IL32263A - Aluminum alloy wire - Google Patents

Description

ALDiEDiltlM AliLOY IHE nan naiwas? An aluminum alloy conductor having an electrical conductivity of at least sixty-one percent (61%) based on the International Annealed Copper Standard and unexpected properties of increased ultimate elongation, bendability and fatigue resistance when compared to a conventional aluminum alloy conductor of the same tensile strength. The conductor is manufactured as a solid wire with insulation, an insulated magnet wire, a multi-fialment conductor, or an insulated telephone cable. The individual wires of the aluminum alloy conductor contain substantially evenly distributed iron aluminate inclusions in a concentration produced by the addition of more than about 0.30 weight percent iron to an alloy mass containing less than about 99.70 weight percent aluminum, no more than 0.15 weight percent silicon, and trace quantities of conventional impurities normally found within a commercial aluminum alloy. The substantially evenly distributed iron aluminate inclusions are obtained by continuously casting an alloy consisting essentially of less than about 99.70 weight percent aluminum, more than 0.30 weight percent iron, no more than 0.15 weight percent silicon and trace quantities of typical impurities to form a continuous aluminum alloy bar, hot-working the bar substantially immediately after casting in substantially that condition in which the bar is cast to form continuous rod which is subsequently drawn into wire without intermediate anneals and annealed after the final draw. After annealing, the wire has the aforementioned novel and unexpected properties of increased ultimate elongation, electrical conductivity of at least sixty-one percent of the International Annealed Copper Standard, and increased bendability and fatigue resistance. The wire is then further processed to produce one of the above-specified end products.

ALUMINUM ALLOY WIRE PRODUCTS AND METHOD OF PREPARATION THEREOF This invention relates to an aluminum alloy conductor suitable for use as an electrical conductor and more particularly concerns an aluminum alloy conductor having an acceptable electrical conductivity and improved elongation, bendability and tensile strength.

The use of various aluminum alloy wires (conventionally referred to as EC wire) as general purpose conductors of electricity is well established in the art. In addition, aluminum alloy wires have been used as wire windings for electromagnets, as multi-filament conductors of electricity, and as telephone cable. The alloys employed therein characteristically have conductivities of at least sixty-one percent {61%) of the International Annealed Copper Standard hereinafter sometimes referred to as IACS) and chemical constituents consisting of a substantial amount of pure aluminum and small amounts of conventional impurities such as silicon, vanadium, iron, copper, manganese, magnesium, zinc, boron and titanium. The physical properties of prior aluminum alloy wire have proven less than desirable in many applications. Generally, desirable percent elongations have been obtained only at less than desirable tensile strengths and desirable tensile strengths have been obtainable only at less than desirable percent elongations. In addition, the bendability and fatigue resistance of prior aluminum alloy wires has been so low that the prior wire has been generally unsuitable for many otherwise desirable applications.

Thus, it becomes apparent that a need has arisen within the industry for an aluminum alloy conductor which has both improved percent elongation and improved tensile strength, and also possesses an ability to withstand numerous bends at one point and to resist fatiguing during use of the conductor. Therefore, it is an object of the present invention to provide an aluminum alloy conductor of acceptable conductivity and improved physical properties such that the conductor may be used in new applications. Another object of the present invention is to provide an aluminum alloy conductor having novel properties of increased ultimate elongation and tensile strength, improved bendability and fatigue resistance, and acceptable electrical conductivity. These and other objects, features and advantages of the present invention will become apparent to those skilled in the art from a consideration of the following detailed descript n of the invention.

In accordance with this invention, an aluminum alloy electrically conductive wire is prepared from an alloy comprising less than about 99.70 weight percent aluminum, more than about 0.30 weight percent iron, and no more than 0.15 weight percent silicon. Preferably, the aluminum content of the present alloy comprises from about 98.95 to less than about 99.45 weight per-cent with particularly superior results being achieved when from about 99.15 to about 99.40 weight percent aluminum is employed. Preferably, the iron content of the present alloy comprises about 0.45 weight percent to about 0.95 weight percent with particularly superior results being achieved when from about 0.50 weight percent to about 0.80 weight percent iron is employed. Preferably, no more than 0.07 weight percent silicon is employed in the present alloy. The ratio between the percentage iron and the percentage silicon must be 1.99:1 or greater. Preferably, the ratio between percentage iron and percentage silicon is 8:1 or greater. Thus, if the present aluminum alloy contains an amount of iron within the low area of the present range for iron content, the percentage of aluminum must be increased rather than increasing the percentage of silicon outside the ratio limitation previously specified. It has been found that properly processed wire, having aluminum alloy constituents which fall within the above-specified ranges, possesses acceptable electrical conductivity, improved tensile strength and ultimate elongation; and in addition, has a novel unexpected property of surprisingly increased bendability and fatigue resistance.

The present aluminum alloy is prepared by initially melting and alloying aluminum with the necessary amounts of iron or other constituents to provide the requisite alloy for processing. Normally, the content of silicon is maintained as low as possible without adding additional amounts to the melt. Typical impurities or trace elements are also present within the melt, but only in trace quantities such as less than 0.05 weight percent each, with a total content of trace impurities generally not exceeding 0.15 weight percent. Of course, when adjusting the amounts of trace elements, due consideration must be given to the conductivity of the final alloy since some trace elements affect conductivity more severely than others.

The typical trace elements include vanadium, copper, manganese, magnesium, zinc, boron and titanium* If the content of titanium is relatively high (but still qute low when compared to the aluminum, iron and silicon content), small amounts of boron may be added to tie-up the excess titanium and keep it from reducing the conductivity of the wire.

Iron is the major constituent added to the melt to produce the alloy of the present invention. Normally, about 0.50 weight percent is added to the typical aluminum component used to prepare the present alloy. Of course, the scope of the present invention includes the addition of more or less iron together with the adjustment of the content of all alloying constituents.

