DE2655433A1 - ELECTRIC CONDUCTOR MADE OF AN ALUMINUM ALLOY - Google Patents

Description

- H. Barteis

Dipl.-Chern. Dr. Brandes Dr.-Ing.Held DipL-Phys. Wolff

SOUTHWIRE COMPANY, 126 Fertilla Street,
Carrollton, Georgia 30117 / USA

Electrical conductor made from an aluminum alloy

8 Munich 22. Thiersch's traBe

Tel. (089) 293297 Telex 0523325 (patwod) Telegram address: wolffpatent, munich

Postal check account Stuttgart 7211 (BLZ 60010070) Deutsche Bank AG, 14/286 (BLZ 60070070)

Office hours: 8 a.m. to 12 p.m., 1 p.m. to 4.30 p.m. except Saturdays

December 6, 1976 25/93 Reg.No. 125

709824/0788

Electrical conductor made from an aluminum alloy.

The invention relates to the production of electrical conductors from an aluminum alloy with improved properties.

Alloys based on aluminum are known to have, due to their comparatively low weight and their comparatively low weight Manufacturing costs found wide areas of application. An area in which aluminum alloys are becoming increasingly popular used is the field of manufacturing electrical conductors, in which copper is increasingly being displaced. Usual known Electrical conductors based on aluminum alloys, for example in the form of wire or cable (also known as EO conductors in the USA) consist essentially of pure aluminum and trace amounts of impurities such as silicon, vanadium, Iron, copper, manganese, magnesium, zinc, boron and titanium.

Although aluminum alloys are advantageous in terms of their weight and their manufacturing costs, it has been found that the known alloys with regard to their usability as electrical conductors still have properties which are not fully satisfactory. One of the main reasons that aluminum alloys for the manufacture of electrical conductors are not yet fully used have been able to prevail, is based on the still partially unsatisfactory physical properties of the previously available standing common aluminum alloy base EC type conductors.

Physical properties, such as thermal stability and tensile strength, leave something to be desired percentage elongation, the ductility and the yield point. The improvement of these physical properties without adversely affecting them the electrical conductivity of the conductors produced would represent a significant advance.

However, it is known that the addition of alloying elements such as in the case of the known aluminum alloys, the conductivity is reduced, although the addition of certain alloy elements reduces the conductivity physical properties can be improved.

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From DT-OS 22 27 523 from 1972 electrical conductors based on aluminum alloys are known which have improved physical properties with good electrical conductivity. The aluminum alloys for producing the conductors are produced by mixing nickel, iron and optionally other alloying elements with aluminum in a furnace to produce a melt of the desired composition. According to DT-OS 22 27 523, advantageous results are obtained when nickel is present in the alloy in a concentration of 0.20 to 1.60% by weight. Very particularly advantageous has proved to when nickel in a concentration of 0.50 to 1.00 weight -% is present, especially in a concentration of about 0.60 to about 0.80 wt .-%.

It has also proven to be advantageous if the iron content is between 0.30 and 1.30% by weight. Particularly advantageous results are _s 40 to 0.80 percent at iron contents of 0 - achieved% and in particular 0.45 to Oj65%..

The aluminum content of the alloys of DT-OS 22 27 523 is about 97 ^ 00 to 99.50 Gevj.-I, in particular from ett ^ a 97 ₉ 80 to about 99.20 wt.

Since the maximum and minimum percentages of aluminum did not coincide with the maximum and minimum percentages for the alloying elements, it was evident that suitable results were not obtained using the respective maximum percentages of all alloying elements In the manufacture of the enamel, it was found to be advantageous if the aluminum contained no more than a total of 0.10 % trace elements or trace impurities before it was added to the melt in the furnace.

If necessary, the alloy described in DT-OS 22 27 523 can be used an additional alloy element or group of alloys Elements included. The total concentration of the, if applicable present alloy elements can be up to about 2.00 wt .-% and is preferably about 1.10 to about 1.50

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Wt%. Particularly advantageous results are obtained when the total concentration of additional alloy elements is about 0.10 to about 1.00 weight percent.

