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
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
  • C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/18—Hardening; Quenching with or without subsequent tempering
• • 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
  • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B1/00—Constructional features of ropes or cables
  • D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
  • D07B1/0606—Reinforcing cords for rubber or plastic articles
  • D07B1/066—Reinforcing cords for rubber or plastic articles the wires being made from special alloy or special steel composition
• • 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
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/008—Martensite

Definitions

• the invention relates to steel wires and methods for obtaining these wires. These threads are used, for example, to reinforce plastic or rubber articles, in particular pipes, belts, plies, tire casings.
• the son of this type commonly used today are made of steel containing at least 0.6% carbon, this steel having a hardened pearlitic structure.
• the tensile strength of these wires is approximately 2800 MPa (megapascals), their diameter generally varies from 0.15 to 0.35 mm, and their elongation at rupture is between 0.4 and 2%.
• These wires are produced by drawing a starting wire, called “machine wire", the diameter of which is of the order of 5 to 6 mm, the structure of this machine wire being a hard structure, consisting of perlite and ferrite. with a high rate of perlite which is generally greater than 72%.
• the drawing operation is interrupted at least once to carry out one or more heat treatments which make it possible to regenerate the initial structure. After the last heat treatment, an alloy deposit, for example brass, on the wire is necessary for the last drawing operation to be carried out correctly.
• the raw material is expensive, because the carbon content is relatively high;
• the wires themselves have a resistance to breakage and a ductility at break which is sometimes insufficient, and they exhibit significant damage as a result of the drawing before heat treatment, because of the great hardness of the wire rod. .
• the object of the invention is to provide a hardened steel wire coated with a metallic alloy, the steel of this wire having a hardened non-pearlitic structure and having a breaking strength and an elongation at break at least as high as known hardened pearlitic steel wires, and less drawing damage than known wires.
• Another object of the invention is to propose, for producing this yarn, a process which does not have the abovementioned drawbacks.
• the metal wire according to the invention comprising a substrate and a coating, has the following characteristics i
• a) it comprises a steel substrate having a content of carbon at least equal to 0.05% and at most equal to 0.6%; b) this steel has a structure comprising more than 90% of hardened returned martensite; c) the substrate is coated with a metal alloy other than steel; d) the diameter of the wire is at least equal to 0.10 mm and at most equal to 0.40 mm; e) the breaking strength of the wire is at least equal to 2800 MPa; f) the elongation at break of the wire is at least equal to 0.4%.
• a steel wire rod is hardened, this steel having a carbon content at least equal to 0.05% and at most equal to 0.6%, this steel comprising from 28% to 96% of proeutectoid ferrite and 72 % to 4% perlite; the rate of deformation ⁇ of this work hardening being at least equal to 3; b) the work hardening is stopped and a hardening heat treatment is carried out on the work hardened wire, this treatment consisting in heating the wire above the transformation point AC3 to give it a homogeneous austenite structure, then in rapidly cooling it below the martensitic transformation end point!
• the invention also relates to assemblies comprising at least one wire according to the invention.
• the invention also relates to articles reinforced at least in part by wires or assemblies in accordance with the preceding definitions, such articles being, for example, hoses, belts, plies, tire casings.
• FIG. 1 shows the structure of the steel of a wire before the heat treatments, during the implementation of the method according to the invention
• FIG. 2 shows the structure of the steel of a wire after the quenching heat treatment, during the implementation of the process according to one invention
• FIG. 3 shows the structure of the steel of a wire brassy, during the implementation of the process according to the invention
• - Figure 4 shows the structure of the steel of a wire according to the invention.
