Composite cable sheathing

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Patent Application. No. 14255/68 arrived 22 X 1968

PATENTS AND REGISTRATION OFFICE

Validity Day on

Ans. widely available on

X 1968 26 IV 1969

Ans. published and the publication published the Priority

VXI 1972 requested from dan 25 X 1967 and 11 IX 1968 (USA, 677 955 »759 117)

OLIN CORPORATION, NEW HAVEN, CONN. USA

Inventor MJ Pryor, Woodbridge and Anthony Ham Hamden »Conn

Ombuds L Fire

Compound material, intended for cable housings and method of manufacture and aluminum alloy for this purpose

Sheaths for underground cables are usually made either of alloy 110 (99.9% pure Cu) or alloy 220 (Copper Development Designation). Alloy 110 is more widely used, especially for medium or large dimension cables.

Air cables are often provided with envelopes of annealed aluminum alloy 1100 (Aluminum Association. Designation).

Cable housings must provide satisfactory mechanical strength, have appropriate electrical conductivity and, when used underground, exhibit high corrosion resistance.

A further problem in the case of underground cables is the attack of rodents, in particular earthen rodents. For this reason, copper sheaths for cables west of Mississippi have a thickness of 0.25 mm, while east of Mississippi, where earthen rodents are relatively rare, a thickness of just 0.13 mm is used.

The relatively scarce supply of copper and the fluctuation in the price of copper have led to the search for other metal systems that would be suitable for cable housings.

Attempts have been made to use stainless steel plated with copper. However, the corrosion resistance of blots in the outer copper coating that occur during use is too variable for this material combination to be used in practice. Copper Dupl.kl. C 22 c 21/02 appears to be cathodic in relation to stainless steel in many underground materials and favors a rapid hole corrosion.

Three-layer materials have also been proposed in US Patent 3,272,911 · However, these composite materials exhibit poor corrosion resistance in the soil.

It is desirable that the material for the cable housings does not contain copper alloy, has acceptable electrical conductivity, has sufficient mechanical strength to prevent attack by rodents or other animals, such as earthen rodents, and exhibits as much corrosion resistance as possible.

To date, no acceptable solution has been obtained for this problem.

However, in accordance with the present invention, it has been found possible to solve the aforementioned problems with a compound material intended for cable housings, comprising a steel core which is metallurgically the dog to a plating plate consisting of an aluminum alloy, preferably having a conductivity of at least 50 0 IACS. This compound food is characterized in that the aluminum alloy contains from 0.2 to 2.0 $ zinc and 0.001 to 0.2 $ hor and either 0.05 to 0.4 $ iron along with 0-0.2 $ silicon. or 0.4 to 1.2 $ silicon together with 0.3 to 1.4 $ magnesium, 0-0.5 $ iron, up to 0.4 µl copper, up to $ 0.2 manganese and up to 0, $ 1 chromium, while the alloy of compounds contains a maximum of $ 0.05 of each element and a total of a maximum of 0.15 with the remainder of the alloy being aluminum.

In preparing this compound material, a metallurgical bond is formed between the plating layer and the steel core, cold rolls the compound material to final thickness, heats the compound material to a temperature of 54 ° C to 625 ° C. cool the compound material to room temperature with a cooling rate of at least 220 ° C / minute and then heat the compound material to a temperature of 120-205 ° C and hold it at that temperature for a period of 15 minutes to 24 hours and cool the compound material to room temperature.

The invention also relates to an aluminum alloy which is suitable for the manufacture of preferred embodiments of the compound material. This alloy contains from 0.2 to 2.0 $ zinc and 0.001 to 0.2 $ hor and either 0.05 »to 0.4 $ iron along with 0-0.2 $ silicon, or 0.4 to 1, 2 $ silicon along with 0.3 to 1.4 $ magnesium, 0-0.5 $ iron, up to 0.4 $ copper, up to 0.2 $ manganese, up to 0.1 $ chromium, and the alloy of compounds contain maximum

$ 0.05 of each element and a total of a maximum of 0.15 with the remainder of the alloy being aluminum.

The invention will be further elucidated in the following with reference to the accompanying drawing.

Fig. 1 is a section through a typical cable housing.

Fig. 2 is an enlarged sub-section through an embodiment of a cable housing according to the invention.

