DK143812B - ELECTRICAL LEADER OF ALUMINUM ALUMINUM AND PROCEDURES FOR PRODUCING IT - Google Patents

Description

(19) DENMARK

| F | (12) PUBLICATION NOTICE on 143812 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 27 ^ 9 / ¾ (51) IntCI.3 0 22 C 21/00 (22) Filing Day 21. May 19¾ (24) Race day 21. May 1969 (41) Aim. available Nov. 22; 19¾ (44) Submitted 1 Oct 2 1981 (86) International Application No. - (86) International Filing Day - (85) Continuation Day - (62) S ta Application No. -

(30) Priority 21. May 1968, 730933 * US

(71) Applicant SOUTHWIRE COMPANY, Carrollton, US.

(72) Inventor Roger John Schoemer, US.

(74) Associate Patent Agent Company Magnus Jensens Eftf.

(54) Electrical conductor of aluminum alloy and its method of manufacture.

The present invention relates to an aluminum alloy electrical conductor and to its process.

The use of wires of various aluminum alloys as electrical conductors is well known. Such aluminum alloy wires are also used as windings in electromagnets, which the multi-core conducts for electricity and as a telephone cable. The alloys used so far have a conductivity of 30% of at least 61% of the conductivity of the international glow copper standard (hereinafter referred to as IACS) and consist of a substantial amount of pure aluminum and the small amounts of t - 2 - 143812 conventional impurities such as silicon, vanadium, iron, copper, manganese, magnesium, zinc, boron and titanium. The physical properties of known aluminum alloy wires have been poorer than desirable in many applications. Thus, desirable fracture extensions are obtained only by insufficient tensile strengths and vice versa. Furthermore, the flexibility and fatigue strength of aluminum alloy wires used so far have been so small that the known wires have been unusable for many otherwise convenient purposes.

The object of the present invention is therefore to provide an aluminum alloy electrical conductor which has both better elongation at break and better tensile strength and is capable of enduring several bends at any point.

At the same time, the manager must of course have an acceptable conductivity.

According to the invention, an electrical conductor of the kind specified in the preamble of claim 1 is peculiar to the characteristic of claim 1.

The invention also relates to a process for producing the present conductor, and according to the invention this method is characterized by the characterizing part of claim 5.

An example of continuous casting and roll rolling to produce a continuous bar is the following:

A continuous casting machine serves to solidify the molten alloy to produce a casting bar which is substantially guided in the form delivered by the casting machine to the rolling mill which serves to heat treat the bar to bar form or other hot-made item.

The continuous casting machine is of a conventional type with a casting wheel provided with a casting roll partially closed by an endless belt carried by the casting wheel and a tensioning roll. The castor and endless belt cooperate to produce a mold in which one end of molten metal is cast and solidified and from the other end the casting bar is substantially removed in the form it solidified.

- 3 - 143812

The rolling mill is also of a conventional type with several rollers in sets that heat treat the bar in a series of deformations.

The continuous casting machine and the rolling mill are arranged in relation to each other so that the casting bar enters the rolling mill immediately after solidification and in the form in which the bar is solidified. The bar is then in a form where it can be heat treated without further heating being required between the two appliances. If it is desirable to control the heat treatment temperature very closely, suitable means may be arranged between the two appliances.

In each roll set there may be two or more rollers arranged diametrically opposite each other or periodically arranged about the axis of movement of the bar through the rolling mill. The rollers are rotated at a predetermined speed by, for example, the electric motor, and the castor is rotated at a rate that is essentially determined by its operation. The rolling mill produces a rod whose cross-sectional area is substantially smaller than the cross-sectional area of the casting bar.

The peripheral surfaces of the rollers in nearby roll sets change configuration, i.e., the casting bar is engaged by rollers of varying configuration and from different directions. The varying surface touches shape the metal in the bar in such a way that it is processed by each roller set and changes the cross-sectional area.

Since each roll set touches the casting bar, it is desirable that it has sufficient volume to fill the gaps between the rollers at all times so that the rollers can effectively treat the metal. However, it is also desirable that the space determined by the rollers in each set is not overfilled so that the casting bar is not forcibly forced into the gap between the rollers.

The generated, non-discharged rod is cold drawn through a series of progressively smaller nozzles without intermediate anneals until a continuous thread of the desired diameter is formed. At the end of these tensile operations, the alloy wire will have a very high tensile strength and an unacceptably low fracture elongation, as well as a conductivity less than usually accepted for an electrical conductor, ie. less than 61¾ IACS.

