CN114381594A - Continuous rapid annealing process for brass-coated pure copper stranded wire high-speed rail through ground wire - Google Patents
Continuous rapid annealing process for brass-coated pure copper stranded wire high-speed rail through ground wire Download PDFInfo
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- CN114381594A CN114381594A CN202111627502.3A CN202111627502A CN114381594A CN 114381594 A CN114381594 A CN 114381594A CN 202111627502 A CN202111627502 A CN 202111627502A CN 114381594 A CN114381594 A CN 114381594A
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- 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
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- 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
- C21D1/26—Methods of annealing
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- 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
- C21D1/34—Methods of heating
- C21D1/42—Induction heating
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The invention relates to the field of processing of metal laminated composite materials, and discloses a continuous rapid annealing process for a brass-coated pure copper stranded wire high-speed rail through ground wire, which adopts rapid induction annealing under the conditions of an annealing temperature of 500-600 ℃, a heating power of 80-200kW, a material conveying speed of 1-20m/min, forced air cooling to below 150 ℃ after heating and air cooling. The invention adopts the medium-frequency induction heating power supply to improve the heating rate, and completely recrystallizes the brass cladding layer and the pure copper stranded wire at higher temperature and in shorter time, thereby avoiding the coarsening of crystal grains of the pure copper caused by lower recrystallization temperature on one hand, and improving the consistency of the annealing temperature of the wire rod on the other hand.
Description
Technical Field
The invention relates to the field of processing of metal laminated composite materials, in particular to a continuous rapid annealing process for a brass-coated pure copper stranded wire high-speed rail through ground wire.
Background
The railway through ground wire is used as a grounding main line of a railway comprehensive grounding system, equipment along a railway is uniformly grounded, signal interference and potential safety hazards caused by potential differences among different equipment are eliminated, and the railway through ground wire is a key material for guaranteeing railway driving safety and realizing high speed, heavy load and intelligent communication of trains. The railway through ground wire consists of a pure copper stranded wire inner conductor with excellent conductivity and flexibility and an outer protective sleeve with soil corrosion resistance, and the outer protective sleeve of the through ground wire is developed into a brass protective sleeve at present from an initial lead protective sleeve along with the continuous development of railway technology. The brass-coated pure copper stranded wire is the latest international generation of through ground wire, and is environment-friendly and long in service life.
At present, the more advanced production process of the brass-coated pure copper stranded wire is to prepare a brass-coated pure copper stranded wire composite blank through solid/liquid continuous casting composite forming, and then to produce a wire rod with a certain diameter through drawing. After the drawing processing reaches a certain deformation, the composite wire blank can generate work hardening, which is not beneficial to continuous processing and the requirement of the product on plasticity, and the work hardening needs to be eliminated through annealing, and the microstructure and the performance are regulated and controlled. However, because the recrystallization temperatures of the brass cladding layer and the pure copper stranded wire core material are different, the conventional heating furnace isothermal annealing can coarsen the crystal grains of the pure copper with lower recrystallization temperature, and further influences the processing and use performance of the composite material. In addition, when the heating furnace is used for isothermal annealing, the temperature uniformity of different parts in the furnace is poor, and the requirements of the brass-coated pure copper stranded wire on the temperature uniformity and consistency cannot be met.
Disclosure of Invention
The invention aims to provide a continuous and rapid annealing process for a brass-coated pure copper stranded wire high-speed rail through ground wire, so as to solve the problem that the processing and use performances are influenced by coarsening of crystal grains of a core material caused by moderate-temperature annealing in the processing process of the through ground wire in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme: a continuous rapid annealing process for a brass-coated pure copper stranded wire high-speed rail through ground wire adopts rapid induction annealing, wherein the conditions of the rapid induction annealing are that the annealing temperature is 500-.
The principle and the advantages of the scheme are as follows: in practical application, in the technical scheme, aiming at the problems of the existing brass-coated pure copper stranded wire isothermal annealing, the inventor comprehensively considers the annealing mode, the annealing temperature, the heating power, the feeding speed and the like from multiple angles. The on-line rapid induction is realized by adopting a rapid induction annealing mode, and the control precision, the speed and the efficiency are high. The annealing temperature has an important influence on the brass-coated pure copper stranded wire crystal grains, and the annealing temperature is a proper annealing temperature verified by practice, so that the brass and the pure copper can be ensured to be basically and completely recrystallized without coarsening of the crystal grains, the hardness of the composite wire can be reduced, the cutting processability of the composite wire is improved, the residual stress can be eliminated, the size of the composite wire is stabilized, and the deformation and crack tendency of the composite wire is reduced. The too high annealing temperature can lead to the brass and pure copper crystalline grain thick, and mechanical properties reduces, and tensile and bending properties descend, and the too low annealing temperature can lead to brass and pure copper only to take place partial recrystallization, and the tissue is inhomogeneous, has a large amount of small-angle grain boundaries, and the hardness descends unobviously, the relatively poor problem of annealing effect. When the annealing parameters are optimized, the heating power and the feeding speed are cooperated to supplement each other, and the heating power and the feeding speed are optimized and matched together to ensure that all parts of the composite line achieve uniform heating effect.