After alloying, the melted aluminum composition is continuously cast into a continuous bar. The bar is then hot-worked in substantially that condition in which it is received from the casting machine. A typical hot-working operation comprises rolling the bar in a rolling mill substantially immediately after being cast into a bar.

One example of a continuous casting and rolling operation, capable of producing continuous rod as specified in this application, is as follows: A continuous casting machine serves as a means for solidifying the molten aluminum alloy metal to provide a cast bar that is conveyed in substantially the condition in which it solidified from the continuous casting machine to the rolling mill, which serves as a means for hot-forming the cast bar into rod or another hot-formed product in a manner which imparts substantial movement to the cast bar along a plurality of angularly disposed axes.

The continuous casting machine is of conventional casting wheel type having a casting wheel with a casting groove partially closed by an endless belt supported by the casting wheel and an idler pulley. The casting wheel and the endless belt cooperate to provide a mold into one end of which molten metal is poured to solidify and from the other end of which the cast bar is emitted in substantially that condition in which it solidified.

The rolling mill is of conventional type having a plurality of roll stands arranged to hot-form the cast bar by a series of deformations. The continuous casting machine and the rolling mill are positioned relative to each other so that the cast bar enters the rolling mill substantially immediately after solidification and in substantially that condition in which it solidified. In this condition, the cast bar is at a hot-forming temperature within the range of temperatures for hot-forming the cast bar at the initiation of hot-forming without heating between the casting machine and the rolling mill. In the event that it is desired to closely control the hot-forming temperature of the cast bar within the conventional range of hot-forming temperatures, means for adjusting the temperature of the cast bar may be placed between the continuous casting machine and the rolling mill without departing from the inventive concept disclosed herein.

The roll stands each include a plurality of rolls which engage the cast bar. The rolls of each roll stand may be two or more in number and arranged diametrically opposite from one another or arranged at equally spaced positions about the axis of movement of the cast bar through the rolling mill. The rolls of each roll stand of the rolling mill are rotated at a predetermined speed by a power means such as one or more electric motors and the casting wheel is rotated at a speed generally determined by its operating characteristics. The rolling mill serves to hot-form the cast bar into a rod of a cross-sectional area substantially less than that of the cast bar as it enters the rolling mill.

The peripheral surfaces of the rolls of adjacent roll stands in the rolling mill change in configuration; that is, the cast bar is engaged by the rolls of successive roll stands with surfaces of varying configuration, and from different directions. This varying surface engagement of the cast bar in the roll stands functions to knead or shape the metal in the cast bar in such a manner that it is worked at each roll stand and also to simultaneously reduce and change the cross-sectional area of the cast bar into that of the rod.

As each roll stand engages the cast bar, it is desirable that the cast bar be received with sufficient volume per unit of time at the roll stand for the cast bar to generally fill the space defined by the rolls of the roll stand so that the rolls will be effective to work the metal in the cast bar. However, it is also desirable that the space defined by the rolls of each roll stand not be overfilled so that the cast bar will not be forced into the gaps between the rolls. Thus, it is desirable that the rod be fed toward each roll stand at a volume per unit of time which is sufficient to fill, but not overfill, the space defined by the rolls of the roll stand.

As the cast bar is received from the continuous casting machine, it usually has one large flat surface corresponding to the surface of the endless band and inwardly tapered side surfaces corresponding to the shape of the groove in the casting wheel. As the cast bar is compressed by the rolls of the roll stands, the cast bar is deformed so that it generally takes the cross-sectional shape defined by the adjacent peripheries of the rolls of each roll stand.

Thus, it will be understood that with this apparatus, cast aluminum alloy rod of an infinite number of different lengths is prepared by simultaneous casting of the molten aluminum alloy and hot-forming or rolling the cast aluminum bar, The continuous rod produced by the casting and rolling operation is then processed in a reduction operation designed to produce continuous wire of various gauges. The unannealed rod (i.e., as rolled to f temper) is cold-draw through a series of progressively constricted dies, without intermediate anneals, to form a continuous wire of desired diameter. At the conclusion of this drawing operation, the alloy wire will have an excessively high tensile strength and an unacceptably low ultimate elongation, plus a conductivity below that which is industry accepted as the minimum for an electrical conductor, i.e., sixty-one percent (61%) of IACS, The wire is then annealed or partially annealed to obtain a desired tensile strength and cooled. At the conclusion of the annealing operation, it is found that the annealed alloy wire has the properties of acceptable conductivity and improved tensile strength together with unexpectedly improved percent ultimate elongation and surprisingly increased bendability and fatigue resistance as specified previously in this application. The annealing operation may be continuous as in resistance annealing, induction annealing, convection annealing by continuous furnaces or radiation annealing by continuous furnaces, or, preferably, may be batch annealed in a batch furnace. When continuously annealing, temperatures of about 450°F to about 1200°F may be employed with annealing times of about five minutes to about 1/10,000 of a minute. Generally, however, continuous annealing temperatures and times may be adjusted to meet the requirements of the particular overall processing operation so long as the desired tensile strength is achieved. In a batch annealing operation, a temperature of approximately 400*F to about 750*F is employed with residence times of about thirty (30) minutes to about twenty-four (24) hours. As mentioned with respect to continuous annealing, in batch annealing the times and temperatures may be varied to suit the overall process so long as the desired tensile strength is obtained. Simply by way of example, it has been found that the following tensile strengths in the present aluminum wire are achieved with the listed batch annealing temperatures and times.

TABLE I TENSILE STRENGTH TEMPERATURE TIME 12,000 to 14,000 650eF 3 hours 14,000 to 15,000 S50eF 3 hours ,000 to 17,000 520eF 3 hours 17,000 to 22,000 480°F 3 hours During the continuous casting of this alloy, a substantial portion of the iron present in the alloy precipitates out of solution as iron aluminate intermetallic compound (FeAlj) , Thus, after casting, the bar contains a dispersion of FeAlj in a supersaturated solid solution matrix. The supersaturated matrix may contain as much as 0.17 weight percent iron. As the bar is rolled in a hot-working operation immediately after casting, the FeAlj particles are broken-up and dispersed throughout the matrix inhibiting large cell formation. When the rod is then drawn to its final gauge size, without intermediate anneals, and then aged in a final annealing operation, the tensile strength, elongation and bendability are increased due to the small cell size and the additional pinning of dislocations by preferential precipitation of FeAl3 on the dislocation sites. Therefore, new dislocation sources must be activated under the applied stress of the drawing operation and this causes both the strength and the elongation to be further improved.