- 4 - 143812

To achieve the desired tensile strength, the thread is completely or partially annealed and cooled. At the end of the annealing process, it has been found that the wire has an acceptable conductivity and improved tensile strength along with unexpectedly improved fracture elongation as well as surprising flexibility and fatigue strength.

The annealing can be done by resistance heating, induction heating, convection heating or radiant heating or by immersion in a bath. For continuous annealing, temperatures of 230-650 ° C with an annealing period of from 5 minutes can be used. to about 10 min. Usually, however, continuous annealing temperature and period will be adjusted to the requirements of the particular total manufacturing operation as long as the desired tensile strength is achieved.

When annealing in a bath, a temperature of 205-400 ° C is used and the thread is annealed for a period of from 30 minutes. to about 24 hours. As mentioned in the case of continuous annealing, time and temperature can be varied only if the desired tensile strength is obtained.

In experiments, it has been found that the following tensile strengths can be obtained at said bath temperatures and time:

TABLE I

Pull of turkey, kg / cm ^ Temperature. ° C Time 840-980 345 3 hours 980-1050 290 3 hours 1050-1190 270 3 hours 1190-1540 250 3 hours

During the continuous casting of the present alloy, a substantial portion of the iron present will appear as Fe Al,. Thus, the casting bar will contain a solution of Fe Al, in a supersaturated solid solution. The supersaturated matrix can contain as much as 0.17 / o Fe. When the bar is rolled in a heat-treating operation immediately after casting, the FeAl 2 particles break up and disperse in the matrix to prevent large cell formation. When the rod is then pulled to its final size without intermediate annealing and then in a final annealing process, tensile strength, fracture elongation and flexibility increase due to the small cell size and the further locking of dislocations upon precipitation of FeAl ^ in the dislocation locations.

Therefore, new dislocation sources must be activated when spending is added during the cold draw, and this affects both strength and fracture extension in a favorable direction.

The properties of the conductor in question are significantly influenced by the size of the FeAl 2 particles. Coarse precipitates in the matrix decrease the elongation and flexion by promoting the nucleation and thus the formation of large cells which decrease the recrystallization temperature of the wire. Finer precipitates increase fracture elongation and flexibility by reducing the nucleation and increasing the recrystallization temperature. Very large precipitates of FeAl ^ make the thread brittle and essentially useless. The boundary between coarse and fine precipitates can be set at a particle size of 200 nm.

A wire No. 12 AWG of the present alloy has a tensile strength of, for example, 1120 kg / cm, a break elongation of 20%, a wire elongation of 2096, a conductivity of 6196 IACS and a flexural strength of 20 bends before breaking. The above sizes are examples, said sizes being in the ranges of 840-1540 kg / cm 2, 4096-596, 6196-6396 IACS and 45-10 bends.

In preparing a final product, minor adjustments to the described process can be made and further operations can be performed. In the manufacture of an insulated conductor, the continuously manufactured rod is treated so as to obtain a wire whose dimension lies between 0000 AWG, corresponding to a cross-sectional diameter of about 10 mm, and 40 AWG, corresponding to a diameter of about 0.1 mm.

After annealing, the wire is provided with continuous insulation. For example, the thread may be passed through an extruder's spray head and surrounded by a thermoplastic coating.

The coated conductor is cooled in air or by contact with a cooling bath. The insulating material must, of course, have the lower insulating ability, and the material must be able to withstand the physical influences to which the thread can be exposed. The thickness of the insulation is usually between 0.5 mm and 15 mm and a preferred material is polyvinyl chloride, but also materials such as neoprene, polypropylene and polyethylene can be used.

- 6 - 143812

For example, a 12 AWG wire which is subsequently insulated to produce an insulated conductor according to the invention has, for example, a tensile strength of 1120 kg / cm, a fracture elongation of 20%, a conductivity of 61% IACS and can be bent 30 times before fracture. 12 AWG threads made from the present alloy have tensile strengths of between 910 and 1540 kg / cm, fracture extensions between 35% and 5%, conductivity between 61% and 63% IACS and can be flexed between 45 and 10 times before fracture. Preferably, threads having a tensile strength in the range of 980-1260 kg / cm are used, a fracture elongation in the range of 30-15%, a conductivity in the range of 61-63% and with a flexibility of 40-15 bends before breaking.

The individual cores of a telephone cable are manufactured in the manner just specified by isolating the wires separately by, for example, an extruder.

