1 %; C ≤ 0.005 %; S ≤ 0.001 %; P ≤ 0.005 %; H ≤ = 0.0003 %; O ≤ 0.001 %; the rest being iron and impurities resulting from preparation of the composition, the composition further satisfying the following relationships: 20 % ≤ Ni + Mo ≤ 27 %; 50 ≤ Co x Mo ≤ 200<; Ti x N ≤ 2 x 10-4. The invention also concerns the resulting strip.

Description

PROCEDE POUR FABRIQUER UNE BANDE OU UNE PIECE DECOUPEE DANS UNE BANDE EN ACIER MARAGING LAMINEE A FROIDPROCESS FOR MANUFACTURING A STRIP OR A CUT PIECE IN A COLD-ROLLED MARAGING STEEL STRIP
La présente invention est relative à un acier maraging particulièrement adapté à la fabrication de pièces nécessitant une très bonne résistance à la fatigue. De nombreuses pièces sont fabriquées à partir de bandes en acier maraging contenant, en % en poids, environ 18% de nickel, 9% de cobalt, 5% de molybdène, 0,5% de titane et 0,1 % d'aluminium, traité pour avoir une limite d'élasticité supérieure à 1800 MPa. Ces bandes sont obtenues par laminage à chaud et laminage à froid. Les bandes ou les pièces découpées dans les bandes sont ensuite durcies par un traitement thermique de durcissement vers 500°C. Les pièces sont éventuellement nitrurées en surface pour améliorer leur tenue en fatigue. Cependant la tenue en fatigue de ces pièces est insuffisante.The present invention relates to a maraging steel particularly suitable for the manufacture of parts requiring very good resistance to fatigue. Many parts are made from maraging steel strips containing, in% by weight, about 18% of nickel, 9% of cobalt, 5% of molybdenum, 0.5% of titanium and 0.1% of aluminum, treated to have an elastic limit greater than 1800 MPa. These strips are obtained by hot rolling and cold rolling. The strips or the pieces cut from the strips are then hardened by a heat treatment to harden around 500 ° C. The parts are optionally nitrided on the surface to improve their resistance to fatigue. However, the fatigue strength of these parts is insufficient.
Afin d'améliorer la tenue en fatigue des pièces, il a été envisagé d'utiliser des aciers maraging ayant des compositions chimiques et des caractéristiques mécaniques différentes, telles que des aciers maraging contenant 18% de nickel, 12 % de cobalt, 4% de molybdène, 1 ,6% de titane et 0,2% d'aluminium, ou des aciers maraging contenant 18 % de nickel, 3% de molybdène, 1 ,4% de titane et 0,1 % d'aluminium, ou encore, des aciers maraging contenant 13% de chrome, 8% de nickel, 2% de molybdène et 1 % d'aluminium. Mais aucun de ces aciers n'a donné de résultats satisfaisants. Les tenues à la fatigue étant toujours inférieures à celle des pièces fabriquées avec l'acier habituel.In order to improve the fatigue resistance of the parts, it has been envisaged to use maraging steels having different chemical compositions and mechanical characteristics, such as maraging steels containing 18% of nickel, 12% of cobalt, 4% of molybdenum, 1.6% titanium and 0.2% aluminum, or maraging steels containing 18% nickel, 3% molybdenum, 1.4% titanium and 0.1% aluminum, or maraging steels containing 13% chromium, 8% nickel, 2% molybdenum and 1% aluminum. However, none of these steels has given satisfactory results. The fatigue strengths are always lower than that of parts manufactured with the usual steel.
Le but de la présente invention est de remédier à cet inconvénient et de proposer une bande ou une pièce en acier maraging ayant une tenue à la fatigue améliorée. A cet effet, l'invention a pour objet un procédé pour de fabrication d'une bande ou une pièce découpée dans une bande en acier maraging laminée à froid. Selon ce procédé, avant d'effectuer le traitement thermique de durcissement, on soumet la bande ou la pièce à une déformation plastique à froid avec un taux d'écrouissage supérieur à 30% et on et on soumet la bande ou la pièce à un recuit de recristallisation de façon à obtenir un grain fin d'indice ASTM supérieur à 8. La composition chimique de l'acier comprend, en poids :The object of the present invention is to remedy this drawback and to propose a band or a piece of maraging steel having improved resistance to fatigue. To this end, the subject of the invention is a method for manufacturing a strip or a part cut from a cold rolled maraging steel strip. According to this method, before carrying out the hardening heat treatment, the strip or the part is subjected to cold plastic deformation with a rate of work hardening greater than 30% and the strip or the part is subjected to annealing. recrystallization so as to obtain a fine grain of ASTM index greater than 8. The chemical composition of the steel comprises, by weight:
12% < Ni < 24,5% 2,5% < Mo < 12% 4,17% < Co < 20% Al% < 0,15%12% <Ni <24.5% 2.5% <Mo <12% 4.17% <Co <20% Al% <0.15%
Ti < 0,1%Ti <0.1%
N < 0,003%N <0.003%
Si < 0,1% Mn < 0,1 %If <0.1% Mn <0.1%
C < 0,005%C <0.005%
S < 0,001 %S <0.001%
P < 0,005%P <0.005%
H < 0,0003% O < 0,001 % le reste étant du fer et des impuretés résultant de l'élaboration, la composition chimique satisfaisant en outre les relations :H <0.0003% O <0.001% the remainder being iron and impurities resulting from the production, the chemical composition satisfying in addition the relationships:
20% < Ni + Mo < 27% 50 < Co x Mo < 200 Ti x N < 2 x 10'4 20% <Ni + Mo <27% 50 <Co x Mo <200 Ti x N <2 x 10 '4
Eventuellement, après le recuit de recristallisation, on soumet la bande ou la pièce à un laminage à froid avec un taux de réduction compris ente 1 % et 10%.Optionally, after recrystallization annealing, the strip or the part is subjected to cold rolling with a reduction rate of between 1% and 10%.