The beneficial effects of this technical scheme lie in:
1. in the technical scheme, a rapid induction annealing mode is adopted, so that the brass coating layer and the pure copper stranded wire can be completely recrystallized at a higher temperature in a shorter time, on one hand, the coarsening of crystal grains caused by the lower recrystallization temperature of the pure copper is avoided, and on the other hand, the consistency of the annealing temperature of the wire rod is improved; the temperature rise speed is high, the temperature is uniform, the heat preservation time is short, fine and uniform pure copper and brass recrystallization textures can be obtained, and the annealed wire rod has excellent comprehensive performance.
2. Compared with the traditional isothermal annealing process, the technical scheme has the advantages that the heating temperature stability is easy to control, and the brass-coated pure copper stranded wire has good structural property consistency after annealing.
3. The technical scheme has high automation degree, greatly improves the production efficiency and is very suitable for mass production.
Preferably, as a modification, the heating power frequency is 3 to 20 kHZ.
In the technical scheme, the frequency of the heating power supply is optimized, the heating speed can be increased, and the heating time is shortened. The power supply frequency is an optimal range verified by practice, the power supply frequency is too high, the skin effect of heating is more obvious, and the heating efficiency is low; too low a frequency of the power supply can overheat the core metal, resulting in insufficient heating of the outer layer metal.
Preferably, as an improvement, the annealing is followed by forced air cooling to 150 ℃ or lower and then air cooling.
In the technical scheme, after annealing, the composite wire can be cooled rapidly through forced air cooling, and the problems of slow cooling and growth and coarsening of crystal grains are avoided. After the temperature is reduced to below 150 ℃, the crystal grains basically stop growing.
Preferably, as a modification, the annealing process is performed under the protection of an inert gas or a reducing gas.
In the technical scheme, in the annealing process, the surface oxidation can be prevented by adopting the protection of inert/reducing gases such as nitrogen, argon or decomposed ammonia and the like.
Preferably, as a refinement, the brass-clad pure copper stranded wire has a diameter in the range of 5-30 mm.
In the technical scheme, by adopting the annealing process, the brass-coated pure copper stranded wire with the diameter of 5-30mm can be rapidly and continuously annealed, the performance of the annealed composite wire can be ensured, and the process has wide application range. If the diameter of the processed composite wire is too large, the problem of incomplete annealing recrystallization can occur, and the mechanical property of the composite wire is influenced; if the diameter of the processed composite wire is too small, the induction annealing coil is too small, the manufacturing difficulty is high, and otherwise, the energy consumption is high.
Preferably, as a refinement, the heating power is from 90 to 150 kW.
In the technical scheme, the heating power is secondarily optimized, and the heating power is matched with the feeding speed, so that the rapid and uniform heating of all parts of the composite wire can be ensured. The problem of inaccurate temperature control can occur due to the fact that the heating power is too high, and the equipment cost is wasted due to the fact that the power is too high; the heating temperature is insufficient due to the excessively low heating power, the recrystallization is insufficient, and the material performance is not uniform.
Preferably, as an improvement, the feeding speed is 2-5 m/min.
In the technical scheme, the feeding speed is secondarily optimized, and the feeding speed is matched with the heating power, so that the rapid and uniform heating of all parts of the composite wire can be ensured. Too fast a material feeding speed can lead to insufficient annealing time, insufficient recrystallization, uneven material performance, and too slow a material feeding speed can lead to coarsening of crystal grains and reduction of tensile and bending properties.
Drawings
FIG. 1 is a microstructure diagram after annealing of example 1.
FIG. 2 is a microstructure diagram of comparative example 1 after annealing.
Detailed Description
The following is a detailed description of the embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents and the like used are all commercially available.
The scheme is summarized as follows:
a continuous rapid annealing process for a brass-coated pure copper stranded wire high-speed rail through ground wire adopts rapid induction annealing, and the annealing process is carried out under the protection of nitrogen, argon or decomposed ammonia gas to prevent surface oxidation. The parameter conditions of the rapid induction annealing are that the annealing temperature is 500-; after annealing, forced air cooling is carried out to below 150 ℃, and then air cooling is carried out. The process is suitable for the diameter range of the brass-coated pure copper stranded wire of 5-30 mm.
Examples 1 to 6 and comparative examples 1 to 5 are examples of the present invention and comparative examples, respectively, each of which differs in the setting of annealing parameters and are described in table 1. Wherein, the cooling mode of air cooling and air cooling is that after heating, the forced air cooling is carried out to below 150 ℃ and then the air cooling is carried out; air cooling means direct natural cooling without forced air cooling. The atmosphere of comparative example "none" means that annealing was not performed under protection of an inert gas or a reducing gas.