Fig. 3 is a sub-section on a larger scale through yet another embodiment of a cable housing according to the invention.

Fig. 4 is a partial section on an enlarged scale through yet another embodiment of a cable housing according to the invention.

Fig. 5 shows schematically a test device of the kind used in the experiment described in Example 3 in the following.

In Fig. 1, a conductive cable 1 is provided with insulation 2. A number of such insulated cables are arranged in an insulating inner sheath 3. The metal casing is generally shown with its structure and is described in more detail below. In addition, the cable bundle may be provided with an insulating outer layer 5, which is also preferably made of polymeric material, for example polyethylene.

It has been found, according to the present invention, that a composite cable housing made of an aluminum alloy such as exterior plating layer, which is metallurgically bonded to a steel core, provides a satisfactory solution to the aforementioned problems found in connection with the cable housings.

Thus, for example, the cable housing 10 shown on an enlarged scale in Figure 2 comprises a part 14 of aluminum alloy metallurgically bonded along an interface 13 to a steel core 12. If desired, the outer surface 15 of the aluminum alloy member may be corrugated, not shown. if an outer insulating layer 5 is used, as shown in Fig. 1.

According to the present invention, it has been found that composite materials comprising an aluminum alloy containing 0.2-2.0% zinc, 0.001-0.2 boron and at least one hardening element, and metallurgically bonded to steel, provide the required, sacrificial action based · corrosion protection, sufficient electrical conductivity and sufficient mechanical strength to withstand attack by az animals. The aluminum alloy must have an electrical conductivity of at least $ 50 by the International Annealed Copper Standard. The boron content ensures that the desired conductivity of 50 IACS is achieved »The zinc content ensures the required galvanic protective effect in relation to steel. In addition to the zinc and boron, the aluminum alloy must contain at least one additional element, which provides the alloy with the required strength.

The preferred zinc content for ensuring galvanic protection · in relation to steel is 0.5, 5-1 »5 zinc. The preferred boron content is 0.004-0.1 µS.

Accordingly, according to one embodiment of the present invention, the aluminum component must contain 0.2-2.0% Zn, 0.001-0.2 $ boron to ensure electrical conductivity, and 0.05-0.4% iron to provide the required strength. The silicon content should not be higher than 0.2%. The content of other pollutants should not exceed $ 0.05 of each pollutant and not more than 0.15%. The preferred zinc content is 0.5-1.5 / ° and the preferred boron content is 0.02-0.2

According to another embodiment of the present invention, the aluminum component contains 0.2-2.0 &lt;$&gt; Zn, 0.001-0.2 $ boron, 0.3-1 »4 1» magnesium, 0.4-1.2 &lt; &gt; silicon, 0-0.5 $ iron, up to 0.4 $ copper, up to 0.2% manganese, up to 0.1% chromium, and other contaminants in an amount of up to 0.05 of each element and a total content of such other compounds not exceeding $ 0.15

The preferred zinc content is 0.5-1.5 and the preferred boron content is 0.004 '0.1 0. The preferred silicon content is 0.5-0.9 $ and the preferred magnesium content is 0.5-0.9. $ ·

In the above-mentioned composite or compound materials, soft steel with as low a carbon content as 0.01% can be used. The steel must contain a carbon content sufficient to p

give a stretch limit of at least 17.5 kp / mm. Steel with a higher carbon content than soft steel can also be used provided the steel material exhibits an extension exceeding $ 5 in the recovery state. The steel provides the compound material with the required strength for resistance to attack by animals and rodents. Of course, if desired, conventional steel alloying elements, for example chromium, magnan, nickel, cobalt, can be used in the usual and suitable levels for alloyed steel. However, for economic reasons it is usually advisable to use unalloyed carbon steel. For certain applications for which higher corrosion resistance is desired, conventional stainless steel series 300 and 400 types and their modifications can be used. Of these materials, materials of type series 300 are generally preferred, since these are generally less brittle than materials of type series 400. However, as stated above, with the usual carbon steel, the required strength of the compound material can be easily achieved.

