Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
  • B22D11/004—Copper alloys
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
  • B22D1/002—Treatment with gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/005—Continuous casting of metals, i.e. casting in indefinite lengths of wire
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
  • B22D11/059—Mould materials or platings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/12—Accessories for subsequent treating or working cast stock in situ
  • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
  • B22D11/1245—Accessories for subsequent treating or working cast stock in situ for cooling using specific cooling agents
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

Definitions

• This invention concerns a method of manufacturing wires, including micro-wires, of Cu-Ag alloys, in particular of an alloy comprising Cu-((3 ⁇ 7.9)% Ag by weight.
• These alloys having the form of rods and coming from a continuous melting and casting line are subject to properly selected heat treatment sequences and drawing into wires, featuring a set of excellent mechanical and electrical properties.
• Cu-Ag alloys may be used as conductors in power supply applications, in the automotive industry, in power supply and signalling systems of high speed railways, in medical appliances and as power supply components of strong magnetic field generator windings.
• copper-based conductor alloys which may also contain Nb, Be, Zn, Sn, Zr, Cr, etc. have been applied in the analysed fields of technology.
• these alloys apart from their relatively high mechanical properties, are characterized by low electrical conductivity.
• Cu-Ag alloys also show exceptionally high values of electrical conductivity.
• a number of global solutions focus on developing these properties by selecting an appropriate technology of obtaining and processing materials. Research in scientific centres and research institutes worldwide is aimed at obtaining wires with excellent mechanical properties and, at the same time, the highest electrical conductivity possible. Production of ingots with various cross-section shapes and limited lengths, and continuous melting and casting systems ensuring that a material with theoretically endless length can be obtained, are amongst commonly known engineering solutions applied to obtain alloys.
• a method for obtaining micro-wires of an alloy with the chemical composition of Cu-(2 ⁇ 14)% Ag by weight is known from a Japanese patent application JP 2000-199042 .
• the description provides for a method of manufacturing microwires with a diameter of 0.01 ⁇ 0.1 mm using eight variants of treatment.
• the research findings presented in the patent description have focused on a material in the form of cast rods with a diameter of 8mm and containing silver as an alloying constituent in the amount of 5 and 10% Ag by weight.
• the scheme for obtaining microwires according to the referred description provides for executing the following treatment sequences. Cast rods ofthe alloy of Cu-10% Ag by weight were subjected to diameter reduction in the drawing process from 10mm to 5 mm, at a set reduction of 61%.
• the deformed material was heat treated at 450 C for 10 h, in order to apply subsequent overall reduction of either 94.2% or 99%.
• the final wire diameter was 1.2mm and 0.5mm, respectively.
• the second of the variants expected, after the initial overall reduction of 61%, a heat treatment at 450 C /10h, the overall reduction of 84%, a heat treatment at 370 C/15 h, followed by the overall reduction of 97.8% to a diameter of 0.3mm, and a subsequent heat treatment 370 C/60 h, and the final overall reduction of 99.6% to a diameter of 0.02mm.
• a heat treatment at 450 C /10h the overall reduction of 84%
• a heat treatment at 370 C/15 h followed by the overall reduction of 97.8% to a diameter of 0.3mm
• a subsequent heat treatment 370 C/60 h a subsequent heat treatment
• the input material was a Cu-Ag alloy ingot with dimensions of 10x10x30mm, obtained by melting in an electric Tamman furnace at a temperature of 1250 C. Alloys from the range of Cu- (1 ⁇ 10)% Ag by weight, Cu-(2 ⁇ 6)% Ag by weight were subjected to a reduction in the drawing process. The heat treatment processes applied in the central phase of the reduction were carried out at temperatures of 400 ⁇ 500 C for a period from 1 to 50 hours in a vacuum or an inert gas atmosphere to avoid oxidation of the material surface.
• the initial material is an ingot with the maximum content of impurities of 10 ppm or less, obtained in the process of mould casting.
• the metal during casting is cooled at a cooling rate of 400 ⁇ 500 C/min.
• the product according to this solution is further processed by e.g. drawing, rolling, etc.
• the heat treatment operations following the plastic working processes are carried out at 300 ⁇ 350 C for 10 ⁇ 20 h, 350 ⁇ 450 C for 5 ⁇ 10 h, or at temperatures of 450 ⁇ 550 C for 0.5 ⁇ 5 h in an inert gas atmosphere.
