DE1954552A1 - Process for the production of thermostatic multilayer metal - Google Patents

Description

DR-INQ. C.IIL.-I.MQ. M. LC. DIPU.-PHYS. DR. OIPL.-PHY «. HÖGER - LEGAL RIGHT-GRIESSBACH-HAECKER PATENT LAWYERS IN STUTTGART

a 37 690 h. 1954552

Oct 24, 1969 -

US Ser.No. 784.778 -

Texas Instruments Incorporated Dallas, Texas, U.S.A.

Process for the production of thermostatic multilayer metal.

The invention relates to a method for producing a thermostatic multilayer metal, in which pure surfaces of at least two different coefficients of thermal expansion having metal layers, of which at least One consists of an oxidizable metal, are brought into contact with one another, and in the case of your feriier these lietallschichten pressed together to reduce their thickness to form a partial metallurgical bond in the solid phase will. - 2 -

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Thermostatic double layer metals consisting of two or more metallurgically interconnected metal layers with different thermal expansion coefficients are usually used in a very thin form, so that the thermostat metals respond to the different thermal expansions of the detailed layers when the temperature changes and they bend or deform. It is known that this use of thermostat metals subjects the bond between the metal layers to considerable stress, so that a metallurgical bond of relatively high quality is required. When the thermostatic metals contain yeast suitable materials, such as one or more layers of iron or an iron alloy, it has been customary to begin the process of manufacture with relatively thick metal ingots in order to achieve the desired bond quality between the ingot materials. These ingots were heated to a temperature of the order of 1093 ° C. and ^{rolled while heated in roll mills at about 60 to 80 c} / o reduction in thickness of the ingots. The interconnected billets were then alternately subjected to a series of additional Y / aling and annealing operations so as to reduce the strength of the composite material to the relatively small thickness required for thermostatic metals. This known method) was successful in forming thermostatic Ketallen with a metallurgical bond of the desired quality, but it is by the V / alzen the bars in the hot condition under application of high pressure for the uplifting Liehe reducing the strength of the thick bar stock, and in particular through the subsequent sequence of further rolling and annealing steps to reduce the connected sweeping layer material to '

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the strength required made the process expensive and one Made up a sizeable share of the cost of thermostat metals, "which contain iron or ferrous alloys.

The invention is now based on the object of a method for the manufacture of thermostat metals using one or more layers of iron or iron alloys to create that is much cheaper than before and results in a high quality metallurgical composite. This object is achieved in the above-mentioned method in that the metal layers on a below their melting temperature lying temperature of one Height to be heated at which the oxides from the contacting intermediate surface of the oxidizable metal layer

be dispersed into this or both metal layers and in the case of a diffusion to bring about a substantially complete interconnection of the contacting Interfaces of the layers is carried out in the solid phase. The procedure can be economical and carried out carefully Control can be carried out while achieving uniform thermostatic properties.

Preferably, the first compressing without heating the strip is achieved by the designed as a strip layers in an overlapping state between aen Yialzen take a V / alzen chair to reduce the strip thickness by about 50 ^cp or more hincurchgeschickt. According to the invention, this first layer material provided with an initial composite is then heated to such a high temperature, preferably in the range between 0.5 to 0.7 of the absolute melting temperature, expressed in Kelving degrees of the strip material with the highest melting temperature, to in essentially all oxides in themselves

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to dissolve the touching intermediate surfaces of the strips and in dispersing the strip material in and around the bond between the strips by diffusion between the strip materials to increase until the calibrated interfaces of the strips are essentially completely in solid phase are connected to each other. .