The properties of the present aluminum alloy wire are significantly affected by the size of the FeAl3 particles in the matrix. Coarse precipitates reduce the percent elongation and bendability of the wire by enhancing nucleation and, thus, formation of large cells which, in turn, lowers the recrystallization temperature of the wire. Fine precipitates improve the percent elongation and bendability by reducing nucleation and increasing the recrystallization temperature.

Grossly coarse precipitates of FeAl3 cause the wire to become brittle and generally unusable. Coarse precipitates have a particle size of above 2,000 angstrom units and fine precipitates have a particle size of below 2,000 angstrom units.

A typical alloy No. 12 AWG wire of the present invention has physical properties of 16,000 psi tensile strength, ultimate elongation of twenty percent (20%), conductivity of sixty-one percent (61%) IACS, and bendability of twenty (£0) bends to break. Ranges of physical properties generally provided by No. 12 AWG wire prepared from the present alloy include tensile strengths of about 12,000 to about 22,000 psi, ultimate elongations of about forty percent (401) to about five percent (5%), conductivities of about sixty-one percent (61%) to about sixty-three percent (63%) and number of bends to break of about forty-five (45) to ten (10).

When preparing particular end products, adjustments in the processing steps may be effected and additional steps may be performed. Thus, when preparing a solid insulated conductor, the continuously prepared rod is processed in a reduction operation designed to produce continuous wire of a gaug< between 0000 gauge AWG (corresponding to a cross-sectional diameter or greatest perpendicular distance between parallel faces of about 0.460 inches) and 40 gauge AWG (corresponding to a cross-sectional diameter or greatest perpendicular distance between parallel faces of about 0.0031 inches). Following annealing, the solid aluminum alloy conductor is continuously insulated in a standard continuous insulating operation, A typical insulating operation comprises passing the solid conductor through an extrusion head. As the conductor passes through an extrusion head, a continuous thermoplastic coat of insulation is generated around the conductor. The coated conductor is then cooled in the air or by contact with a cooling bath. The insulating material should be one which is capable of insulating the solid conductor and the material should be of a thickness sufficient to insulate the solid conductor and withstand the physical hazards associated with solid insulated conductors. Typical thicknesses of insulation are between about l/64ths of an inch and 3/64ths of an inch, A preferred thermoplastic insulating material is poly (vinyl chloride) , but other coatings such as neoprene, polypropylene and polyethylene may also be employed.

A typical No. 12 AWG solid wire, which is subsequently insulated to produce the solid insulated conductor of the present invention, has physical properties of 16,000 psi tensile strength, ultimate elongation of twenty percent (20%), conductivity of sixty-one percent (61%) IACS, and bendability of thirty (30) bends to break. Ranges of physical properties generally provided by a suitable No. 12 AWG solid wire prepared from the present alloy include tensile strengths of about 13,000 to about 22,000 psi, ultimate elongations of about thirty-five percent (35%) to about five percent (5%), conductivities of about sixty-one percent (61%) to about sixty-three percent (63%), and number of bends to break of about forty-five (45) to ten (10). Preferred wires for use in the present invention have a tensile strength of between 14,000 and 18,000 psi, and ultimate elongation of between thirty percent (30%) and fifteen percent (15%), a conductivity of between sixty-one percent (61%) and sixty-three percent (63%) and number of bends to break of between forty (40) and fifteen (15) « When preparing an insulated telephone cable, the continuously prepared rod is processed in a reduction operation designed to produce continuous wire of a gauge between No. 12 AWG (cross-sectional diameter or greatest perpendicular distance between parallel faces of 0,081 inches) and No, 30 AWG (cross-sectional diameter or greatest perpendicular distance between parallel faces of 0.0100 inches). Following annealing, the aluminum alloy wire is continuously insulated in a standard continuous insulating operation* A typical insulating operation comprises passing the wire through an extrusion head. As the wire passes through the head, a continuous thermoplastic coat of insulation is generated around the conductor. The coated conductor is then cooled in the air or by contact with a cooling bath. The insulating material should be one which is capable of insulating the wire and the material should be of a thickness sufficient to insulate the wire and withstand the physical hazards associated with the processing of the wire into a telephone cable. Typical thicknesses of insulation are between about 0.001 inches and 0,20 inches, A preferred insulating material is polyethylene, but other coatings such as neoprene, polypropylene and polyvinyl chloride may also be employed.

After insulation is applied to the individual wires, two or more of the insulated wires are brought together and twisted as a pair. These pairs may then be cabled into groups and these groups may be subsequently cabled into larger groups or cables. These groups or cables are then fed through a second extrusion head where an outer sheath of insulation is applied around the individually insulated wires. Alternatively, the groups or cables may be wrapped with a thin sheet or tape of plastic material prior to application of the outer sheath of insulation. As the insulated telephone cable emerges from the second extrusion head, it is cooled in the air or by contact with a cooling bath. The exterior insulation material is, preferably, polyethylene with other thermoplastic materials such as polypropylene, polyvinyl chloride and neoprene being suitable. The finished telephone cable may be additionally sheathed or armored in conventional fashion, if such is desired. A typical No. 18 AWG aluminum alloy wire suitable for use in the telephone cable of the present invention has physical properties of 17,000 psi tensile strength, ultimate elongation of fourteen percent (144) and conductivity of sixty-one percent (61%) IACS. Ranges of physical properties generally provided by a suitable No, 18 AWG wire prepared from the present alloy include tensile strengths of about 13,000 to about 22,000 psi, ultimate elongations of about forty percent (40%) to about five percent (5%) and conductivities of about sixty-one percent (61%) to about sixty-three percent (63%), Preferred wires have a tensile strength of between 16,000 and 18,000 psi, an ultimate elongation of between twenty percent (20%) and ten percent (10%) and a conductivity of between sixty-one percent (61%) and sixty-three percent (63%) .