• the schedule of obtaining products of the Cu-(1 ⁇ 3.5)% Ag by weight according to this invention provides for drawing to a diameter of 0.05mm or less.
• the tensile strength of the final material is within the range of 800 ⁇ 1200 MPa, while the electric conductivity is within the range of 80 ⁇ 84% IACS.
• This solution also assumes, at a certain stage of obtaining wires from the alloy of Cu-(1 ⁇ 3.5)% Ag by weight, an additional holding process at temperatures of 600 ⁇ 900 C for a very short time, i.e. from 5 to 120 seconds.
• a disadvantage shared by the solutions is underutilization of a possibility to advantageously develop the microstructure ofCu-Ag alloys, and a relatcd possibility to manufacture wires with an even higher set of mechanical and electrical properties.
• thermo-mechanical treatment processes conducted at unfavourably selected temperature ranges, combined with an overly extended heat treatment time, do not influence effectively the maximisation of mechanical and electrical properties.
• additional intermediate heat treatments inherent to the whole production cost generation, used at an improper stage of wire production, do not translate fully into a high set of mechanical and electrical properties of the final product.
• the objective of the invention is to present a consistent, integrated method for manufacturing wire components, including microwires, comprising the continuous melting and casting process of rods of Cu-Ag alloys and a sequential heat treatment combined with drawing, enabling wires, including micro-wires to be obtained with a tensile strength Rm within the range of 1100 ⁇ 1400 MPa and simultaneously an electrical conductivity within the range of 68 ⁇ 84% IACS.
• the Cu-Ag alloys have the possibility of mutual limited solubility in the solid state of silver in copper and copper in silver.
• the alloy microstructure consists of a matrix comprising mainly copper containing a certain amount of not precipitated silver, and precipitates rich in silver, containing also a small amount of not precipitated copper.
• the structure at a longitudinal section of the wires (microwires) consists of very numerous, thin, considerably elongated fibres almost wholly comprising silver with a small admixture of copper and the matrix comprising almost wholly of copper.
• the diameter of these fibres has nanometric dimensions.
• the materials in the form of copper and silver with a high chemical purity are melted at a temperature of 1083 ⁇ 1300 C in a graphite crucible placed in a furnace, and subsequently continuously cast at a temperature of 1083 ⁇ 1300 C, in an inert gas atmosphere using a graphite mould, at primary cooling conditions (mould cooling) and secondary cooling conditions (the solidified alloy after leaving the mould), and subs the casting obtained with this method is subjected to a thermo-mechanical treatment.
• the obtained casting is solution annealed at a temperature of 600 ⁇ 779.1 C for 0.5 ⁇ 100 hours, and subsequently quenched and, subsequently, it is drawn, with a true strain measure of 0.1 ⁇ 1, and next it is subject to processes of another two-stage heat treatment, followed by a deformation in the drawing process into final cross-section wires.
• the obtained casting is solution annealed at a temperature of 600 ⁇ 779.1 C for 0.5 ⁇ 100 hours, and subsequently quenched, and next it is subjected to processes of a further two-stage heat treatment, followed by drawing into final cross-section wires.
• the first stage involves holding at 150 ⁇ 300 C for 0.1 ⁇ 100 hours, followed by the second stage which is holding at 300 ⁇ 500 C for 0.1 ⁇ 20 hours followed by slow cooling.
• At least one intermediate heat treatment occurs within 200 ⁇ 600 C for 0.1 ⁇ 50 hours, followed by slow cooling.
• At least one intermediate heat treatment occurs at 600 ⁇ 900 C for 0.1 ⁇ 1000 seconds, followed by quenching.
• final cross-section wires are subjected to a heat treatment at a temperature of 50 ⁇ 300°C for 0.1 ⁇ 1000 hours.
• the casting is water quenched.
• the casting is oil quenched.
• the casting is liquid nitrogen quenched.
• the casting is emulsion quenched.
• the graphite crucible is made of a high purity graphite, wherein alloying constituents are placed under a charcoal or graphite layer.
• the graphite crucible is placed in protective atmosphere.
• the graphite mould is cooled with a system that is mounted on It, through which a cooling agent flows (the primary cooling system).
• the casting leaving the mould is additionally cooled by a cooling agent fed directly onto the casting (the secondary cooling system).
• the following technical and functional effects have been obtained, namely a possibility to form a set ofexcellent electrical and mechanical properties of the product, reduction of manufacturing costs thanks to properly selected thermo-mechanical treatments, a possibility to select the optimum conditions of the thermo-mechanical treatment sequence in order to obtain the required mechanical and electrical properties, an advantageous ratio of weight to mechanical parameters of the obtained products.