De préférence, l'acier maraging est refondu sous vide par le procédé VAR ou refondu une première fois sous vide par le procédé VAR ou sous laitier électroconducteur par le procédé ESR et refondu une seconde fois sous vide par le procédé VAR.Preferably, the maraging steel is remelted under vacuum by the VAR process or remelted a first time under vacuum by the VAR process or under electroconductive slag by the process ESR and remelted a second time under vacuum by the VAR process.
L'invention concerne également une bande ou pièce, d'épaisseur inférieure à 1 mm, en acier maraging ayant un grain fin d'indice ASTM supérieur à 8 et une limite d'élasticité après durcissement supérieure à 1850 MPa. La bande ou la pièce ainsi obtenue peut être utilisée pour la fabrication de pièces telles que des courroies. Ces pièces sont durcies par un traitement de durcissement entre 450 et 550°C pendant 1 à 10 heures qui peut être suivi d'une nitruration en surface.The invention also relates to a strip or part, of thickness less than 1 mm, made of maraging steel having a fine grain of ASTM index greater than 8 and a yield strength after hardening greater than 1850 MPa. The strip or the part thus obtained can be used for the manufacture of parts such as belts. These parts are hardened by a hardening treatment between 450 and 550 ° C for 1 to 10 hours which can be followed by nitriding on the surface.
L'invention va maintenant être décrite plus en détails mais de façon non limitative.The invention will now be described in more detail, but without limitation.
Pour fabriquer une bande laminée à froid en acier maraging selon l'invention, on élabore l'acier en visant un carbone inférieur à 0,005% puis en désoxydant à l'aluminium. L'acier ainsi élaboré est coulé sous forme d'électrodes de refusion. Ces électrodes sont soit refondues sous vide (procédé VAR, « Vacuum Arc Remelting » connu en lui-même ) pour former des lingots ou des brames, soit refondues une première fois sous vide (VAR) ou sous laitier électroconducteur (procédé ESR, « Electro Slag Remelting », connu en lui-même) pour former des secondes électrodes qui sont elles-mêmes refondues sous vide (VAR) pour former des lingots ou des brames. On réalise ainsi soit une simple refusion VAR soit une double refusion VAR + VAR ou ESR + VAR. Ces refusions permettent d'épurer le métal et d'améliorer la qualité de la solidification en réduisant les ségrégations. En particulier, la refusion ESR permet d'abaisser la teneur en soufre, et la refusion VAR permet d'abaisser la teneur en azote et en hydrogène.To manufacture a cold rolled strip of maraging steel according to the invention, steel is produced by targeting a carbon of less than 0.005% and then by deoxidizing with aluminum. The steel thus produced is cast in the form of reflow electrodes. These electrodes are either remelted under vacuum (VAR process, “Vacuum Arc Remelting” known in itself) to form ingots or slabs, or remelted a first time under vacuum (VAR) or under electroconductive slag (ESR process, “Electro Slag Remelting ", known in itself) to form second electrodes which are themselves remelted under vacuum (VAR) to form ingots or slabs. This produces either a single VAR reflow or a double VAR + VAR or ESR + VAR reflow. These rejections make it possible to purify the metal and improve the quality of solidification by reducing segregation. In particular, the ESR remelting makes it possible to lower the sulfur content, and the VAR remelting makes it possible to lower the nitrogen and hydrogen content.
Les lingots ou brames sont alors laminés à chaud après réchauffage aux environs de 1200°C, et par exemple entre 1150°C et 1250°C pour obtenir des bandes laminées à chaud de quelques millimètres d'épaisseur, et par exemple d'environ 4,5 mm d'épaisseur.The ingots or slabs are then hot rolled after reheating to around 1200 ° C, and for example between 1150 ° C and 1250 ° C to obtain hot rolled strips a few millimeters thick, and for example about 4 , 5 mm thick.
Les bandes laminées à chaud sont décapées puis laminées à froid avec un ou plusieurs recuits de recristallisation pour obtenir des bandes laminées à froid d'épaisseur inférieure à 1 mm, et par exemple de 0,4 mm ou de 0,2 mm d'épaisseur.The hot-rolled strips are pickled and then cold-rolled with one or more recrystallization anneals to obtain cold-rolled strips of thickness less than 1 mm, for example 0.4 mm or 0.2 mm thick .
Le dernier traitement de recuit de recristallisation intermédiaire est effectué à une épaisseur telle que la bande laminée à froid ait un taux d'écrouissage supérieur à 30% et mieux supérieur à 40%.The last intermediate recrystallization annealing treatment is carried out at a thickness such that the cold-rolled strip has a work hardening rate greater than 30% and better still greater than 40%.