When preparing an insulated magnet wire, the continuously prepared rod is processed in a reduction operation designed to produce continuous wire of a gauge between 8 gauge AWG (cross-sectional diameter or greatest perpendicular distance between parallel faces of 0.128 inches) and 40 gauge AWG (cross-sectional diameter or greatest perpendicular distance between parallel faces of 0,0031 inches). The unannealed rod (i.e., as rolled to f temper) is cold-drawn through a series of progressively constricted dies, without intermediate anneals, to form a continuous wire of desired diameter. If a cross-sectional shape other than round is desired, the drawn wire may be worked to a proper shape by cold-rolling or further drawing through appropriately shaped rollers or dies to produce the shaped wire. Typical cross-sectional shapes other than round are square and rectangular.

Following annealing, the aluminum alloy wire is continuously insulated in a standard magnet wire continuous insulating operation. A typical insulating operation comprises passing the solid conductor through a bath of enamel. As the conductor passes through the bath, a continuous insulating enamel coat is applied around the conductor. The coated conducto is then baked in a continuous furnace. The insulating enamel should be one which is capable of insulating the solid conductor and the enamel should be of a thickness sufficient to insulate the solid conductor and withstand the physical hazards associated with winding of magnet wire. The preferred insulating material i an enamel such as the oleoresinous type, but other coatings such as fabrics, polyethylene, polypropylene, poly (vinyl chloride), polyurethanes, epoxies, a polyvinyl formal resin, a polyvinyl formal resin and an overcoat of nylon, a urethane modified polyvinyl formal resin, an acrylic resin, a polyurethane base and a nylon overcoat, a modified polyester base with a linear polyester overcoat, a polyimide resin, cotton yarn and polyesters may also be employed. Typically, thermoplastic materials are applied by means of an extrusion head which coats the conductor with the thermoplastic material as the conductor moves through the head, A typical No. 12 AWG solid insulated magnet wire of the present invention is prepared from a solid wire which has physical properties of 16,000 psi tensile strength, ultimate elongation of twenty-five percent (20%), conductivity of sixty-one percent (614) IACS, and bendability of thirty (30) bends to break. Ranges of physical properties generally provided by a suitable No. 12 AWG wire prepared from the present alloy include tensile strengths of about 12,000 to about 17,000 psi, ultimate elongations of about forty percent (40%) to about fifteen percent (15%), conductivities of about sixty-one percent (61%) to about sixty-three percent (63%), and number of bends to break of about forty-five (45) to about fifteen (15). Preferred wires suitable for use in the present invention have a tensile strength of between 13,000 and 15,000 psi, an ultimate elongation of between thirty-five percent (35%) and twenty-five percent (25%), a conductivity of between sixty-one percent (61%) and sixty-three percent (63%) and number of bends to break of between thirty-five (35) and twenty (20).

When preparing a multi-filament conductor, the continuously prepared rod is processed in a reduction operation designed to produce continuous, individual filaments of wire of a gauge between 0000 gauge AWG (cross-sectional diameter or greatest perpendicular distance between parallel faces of 0.460 inches) and 40 gauge AWG (cross-sectional diameter or greatest Ψ Following annealing, the individual filament of wire is stranded with other similarly produced alloy wires to produce a multi-filament stranded conductor. The stranded conductor is then continuously insulated in a standard continuous insulating operation. A typical insulating operation comprises passing the stranded conductor through an extrusion head. As the conductor passes through the head, a continuous thermoplastic coat of insulation is generated around the conductor. The coated conductor is then cooled in the air or by contact with a cooling bath. The insulating material should be one which is capable of insulating the multi-filament conductor and the material should be of a thickness sufficient to insulate the conductor and withstand the physical hazards associated with stranded insulated conductors. Typical thicknesses of insulation are between about .001 of an inch and .400 of an inch. A preferred thermoplastic insulating material is poly (vinyl chloride) , but other coatings such as neoprene, rubber, polyethylene, polypropylene and cross-linked polyethylene may be employed.

A typical individual No, 12 AWG solid insulated strand, which is subsequently grouped into a multi-filament conductor, has physical properties of 16,000 psi tensile strength, ultimate elongation of twenty percent (201), conductivity of sixty-one percent (61%) IACS, and bendability of thirty (30) bends to break. Ranges of physical properties generally provided by a suitable No. 12 AWG strand prepared from the present alloy include tensile strengths of about 13,000 to about 22,000 psi, ultimate elongations of about thirty-five percent (35%) to about five percent (5%), conductivities of about sixty-one percent (61%) to about sixty-three percent (63%), and number of bends to break of about forty-five (45) to ten (10). Preferred strands for use in present conductor have a tensile strength of between 13,000 and 18,000 psi, an ultimate elongation of between thirty percent (30%) and fifteen percent (15%), a conductivity of between sixty-one percent (61%) and sixty-three percent (63%), and number of bends to break of between forty (40) and fifteen (15), The individual strands of wire formed from the present alloy may be grouped together prior to the insulation thereof in several formations including concentric stranding, bunch stranding, parallel stranding and rope lay stranding. In concentric stranding, a strander conventionally strands in a h elical fashion six or more wire strands about a central wire strand. The stranded unit is then passed through the extrusion head of an extruder where insulation is applied around the outer surfaces of the stranded unit.

In buch stranding, individual wires are brought together with some twisting of the unit of wires and insulation is applied around the outer surfaces of the stranded unit.

In parallel stranding, individual wires are brought together in parallel fashion with no twisting of the unit of wires and insulation is applied around the outer surfaces of the stranded unit.