After the insulation is applied, two or more threads are twisted together in sets. Such sets can then be twisted into groups and multiple groups can be twisted into a cable. The cable is passed through an extruder's spray head, thereby generating an insulation layer surrounding the individual insulated wires. Alternatively, the cable may be wrapped with a thin band of plastic material before the outer insulation layer is applied. When the insulated cable leaves the extruder, it is cooled in the air or in a cooling bath. The outer insulating material is preferably polyethylene, but other thermoplastic materials such as polypropylene, polyvinyl chloride and neoprene are also suitable. The insulated telephone cable can finally be reinforced in the usual way if desired.

An 18 AWG wire according to the invention suitable for use in a telephone cable has a tensile strength in the range of 910-1540 kg / cm, a break elongation in the range 40-5% and a conductivity in the range 61-63%.

In the manufacture of an insulated magnetic wire, the continuously produced rod is drawn to a wire between 8 AWG, corresponding to a cross-sectional diameter of approx. 3 mm, and 40 AWG, corresponding to a diameter of 0.04 mm. The non-annealed rod is cold drawn through a series of progressively narrowing molds without intermediate anneals to form a continuous wire of the desired diameter. If a non-circular cross-sectional shape is desired, the drawn wire can be rolled or pulled through an orifice with a brightening of the desired shape.

Often, magnetic wires whose cross sections are square or rectangular are used.

After annealing, the aluminum alloy wire is drawn through an enamel bath. The wire is thereby coated with a layer of enamel cured in an oven. The insulating enamel must, of course, have sufficient insulating capacity and thickness for the use of the thread, and the enamel must be able to withstand the physical stresses that the thread may be exposed to. The preferred insulating material is a resin type enamel, but other coating materials such as fabric, polyethylene, polypropylene, polyvinyl chloride, polyurethane, epoxy, a polyvinyl formal resin, a polyvinyl formal resin with a nylon coating, a urethane modified polyvinyl resin, a nylon coating, a modified polyester resin with a linear polyester coating, polylmid resin, cotton swab and polyester may also be used. The thermoplastic insulations can of course be applied by means of an extruder.

A 12 AWG insulated magnetic wire according to the invention is made from a wire whose tensile strength is in the range of 840-1190 kg / cm, whose elongation at break is in the range of 40-1596, whose conductivity is in the range of 61-6396, and whose flexibility is in the range of 45- 15 bends before breaking.

In the manufacture of a multi-wire conductor, the continuously produced rod is drawn into threads whose dimension lies in the range of 0000 AWG - 40 AWG. After annealing, a number of these threads are turned into a multi-thread leader. This conductor is isolated in one of the aforementioned ways, for example with a polyvinyl chloride coating.

The wires used in the multi-wire conductor may be 12 AWG wires having a tensile strength in the range of 910-1540 kg / cm 2, p preferably 1120 kg / cm 2, a fracture extension in the range 35-596, preferably 20J6, a conductivity in the range 61- 6396 IACS, preferably 6196, and a bend in the range of 45-10, preferably 30 bends before breaking.

The invention will now be illustrated in connection with a number of examples.

- 8 - 143812

Example 1

In comparison, a leader of the known composition earns $ 99.73 Al, $ 0.18 Fe, $ 0.059 Si and usual impurities. Such a leader is called an EC leader. The conductor of the invention is prepared with the following composition in $ 99.45 Al, 0.45 $ Fe, $ 0.056 Si, and usual impurities. Both alloys are cast into continuous bars and hot rolled into continuous bars. The alloys are then cold-drawn to a continuous 12 AWG wire. Parts of the threads are annealed at varying temperatures and times to obtain threads of different tensile strengths. A number of specimens are examined for flexibility. At equal strength and stretch, the test equipment fatigues each sample under a bend of about 135 °. The thread is bent around a pair of mandrels whose diameter is equal to the wire diameter. The distance between the mandrels is one to one and a half times the diameter. A bend is recorded after the specimen is bent over the mandrels in one direction, straightened out, bent in the opposite direction and again straightened out. For the two alloys, the relationship between tensile strength and ductility (number of bends per fracture) shown in Table IIA was recorded.