La bande ainsi écrouie est recuite, par exemple au four à passage, pour obtenir un grain fin d'indice ASTM supérieur à 8 (correspondant à un diamètre moyen des grains inférieur à 20 microns), et mieux supérieur à 10 (correspondant à un diamètre moyen des grains inférieur à 10 microns); la taille de grain étant déterminée selon la norme ASTM E112.The strip thus hardened is annealed, for example in a passage oven, to obtain a fine grain of ASTM index greater than 8 (corresponding to an average grain diameter less than 20 microns), and better still greater than 10 (corresponding to a diameter grain size less than 10 microns); the grain size being determined according to ASTM E112.
Le traitement de recuit destiné à obtenir un grain fin est réalisé sous atmosphère protectrice en ajustant convenablement les paramètres température et durée. Ces paramètres dépendent des conditions particulières de réalisation du traitement thermique et l'homme du métier sait déterminer ces paramètres dans chaque cas particulier. Dans le cas d'un traitement réalisé dans un four à passage en continu, la durée (c'est à dire le temps de séjour d'un point quelconque de la bande dans le four) est comprise entre 10s et 1 minute, et la température de consigne du four est comprise entre 900°C et 1100°C; l'atmosphère du four peut être de l'argon avec une température de rosée inférieure de préférence à - 50°C.The annealing treatment intended to obtain a fine grain is carried out under a protective atmosphere by suitably adjusting the temperature and duration parameters. These parameters depend on the particular conditions for carrying out the heat treatment and those skilled in the art know how to determine these parameters in each particular case. In the case of a treatment carried out in a continuous passage oven, the duration (that is to say the residence time of any point of the strip in the oven) is between 10 s and 1 minute, and the setpoint temperature oven is between 900 ° C and 1100 ° C; the atmosphere of the oven can be argon with a dew temperature preferably below -50 ° C.
Afin d'améliorer la planéité de la bande et, si nécessaire, de parfaire la transformation martensitique, la bande peut, en outre, être soumise à un laminage à froid léger avec un taux de réduction compris entre 1% et 10%, ce qui conduit à un taux d'écrouissage de même valeur.In order to improve the flatness of the strip and, if necessary, to perfect the martensitic transformation, the strip can, moreover, be subjected to a light cold rolling with a reduction rate of between 1% and 10%, which leads to a work hardening rate of the same value.
On peut alors découper dans la bande une pièce et mettre en forme cette pièce, par exemple par pliage, puis effectuer sur celle-ci un traitement de durcissement consistant en un maintien entre 450 et 550°C pendant 1 à 10heures. A noter que, lorsque la température de traitement se situe dans la partie supérieure de la plage de température (500 à 550°C), la ductilité est améliorée et la limite élastique est légèrement abaissée.It is then possible to cut a piece from the strip and to shape this piece, for example by folding, then carry out on it a hardening treatment consisting in maintaining between 450 and 550 ° C. for 1 to 10 hours. Note that when the treatment temperature is in the upper part of the temperature range (500 to 550 ° C), the ductility is improved and the elastic limit is slightly lowered.
Le traitement de durcissement peut également être effectué au four à passage à une température comprise entre 600°C et 700°C pendant un temps compris entre 30 secondes et 3 minutes.The hardening treatment can also be carried out in a passage oven at a temperature between 600 ° C and 700 ° C for a time between 30 seconds and 3 minutes.
On obtient ainsi une pièce constituée d'un métal ayant une limite d'élasticité élevée et une tenue à la fatigue excellente.This gives a part made of a metal having a high yield strength and excellent fatigue resistance.
Pendant le traitement de durcissement ou après celui-ci, la pièce peut être durcie en surface par un traitement de nitruration réalisé par un maintien de quelques heures vers 500°C dans un mélange gazeux réactif riche en azote.During or after the hardening treatment, the part can be hardened on the surface by a nitriding treatment carried out by keeping it for a few hours at around 500 ° C. in a reactive gas mixture rich in nitrogen.
Dans une variante, des ébauches de pièces peuvent être découpées dans des bandes laminées à froid d'épaisseur supérieure à l'épaisseur finale voulue pour les pièces. Ces ébauches sont mises en forme, éventuellement soudées, puis laminées à froid jusqu'à l'épaisseur finale de façon à avoir un taux d'écrouissage supérieur à 30% ou mieux supérieur à 40%. Les pièces sont alors recuites dans les mêmes conditions que ce qui vient d'être décrit, de façon à obtenir un grain fin d'indice ASTM supérieur à 8, ou mieux supérieur à 10, puis soumises à un traitement de durcissement comme indiqué ci-dessus. La limite d'élasticité obtenue est élevée et la tenue à la fatigue est excellente. On peut également fabriquer des pièces par découpage, par exemple par découpage chimique, dans des bandes durcies. L'ensemble du procédé, y compris le traitement thermique de durcissement, est alors appliqué à la bande. Ces pièces sont, par exemple, des grilles support de circuits intégrés. L'acier maraging qu'il est préférable d'utiliser pour obtenir de très bonnes propriétés en fatigue et une limite d'élasticité supérieure à 1850 MPa, contient principalement, en % en poids:Alternatively, blanks of parts can be cut from cold-rolled strips of thickness greater than the final thickness desired for the parts. These blanks are shaped, possibly welded, then cold-rolled to the final thickness so as to have a work hardening rate greater than 30% or better still greater than 40%. The parts are then annealed under the same conditions as what has just been described, so as to obtain a fine grain of ASTM index greater than 8, or better still greater than 10, then subjected to a hardening treatment as indicated above. above. The yield strength obtained is high and the resistance to fatigue is excellent. Parts can also be produced by cutting, for example by chemical cutting, from hardened strips. The entire process, including the hardening heat treatment, is then applied to the strip. These parts are, for example, integrated circuit support grids. The maraging steel, which it is preferable to use to obtain very good fatigue properties and an elastic limit greater than 1850 MPa, contains mainly, in% by weight:
- de 12% à 24,5% de nickel, - de 2,5% à 12% de molybdène,- from 12% to 24.5% of nickel, - from 2.5% to 12% of molybdenum,
- de 4, 17% à 20% de cobalt, le reste étant du fer et des impuretés ou des éléments résiduels en faible quantité résultant de l'élaboration.- from 4.17% to 20% of cobalt, the remainder being iron and impurities or residual elements in small quantity resulting from the production.