The aluminum component must be at least $ 25 in the thickness of the compound material. A preferred aluminum to steel thickness ratio is 7: 3 ·

The process used for bonding the aluminum component to the steel core is not critical, provided a satisfactory metallurgical bond which is free of intermetallic compounds is obtained. The bonding can thus be achieved by the method described in Swedish patent specification 316 «354. In the same process, core materials with a thickness less than 13 mm are used, and. a plating material in the form of sheet having a thickness of less than 6.4 mm, wherein core material and plating material are rolled so that a preliminary bond is obtained, after which the thus obtained weakly bonded material is cold rolled with a reduction degree of at least 50 $. In the preparation of compound core material with iron core, the preparatory or preliminary bonding is accomplished by rolling with a reduction degree of 40-65 $, the scope of subsequent cold rolling having to be carried out with a reduction degree of at least another $ 10 to a total reduction degree of at least 60 If desired ,, however, the bonding can be effected by heating the core material, as disclosed in U.S. Patent Application 638,668 and U.S. Patent 3,381,365 to a temperature of at least 150 ° C_O Still another process in which a cooling treatment is carried out so that only one of the components is recrystallized can be used. However, the aforementioned process according to Swedish patent specification 316,354 is preferred.

After the bonding is established, the cold material is rolled to the desired final thickness.

If the compound material comprises the aluminum alloy described above containing 0.02-2 $ zinc, 0.001-0.2 $ boron, 0.05-0.4 $ iron, only annealing is required for 1-60 minutes at 54O-595 ° C before use. This treatment ensures the softening of the iron core and of the aluminum plating layer.^;

However, an aluminum alloy containing zinc, boron, magnesium and silicon of the type specified requires heat treatment to provide optimum strength, ductility and electrical conductivity. Since the compound material is cold rolled to the desired final thickness, it should be heat treated at 54O-79O ° C for a period of 1-60 minutes depending on the thickness. This treatment ensures softening of the iron core. The compound material should then be cooled to room temperature at a rate of at least 220 ° C per minute, with room temperature referring to a temperature below 150 ° C.

The compound material should then be heated to a temperature of 120-205 ° C for a period of 15 minutes to 24 hours. The preferred temperature range for the latter heat treatment is 15O-165 ° C for a period of 2-8 hours. This treatment achieves a tensile limit of at least 24.5 kp / mm and a conductivity of at least $ 52 IACS. The compound material is then ready for forming into the jacket shown in Fig. 1.

When using aluminum materials containing less than 0.5 $ silicon, for example the Al-Zn-B-Ee alloy described above, it is particularly suitable to apply an aluminum alloy coating layer having a thickness of 5-10 $ of compound material et aluuinium part containing 346809 the silicon at least 0.5% to prevent deterioration of the bond between the aluminum part and the steel part during annealing.

It has been found that during the annealing process used to soften the iron component, the strength and formability of the bond between the aluminum component and the iron component deteriorate. It has been found that this effect is obtained even if the silicon content of the aluminum component is as high as 0.75%.

It has been found that the deterioration of the bonding is due to the formation of intermetallic compounds at the interface between the core and the plating layer.

According to the present invention, it has been found that this deterioration of the bonding can be avoided by applying an additional layer of aluminum containing at least 0.5% and preferably 0.75% silicon between the iron component and the aluminum component described above. The silicon content of this additional aluminum weight should be 0.5-5% and preferably 0.75-2%.

The layer may also contain other conventional alloying elements besides silicon. However, the magnesium content must be less than 1.0% and preferably less than 0.2% to ensure that sufficient silicon is available to counteract deterioration of the bond. Of course, at the lowest silicon content, the magnesium content must be in the corresponding amount low. The contents of other alloying elements besides magnesium and silicon may be as follows: Copper, iron, chromium and nickel can be used in concentrations up to 1.5%. Titanium, zinc and manganese can be used in concentrations up to 1%.

It will therefore be apparent to those skilled in the art that a plurality of alloying elements can be incorporated into silicon-containing aluminum alloy layers of the invention without thereby impairing the ability of the layer to counteract deterioration of the aluminum-iron bond.

When using a two-layer compound material, the addition of the silicon-containing layer further results in obtaining a compound layer composed of three layers. 0m the iron component is plated on both sides with the aluminum component a compound material is made up of five layers.

As can be seen in Figure 3, the layer 30 of aluminum containing silicon is applied between the aluminum component 31 and the iron or steel component 32.