Additional alloy elements that can be used include the following:

Additional alloy elements

Magnesium Cesium Dysprosium

Cobalt yttrium terbium

Copper scandium erbium

Silicon thorium neodynium

Zirconium tin indium

Cerium zinc boron

Noihium bismuth thallium

Hafnium antimony rubidium

Lanthanum Vanadium Titanium

Tantalum rhenium carbon

Further elements can be present in trace amounts, provided that they do not adversely affect the mechanical, electrical and physical properties of the conductor to be manufactured »

Particularly advantageous results will be obtained using the following receive additional elements:

Additional alloying elements used with preference

Magnesium Zirconium Scandium

Cobalt Niobium Thorium

Copper tantalum rare earth metals

Silicon yttrium carbon

Particularly advantageous results are obtained when using cobalt or magnesium as additional alloy elements. as

709824/0786

ORIGINAL INSPECTED

It has proven advantageous to use magnesium or cobalt in concentrations of about 0.001% by weight to about 1.00% by weight, in particular to be used in concentrations of about 0.025 to about 0.50 wt. Optimal results are obtained when using magnesium or cobalt is present in amounts from about 0.03 to about 0.10 percent by weight.

According to the method known from DT-OS 22 27 523, Manufacture electrical conductors based on aluminum alloys, which have improved physical properties compared to common conductors based on aluminum alloy of the EC type are marked, with the conductors having comparable electrical conductivities exhibit. However, the known alloys do not have sufficient ductility to carry out the continuous To facilitate process steps or to lead to a wire or cable that has advantageous elongation properties. In particular, it has been shown that when the known alloys are used, the initially cast rod has a tendency to split and cracking during continuous rolling and cold drawing. It has also been shown that the to be produced wire or cable material often consists of intermetallic compounds deposits, which after Cold distortion of the material can lead to unsatisfactory ductility or ductility.

The present invention was therefore based on the object of producing an electrical conductor based on an aluminum alloy, the ductility of which is improved compared to the conductor which can be produced by the method of DT-OS 22 27 523. The alloy should be made in such a way that it can be continuously rolled out or cold-drawn without crevices and cracks occurring. The alloy should also enable the production of a wire which, in the form of a wire of type no. 10A.WG, has an elongation of at least 12 % in the fully annealed state.

The invention was based on the knowledge that the asked

709824/0788

ORIGINAL INSP & OTcD

The problem can be solved by not changing the copper concentration can rise above a maximum value. Furthermore, it has been found that further improvements can be obtained if the concentrations of the additional alloying elements listed in DT-OS 22 27 523 are precisely controlled and within certain limits Limit values holds, especially with regard to the elements magnesium and silicon.

The subject of the invention is accordingly a process for the production of an electrical conductor from an aluminum alloy with a minimum conductivity of at least 58 % IACS of good thermal stability, a tensile strength of at least 844 kg /

2 kg / cm2

cm and a yield strength of at least 56 2 /, measured on a fully annealed wire in which you can:

(a) an alloy of 0.20 to 1.60 wt. % nickel, 0.30 to 1.30 wt. % iron, up to a total of 2.00 wt. % additional alloying elements, including copper, magnesium and Silicon and 97.00 to 99.50 wt. I aluminum, which may contain the usual trace elements,

(b) Pour the alloy into a moving mold consisting of a around the circumference of a rotating casting drum extending groove or groove and a metal band, which on a part the groove or groove rests, is formed,

(c3 the cast alloy immediately after casting, as long as the alloy is practically still in the as-cast state, hot rolled into an endless rod and

(d) draws the rod out to the desired final thickness by wire forming, without annealing before pulling out or while pulling out,

which is characterized in that one to improve the ductility of the conductor is based on an alloy with a copper content of less than 0.05% by weight.

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Characterized in that the copper content of the alloy is less than 0.05 wt ⁰ O, the formation of cuprous oxide particles is inhibited or prevented and a continuous rolling and warping possible without that the product gaps and cracks occur.

Further improved results with regard to the ductility of the material to be produced are obtained when the magnesium content of the alloy is less than 0.1% by weight, when the silicon content is above 0.15% by weight. When using such alloys, wires with an elongation of at least 12 %, measured on a wire of the type No. 10 AWG in the fully annealed state, can be obtained.

Although copper is an effective hardening agent, if more than 0.05 wt% copper is used in the alloy, extremely hard cuprous oxide particles are generated which lead to the formation of cracks and crevices if the continuously produced Product is rolled out and cold-drawn.