Afin d'obtenir un point Ms (température de début de transformation martensitique) voisin de 200°C, les teneurs en nickel et molybdène doivent être telles que 20% < Ni + Mo < 27%, et de préférence telles que 22% < Ni + Mo < 25%.In order to obtain a point Ms (martensitic transformation start temperature) close to 200 ° C., the nickel and molybdenum contents must be such that 20% <Ni + Mo <27%, and preferably such that 22% <Ni + Mo <25%.
Afin d'obtenir une limite d'élasticité, après traitement thermique de durcissement, supérieure à 1850 MPa, les teneurs en cobalt et molybdène doivent être telles que Co x Mo > 50, et de préférence telles que Co x Mo > 70. En effet, plus ce produit est élevé, plus la limite d'élasticité est élevée. Mais, pour obtenir une ductilité suffisante, les teneurs en cobalt et molybdène doivent être telles que Co x Mo < 200, et de préférence telles que Co x Mo < 120. Ces valeurs correspondent respectivement à des limites d'élasticité inférieures à environ 3000 MPa et 2500 MPa. Le molybdène a un effet favorable sur le durcissement par nitruration en surface. Pour obtenir un bon durcissement, la teneur en molybdène doit, de préférence, être supérieure à 4%, et mieux supérieure à 6%. Mais, il est préférable qu'elle reste inférieure à 8% pour limiter les problèmes de ségrégation et pour faciliter les opérations de transformation à chaud ainsi que pour améliorer la ductilité du produit final. Deux plages préférentielles de teneurs en molybdène peuvent être définies:In order to obtain an elastic limit, after thermal hardening treatment, greater than 1850 MPa, the cobalt and molybdenum contents must be such that Co x Mo> 50, and preferably such that Co x Mo> 70. Indeed , the higher this product, the higher the elastic limit. However, in order to obtain sufficient ductility, the cobalt and molybdenum contents must be such that Co x Mo <200, and preferably such that Co x Mo <120. These values correspond respectively to elastic limits less than around 3000 MPa and 2500 MPa. Molybdenum has a favorable effect on hardening by surface nitriding. To obtain good curing, the molybdenum content should preferably be greater than 4%, and better still greater than 6%. However, it is preferable for it to remain below 8% to limit the problems of segregation and to facilitate the hot transformation operations as well as to improve the ductility of the final product. Two preferred ranges of molybdenum contents can be defined:
- 4,17 à 6 % de Mo qui correspond à des produits possédant une très bonne aptitude à la transformation à chaud et à froid ainsi qu un très bon compromis entre limite élastique élevée et bonne ductilité et ténacité. - 6 à 8 % de Mo qui correspond à des aciers à très haute limite élastique ou plus économiques car de teneur réduite en cobalt.- 4.17 to 6% of Mo which corresponds to products having a very good aptitude for hot and cold transformation as well as a very good compromise between high elastic limit and good ductility and toughness. - 6 to 8% of Mo which corresponds to steels with very high elastic limit or more economical because of reduced cobalt content.
En combinant toutes ces conditions, on peut définir les domaines de composition préférentiels suivants pour les éléments principaux: 1) afin d'obtenir une limite d'élasticité supérieure à 1850 MPa et une aptitude moyenne au durcissement par nitruration:By combining all these conditions, the following preferential composition domains can be defined for the main elements: 1) in order to obtain a yield strength greater than 1850 MPa and an average suitability for hardening by nitriding:
17% < Ni < 20% 4,17% < Mo < 6% 13%<Co<17%17% <Ni <20% 4.17% <Mo <6% 13% <Co <17%
20% < Ni + Mo < 27% Co x Mo > 5020% <Ni + Mo <27% Co x Mo> 50
2) afin d'obtenir une limite d'élasticité supérieure à 1850 MPa et une aptitude forte au durcissement par nitruration: 15% < Ni < 17%2) in order to obtain a yield strength greater than 1850 MPa and a strong suitability for hardening by nitriding: 15% <Ni <17%
6% < Mo < 8% 8,75%<Co<13% 20% < Ni + Mo < 27% Co x Mo > 50 3) afin d'obtenir une limite d'élasticité supérieure à 2000 MPa et un point Ms plus favorable:6% <Mo <8% 8.75% <Co <13% 20% <Ni + Mo <27% Co x Mo> 50 3) in order to obtain a yield strength greater than 2000 MPa and a point Ms plus favorable:
15% < Ni < 21% 4,17% < Mo < 8% 8,75% <Co< 17,5% 22%<Ni + Mo<25%15% <Ni <21% 4.17% <Mo <8% 8.75% <Co <17.5% 22% <Ni + Mo <25%
Co x Mo > 70Co x Mo> 70
4) afin d'obtenir une limite d'élasticité supérieure à 2000 MPa et un point Ms plus favorable et une aptitude moyenne au durcissement par nitruration:4) in order to obtain a yield strength greater than 2000 MPa and a more favorable point Ms and an average suitability for hardening by nitriding:
17% < Ni < 20% 4% < Mo < 6%17% <Ni <20% 4% <Mo <6%
13%<Co<17,5%13% <Co <17.5%
22% < Ni + Mo < 25%22% <Ni + Mo <25%
Co x Mo > 70Co x Mo> 70
5) afin d'obtenir une limite d'élasticité supérieure à 2000 MPa et un point Ms plus favorable et une aptitude forte au durcissement par nitruration:5) in order to obtain a yield strength greater than 2000 MPa and a more favorable point Ms and a strong ability to harden by nitriding:
15% < Ni < 17%15% <Ni <17%
6% < Mo < 8%6% <Mo <8%
8,75%<Co<13%8.75% <Co <13%
22% < Ni + Mo < 25% Co x Mo > 70 Outre les éléments principaux dont les domaines de composition viennent d'être décrits, les éléments résiduels doivent être contrôlés de façon rigoureuse pour obtenir de bonnes propriétés de ductilité et de résistance à la fatigue. Ces limitations sont notamment :22% <Ni + Mo <25% Co x Mo> 70 In addition to the main elements whose composition domains have just been described, the residual elements must be rigorously checked in order to obtain good ductility and fatigue resistance properties. These limitations include:
Al% < 0,15%Al% <0.15%
Ti < 0,1 %Ti <0.1%
N < 0,003%N <0.003%
Si < 0,1% Mn < 0,1%If <0.1% Mn <0.1%
C < 0,005%C <0.005%
S < 0,001%S <0.001%
P < 0,005%P <0.005%
H < 0,0003% O < 0,001%H <0.0003% O <0.001%
Pour chacun de ces éléments la teneur minimale peut être 0% ou des traces.For each of these elements the minimum content can be 0% or traces.
De plus, et pour obtenir une tenue à la fatigue améliorée des courroies, les teneurs en azote et titane doivent être telles que : Ti x N < 2 x 10"4, ou mieux, < 1 x 10"4.In addition, and in order to obtain improved fatigue resistance of the belts, the nitrogen and titanium contents must be such that: Ti x N <2 x 10 "4 , or better, <1 x 10 " 4 .
A titre d'exemple et de comparaison, on a réalisé des bandes en acier maraging de composition :By way of example and comparison, maraging steel strips of composition have been produced:
Ni=18,1% Co=16,2% Mo=5,3% Al=0,020% Ti=0,013% Si=0,03% Mn=0,03% C=0,003% Ca<0,0005% S=0,0007% P=0,002 N=0,0023% O<0,001 % H<0,0001%, le reste étant du fer et des impuretés. Ces impuretés sont notamment le cuivre et le chrome dont les teneurs sont : Cu=0,07% et Cr=0,06%. Le point de transformation martensitique Ms de cette coulée est égal à +195°C.Ni = 18.1% Co = 16.2% Mo = 5.3% Al = 0.020% Ti = 0.013% Si = 0.03% Mn = 0.03% C = 0.003% Ca <0.0005% S = 0.0007% P = 0.002 N = 0.0023% O <0.001% H <0.0001%, the rest being iron and impurities. These impurities are in particular copper and chromium, the contents of which are: Cu = 0.07% and Cr = 0.06%. The martensitic transformation point Ms of this casting is equal to + 195 ° C.
Ces bandes ont été laminées à froid jusqu'à l'épaisseur de 0,4mm, avec un taux d'écrouissage final de 70%.These strips were cold rolled to the thickness of 0.4mm, with a final work hardening rate of 70%.
Une première bande A, donnée à titre d'exemple, a été recuite au four à passage sous hydrogène à 1020°C pendant 1 minute pour obtenir un grain fin d'indice ASTM 11 puis durcie par maintien à 490°C pendant 3 heures.A first strip A, given by way of example, was annealed in a hydrogen oven at 1020 ° C for 1 minute to obtain a fine grain of ASTM 11 index and then hardened by maintaining at 490 ° C for 3 hours.
Une deuxième bande B, donné à titre de comparaison, a été recuite au four à passage à 1150°C pendant 1 minute pour obtenir un grain grossier d'indice ASTM 7 puis durcie par maintien à 490°C pendant 3 heures. Des essais comparatifs de tenue en fatigue ont été réalisés avec les bandes A et B par traction ondulée, à 25 hertz, avec une contrainte maximale de 750 MPa et une contrainte minimale de 75 MPa.A second strip B, given for comparison, was annealed in a passage oven at 1150 ° C for 1 minute to obtain a coarse grain of index ASTM 7 and then hardened by maintaining at 490 ° C for 3 hours. Comparative fatigue resistance tests were carried out with bands A and B by wavy traction, at 25 hertz, with a maximum stress of 750 MPa and a minimum stress of 75 MPa.
Pour la bande A conforme à l'invention, la limite de fatigue a été supérieure à 8 x 108 cycles, alors que pour la bande B, la limite de fatigue était égale à 5 x 108 cycles. Ces résultats montrent l'intérêt d'un grain fin pour améliorer la tenue à la fatigue de ces bandes.For band A according to the invention, the fatigue limit was greater than 8 × 10 8 cycles, while for band B, the fatigue limit was equal to 5 × 10 8 cycles. These results show the advantage of a fine grain for improving the fatigue resistance of these strips.