In rope lay stranding, individual uninsulated concentrically stranded or bunched cables are concentrically stranded or bunched into a composite cable. Insulation is then applied to the outer surfaces of the composite cable as a whole. > It has been found that stranding and insulating wires of the present alloy yields a cable which has improved bendability over solid insulated conductors, and, in addition, has improved bendability over stranded and insulated EC alloy wire.

A more complete understanding of the invention will be obtained from the following examples.

EXAMPLE NO. 1 A comparison between prior EC aluminum wire and the present aluminum alloy wire is provided by preparing a prior EC alloy with aluminum content of 99.73 weighe percent, iron content of 0.18 weight percent, silicon content of 0.059 weight percent, and trace amounts of impurities. The present alloy is prepared with aluminum content of 99.45 weight percent, iron content of 0.45 weight percent, silicon content of 0,056 weight percent, and trace amounts of typical impurities. Both alloys are continuously cast into continuous bars and hot-rolled into continuous rod in similar fashion. The alloys are then cold-drawn through successively constricted dies to yield No. 12 AWG continuous wire. Sections of the wire are collected on separate bobbins and batch furnace-annealed at various temperature and for various lengths of time to yield sections of the prior EC alloy and the present alloy of varying tensile strengths. Several samples of each section are tested in a device designed to measure the number of bends required to break each sample at a particular flexure point. Through uniform force and tension, the device fatigues each sample through an arc of approximately 135 degrees.

As shown in Table IIA, the present alloy has a surprisingly improved property of bendability over conventional EC alloy.

Several samples of the present alloy No. 12 AWG wire and EC alloy No. 12 AWG wire, processed as previously specified, are then tested for percent ultimate elongation by standard testing procedures. At the instant of breakage, the increase in length of the wire is measured. The percent ultimate elongation is then figured by dividing the initial length of the wire sample into the increase in length of the wire sample. The tensile strength of the wire sample is recorded as the pounds per square inch of cross -sectional diamter required to break the wire during the percent ultimate elongation test. The results are as follows: TABLE IIB EC ALLOY PRESENT ALLOY TENSILE PERCENT ULTIMATE TENSILE PERCENT ULTIMATE STRENGTH ELONGATION STRENGTH ELONGATION 13,500 30.8% ,000 30.5% 14,300 30 % 12,700 21 % 15,525 24 % 13,500 14 % 16,150 19 % 14,200 11.5% 16,550 16 % ,000 8 % 17,200 13.2% 16,500 3.5% 18,270 8.6% 18,300 2 % 19,000 6.7% As shown in Table IIB, the present alloy has a surprisingly improved property of percent ultimate elongation over conventional EC alloy.

EXAMPLES 2 THROUGH 7 Six aluminum alloys are prepared with varying amounts of major constituents. Those alloys are reported the following table: TABLE III EXAMPLE 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 99.36 0.540 0.064 6 99.275 0.680 0.015 7 99.20 0.750 0.030 The six alloys are then cast into six continuous bars and hot-rolled into six continuous rods. The rods are cold' drawn through successively constricted dies to yield No. 12 AWG wire. The wire produced from the alloys of examples No. 2 and No. 4 are resistance annealed and the remainder of the examples are batch furnace annealed to yield the tensile strengths reported in Table IV. After annealing, each of the wires is tested for percent conductivity, tensile strength, percent ultimate elongation and average number of bends to break by standard -ρ testing procedures for each, except that the procedure specified in Example No. 1 is used for determining average number of bends to break. Those results are reported in the following table .

TABLE IV CONDUCTIVITY TENSILE % ULTIMATE AVERAGE NO. OF EXAMPLE NO. IN % IACS STRENGTH ELONGATION BENDS TO BREAK 2 62.8 15,150 8.1 15 1/2 3 61.3 15,153 28.0 27 1/2 4 61.5 15,152 37.5 28 61.5 15,152 35.0 28 1/2 6 61.25 14,300 28.0 32 7 61.2 15,800 25 28 From a review of these results, it may be seen that Example No. 2 falls outside the scope of the present invention in percentage of components . In addition, it will be noted for Example No. 2 that the percentage of ultimate elongation is somewhat lower than desirable and the average number of bends to break the sample is lower than the remaining examples.

EXAMPLE NO. 8 An aluminum alloy is prepared with an aluminum content of 99.42 weight percent, iron content of 0,50 weight percent, silicon content of 0,055 weight percent and trace amounts of typical impurities. The alloy is cast into a continuous bar which is hot-rolled to yield a continuous rod.

The rod is then cold-drawn through successively constricted dies to yield No, 12 AWG wire. The wire is collected on a 30 inch bobbin until the collected wire weighs approximately 250 pounds. The bobbin is then placed in a cold General Electric Bell Furnace and the temperature therein is raised to 480eF. The temperature of the furnace is held at 480°F for three hours, after which the heat is terminated and the furnace cools to 400°F. The furnace is then quick cooled and the bobbin is removed.

Under testing, it is found that the alloy wire has a conductivity of 61,6% IACS, a tensile strength of 16,500 psi, a percentage of ultimate elongation of twenty percent (20%), and a number of bends to break of eighteen (18) .

EXAMPLE NO. 9 Example No, 8 is repeated except the Bell Furnace temperature is raised to 500eF and held for three hours prior to cooling. The annealed alloy wire has a conductivity of 61.4% IACS, a tensile strength of 15,000 psi, a percentage of ultimate elongation of twenty-seven percent (27%), and a number of bends to break of twenty-eight (28).