• the method for obtaining m crow res from Cu Ag alloys is descr bed with the embodiment examples below.
• the material was then subjected to the thermo-mechanical treatment processes.
• the casting was solution-annealed at a temperature of 750 C for 20 hours, and subsequently oil quenched to preserve the homogeneous structure of the material.
• the primary ageing (the first stage) was conducted at 300 C for 20 hours.
• the secondary ageing (the second stage) was conducted at the temperature of 450 C for 10 hours.
• the alloy microstructure consisted of very numerous fine silver precipitates in the copper matrix.
• the material was drawn into wires with a true strain of 2.7, followed by an intermediate heat treatment that consisted in holding at a temperature of 400 C for 2 hours.
• the material was drawn into the final diameter wires. In order to enhance the electric properties, the final diameter wires were subjected to a heat treatment at a temperature of 240°C for 2 hours.
• the casting was solution-annealed at a temperature of 750 C for 10 hours, and subsequently it was water quenched in order to preserve the homogeneous structure of the material. After this process, it was necessary to conduct a two-stage ageing processes, in order to extract as much silver as possible from the homogeneous solid solution of Cu-Ag.
• the primary ageing (the first stage) was conducted at 200 C for 20 hours.
• the secondary ageing (the second stage) was conducted at a temperature of 450 C for 10 hours.
• the alloy microstructure consisted of very numerous fine silver precipitates in the copper matrix. Next, the material was drawn into the final diameter wires.
• the final diameter wires were subjected to a heat treatment at a temperature of 180°C for 10 hours.
• the materials in the form of high purity silver pellets of 99.99% and OFE copper were melted at a temperature of 1220 C in a graphite crucible placed within an induction furnace.
• the continuous casting process was conducted at a temperature of 1220°C in an inert gas atmosphere.
• the continuous casting of rods with a chemical composition of Cu-7% Ag by weight, using a graphite mould was performed in primary cooling (mould cooling) and secondary cooling (of the solidified alloy after leaving the mould) conditions.
• thermo-mechanical treatment processes were subjected to the thermo-mechanical treatment processes.
• the casting was solution-annealed at a temperature of 750 C for 20 hours, and then quickly water quenched in order to preserve the homogeneous structure of the material.
• the two-stage ageing process was carried out, which was to extract as much silver as possible from the homogeneous solid solution of Cu-Ag.
• the primary ageing (the first stage) was conducted at 300 C for 20 hours.
• the secondary ageing (the second stage) was conducted at a temperature of 450 C for 10 hours.
• the alloy microstructure consisted of very numerous fine silver precipitates and a copper matrix.
• the material was drawn into wires of the final diameter.
• the wires of the final diameter were subjected to heat treatment at a temperature of 150°C for 100 hours.
• the final microstructure of the wire as observed on its longitudinal section, presents very numerous, elongated, thin silver bands on the background of a copper matrix, favourable for obtaining a set of high mechanical properties and a high electrical conductivity of the product.
• the solution according to the invention is a previously unknown, consistent, integrated method of manufacturing finished rods as a result of the continuous melting and casting process of Cu-Ag alloys that feature a high chemical purity with an allowable oxygen content in the alloy of 3 ppm or less and other impurities up to max. 20 ppm.
• the chemical composition and the structure of Cu-Ag alloy rods obtained on the basis of the solution according to the invention are constant along the whole length of the casting.
• the final product in the form of wires is only obtained by drawing of continuously cast rods, using dies with a round profile or other.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Conductive Materials (AREA)
• Metal Extraction Processes (AREA)
• Continuous Casting (AREA)

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Cited By (4)

Citations (6)

• 2013
  • 2013-04-05 PL PL403443A patent/PL221274B1/pl unknown
• 2014
  • 2014-04-04 LT LTEP14461523.4T patent/LT2873475T/lt unknown
  • 2014-04-04 ES ES14461523T patent/ES2706474T3/es active Active
  • 2014-04-04 EP EP14461523.4A patent/EP2873475B1/de active Active
  • 2014-04-04 SI SI201431053T patent/SI2873475T1/sl unknown
  • 2014-04-04 PL PL14461523T patent/PL2873475T3/pl unknown
  • 2014-04-04 HU HUE14461523A patent/HUE041639T2/hu unknown

Patent Citations (6)

Non-Patent Citations (2)

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