Les bandes A et B avaient toutes les deux une limite d'élasticité supérieure à 1850 MPa. Afin de mettre en évidence l'intérêt particulier de la composition chimique préférentielle de l'acier maraging conformément à l'invention, on a également fabriqué une bande en acier maraging contenant 18% de nickel, 9% de cobalt, 5% de molybdène, 0,5% de titane et 0,1% d'aluminium. Cette bande a été fabriquée par le procédé selon l'invention, le grain avait un indice ASTM de 10 et la limite d'élasticité était de 1910 MPa. La limite de fatigue mesurée dans les mêmes conditions d'essai que dans le cas précédent était de 2 x 108 cycles.Bands A and B both had an elastic limit greater than 1850 MPa. In order to highlight the particular advantage of the preferred chemical composition of the maraging steel in accordance with the invention, a strip of maraging steel was also produced containing 18% nickel, 9% cobalt, 5% molybdenum, 0.5% titanium and 0.1% aluminum. This strip was manufactured by the method according to the invention, the grain had an ASTM index of 10 and the elastic limit was 1910 MPa. The fatigue limit measured under the same test conditions as in the previous case was 2 x 10 8 cycles.
Ces bandes peuvent avantageusement être utilisées pour fabriquer des courroies ou tout autre produit, tel que des grilles support de circuits intégrés.These bands can advantageously be used to manufacture belts or any other product, such as grids supporting integrated circuits.
A titre d'exemple, avec des bandes conformes à l'invention on a fabriqué des courroies de transmission pour moteur à combustion interne constituées de cavaliers maintenus par des anneaux constitués de bandes étroites conformes à l'invention et dont les deux extrémités sont soudées. Ces courroies ont une durée de vie plus de dix fois supérieure à la durée de vie de courroies identiques mais fabriquées avec des bandes en acier maraging conforme à l'art antérieur. By way of example, with bands according to the invention, transmission belts for internal combustion engines are made up of jumpers held by rings made up of narrow bands according to the invention and the two ends of which are welded. These belts have a lifespan more than ten times longer than the lifespan of identical belts but manufactured with strips of maraging steel in accordance with the prior art.

Claims

REVENDICATIONS
1- Procédé pour la fabrication d'une bande ou d'une pièce découpée dans une bande en acier maraging laminée à froid et durcie par un traitement thermique de durcissement, caractérisé en ce que, avant d'effectuer le traitement thermique de durcissement, on soumet la bande ou la pièce à une déformation plastique à froid avec un taux d'écrouissage supérieur à 30% et on soumet la bande ou la pièce à un recuit de recristallisation de façon à obtenir un grain fin d'indice ASTM supérieur à 8, la composition chimique de l'acier comprenant, en % en poids :1- A method for manufacturing a strip or a piece cut from a cold-rolled maraging steel strip hardened by a hardening heat treatment, characterized in that, before carrying out the hardening heat treatment, subjecting the strip or the part to cold plastic deformation with a rate of work hardening greater than 30% and the strip or the part is subjected to recrystallization annealing so as to obtain a fine grain of ASTM index greater than 8, the chemical composition of the steel comprising, in% by weight:
12% < Ni < 24,5%12% <Ni <24.5%
2,5% < Mo < 12%2.5% <MB <12%
4,17%<Co<20%4.17% <Co <20%
Al%<0,15% Ti<0,1%Al% <0.15% Ti <0.1%
N < 0,003%N <0.003%
Si < 0,1%If <0.1%
Mn<0,1%Mn <0.1%
C < 0,005% S < 0,001%C <0.005% S <0.001%
P < 0,005%P <0.005%
H < 0,0003%H <0.0003%
O< 0,001% le reste étant du fer et des impuretés résultant de l'élaboration, la composition chimique satisfaisant en outre les relations :O <0.001% the remainder being iron and impurities resulting from the production, the chemical composition also satisfying the relationships:
20% < Ni + Mo < 27%20% <Ni + Mo <27%
50 < Co x Mo < 20050 <Co x Mo <200
TixN<2x10"4 TixN <2x10 "4
2 - Procédé selon la revendication 1 caractérisé en ce que, après le recuit de recristallisation, on soumet la bande ou la pièce à un laminage à froid avec un taux de réduction compris entre 1% et 10%. 3 - Procédé selon la revendication 1 ou la revendication 2 caractérisé en ce que l'acier maraging est refondu sous vide par le procédé VAR ou refondu une première fois sous vide par le procédé VAR ou sous laitier électroconducteur par le procédé ESR et refondu une seconde fois sous vide par le procédé VAR.2 - Process according to claim 1 characterized in that, after the recrystallization annealing, the strip or the part is subjected to cold rolling with a reduction rate of between 1% and 10%. 3 - Process according to claim 1 or claim 2 characterized in that the maraging steel is remelted under vacuum by the VAR process or remelted a first time under vacuum by the VAR process or under electroconductive slag by the ESR process and remelted a second times under vacuum by the VAR process.
4 - Procédé selon l'une quelconque des revendications 1 à 3 caractérisé en ce que le traitement thermique de durcissement consiste en un maintien entre 450°C et 550°C pendant 1 à 10 heures.4 - Process according to any one of claims 1 to 3 characterized in that the hardening heat treatment consists in maintaining between 450 ° C and 550 ° C for 1 to 10 hours.