EXAMPLE NO. 10 Example No. 8 is repeated except the Bell Furnace temperature is raised to 600°F and held for three hours prior to cooling. The annealed alloy wire has a conductivity of 61.2% IACS, a tensile strength of 14,000 psi, a percentage of elongation of 30%, and a number of bends to break of 43, bar which is hot-rolled to yield a continuous f temper rod of 3/8 inch diameter. The rod is then cold-drawn on a Synchro Style No. F x 13 wire drawing machine which includes a continuous in line annealer. The rod is drawn to No. 12 AUG wire at a finishing speed of 2,000 feet per minute and the in line annealer voltage at preheater No. 1 is 35 volts, at pre-heater No. 2 is 35 volts, and at the annealer is 22 volts. The three transformer taps are set at No. 5. The annealed alloy wire has a conductivity of sixty-two percent (62%) IACS, a tensile strength of 16,300 psi, and a percentage ultimate elongation of twenty percent (201) .

EXAMPLE NO. 14 SOLID INSULATED CONDUCTOR An aluminum alloy is prepared with an aluminum content of 99.42 weight percent, iron content of 0.50 weight percent, silicon content of 0.055 weight percent and trace amounts of typical impurities. The alloy is cast into a continuous bar which is hot-rolled to yield a continuous rod. The rod is then cold-drawn through successively constricted dies to yield No. 12 A G wire. The wire is collected on a 30 inch bobbin until the collected wire weighs approximately 250 pounds. The bobbin is then placed in a cold General Electric Bell Furnace and the temperature therein is raised to 480°F. The temperature of the furnace is held at 480°F for three hours after which the heat is terminated and the furnace cools to 400°F. The furnace is then quick cooled and the bobbin is removed. The annealed wire is then passed through an extrusion head and insulated wit^ poly (vinyl chloride). Under testing, it is found that the β insulated alloy wire has a conductivity of 61,6% IACS and improved physical properties.

EXAMPLE NO. 15 SOLID INSULATED CONDUCTOR The alloy of Example No. 14 is cast into a continuous bar which is hot-rolled to yield a continuous f temper rod of 3/8 inch diameter. The rod is then cold-drawn on a Synchro Style No. F x 13 wire drawing machine which includes a continuous in line annealer. The rod is drawn to No. 12 AWG wire at a finishing speed of 2,000 feet per minute and the in line annealer voltage at preheater No. 1 is 35 volts, at pre-heater No. 2 is 35 volts, and at the annealer is 22 volts. The three transformer taps are set at No. 5. The annealed wire is continuously insulated by passing through an extrusion head where poly (vinyl chloride) is applied. The annealed and insulated alloy wire has a conductivity of sixty-two percent (62%) IACS, and improved physical properties.

It should be understood that the present invention in part concerns a solid aluminum alloy insulated conductor.

Also included within the scope of the expression "solid insulated conductor" are insulated cables made up of individual solid insulated aluminum alloy conductors. Particular examples of specific solid insulated conductors or cables formed therefrom as encompassed by the present invention include building wire, NM sheath cable, underground building wire, feeder cable, type TW single wire, harness wire, neon sign cable, radio hook-up wire, fire alarm and burglar alarm wire, fixture wire, control wire, machine tool wire, enunciator wire, DD service entrance wire, and rialroad signal cable.

EXAMPLE NO. 16 INSULATED TELEPHONE CABLE An aluminum alloy is prepared with an aluminum content of 99.42 weight percent, iron content of 0.50 weight percent, silicon content of 0.055 weight percent and trace amounts of typical impurities. The alloy is cast into a ]| continuous bar which is hot-rolled to yield a continuous rod. The rod is then cold-drawn through successively constricted dies to yield No. 12 AWG wire. The wire is collected on a 30 inch bobbin until the collected wire weighs approximately 250 pounds. The bobbin is then placed in a cold General Electric Bell Furnace and the temperature therein is raised to 480°F, The temperature of the furnace is held at 480°F for three hours, after which the heat is terminated and the furnace cools to 400eF. The furnace is then quck cooled and the bobbin is removed. The annealed wire is then passed through an extrusion ]| head and insulated with polyethylene. Two of the individually insulated wires are then brought together with no twist and fed into a second extrusion head where the two insulated wires are coated with an exterior sheath of polyethylene insulation.

EXAMPLE NO. 17 INSULATED TELEPHONE CABLE The alloy of Example No. 16 is cast into a continuous bar which is hot-rolled to yield a continuous f temper rod of 3/8 inch diameter. The rod is then cold-drawn on a Synchro Style No. F x 13 wire drawing machine which includes a continuous in line annealer. The rod is drawn to No. 12 A G wire at a finishing speed of 2,000 feet per minute and the in line annealer voltage at preheater No. 1 is 35 volts, at pre-heater No. 2 is 35 volts, and at the annealer is 22 volts. The three transformer taps are set at No. 5. The annealed wire is continuously insulated by passing through an extrusion head where polyporpylene is applied. Eight of the individually insulated wires are stranded together in conventional fashion and fed into a second extrusion head where the stranded unit is coated with an exterior sheath of polypropylene.

It should be apparent that the individual wires of the telephone cable may be processed so that they have a tensile strength high enough to withstand the rigors of an insulating operation when using polyethylene as the insulating material. Since polyethylene is the standard insulation material, it is necessary that the individual wires be capable of withstanding insulation with that material. If, however, polypropylene is used as the insulating material, the tensile strength may be reduced, thus increasing percent ultimate elongation and yielding a cable with high flexibility. The tensile strength may be lowered in this particular embodiment because the wire does not have to be pulled through the extrusion head with as great a force when applying polypropylene . as the insulating material.

In addition, it should be understood that when more than two individually insulated wires are employed in the telephone cable, the wires may be stranded together in several formations such as are produced by concentric stranding, bunch stranding, alternate twist stranding, parallel stranding and rope lay stranding or by forming pairs and then cabling. After stranding or cabling, the unit of wires is then insulated as mentioned previously. It should also be understood that the number of wires grouped together in the cable is practically limitless and the present cable includes that number of wires which have previously been employed in conventional telephone cables and also the addition of any taping or sheathing prior to or subsequent to an extrusion or tubing operation.