TABLE 1
The continuous rapid annealing process of brass-clad pure copper stranded wire is described in detail by taking example 1 as an example: a brass-clad pure copper strand (10 mm in diameter) with a drawing deformation of 63% was subjected to continuous rapid annealing, and examples selected were a clad material of H68 brass and a core material of T2 pure copper, wherein the chemical composition of H68 brass was Cu-31.2 wt% Zn-0.5 wt% Ni-0.1 wt% Fe.
The annealing process is performed under the protection of nitrogen to prevent surface oxidation. The parameter conditions of the rapid induction annealing are that the annealing temperature is 600 ℃, the heating power is 96kW, the material conveying speed is 2.4m/min, and the heating power frequency is 10 kHZ; after annealing, forced air cooling is carried out to below 150 ℃, and then air cooling is carried out.
The first experimental example: hardness test
The hardness of brass and pure copper before and after annealing in each example and comparative example was measured, and three parallel tests were performed for each group, and the results were expressed as an average, and the hardness was measured by a microhardness tester, and the results are shown in table 2.
TABLE 2
As can be seen from the data in Table 2, before annealing, the hardness of brass and the hardness of pure copper are 239HV and 134HV respectively, the annealing temperature, the heating power and the feeding speed are reasonable in the embodiment of the invention, the brass and the pure copper are completely recrystallized basically, the hardness is obviously reduced, the hardness difference between the brass and the pure copper is reduced, and the subsequent coordinated deformation of the two materials is facilitated. In the comparative example 1, the annealing temperature, the heating power and the feeding speed are unreasonable, and after annealing, brass and pure copper are only partially recrystallized, so that the structure is uneven, a large number of small-angle crystal boundaries exist, the hardness is not obviously reduced, and the annealing effect is poor; the hardness difference between brass and pure copper is basically not changed, which is not beneficial to the subsequent coordination deformation of the two materials. In comparative example 2, the skin effect was enhanced due to the excessively high heating power, resulting in partial melting of the surface of the wire rod. In comparative examples 3 and 5, the crystal grains were coarsened due to too slow feed rate or too slow cooling rate after annealing. In comparative example 4, the material feeding speed is too high, so that the annealing time is insufficient, the recrystallization is insufficient, and the material performance is not uniform; in comparative example 6, since there is no gas shield, the surface of the wire rod is seriously oxidized.
Experiment example two: microstructure of
The microstructure test was performed on the brass and the pure copper after annealing in example 1 and comparative example 1, and the results are shown in fig. 1 and fig. 2, respectively. Wherein FIG. 1 is the annealed microstructure of example 1, with brass on the left and pure copper on the right; fig. 2 shows the annealed microstructure of comparative example 1, brass on the left and pure copper on the right. In fig. 1, both brass and pure copper were substantially completely recrystallized and had uniform structures, and in comparative example 1, brass and pure copper were only partially recrystallized after annealing, had non-uniform structures, had a large number of small-angle grain boundaries, had insignificant decrease in hardness, and had poor annealing effects.
The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.
Claims (7)
1. A continuous rapid annealing process for a brass-coated pure copper stranded wire high-speed rail through ground wire is characterized by comprising the following steps of: the rapid induction annealing is adopted, and the conditions of the rapid induction annealing are that the annealing temperature is 500-.
2. The continuous rapid annealing process for the brass-clad pure copper stranded wire high-speed rail through ground wire according to claim 1, characterized in that: the heating power frequency is 3-20 kHZ.
3. The continuous rapid annealing process for the brass-clad pure copper stranded wire high-speed rail through ground wire according to claim 2, characterized in that: after annealing, forced air cooling is carried out to below 150 ℃, and then air cooling is carried out.
4. The continuous rapid annealing process for the brass-clad pure copper stranded wire high-speed rail through ground wire according to claim 3, characterized in that: the annealing process is carried out under the protection of inert gas or reducing gas.
5. The continuous rapid annealing process for the brass-clad pure copper stranded wire high-speed rail through ground wire according to claim 4, characterized in that: the diameter range of the brass-coated pure copper stranded wire is 5-30 mm.
6. The continuous rapid annealing process for the brass-clad pure copper stranded wire high-speed rail through ground wire according to claim 5, characterized in that: the heating power is 90-150 kW.
7. The continuous rapid annealing process for the brass-clad pure copper stranded wire high-speed rail through ground wire according to claim 6, characterized in that: the feeding speed is 2-5 m/min.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117467833A (en) * | 2023-12-28 | 2024-01-30 | 尚纬股份有限公司 | Online continuous annealing device and method for stranded aluminum alloy conductor |
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- 2021-12-28 CN CN202111627502.3A patent/CN114381594A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103468923A (en) * | 2013-08-15 | 2013-12-25 | 王玉凯 | Continuous annealing production line for metal wire rods |
| CN103710522A (en) * | 2013-12-31 | 2014-04-09 | 北京科技大学 | Copper-clad aluminium composite flat cable induction continuous annealing equipment and process using equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117467833A (en) * | 2023-12-28 | 2024-01-30 | 尚纬股份有限公司 | Online continuous annealing device and method for stranded aluminum alloy conductor |
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