Since a product manufactured in the usual known manner is homogenized prior to rolling for the purpose of refining the grain structure the copper content of the alloy need not be closely monitored in this case. On the other hand, it will be like the In the method of the invention, the alloy is processed in a continuous manner, i.e. the cast rod becomes virtually instantaneous rolled out in the cast state after its manufacture, the advantage of a homogenization step cannot be achieved exploit.

In contrast, the invention is based on the knowledge that the advantages of a homogenization stage are also obtained when when the copper content of the alloy is closely monitored to avoid brittleness, which can lead to cracks and crevices leads in the rod if this according to the method according to the invention is further processed.

265B433

It has also proven to be particularly advantageous if the silicon and magnesium concentrations are precisely monitored. In particular, it has been shown that when the silicon content is above 0.15% by weight, the magnesium content is below 0.1% by weight should lie. This results in a further improvement in ductility achieved after cold drawing, when the alloy was cast and rolled out in the manner described.

The melt required to carry out the method of the invention can be produced in the manner known from DT-OS 22 27 5 23 , the content of copper and possibly magnesium and silicon being monitored in the manner indicated. The aluminum alloy produced is then continuously cast into an endless rod, for which purpose a conventional continuous rod working casting device can be used. Immediately after casting, the cast rod is hot-worked in a roller mill to produce an endless alloy belt. In this case, according to the 22 27 523 described in DT-OS Procedure to be worked.

The manufacture of wires of various thicknesses is carried out by subjecting the endless strips obtained by casting and rolling to an exhaust process. The non-tempered strip (ie rolled out for f-tempering (as rolled to f temper)) is then cold-drawn through a series of progressively decreasing molds, without the cold-drawing process being preceded by tempering or without tempering in between, xv ^r whether an endless wire of the desired diameter is produced.

It has been shown that the elimination of intermediate tempering to improve the physical properties of the wires leads. Processing with the inclusion of intermediate tempering can be useful if the requirements with regard to the physical properties of the wires are reduced.

The conductivity of the hard-drawn wire is at least 57 % IACS Is a greater conductivity or an increased one

709824/0788

* AA-

If elongation is desired, the wire can be annealed or partially annealed after the desired wire size has been obtained and cooled. A fully annealed wire has a conductivity of at least 58 % IACS. At the end of the drawing operation and, if necessary, the annealing operation, the wire has improved tensile strength properties and an improved yield point as well as improved thermal stability, improved ultimate elongation and increased ductility and improved fatigue resistance.

The annealing operation can be carried out continuously like in resistance annealing, induction annealing, convection annealing by continuously operating ovens or radiation annealing continuously operating ovens or preferably batchwise in a batch oven.

In the case of continuous tempering, for example, temperatures of about 2 32 ° C. to about 65O ° C. can be used, with tempering temperatures of about 5 minutes to about 1/10000 of a minute. In general, however, continuous tempering temperatures and tempering times can be set which are adapted to the requirements of the overall process and as long as the desired physical properties are achieved. In a batch-wise tempering operation, temperatures have been found from about 2Ü4 ° C to about 400 ⁰ C to be advantageous, with residence times of about 30 minutes to about 24 hours. As in the case of continuous tempering, the times and temperatures can also be changed and adapted to the overall process in the case of a batch process, as long as the desired physical properties are achieved.

It has been shown that the properties of a fully annealed type 10 A.W.G. soft wire made using an alloy of the type according to the invention lie in the following ranges:

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_ο depth
kg / cm ^

2 conductivity tensile strength elongation yield point kg / cm

58% - 631 844 - 1688 12% - 30% 562 - 1265

The following examples are intended to illustrate the invention in more detail.

example 1

First, various melts were produced by adding 1816 g of molten aluminum with less than 0.101 Trace element impurities are those given in the table below Elements were added in the specified concentrations. Graphite crucibles were used to produce the melts, with the exception of the cases in which the alloying elements used consisted of known carbide formers, in which cases crucibles made of alumina were used. The mixtures were heated to such temperatures for so long that melts were obtained, so that a complete solution of the alloying elements in the aluminum could take place. To prevent oxidation, the Melting maintain an argon atmosphere.

The melts produced were then continuously used Cast in a continuously operating casting device and immediately afterwards by means of a roller mill to form endless rods a diameter of 9.525 mm hot rolled. The hard rods obtained were then cold-drawn without prior annealing has been or has been annealed in between. Wires 0.259 cm in diameter of the No. 10 A.W.G. Subsequently, the wires were annealed at 343 ° C. for 5 minutes, whereby soft wires were obtained.