Fig. 5 shows one of five layers of compound material, in which the steel component 40 is surrounded by two silicon-containing aluminum layers and 42. The aluminum components 43 and 44 are applied to the outside of the compound material.

In all cases, the thickness of the additional layer applied should amount to 5-10% of the thickness of the aluminum component.

It has been found that if such a compound material is annealed at a temperature of 540-565 ° C to soften the iron component and improve its formability, no deterioration of the bonding strength or formability of the compound material is obtained.

The silicon-containing aluminum layer can be bonded to the aluminum component described above with any method well known in the art for producing such plated materials. For example, the methods described in U.S. Pat. No. 3,381,366 can be used which can be summarized as follows: An aluminum core (the aluminum component) is used in the form of a sheet having a thickness less than 13 mm and a plating layer (the aluminum alloy containing silicon) is applied. ) in sheet form with a thickness of less than 6.4 mm, the core heats to a temperature of 65-56.5 ° C, the core and the plating layer coalesce at a rate of at least

7.5 and preferably 30 m / minute in a knit having a degree of reduction of 35-80%, wherein the core and plating layer are first brought together in the roll gap and wherein the plating layer is first contacted with the roll before the plating layer is brought into contact with the core, and the enclosed angle between the core and the plating layer upon entry between the rollers exceeds 5 °;

The compound layer of aluminum layer thus produced and the aluminum compound material of aluminum layer and the aluminum component are then bonded to the steel component. When bonding the aluminum composite material to the steel component, the side of the aluminum compound material (or aluminum compound material) constituting the silicon-containing layer is bonded to the steel component by the method of aluminum and steel bonding described above. By using this method, tendency to deteriorate the bond during annealing is avoided.

After bonding, cold rolling to final thickness and annealing and / or heat treatment, the compound material is ready for use with the cable bundle shown in Figure 1, using conventional methods well known to those skilled in the art.

The invention is further illustrated by the following embodiments, which are not intended to limit the scope of the invention.

Example T. Alloys of the composition set forth below are prepared in the form of sheets having a thickness of 1.5 mm.

<td>Alloy no</td><td> 1</td>

<td>Ki sel</td><td> 0,06</td>

<td>Iron</td><td> 0,14</td>

<td>Bor</td><td> 0,011</td>

<td>Zinc</td><td> 0,97</td>

<td>Copper</td><td> 0,003</td>

<td>Alloy no</td><td> 2</td>

<td>Silicon</td><td> 0,63</td>

<td>Iron</td><td> 0,20</td>

<td>Bor</td><td> 0,025</td>

<td>Magnesi um</td><td> 0,56</td>

<td>Zinc</td><td> 0,97</td>

<td>Copper</td><td> 0,003</td>

<td>Alloy no</td><td> 3</td>

<td>Silicon</td><td> 0,37</td>

<td>Iron</td><td> 0,05</td>

<td>Bor</td><td> 0,001</td>

<td>Magnesium</td><td> 0,62</td>

<td>Tin</td><td> 0,09</td>

<td>Copper</td><td> 0,001</td>

<td>Alloy no</td><td> 4</td>

Fisher pure zinc Zinc 99.99% +

The alloys 1-3 were castillated and subjected to surface scouring to a thickness of 38 mm. Alloys 1 and 2 were homogenized at 540 ° C for one hour. Alloy 1 was cooled in stagnant air to room temperature while alloys 2 and 3 were cooled in stagnant water to room temperature. Alloy 2 was then aged at 165 ° C for eight hours and Alloy 3 was aged at 177 ° C for five hours.

Example 2. After preparation and pretreatment in the manner set forth in Example 1, the alloys 1-3 were tested and exhibited the following characteristics.

<td>Alloy No</td><td>Crime- limit? kg / mnr</td><td>Route limit? kg / mm</td><td>Extension %</td><td>Electrical conductivity% IACS</td>

<td> 1</td><td> 6,9</td><td> 3,4</td><td> 32</td><td> 59</td>

<td> 2</td><td> 27,0</td><td> 24,6</td><td> 10,0</td><td> 52</td>

<td> 3</td><td> 20,0</td><td> 17,5</td><td> 11 „0</td><td> 53</td>

<td>Example 3.</td><td></td><td></td><td>The alloy wheels</td><td>1-4 was connected to objects</td>

of soft frame of commercial squall in the type 1010 with equal surface area in the galvanic cell arrangement set forth below.