In a preferred embodiment of the invention the material held together with an initial bond to the desired high temperature in a single batch heated and kept at this temperature until the oxides are completely dispersed from the strip surfaces and the bond between the strips is increased to such an extent that until the strip areas are essentially completely bonded to one another. According to another feature of the Invention is the initially partially bonded multilayer material before the final bond is established

preferably to a temperature below the / mentioned temperature heated or sintered so as to establish the bond between the Strelfen materials to be reinforced so that the bond strength is sufficient to support the backing material for the later process steps to stick together safely. The multilayer material is then subsequently heated to a higher temperature. progressively along the length of the multilayer material heated so as to remove the oxides from the contacting interfaces of the strips or layers in the 'multilayer material to disperse in and to complete the bond between the strips. For example, according to According to the invention, the initially bonded and sintered multilayer material by a strip annealing device known per se be sent through, in which the multilayer material to the desired "higher temperature pro-

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heated gressively along the length of the strip the higher temperature and the speed at which the multilayer material is blown through the heat exchanger is moved through, is chosen so that a dispersion of the oxides and a completion of the Strip composite achieved in the manner described above will.

Further features and advantages of the invention emerge from the following description in connection with the drawing, which the embodiments of the invention of the closer explained. In the drawing show:

Fig. 1 block diagrams to explain -'der From ^un management examples of the method according to the invention,

Mg. 3 a partial longitudinal section through an initially connected multi-layer material for the representation of a according to the method according to the invention ' manufactured intermediate,

Pig. 4- a partial longitudinal section similar to Pig. 3 for

Representation of the properties of a thermostat metal, which is produced by the method according to the invention. '"·

According to the method according to the invention, as shown schematically in Pig.1, thin elongated strips are made various materials, for example of iron "or Iron alloys with relatively high or low coefficients of thermal expansion, cleaned in order to remove coarse impurities from the strip surfaces «In this

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In connection with this, it should be noted that the term "iron alloys" as used here includes all metal alloys in which iron ^{comprises at least 50 ό} , ί> of the alloy. This cleaning step is carried out in a conventional manner known per se and may consist in passing the strips through degreasing baths, heating the strips in a reduced atmosphere to remove the thick oxide films from the strip surfaces and abrading, sanding off or treating the strip surfaces with wire brushes v / earth in order to connect the composite to the surface. remove inhibitory barriers. For example, if a thermostat metal is to be produced with layers of alloy B and alloy 10 according to the invention, elongated strips of these metals will be about 1.016 to 5.08 mm thick and 5.08 to 35.56 cm wide or more preferably unwound from spools, passed through a conventional degreasing bath and then subjected to rubbing in air by means of wire brushes on the main surfaces of the strips so as to remove the coarse contaminants from the strip surfaces. Alloy 3 is a ferrous alloy of relatively high thermal expansion coefficient consisting fi from about 22 nickel, 3 ^c p chromium and the balance iron, while the alloy 10 is a ferrous alloy of relatively low thermal expansion coefficient and 36 includes io nickel and the balance iron.

The thin iron or iron alloy strips then become like this brought together that the cleaned main surfaces of the

one

Touch strips. Then the strips with / sufficient Thickness reduction compressed in order to create a preliminary metallurgical bond of the strips in more solid Phase to achieve. The cleaned strips are

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wise fed from the coils one above the other and in this layer is sent through between the rollers of a roller frame by removing the strips with sufficient thickness reduction are pressed together in order to achieve the desired bond in the solid phase. It is special economical, the strips at room temperature or at a temperature only slightly above room temperature to squeeze, as it results from the heating by one of the aforementioned cleaning steps. The iron or However, iron alloy strips can also operate at higher temperatures heated up to approximately 537 ° C prior to compression so as to facilitate the thickness reduction of the strips according to the invention.