The following table 1 shows the concentrations of the alloying elements used, nickel and iron, as well as the properties of the wires produced.

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Fe ZF ⁺ Table 1 % Elongation % IACS ⁺⁺ Ni 1.00 1225 12.5 60.40 0.30 0.70 1281 25.6 59.73 0.80 0.60 1253 26.1 59.97 1.00 0.40 1246 24.8 59.52 1.50

+ 2

= Tensile strength in kg / cm = conductivity

Example 2

It was a further melt of an alloy as described in Example 1, the following composition in wt -% had.:

Nickel: 0.60 %

Iron: 0.90 %

Magnesium: 0.15 %

Aluminum: rest

The melt was processed into a No. 10 soft wire. The physical properties of the wire produced were as follows:

Tensile strength = 1274 kg / cm ²

Final elongation = 25.2 %

Conductivity = 59.10% IACS

Example 3

According to the method described in Example 1, a further melt was made from an alloy in the context given below produced in% by weight:

26bb433

Nickel: 0.40 %

Iron: 1.10 %

Aluminum: rest.

The melt was in turn turned into a No. processed. The physical properties of the manufactured Wire were as follows:

Tensile strength = 1218 kg / cm ² final elongation = 14.1 a

Conductivity = 60.30 % IACS

Example 4

According to the method described in Example 1, a further melt of the composition given below in% by weight manufactured:

Nickel: 1.60 %

Iron: 0.30 %

Aluminum: rest

The melt was then made into a No. 10 soft wire in turn. The physical properties of the wire were as follows:

Tensile strength = 1204 kg / cm ² final elongation = 27.5 ο

Conductivity = 59.1 % IACS

Example 5

According to the method described in Example 1, a further melt was made from an alloy of the composition given below produced in weight I:

709824 / 078S

Nickel: 0.20 %

Iron: 1.30 %

Aluminum: rest

The melt was processed into a No. 10 soft wire. The physical properties of the wire were as follows:

Tensile strength = 1225 kg / cm ²
Final elongation = 13.5 %

Conductivity = 61.05 % IACS

Example No. 6

According to the method described in Example 1, a further melt was produced from an alloy of the composition given below in weight ⁰ O:

Nickel: 0.80 %

Iron: 0.45 %

Cobalt: 0.10 %

Aluminum: rest

The melt was then processed into a No. 10 soft wire. The physical properties of the wire were as follows:

Tensile strength = 1250 kg / cm ² final elongation = 23.6 %

Conductivity = 59.8 IACS

An analysis of an alloy with 0.80% by weight of nickel and 30% by weight Iron (remainder aluminum) showed that the aluminum alloy, after cold working, deposits of intermetallic compounds contained. One of these compounds was known as nickel aluminate (NiAl,) and another compound identified as iron aluminate (FeAl,). The nickel intermetallic compound was found to be very stable, especially at high temperatures. The nickel compound had des

70982 A / 0786

furthermore a very low tendency during the tempering of the product melt together from the indicated alloy and the connection was found generally to be with the aluminum matrix as incoherent. The mechanism of reinforcement of this alloy is clearly based in part on in the aluminum matrix dispersed nickel intermetallic compound. The precipitate obviously tends to close up the areas that occur during the Cold working of the wire made from the alloy can be produced. An investigation of the nickel intermetallic compound Existing deposit in a cold drawn wire indicated that the deposits were oriented in the direction of draw. Further It was found that the deposits can have a rod-shaped, platelet-shaped or spherical configuration.

It has also been shown that other intermetallic Can form compounds, depending on the constituents of the melt produced in the individual case and those used in the individual case relative concentrations of the alloying elements. These intermetallic compounds can include, for example:

Ni ₂ Al ₃ , MgCoAl, Fe ₂ Al ₅ , Co ₂ Al ₉ , Co ₄ Al ₁₃ , CeAl ₄ , CeAl ₂ , VAl ₁₁ , VAl ₇ , VAl ₆ , VaI ₃ , VaI ₁₂ , Zr ₃ Al, Zr ₂ Al , LaAl ₄ , Al ₃ Ni ₂ , Al ₃ Fe ₅ , Fe ₃ NiAl ₁₀ , FeNiAl ₉

The intermetallic compounds made of iron aluminate also contribute to clogging of imperfections during cold working of the wire. A review of the deposits of intermetallic iron compounds in a cold drawn one Wire found the deposits to be virtually uniformly distributed throughout the alloy and to have a particle size of less than 1 micron. If the wire is distorted without tempering in between, the particle size is the intermetallic Iron compounds at less than 200OA *.