- EXAMPLE NO. 18 INSULATED MAGNET WIRE An aluminum alloy is prepared with an aluminum content of 99.42 weight percent, iron content of 0,50 weight percent, silicon content of 0.055 weight percent and trace amounts of typical impurities. The alloy is cast into a continuous bar which is hot-rolled to yield a continuous rod. The-rod is then cold-drawn through successively constricted dies to yield No. 12 AWG round wire. The wire is collected on a inch bobbin until the collected wire weighs approximately 250 pounds. The bobbin is then placed in a cold General Electric Bell Furnace and the temperatue therein is raised to 480°F.

The ter perature of the furnace is held at 480°F for three hours, after which the heat is terminated and the furnace cools to 400 °F. The annealed wire is then passed through an enameling bath and insulated with enamel. Under testing, it is found that the insulated alloy magnet wire has a conductivity of 61,6% IACS, a tensile strength of 16,700 psi, and a percentage of ultimate elongation of 19.8%.

One of the more interesting aspects of the present magnet wire alloy is that during the annealing operation, the percentage elongation increases at a higher tensile strength than when annealing EC magnet wire alloy. In addition, when annealing EC magnet wire alloy, one must take the wire alloy almost to a dead soft condition before the percentage elongation begins to improve. With the present alloy, the percentage elongation improves more steadily as annealing times and temperatures are increased, and it is possible to achieve an acceptable percentage elongation well before attaining a dead soft condition in the wire.

EXAMPLE NO. 19 INSULATED MULTI -FILAMENT CONDUCTOR An aluminum alloy is prepared with an aluminum content of 99.42 weight percent, iron content of 0.50 weight percent, silicon content of 0.055 weight percent and trace amounts of typical impurities. The alloy is cast into a continuous bar which is hot-rolled to yield a continuous rod. The rod is then cold-drawn through successively constricted dies to yield No. 12 AWG wire. The wire is collected on a 30 inch bobbin until the collected wire weighs approximately 250 pounds. The bobbin is then placed in a cold General Electric Bell Furnace and the temperature therein is raised to 480°F. The temperature of the furnace is held at 480°F for three hours, after which the heat is terminated and the furnace cools to 400°F. The annealed wire is then concentrically stranded by a tubular strander with six other wires produced in a similar fashion.

The stranded unit is then passed through an extrusion head and S insulated with poly (vinyl chloride). Under testing, it is found that the multi-filament insulated alloy wire has a conductivity of 61.6% IACS, and improved physical properties.

EXAMPLE NO. 20 0 INSULATED MULTI -FILAMENT CONDUCTOR An aluminum alloy is prepared with an aluminum content of 99.42 weight percent, iron content of 0.50 weight percent, silicon content of 0.05S weight percent and trace amounts of typical impurities. The alloy is cast into a continuous bar which is immediately hot-rolled to yield a continuous rod. The rod is then cold-drawn through successively constricted dies, without intermediate anneals, to yield No. 12 A G hard wire.

The hard wire is then concentrically stranded by a tubular strander with six other wires produced in a similar fashion. The stranded unit is then collected on a 30 inch bobbin until the collected wire weighs approximately 250 pounds. The bobbin is then placed in a cold General Electric Bell Furnace and the temperature therein is raised to 480°F for three hours, after which the heat is terminated and the furnace cools and the bobbin is removed. The stranded unit is then fed from the bobbin to and through an extrusion head and insulated with polyvinyl chloride. Under testing, it is found that the multi-filament insulated alloy wire has a conductivity of 61.6% IACS, and improved physical properties.

It should be understood that the present invention at least in part concerns insulated aluminum alloy multifilament conductors. Particular examples of specific insulated multi-filament conductors or cables include building cable, auto ignition and primary cable, underground building cable, battery cable and battery cable ground wire, aircraft cable, harness cable, neon sign cable, radio hook-up cable, fire alarm and burglar alarm cable, fixture cable, control cable, machine tool cable, enunciator cable, heater cord, lamp cord, flexible electric cord, welding and mining cable, locomotive cable, armor cable, SEU cable with a flexible cross-link polyolefin insulation, service drop, braided cable, appliance cable, and composite cable of aluminum or copper strands about a steel or aluminum alloy core.

For the purpose of clarity and unless there is a contrary indication in the specification, the following terminology used in this application is explained as follows: Rod - A solid product that is long in relation to its cross-section. Rod normally has a cross-section of between three inches and 0.375 inches.

Wire - A solid wrought product that is long in relation to its cross-section, which is square or rectangular with sharp or rounded corners or edges, or is round, a regular hexagon or a regular octagon, and whose diameter or greatest perpendicular distance between parallel faces is between 0.375 inches and 0.0031 inches.

While this invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and as defined in the appended claims.

Claims (1)