• an unworked wire rod 5.5 mm in diameter is used.
• This wire rod is made of steel, the characteristics of which are as follows:
• the machine wire is descaled, it is coated with a wire-drawing soap, for example borax, and it is drawn dry to obtain a wire with a diameter of 1.1 mm, which corresponds to a rate of deformation ⁇ slightly greater than 3.2.
• a wire-drawing soap for example borax
• the drawing is easily carried out thanks to the relatively ductile structure of the wire rod.
• a steel with 0.7% of carbon not hardened has a breaking strength R of approximately 900 MPa and an elongation at break A of approximately 8%, that is to say that it is much less ductile.
• this wire drawing is carried out at a temperature below 0.3 for the purpose of simplification, although this is not essential, the drawing temperature may possibly equal or exceed 0.3 T Formula.
• Figure 1 shows the section of a portion 1 of the structure of the wire thus obtained.
• This structure consists of elongated blocks 2 of cementite and elongated blocks 3 of ferrite, the largest dimension of these blocks being oriented in the drawing direction.
• the following heat treatments are then carried out on the wire thus obtained: -
• the wire is heated by convection in a muffle oven to bring it to 950 ° C, that is to say above the transformation point AC3, and it is maintained for 30 seconds at this temperature so as to obtain a homogeneous austenite structure;
• the wire is then cooled, in a gas ring, produced by a turbine, to a temperature of 75 ° C, that is to say below the end point of martensitic transformation (Martensite Finish) in less than 3.5 seconds to obtain a structure with more than 90% martensite in slats.
• a gas ring produced by a turbine
• FIG. 2 represents a section of a portion 4 of the structure thus obtained, the martensite slats being represented by the reference 5.
• the wire is then degreased. Then it is copper, then it is coated with zinc electrolytically at room temperature. It is then heat treated by Joule effect at 540 ° C (813 K) for 2.5 seconds, then cooled to room temperature (about 20 ° C, or 293 K).
• This latter treatment makes it possible to obtain brass by diffusion of copper and zinc, as well as, for steel, a structure comprising more than 90% of returned martensite.
• the thickness of this layer of brass is small (of the order of a micrometer) and it is negligible compared to the diameter of the wire.
• FIG. 3 represents a section of a portion 6 of the structure of the wire thus obtained.
• This structure comprises precipitates of carbides 7, distributed almost homogeneously in a matrix 8 of ferritic type. This structure is obtained thanks to heat treatments previous, and it is kept when cooling to room temperature.
• the precipitates 7 generally have dimensions at least equal to 0.005 ⁇ m (micrometer) and at most equal to 1 ⁇ m.
• the temperature of the wire, during this drawing, is necessarily less than 0.3 T_.
• the brass thickness of the wire thus drawn is very small, of the order of a tenth of a micrometer.
• FIG. 4 represents a longitudinal section of the portion 9 of the steel of this wire according to the invention thus obtained.
• This portion 9 has a structure of the hardened returned martensite type consisting of carbides 10 of elongated shape which are practically parallel to each other and the largest dimension of which is oriented along the axis of the wire, that is to say along the direction of drawing shown schematically by the arrow F in FIG. 4. These carbides 10 are arranged in a hardened die 11.
• This wire according to the invention has a breaking strength of 3000 MPa and an elongation at break of 0.7%.
• the machine wire is descaled, it is coated with a layer of wire-drawing soap, for example borax, and it is drawn dry to obtain a wire with a diameter of 0.9 mm, which corresponds to a rate of deformation ⁇ slightly higher than 3.6.
• the structure obtained is similar to that shown in FIG. 1.
• the following heat treatments are then carried out on the wire thus obtained:
• the wire is heated by the Joule effect to bring it to 1000 ° C. for 3 seconds, that is to say above the transformation point AC3 so as to obtain a homogeneous austenite structure.
• the wire is then cooled in an oil bath to a temperature of 100 ° C., that is to say below the end point of transformation M consult, in less than 3 seconds so as to obtain a structure comprising more than 90% martensite in slats, the structure of the wire obtained being in accordance with FIG. 2.
• the wire is then degreased. Then it is copper, then it is coated with zinc electrolytically at room temperature. It is then treated theoretically by Joule effect at 540 ° C (813 K) for 2.5 seconds, then it is cooled to room temperature, these treatments being identical to Example 1.