A property of highly conductive wires based on aluminum alloys, the historical tests for tensile strength, percentage elongation and electrical conductivity is not affected, the possible change in properties

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as a result of reductions or fluctuations in the temperature of cables or strands. Obviously, the maximum working temperature of a cable or a strand or a series of cables or strands is influenced by these temperature characteristics. This Charakterisfi.k is further important I so from a manufacturing standpoint, as "ifiele, 1 ie approximately .-- · .- ■ / process the application of comparatively ^high: require Härtungsteniperaturen '- -; .. ■ - .... .-....- ■ -. ■;

Surprisingly, it has been shown that the erfindungsgeniäß. manufacturable aluminum alloy wires have a thermal stability that is above the thermal stability of conventional known wires based on aluminum alloys. ·

Under an aluminum alloy rod, here is a solid one To understand product that is long in terms of its cross-section. In the case of the staffs mentioned here, it was normally around those with a cross-section of 0.95 25 to 7.62 cm.

An aluminum alloy wire is understood here to mean a solid machined product: which is long in cross-section and which has a square or angular cross-section ; with sharp or rounded corners or edges or thezJ3. has a round cross-section or the cross-section of a regular hexagon, or a regular octagon and whose diameter, or largest, perpendicular distance between parallel surfaces is 0.007874 to 0.9499 cm, υ; ::

7 0 9 8 2 A / 0 7 8 6 originally inspected

Claims (7)

Claims Process for the production of an electrical conductor from an aluminum alloy with a minimum conductivity of at least 58 % IACS, good thermal stability, a tensile strength of at least 844 kg / cm and a yield point of at least 562 kg / cm, measured on a fully annealed Wire, in which one: (a) an alloy of 0.20 to 1.60 wt% nickel, 0.30 to 1.30 % By weight iron, up to a total of 2.00% by weight additional alloying elements, including copper, magnesium and silicon and 97.00 to 99.50 wt .-? · aluminum, whichever is customary May contain trace elements, produces, (b) Pour the alloy into a moving mold consisting of a around the circumference of a rotating casting drum extending groove and a metal band which is on part of the groove rests on, is formed, (c) the cast alloy immediately after casting for as long as the alloy is practically still in the as-cast state, hot rolled into an endless rod and (d) draws the rod out to the desired final thickness by wire forming, without annealing before pulling out or while pulling out, characterized in that the conductor of an alloy with a copper content of less than 0.05 for improving the ductility -. emanating%. 2. The method according to claim 1, characterized in that one starts from an alloy, the magnesium content of which is less than 0.1 wt .- ⁰ S when the silicon content is above 0.15 wt .- I. 3. Process according to Claims 1 and 2, characterized in that one 70 982A / 0786 * 26bb433 starts from an aluminum alloy which is 0.60 to 0.80 wt .- 'i Contains nickel and 0.45 to 0.65 Geis -.- 'a iron. 4. The method according to any one of claims 1 to 3, characterized in that that an alloy is produced in process step (a) which 0.10 to 1.00% by weight of the following alloy constituents: Magnesium, niobium, tantalum, silicon and / or zirconium. 5. The method according to any one of claims 1, 2 or 4, characterized in that one adds in the process stage (a) as much magnesium, an alloy is obtained, in addition to aluminum 0.60 to 0.80 wt -.% Nickel, Contains 0.45 to 0.65% by weight of iron and 0.03 to 0.10% by weight of magnesium. 6. The method according to any one of claims 1 or 4, characterized in that so much niobium and tantalum are added in process step (a) that an alloy is obtained which contains, in addition to aluminum: 0.60 wt .- 's nickel,
0.65% by weight of iron,
0.30 wt. Ί niobium and
0.18 wt% tantalum. 7. The method according to any one of claims 1 or 4, characterized in that so much zirconium is added in process step (a) that an alloy is obtained which contains, in addition to aluminum: 0.80 wt .- ΐ nickel,
0.45% by weight of iron and
0.60% by weight zirconium. 709824/0788