The apparatus shown in Fig. 5 comprised two quartz cells 20 and 30. As electrolyte 23, 0.1 M NaCl was used. In the cell, the alloy specimen 21 and a soft steel specimen 22 were applied. The specimens had dimensions of 5 cm x 1 cm and were fitted with narrow strips 21S and 22S, extending up to a holder 25. Platinum wires 26 and 27 were inserted through a rubber cork 28 provided with an opening to atmosphere 28A and these platinum wires were connected to a Sargent Model MR type printer with wires 26A and 27A. The printer, which included an input resistor of the size of 1000 ohms, was connected in parallel to a shunt line of zero resistance, which included an on and off switch 29.

The second quartz cell 30 was connected to the first quartz cell 20 with a salt bridge 31 of conventional design. Of course, cell 30 also uses an 0.1 M NaCl solution. A standard potassium electrode 32 was immersed in a saturated potassium chloride solution 34 isolated from the NaCl solution in cell 30 with a glass vessel 33.

In the lower portion of the glass vessel 33, a porous plug 35 was provided which allows electrical connection with the NaCl electrolyte but prevents mixing of KCl and NaCl. A conduit 36 ​​was provided through a glass-to-metal1 seal 37, and this conduit was connected to a Leeds and Northrup Speedomax resistor 41 of 1 megohm type. A line 27B from the soft steel specimen was also connected to the printer Speedomax. This coupling allowed measurement of the corrosion potential of the steel when the switch 29 was set in the closed position, the potential being measured relative to the calomel standard electrode 32.

With the Sargent type printer, the current passing through the cell and the input resistor 1000 ohms of the instrument were measured when the switch 29 was set in the open position;

Knowing the surface area of ​​the specimens, the total charge 346809 το the amount in columns supplied to the soft steel specimen can be calculated. during the test.

Galvanic tests were conducted over a period of 168 hours to determine the degree of cathodic protection obtained with alloys 1-4 relative to soft steel cathodes. These tests also enabled anode efficiency determinations, which in turn are related to the rate at which the consumable protective coating is destroyed.

<td colspan="2">They are listed below</td><td>results</td><td>obtained with the alloys</td>

<td> 1-4:</td><td></td><td></td><td></td>

<td>Alloy No</td><td>Total charge amount added to the part of soft steel per cm2 and 168 hours</td><td>Anodic efficiency,?</td><td>Degree of Average of corrosion protection of soft potential steel</td>

<td> 1</td><td> 15,09</td><td> 100</td><td>Full -0.85</td>

<td> 2</td><td> 10,14</td><td> 49</td><td> -0,80</td>

<td> 3</td><td> 9,72</td><td> 55</td><td>Incomplete- -0.77 The weight loss of the steel was only reduced by .60%</td>

<td> 4</td><td> 27,8</td><td> 4</td><td>Full -1.00</td>

Example 4. Metallurgically bonded compound alloys of alloys 1 and 2 were made with a 1010 soft steel core. . A thin layer of the same aluminum alloy with a thickness of 0.025 mm was plated on the opposite side of soft steel.

The cold plating process described in the aforementioned U.S. Patent 3,381,365 was used. The bond is achieved with a cold reduction degree of 70? at the bonding step. after which the compound material was cold rolled 30? to the final thick. seemed 0.28 mm.

The compound metal articles were then subjected to the special heat treatment cycles specified for the alloys of Example 1, thereby ensuring the softening of the core of soft steel and a suitable polymeric core.

equal treatment of the aluminum alloy plating.

A control sample comprising copper alloy 110 plated on 10110 soft steel with a substrate coating of aluminum alloy 1100 according to the Aluminum Association Designation was used for control testing. The latter material is a commercially available compound material, previously used as a material for sheathing cables. The dimensions of the individual layers were as follows:

Alloy 110 0.051 mm

Soft steel of the type

1010 0.076 mm

Aluminum Alloy 1100 0.127

A second control sample »copper alloy 110 plated on soft steel of type 1010 with a substrate coating of copper alloy 110 was also used. This compound material had a thickness of 0.15 mm and the three layers of the compound material all had the same thickness.