• the structure obtained for this brass-plated wire is similar to that shown in FIG. 3.
• the temperature of the wire during this drawing is less than 0.3 T Surprise.
• the steel of the wire according to the invention thus obtained has a structure similar to that shown in FIG. 4.
• This wire has a breaking strength equal to 2850 MPa and an elongation at break equal to 1%.
• a wire of 1.1 mm diameter obtained in the same way as in Example 1 by drawing the machine wire is heated by Joule effect at 1000 ° C for 3 seconds, that is to say above the point of transformation AC3 so as to obtain a homogeneous austenite structure.
• the wire is then cooled, in a gas ring produced by a turbine, to a temperature of 100 ° C., that is to say below the end of transformation point M .., in less than 3 seconds , so as to obtain a structure comprising more than 90% of martensite in slats.
• This wire, according to the invention has a breaking strength equal to 3200 MPa and an elongation at break equal to 0.6%.
• the diffusion treatment to obtain the alloy is carried out at the same time as the tempering of the wire, which avoids an additional diffusion operation and therefore limits the manufacturing costs while allowing overall online treatment of the wire, from the wire machine until final thread;
• the wire obtained has a breaking strength and an elongation at break of values at least equal to those of conventional wires, which therefore results in a breaking energy at least equal to that of conventional wires;
• the yarn obtained has better resistance to corrosion than conventional yarns due to its low carbon content.
• the structure, at the end of this quenching comprises more than 90% martensite, this structure can be made up entirely of martensite.
• the martensite obtained after quenching has a slatted structure, as described in the examples.
• the steel of the wire according to the invention, and therefore the starting machine wire has a carbon content at least equal to 0.2% and at most equal to 0.5%.
• the steel of the wire according to the invention and therefore in the starting machine wire there are the following compositions: 0.3% ⁇ Mn ⁇ 0.6%; 0.1% ⁇ If ⁇ 0.3%; P ⁇ 0.02%; S ⁇ 0.02%; Al ⁇ 0.02%; N ⁇ 0.006%.
• the starting wire rod has a proeutectoid ferrite content at least equal to 41%, and at most equal to 78% and a perlite content at least equal to 22% and at most equal to 59%;
• the rate of deformation ⁇ during work hardening before the heat treatments is at least equal to 3.2 and at most equal to 6;
• the rate of deformation ⁇ during the final work hardening after the heat treatments is at least equal to 3 and at most equal to 5;
• the quenching heat treatment is carried out with a cooling rate at least equal to 250 ° C / second.
• the wire work hardening in the previous examples is carried out by drawing, but other techniques are possible, for example rolling, possibly associated with drawing, for at least one of the work hardening operations.
• the invention is not limited to the embodiments described above, this is for example the case that the invention applies to cases where an alloy other than the brass, with two metals, or more than two metals, for example ternary copper - zinc - nickel, copper - zinc - cobalt, copper - zinc - tin alloys, the main thing being that the metals used are capable of forming an alloy, by diffusion, at a temperature at least equal to 0.3 coordinatorand at most equal to 0.5 T_.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)
• Metal Extraction Processes (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9409795

Family Applications (1)

Country Status (11)

Families Citing this family (14)

Family Cites Families (8)

• 1991
  • 1991-02-14 FR FR9101869A patent/FR2672827A1/fr active Pending
• 1992
  • 1992-02-12 RU RU9293054533A patent/RU2096496C1/ru active
  • 1992-02-12 DE DE69203228T patent/DE69203228T2/de not_active Expired - Fee Related
  • 1992-02-12 JP JP4506381A patent/JPH06505308A/ja active Pending
  • 1992-02-12 ES ES92906734T patent/ES2074883T3/es not_active Expired - Lifetime
  • 1992-02-12 WO PCT/FR1992/000134 patent/WO1992014811A1/fr active IP Right Grant
  • 1992-02-12 US US08/098,378 patent/US5503688A/en not_active Expired - Lifetime
  • 1992-02-12 EP EP92906734A patent/EP0571521B1/de not_active Expired - Lifetime
  • 1992-02-12 AU AU15652/92A patent/AU667190B2/en not_active Ceased
  • 1992-02-12 CA CA002099872A patent/CA2099872A1/fr not_active Abandoned
  • 1992-02-12 BR BR9205631A patent/BR9205631A/pt not_active IP Right Cessation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events