TABLE IIA

EC alloy Alloy according to the invention

Tensile strength Tensile strength kg / cmg Capacity kg / cmr Capacity 706 43 1/2 945 44 895 24 1001 43 943 21 1/2 1057 36 992 14 1122 29 1/2 1064 13 3/4 1194 23 1127 11 1199 18 1199 9 3/4 1278 14 1273 8 3/5 1370 13 1615 5 1/2 1770 4 3/4 2052 4 2519 3 l / 2 The flexibility is shown in Table IIA as the number of bends before breaking and it is seen that the alloy according to the invention has considerably greater flexibility than EC alloys.

- 9 - 143812

With the same 12 AWG threads measurements of the fracture extension were made. The results of these measurements are presented in Table IXB.

TABLE IIB

Alloy according to the invention

Tensile Strength Tensile Strength kg / cm2 Fracture Elongation kg / cmz Fracture Elongation 945 30.8 # 700 30.5% 1001 30% 889 21% 1087 24% 945 14% 1131 19% · 994 11.5% 1159 16% 1050 8% 1204 13, 2% 1155 3.5% 1279 8.6% 1281 2% 1330 6.7%

Thus, also with respect to fracture extension, the alloy according to the invention has better properties than the previously known EC alloy.

Examples 2-7

Six aluminum alloys are manufactured with the following compositions:

TABLE III

Alloy No.% Al% Fe% Si 2 99.73 0.180 0.059 3 99.52 0.385 0.063 4 99.46 0.450 0.056 5 99.36 0.540 0.064 6. 99,275 0.680 0.015 7 99.20 0.750 0.030

The six alloys are cast into hot-rolled bars.

The rods thus produced are cold-drawn to form 12 AWG threads. The threads produced by the alloys 2 and 4 are resistance-annealed and the other threads are annealed in a bath. By annealing, the tensile strengths listed in Table IV are obtained. After annealing, each thread for breaking elongation, tensile strength, conductivity and number of bends before fracture is examined by applying the usual examination procedure except for the study of the thread flexibility performed as set forth in Example 1. in Table IV.

TABLE IV

Alloy Conductivity Tensile Strength Fr.% IACS kg / cm Length Flexibility 2 62.8 1061 8.1 15 1/2 5 61.3 1061 28.0 27 1/2 4 61.5 1061 37.5 28 5 61, 5 1061 35.0 28 1/2 6 61.25 1001 28.0 32 7 61.2 1106 25 28

It will be seen from the tables that alloy # 2 falls outside the scope of the invention and that the breaking elongation for strands of this alloy is somewhat lower than desirable and that the flexibility is substantially lower than for strands of alloys 3-7.

Example 8

An alloy containing 99.42% Al, 0.50% Fe, 0.055% Si as well as usual impurities is prepared. The alloy is cast into a bar which is hot rolled into a continuous bar. The rod is cold-drawn to a 12 AWG thread and wound on a roll about 75 cm in diameter until the thread content of the roll weighs about 125 kg. The roll of the wire is placed in an oven and the temperature is raised to about 250 ° C. This temperature is maintained for 3 hours, after which the oven is cooled to 205 ° C. Then, quickly cool the oven and roll out. Experiments with this thread show a conductivity of 61.6% IACS, a tensile strength of 1155 kg / cm, a fracture elongation of 20%, and 18 bends before fracture.

Example 9

This is a repeat of Example 8 except that the oven temperature is raised to 260 ° C. The conductivity of the annealed wire is 61.4% IACS, the tensile strength is 1050 kg / cm, the elongation at break 27%, and the wire can be bent 28 times before breaking.

- 11 - 143812

Example 10

This is also a repeat of Example 8, but the temperature in the oven is now 315 ° C. For this thread, the following properties can be obtained: Conductivity 61.2% IACS, tensile strength 980 p kg / cm, breaking elongation 30% and flexural bed 43 bends before breaking.

Example 11

This is a repeat of Example 10, but the temperature 315 ° C is maintained for only 1 1/2 hours. The properties of the annealed wire are: Conductivity 61.5% IACS, tensile strength 1120 p kg / cm, breaking elongation 22% and flexible bed 23.

Example 12

The alloy mentioned in Example 8 is cast into a bar which is hot-rolled into a rod whose diameter is about 10 mm. The bar is cold-drawn to a 14 AWG wire. This wire is once again pulled into a device Synchro Model BG-16, which simultaneously makes a resistance annealing. The wire is drawn herein to a 28 AWG wire at a speed of about 1 m / min. and the annealing voltage 52 V. The annealed wire has a conductivity of 62% IACS, a tensile strength of 1082 kg / cm, a breaking elongation of 25% and a flexibility which is very large due to the small diameter of the wire.