5 - Procédé selon la revendication 4 caractérisé en ce que pendant le traitement thermique de durcissement ou après celui-ci, on durcit la surface de la pièce par nitruration.5 - Process according to claim 4 characterized in that during the curing heat treatment or after it, the surface of the part is hardened by nitriding.
6 - Procédé selon l'une quelconque des revendications 1 à 3 caractérisé en ce que le traitement thermique de durcissement est effectué au four à passage à une température comprise entre 600°C et 700°C pendant un temps compris entre 30 secondes et 3 minutes.6 - Method according to any one of claims 1 to 3 characterized in that the hardening heat treatment is carried out in a passing oven at a temperature between 600 ° C and 700 ° C for a time between 30 seconds and 3 minutes .
7 - Procédé selon la revendication 6 caractérisé en ce que après le traitement thermique de durcissement, on durcit la surface de la pièce par nitruration.7 - Method according to claim 6 characterized in that after the hardening heat treatment, the surface of the part is hardened by nitriding.
8 - Bande ou pièce, d'épaisseur inférieure à 1 mm, en acier maraging caractérisé en ce que l'acier dont est constitué la bande ou la pièce a un grain fin d'indice ASTM supérieur à 8 et en ce que la composition de l'acier comprend, en % en poids :8 - Strip or piece, of thickness less than 1 mm, in maraging steel characterized in that the steel from which the strip or piece is made has a fine grain of ASTM index greater than 8 and in that the composition of the steel comprises, in% by weight:
12% < Ni < 24,5% 2,5% < Mo < 12% 4,17% < Co < 20% Al% < 0,15%12% <Ni <24.5% 2.5% <Mo <12% 4.17% <Co <20% Al% <0.15%
Ti < 0,1 %Ti <0.1%
N 0,003%N 0.003%
Si < 0,1 %If <0.1%
Mn < 0,1% C < 0,005%Mn <0.1% C <0.005%
S < 0,001%S <0.001%
P < 0,005%P <0.005%
H < 0,0003% O < 0,001% le reste étant du fer et des impuretés résultant de l'élaboration, la composition chimique satisfaisant en outre les relations :H <0.0003% O <0.001% the remainder being iron and impurities resulting from the production, the chemical composition satisfying in addition the relationships:
20% < Ni + Mo < 27% 50 < Co x Mo < 200 Ti x N < 2 x 10"4 20% <Ni + Mo <27% 50 <Co x Mo <200 Ti x N <2 x 10 "4
L'acier ayant une limite d'élasticité après durcissement supérieur à 1850 MPa.Steel having a yield strength after hardening greater than 1850 MPa.
9 - Courroie de transmission comportant au moins une bande ou une pièce conforme à la revendication 89 - Transmission belt comprising at least one band or part according to claim 8
10 - Grille support de circuits intégrés constituée d'une pièce conforme à la revendication 1. 10 - Integrated circuit support grid consisting of a part according to claim 1.
EP01996631A 2000-11-17 2001-11-16 Method for making a strip or a workpiece cut out from a cold rolled maraging steel strip Expired - Lifetime EP1339880B1 (en)

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FR0014807A FR2816959B1 (en) 2000-11-17 2000-11-17 PROCESS FOR MANUFACTURING A STRIP OR A CUT PIECE IN A COLD-ROLLED MARAGING STEEL STRIP
PCT/FR2001/003595 WO2002040722A1 (en) 2000-11-17 2001-11-16 Method for making a strip or a workpiece cut out from a cold rolled maraging steel strip

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016170397A1 (en) 2015-04-23 2016-10-27 Aperam Steel, product made of said steel, and manufacturing method thereof

Families Citing this family (14)

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EP1826282B1 (en) 2002-11-19 2010-01-20 Hitachi Metals, Ltd. Method of producing a maraging steel
GB2406891B (en) * 2003-10-07 2006-09-27 Renold Plc A transmission chain
KR20120078757A (en) * 2007-07-11 2012-07-10 히타치 긴조쿠 가부시키가이샤 Maraging steel and maraging steel for metallic belt
US8747574B2 (en) 2009-03-26 2014-06-10 Hitachi Metals, Ltd. Maraging steel strip
CN105209188B (en) 2013-06-07 2017-10-13 Vdm金属有限公司 The method for preparing metal foil
EP3004408B1 (en) 2013-06-07 2017-08-09 VDM Metals International GmbH Method for producing a metal film
CN104197105A (en) * 2014-08-28 2014-12-10 安徽中臣机电装备科技有限公司 Stainless steel pipe
NL1041468B1 (en) * 2015-09-08 2017-03-22 Bosch Gmbh Robert Metal ring component of a drive belt for a continuously variable transmisson.