The four sample pieces of compound material measuring 5 x 8 cm were mechanically engraved with a VDremel tool to expose the core of soft steel. In the treatment of the compound materials with copper, the engraving was carried out through the copper surface, as this is subjected to the effect of corrosion in the soil. The engraving of compound material coated with alloys 1 and 2 was carried out through the thicker aluminum layers.

The specimens were submerged with the shorter dimension vertically 5 cm below the surface in fine sandy Charlton clay at maximum distance from each other and with 1.96 dm clay for each sample in plastic boxes. The initial pH of the soil was 4.22 and the moisture content was 29%. The soil boxes were placed in a salt spray box, kept at 38 ° C and contained an open container of 0.5% potassium nitrate solution for maintaining constant moisture content during the test.

After one month of exposure, the specimens were removed from the insulation and cleaned prior to examination. Samples of steel plated with aluminum alloys 1 and 2 were cleaned by immersion for five minutes at 82 ° C in 20 parts of chromium trioxide, 15 parts of orthophosphoric acid and 65 parts of distilled water. After cleaning, the specimens were rinsed and dried. The copper-plated control samples were cleaned in 20% sulfuric acid at 73 ° C for five seconds and then rinsed and dried.

Compound material of steel plated with aluminum alloy # 1 did not at any point perforate the steel surface exposed by the engraving. The exposed steel was mainly gray in addition to a few localized brown rust spots, and this showed that the plating of the aluminum alloy No. 1 had acted as galvanic protection or consumption protection for the steel in the moist acidic soil. The aluminum plating of alloy # 1 exhibited corrosion pits in some places at some distance from the engraved lines, but the corrosion was normal for aluminum alloys in such aggressively acting soil

Compound material of steel plated with aluminum alloy No. 2 exhibited. nor perforation in the places where the steel was exposed to the impact of the earth along the engraved lines. The random rust spots on the exposed steel surface, which were observed on the compound metal material of steel with aluminum alloy # 1, however, were largely not obtained on the compound metal material plated with alloy # 2. Furthermore, the surface of aluminum alloy # 2 exposed to the impact of the soil used in the test showed general discoloration but no significant pitting at the distance from the engraved lines.

In contrast, control samples of compound steel plated with copper alloy 110 exhibited devastating corrosion at the engraved lines. The entire thickness of the steel part had been completely removed at the exposed engraving lines in the control sample of the alloys 110-1010-110 by galvanic corrosion so that the copper plating layer on the back had been exposed. Complete perforation of the steel was also obtained from a control sample of commercially available compound material of the alloys 110-1010-1100, but the total amount of steel destroyed and removed at the engraved or drawn line was smaller than that of the control sample of the alloy types 110-1010 -110. This was due to a consumption-based galvanic protective effect of the underlying 1100 'aluminum alloy, which had been exposed in many places along the line.

Example 5. A compound material whose aluminum component contained 1% zinc, 0.1% boron, 0.2% iron and 0.2% silicon, and of other elements not more than 0.5% of each in a combined total amount of 1%. 5% was plated on both sides of a steel core with a carbon content of 0.25% in the manner disclosed in U.S. Patent 3,381,365. The resulting compound material had a thickness of about 0.225 mm (0.15 Al / 0.075 steel). After bonding, the compound was cold rolled and annealed at a temperature of 580 ° C for one hour. The compound material was then cooled to room temperature at a rate in excess of 220 ° C / minute.

The compound material was brittle and showed unsatisfactory moldability. The bond was extremely weak and could be pulled apart by hand.

Example 6. A compound material of the composition set forth in Example 5 was band annealed in an electric resistance furnace with a heating zone length of 2.7 meters and a width of 98 cm. The tape was passed through the furnace at a rate of 3.6 meters / minute. The length of the heating zone was 2.4 meters and the temperature was maintained at 727-738 ° C.

After cooling to room temperature at a rate of 220 ° C / minute, a brittle compound material was obtained, which could be pulled apart by hand.

Example 7. An aluminum alloy containing 0.75% silicon, 0.2% iron, 0.01% magnesium and less than 0.1% of all other elements and a total content of other elements less than 0.5% were bonded to an aluminum component with the same composition as the aluminum component used in the experiment of Example 1, using the bonding method set forth in U.S. Pat. No. 3,381,366.