Example 13

The alloy mentioned in Example 8 is cast into a bar, of which, in the aforementioned manner, a 12 AWG wire is produced in a Synchro Style No. F x 13 tractor with built-in ejector. The thread is covered at a rate of about 1/2 m / min. through a preheater whose voltage is 35 V, another preheater whose voltage is also 35 V, and the anneal, whose voltage is 22 V. The annealed wire has a conductivity p of 62% IACS, a tensile strength of 1141 kg / cm and a break elongation of 20%.

Example 14 - 12 - 143812

An aluminum alloy is produced containing 99 * 42% Al, 0.50 Fe, 0.055% Si and usual impurities. In the previously described method, a 12 AWG wire is produced. This wire is treated as in Example 8. The annealed wire is passed through an extruder's spray head and is surrounded here by polyvinyl chloride. Tests show that the insulated wire has a conductivity of 6.16% XACS.

Example 15

The annealed wire mentioned in Example 13 is insulated in an extruder with polyvinyl chloride. The resultant insulated conductor has a conductivity of 62% IACS.

Example 16

The annealed wire mentioned in Example 14 is passed through an extruder and insulated herein with polyethylene. Two of the thus isolated wires are brought together without twisting and passed through another extruder, the two insulated conductors being surrounded by an outer layer of polyethylene.

Example 17

Eight of the annealed wires mentioned in Example 13 are conventionally switched to a cable after each wire is insulated.

The cable is passed through a further extruder and covered by an outer layer of polypropylene.

The individual wires must be treated such that their tensile strength is sufficient to withstand the rigidity of the insulation process when using polyethylene as insulating material. Since polyethylene is the most commonly used material for this purpose, individual wires must withstand the insulation with this material. By contrast, when polypropylene is used, the tensile strength can be reduced, thereby increasing the elongation at break and obtaining a cable which is very flexible. The tensile strength can be reduced because the threads do not have to be pulled through the extruder's spray head with as much force as when using polypropylene.

143812

Examples 18-13

The annealed wire mentioned in Example 14 is passed through an enamel bath. During experiments, it has been found that the insulated magnetic wire produced has a conductivity of 61.6% p IACS, a tensile strength of 1169 kg / cm and a breaking elongation of 19.8%. It is important to note that in the alloy according to the invention, the fracture elongation increases during annealing at a higher tensile strength than when annealing the EC alloy. Furthermore, when annealing the EC alloy, it is necessary to bring the alloy to a softened state before the fracture extension begins to become more satisfactory.

In the alloy of the invention, the fracture elongation is still improved as annealing time and temperature grow, and it is possible to obtain an acceptable elongation before the thread becomes soft.

Example 19

A number, for example, seven of the strands referred to in Example 14 are wound together on said roll and annealed as described in the example. The resulting annealed multi-cored conductor has a conductivity of 61.6% IACS.

Claims (5)

1. An annealed aluminum alloy electrical conductor having a diameter or maximum distance between parallel surfaces of between 100 mm and 0.1 mm and an electrical conductivity of at least 6196 IACS, characterized in that the conductor contains substantially evenly spaced FeAl enclosures of a particle size less than 200 nm, which inclusions occur in the concentration formed by the addition of from 0.30% to 0.95% Fe to an alloy mass consisting essentially of from 98.95 to 99.70% Al, 0.015 -0.15 Si as well as trace quantities of common impurities. Conductor according to claim 1, characterized in that the inclusions occur in the concentration formed by the addition of from 0.45 to 0.95% Fe to an alloy mass consisting essentially of from 98.95 to 99.45% Al , not more than 0.07% Si and not more than about 0.15% total of common impurities. Conductor according to claim 1, characterized in that the inclusions are present in the concentration formed by the addition of from 0.50 to 0.80% Fe to an alloy mass consisting essentially of from 99.15 to 99.40% Al , not more than 0.07% Si and not more than about 0.15% total of common impurities. Conductor according to claims 1-3, characterized by comprising a coating of insulating material, wherein two or more of the insulated conductors are assembled arbitrarily and surrounded by a common waterproof sheath. Process for producing an aluminum alloy electrical conductor with substantially evenly spaced FeAl enclosures as claimed in claims 1-4, characterized in that 98.95 - 99.70% Al, 0.30 - 0.95 % Fe and not more than 0.15% Si as well as usual impurities are fused, the melt is used for casting a continuous bar, hot casting the casting bar through a series of rollers.