1. Annealed aluminum alloy wire having a diameter or greatest perpendicular distance between parallel faces of between 3 Q§; inches and 0.0031 inches and an electrical conductivity of at least sixty-one percent (61%) of the International Annealed Copper Standard characterized by the fact that the alloy wire has improved percent ultimate elongation, tensile strength and bendability and contains substantially evenly distributed iron aluminate inclusions having a particle size of less than 2,000 angstrom units, said inclusions being present in a concentration produced by the addition of about 0.45 to about 0.95 weight percent iron to an alloy mass consisting essentially of from about 98.95 to less than 99.45 weight percent aluminum, no more than about -(FFzjb weightpercent silicon and trace quantities of conventional impurities. , 2, Annealed aluminum alloy wire of Claim 1 characterized by the fact that the alloy wire contains substantially evenly distributed iron aluminate inclusions in a concentration produced by the addition of about 0.50 to about 0.80 weight percent iron to an alloy mass consisting essentially of about 99.15 to about 99.40 weight percent aluminum, abQu 7j3.015 t6-about 0_Q7 weight percent silicon and no more than about 0.15 total weight percent of conventional impurities. 3. Annealed aluminum alloy wire of Claim 1 characterized by the fact the alloy wire includes a coat of insulating material and two or more of the insulated wires are optionally gathered together and coated with an outer-jacket of weatherproofing material. Annealed aluminum alloy wire of Claim 1 characterized by the fact that the alloy wire contains iron aluminate inclusions in a concentration produced by the presence of 0.45 to about 0.95 weight percent iron in an alloy mass consisting essentially of about 98.95 to less than 99.45 weight aluminum; about 0.015 to about 0.15 weight percent silicon, from 0.0001 to 0.05 weight percent each of trace elements selected from the group consisting of vanadium, copper, manganese, magnesium, zinc, boron, and titaniu the total trace element content to be from 0.004 to 0.15 weight percent and a majority of the iron aluminate inclusions having a particle size of less than 2,000 angstrom units. S Annealed aluminum alloy wire having a diameter or greatest perpendicular distance between parallel faces of between 0.374 inches and 0.0031 inches and an electrical conductivity of at «· least sixty-one percent (61%) of the International Annealed Copper Standard characterized by the fact that the alloy wire conta from about 0.55 to 0.95 weight percent iron; from 0.015 to 0.15 weight percent silicon; from 0.0001 to 0.05 weight percent each of trace elements selected from the group consisting of vanadium, copper, manganese, magnesium, zinc, boron and titanium, the total trace element content to be from 0.004 to 0.15 weight percent; and from 98.95 to less than 99.45 weight percent aluminum, said alloy having an iron:, to silicon ratio of 8:1 or greater. ©» Process for preparing an aluminum alloy wire having substantially evenly distributed iron aluminate inclusions with a particle size of less than 2,000 angstrom units and an electrical conductivity of at least sixty-one percent (61¾) IACS characterized by the steps of: (a) Alloying from about 98.95 to less than about 99 «45 weight percent aluminum, about 0,45 to about 0.95 weight percent iron, no more than about 0. is ' weight percent silicon, and trace quantities of conventional impurities; (b) Continuously casting the alloy in an endless casting mold to form a continuous bar; (c) Withdrawing the continuous bar from the mold and continuously hot-rolling the bar through a series of roll stands, said rolling being initiated substantially immediately after removal of the bar from the mold while the bar is still at a hot-rolling temperature; % (d) Drawing the rod with no intermediate anneals through a series of progressively constricted dies to form wire; and (e) Annealing or partially annealing the wire. T. Process for preparing an aluminum alloy wire as described in Claim 1 further characterized by the fact that step (a) consists essentially of. alloying about 99.15 to about 99.40 weight percent aluminum, about 0.50 to about 0.80 weight percent iron, about''^ ΌΪ5"Η:ο about -0.07 weight percent silicon, and no more than about 0.15 total weight percent of conventional impurities. ; - ~ Process for preparing an aluminum alloy wire 'having an electrical conductivity of at least sixty-one percent (61¾) IACS comprising the steps of: 11 (a) · Alloying from about 98.95 to less than 09.54 voight percent aluminum, about 0.45 to about 0.95 weight percent iro , about 0.015· to about 0.15 weight percent silicon, and about 0.0001 to 0.05 weight percent each of trace elements selected from the group consisting of vanadium, copper, manganese, zinc, boron, and titanium, the total trace element content being from about 0.004 to 0.15 weight percent and the ratio of iron co silicon being at least 8:1; (b) Casting the alloy to form a cast bar; (c) Hot-rolling the cast bar through a series of roll s ands to form a rod; (d) Drawing the rod with no intermediate anneals through a series of progressively constricted dies to form wire; n (e) ' Annealing or partially annealing the wire. < .4 Process for preparing an aluminum alloy wire as described in Claim 1 further characterized by the fact that insulation material is coated around the annealed wire of step (e) and two or more of the insulated wires are optionally gathered together and coated with an outer-jacket of weather-proofing material. ¾$. Process for preparing an aluminium alloy-substantially as hereinbefore described vith reference to the Examples* 11. An aluminium alloy, whenever obtained by the process according to any of Claims έ to M.S.Levison Agent for J!Cpplic -. 12. Process for preparing an aluminum alloy rod comprising the steps of: a. Alloying from about 98.95 to about 99.54 weight percent aluminum, from about 0.45 to about 0.95 weight percent iron, about 0.015 to about 0.15 weight percent silicon and from about 0.0001 to 0.05 weight percent each of trace elements selected| - from the group consisting of vanadium, copper, manganese, zinc, boron, and titanium; the total 0 Weight percent of trace elements being from 0.004 to 0.15 weight percent and the ratio of iron content to silicon content being at least 1.99:1; b. Continuous casting the alloy to form a continuous cast bar; and without any preliminary or intermediat 5 anneals initiating hot working the cast bar to form an aluminum alloy rod before the cast bar has coole to a temperature below its hot working temperature. 13. Process for preparing an aluminum alloy wire 0 having substantially evenly distributed iron aluminate inclusions of a particle size of less than 2,000 angstrom units and an electrical conductivity of at least 61 percent IACS comprising the steps of: a. Alloying less than about 99.70 weight percent 5 aluminum with more than about 0.30 weight percent iron, about 0.015 to about 0.15 weight percent silicon and trace quantities of impurities, the ratio of iron content to silicon content being at least 1.99 to 1; b. Casting the alloy into a bar; c. Hot-rolling the bar to form rod; d. Drawing the rod with no preliminary or intermediate anneals to form wire with a conductivit of less than 61% IACS ; and e. Annealing or partially annealing the wire. 14. Process for preparing an aluminum alloy wire having substantially evenly distributed iron aluminate inclusions of a particle size of less than 2,000 angstrom units and an electrical conductivity of at least 61 percent IACS comprising the steps of: a. Alloying less than about 99.70 weight percent aluminum with more than about 0.30 weight percent iron, no more than about .0.15 weight percent silico and trace quantities o.f impurities; b. Continuously casting the alloy into a continuous bar; c. Continuously rolling the bar in substantially that condition in which it was cast into a bar to form a continuous rod; d. Drawing the rod with no preliminary or intermediate anneals to form wire; and . e. Annealing or partially annealing the wire. For andon behalf of the Applicant