This compound material, in turn, was bonded to a steel component of the same composition as the steel component specified in Example 5 (0.25% carbon). The surface of the silicon-containing aluminum layer was bonded to the steel by the method disclosed in U.S. Patent Application No. 549,319. The resulting compound material had a thickness of about 0.24 mm (0.15 Al / 0.015 Al / 0.075 steel). The compound layer composed of three layers was then cold rolled and annealed at 580 ° C.

After cooling to room temperature at a rate in excess of 220 ° C / minute, the compound material was malleable and the steel-aluminum bond was very strong. A traction greater than 18 kp / cm width was required to break the bond.

Example 8. The compound layer made of three layers, set forth in Example 7, was annealed in a furnace of the kind set forth in Example 2 and maintained at a temperature of 727-738 ° C at a rate of 3.6 meters / minute.

After cooling to room temperature at a rate in excess of 220 ° C / min, the compound material was moldable and the bond between steel and aluminum was very strong. Thus, a pull-apart force of more than 18 kp / cm width was required to destroy the bond.

Example 9. An aluminum component with a single content of? zinc, 0.1? boron and 0.2% copper, 1% magnesium, 0.45% silicon,

0.1 manganese and 0.5% chromium and other elements in an amount of up to 0.05% of each and a total of 0.15% maximum bound to a steel component containing 0.25% carbon in the manner specified in Swedish patent specification 316 * 354. The compound material had a thickness of about 0.225 mm (0.15 Al / 0.075 steel). The compound material was then cold rolled to the desired final thickness and annealed at a temperature of 50 ° C for a period of ten months.

After cooling to room temperature at a rate in excess of 220 ° C / minute, the compound material was found to lack moldability and the components could be pulled apart by hand.

Example 10. The experiment of Example 9 was repeated using the furnace and band annealing indicated in Examples 6 and 8.

After cooling to room temperature at a rate in excess of 220 ° C / minute, the compound material proved to be brittle and the bonding was weak so that the components could be pulled apart by hand.

Example 11. An aluminum alloy containing 0.75% silicon, 0.2% iron, 0.01% magnesium and of all other elements less than 0.1% and a total of less than 0.5% were bonded to that of Example 1 in the manner disclosed in U.S. Pat. No. 3,381,366. This compound material was then bonded to a steel core containing 0.25% carbon with the siliceous layer closest to the steel component. The bonding was carried out using the method described in Swedish patent specification 316,354.

The resulting compound metal material had a thickness of about 0.24 mm (0.15 Al / 0.015 Al / 0.075 steel). The compound metal material was heated to a temperature of 580 ° C for one hour.

After cooling to room temperature at a rate in excess of 220 ° C / minute, the compound material proved to be malleable and the bonding was very strong. Thus, a traction force of more than 18 kp / cm width was required to disassemble the components.

Example 12. The three-layer compound material, described in Example 11, was annealed using the oven and conditions described in Examples 6 and 8.

After cooling to room temperature at a rate exceeding 220 ° C / minute, the compound metal material was found to be malleable and to have very good bonding strength. Thus, a tensile force exceeding 18 kp / cm width was required for disassembly of the steel-aluminum bond.

Example 13. A compound layer made of five layers was made in which a steel component was plated on both sides with aluminum compound layer. The aluminum compound layers were composed of an aluminum component and an aluminum alloy layer. The alumina component had the composition of Example 1. The aluminum alloy layers contained 0.75% silicon. The aluminum alloy layer was first bonded to the aluminum component in the manner disclosed in U.S. Patent 3,381,366. These two aluminum compound materials are then bonded to the steel core in the manner stated in Swedish patent specification 316,354. The resulting composite material had a thickness of about 0.48 mm (0.15 Al / 0.015 Al / 0.075 steel / 0.005 Al / 0.05 Al).

The five-layer compound material was band annealed using the oven and conditions set forth in Examples 6 and 8.

After cooling to room temperature at a rate in excess of 220 ° C / minute, the compound metal material proved to be malleable and the bond strength was very good. Thus, a tear-off force was required to exceed 18 kp / cm width to disassemble the steel-aluminum bond.

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