WO2017064537A1 (en) 2015-10-15 2017-04-20 Aperam Steel, product created from said steel, and manufacturing method thereof
CN107419196B (en) * 2017-09-18 2019-12-20 东北大学 Yield ratio controllable ultralow-carbon easy-to-weld medium manganese steel for automobiles and preparation method thereof
JP2019189927A (en) * 2018-04-27 2019-10-31 トヨタ自動車株式会社 Endless metal ring and manufacturing method of the same
RU2686706C1 (en) * 2018-06-01 2019-04-30 Общество с ограниченной отвественностью "Лаборатория специальной металлургии" (ООО "Ласмет") Martensite high-strength steel 01h18k9m5t
CN113774289A (en) * 2021-08-25 2021-12-10 哈尔滨工程大学 2700 MPa-grade high-ductility high-corrosion-resistance maraging stainless steel and preparation method thereof
CN115786813B (en) * 2022-11-09 2024-06-11 成都先进金属材料产业技术研究院股份有限公司 Maraging steel plate and preparation method thereof

Family Cites Families (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3093519A (en) * 1961-01-03 1963-06-11 Int Nickel Co Age-hardenable, martensitic iron-base alloys
US3178324A (en) * 1963-06-03 1965-04-13 United States Steel Corp Method of producing ultrafine grained steel
US3341372A (en) * 1965-07-12 1967-09-12 Int Nickel Co Process for heat treating cast maraging steels
US3642595A (en) * 1969-09-23 1972-02-15 Us Air Force Thermal grain refinement of maraging steel
JPS5214518A (en) * 1975-07-25 1977-02-03 Hitachi Ltd Process for manufacturing a rotatable drum for the centrifugal separat or for concentrating uranium
JPS5262119A (en) * 1975-11-19 1977-05-23 Hitachi Ltd Process for producing rotor of centrifugal separator used for concentr ation of uranium
JPS60234920A (en) * 1984-05-04 1985-11-21 Nippon Kokan Kk <Nkk> Manufacture of ultrahigh tensile maraging cold rolled steel plate
JPH01142021A (en) * 1987-11-27 1989-06-02 Sumitomo Metal Ind Ltd Manufacture of seamless metallic belt
JPH01142052A (en) * 1987-11-27 1989-06-02 Sumitomo Metal Ind Ltd Seamless metallic belt and its production
JPH01162726A (en) * 1987-12-18 1989-06-27 Kobe Steel Ltd Manufacture of cold rolled 18%ni maraging steel sheet
JP2909089B2 (en) * 1989-04-26 1999-06-23 日立金属株式会社 Maraging steel and manufacturing method thereof
US5246511A (en) * 1990-05-14 1993-09-21 Hitachi Metals, Ltd. High-strength lead frame material and method of producing same
US5792286A (en) * 1991-12-13 1998-08-11 Nkk Corporation High-strength thin plate of iron-nickel-cobalt alloy excellent in corrosion resisitance, repeated bending behavior and etchability, and production thereof
FR2694303B1 (en) 1992-07-30 1994-10-21 Metalimphy Process for the development of soft magnetic alloys with very high permeability and alloys resulting therefrom.
FR2733630B1 (en) * 1995-04-27 1997-05-30 Imphy Sa CONNECTING LEGS FOR ELECTRONIC COMPONENT
FR2737043B1 (en) 1995-07-18 1997-08-14 Imphy Sa IRON-NICKEL ALLOY FOR TENTED SHADOW MASK
FR2745298B1 (en) 1996-02-27 1998-04-24 Imphy Sa IRON-NICKEL ALLOY AND COLD-ROLLED TAPE WITH CUBIC TEXTURE
FR2753017B1 (en) 1996-08-29 1998-10-16 Imphy Sa STEP BY STEP MOTOR FOR WATCHMAKING WHOSE STATOR IS CONSISTING OF A SOFT MAGNETIC ALLOY AND SOFT MAGNETIC ALLOY
FR2765724B1 (en) 1997-07-04 1999-08-13 Imphy Sa SOFT MAGNETIC ALLOY OF FE-NI-CR-TI TYPE FOR MAGNETIC CIRCUIT OF A HIGH SENSITIVITY RELAY
FR2774099B1 (en) * 1998-01-23 2000-02-25 Imphy Sa STEEL MARAGING WITHOUT COBALT
IL128067A (en) 1998-02-05 2001-10-31 Imphy Ugine Precision Iron-cobalt alloy
FR2786504B1 (en) 1998-12-01 2001-01-05 Imphy Sa CULINARY CONTAINER FOR INDUCTION HEATING AND ALLOY FOR MAKING SUCH A CONTAINER
US6350293B1 (en) * 1999-02-23 2002-02-26 General Electric Company Bottom pour electroslag refining systems and methods
US6309474B1 (en) * 1999-03-04 2001-10-30 Honda Giken Kogyo Kabushiki Kaisha Process for producing maraging steel
FR2791704B1 (en) 1999-04-02 2001-05-25 Imphy Ugine Precision SOFT MAGNETIC ALLOY FOR WATCHMAKING
JP4178490B2 (en) * 1999-06-08 2008-11-12 日立金属株式会社 Maraging steel with high fatigue strength and maraging steel strip using it
JP4507149B2 (en) * 1999-12-24 2010-07-21 日立金属株式会社 Maraging steel for power transmission belt with high fatigue strength and maraging steel strip for power transmission belt using the same
DE60033772T2 (en) * 1999-12-24 2007-10-31 Hitachi Metals, Ltd. Martensitic hardening steel with high fatigue strength and martensitic hardening steel strip
JP4427772B2 (en) * 1999-12-24 2010-03-10 日立金属株式会社 Maraging steel with high fatigue strength and maraging steel strip using it

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0240722A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016170397A1 (en) 2015-04-23 2016-10-27 Aperam Steel, product made of said steel, and manufacturing method thereof
CN114807776A (en) * 2015-04-23 2022-07-29 艾普伦 Steel, product made of said steel and method for manufacturing same

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ES2287187T3 (en) 2007-12-16
TW539746B (en) 2003-07-01

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