In this context it should be noted that Eisenoder Iron alloy materials, used in the usual way for Formation of thermostat metals are used to have a coating of oxides on their surface, even when action taken to remove such oxide films. Therefore, when the strips are compressed, these oxides retard the formation of the metallurgical bond between the strips. However, if there is sufficient reduction in strip material, so the oxide films are so broken that parts of pure xetal surfaces of the strip materials come into contact and with each other during the above-described compression - in order to achieve the desired initial or preliminary metallurgical bond. As in Fig.3 shown, have the strips 10 and 12 with relative high or low coefficient of thermal expansion Oxiafilne 14 and 16 at their touching intermediate surfaces 18 and 20. If, however, the strips with sufficient thickness reduction are pressed together, the oxide films are broken

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and an initial or partial metallurgical bond "is created between the strips as indicated at 22. However, essentially lens-like inclusions remain between the strips (see Pig. 3) in which the the remaining areas covered by the oxide films 14 and 16 are not connected to each other. It is still "on it pointed out that although the oxide films H and 16 in Fig.3 to Explanation are shown spaced from each other, however, the oxide films 14 and 16 normally also within this Inclusions touch to now this provisional composite of the Iron or iron alloy strips to be achieved this preferably by about 50 to; 80-yo reduced in thickness, . -

According to the invention, the preliminarily bonded multilayer material 24 according to FIG. 3 is now subjected to a treatment at a high temperature. The treatment temperature is chosen to achieve a twofold purpose, namely, to dissolve or disperse the oxide films H and 16 from the contacting interfaces 18, 20 of the strips 10 and 12 into the strip material and to increase the initial one Bond between the strips by diffusion within the strip material until the touching intermediate surfaces of the strips are completely connected to one another in a solid phase. It should be noted that diffusion within the iron or iron alloy materials, ie the materials commonly used for thermostatic metals, can be achieved at temperatures of the order of 815 ° C or less, and that treatment of the non-ferrous layer material 24 at this temperature the initial

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Composite of the multilayer material 24 at least in some ways Increased scope. The dispersion of the oxide films away from the contacting interfaces of the strips 10, 12. must, however take place before the strips can be fully bonded together. This dispersion of the oxides occurs with such iron or iron alloy materials, within a practically applicable time only if the multilayer material is treated for a sufficient period of time at a temperature in the range between about 0.5 to 0.7 of the absolute melting temperature of the strip materials, expressed in Kelving degrees.

According to the method according to the invention, as shown in Fig.1 is shown schematically, a batch is therefore one an initial composite multilayer material 24 undergoing high temperature treatment in a conventional manner Bell annealing furnace or the like. subject. For example, if that Multilayer material an alloy B and an alloy 10, as described above, which has an absolute melting temperature of approximately 1800 ° Kelvin (approximately 1804 ° el and 1760 ° Kelvin (approx. 1765 ° C), then coils with the multilayer material having an initial composite 24 from about 907.2 kg to a temperature in the range between about 880 ° Kelvin (about 882 ° C) to about 1260 ° Kelvin (about 1260 ° C) in a bell annealing furnace heated for about half an hour to two hours, the duration of the treatment depending on the treatment temperature is chosen so that essentially those present on the contacting intermediate surfaces of the strips Oxides dissolved and into the strip materials' are dispersed in, and that essentially the strip surfaces are completely connected to one another :. Before-

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For example, a temporarily bonded multilayer material is added from alloys B and 10 at a temperature of about 1150 ° Kelvin (about 1148 ° C) Treated for about 1 hour. During this treatment, the interfacial oxides 14, 16 according to FIG. 3 are essentially completely dissolved and removed from the strip areas dispersed away into the strip materials, like this is indicated at 26 in Pig.4, so that only a few small oxide particles on the interface between the Streaks remain. These remaining oxide particles assume a substantially spherical shape, so that they . a minimal impact on the. Bond strength at the Zwi- ™ exercise area. The multilayer material is also characterized after this treatment by a grain growth, which is an indication of the diffusion, which the initial Composite, as shown at 22 in Figure 3, increased so that the touching intermediate surfaces of the alloys B and 10 essentially completely, as at 28 in Pig. 4 indicated, connected to one another, and thus a substantially fully connected thermostatic multilayer material 30 is present.

The thermostatic multilayer material 30 according to the He-. finding has excellent bond strength and moreover, mostly the same thermostatic Properties like a comparable thermostat material produced by a "known process. The connected and heat-treated material is also relatively thin, so in some cases it can be used as a thermostat material without additional thickness reduction can be used: - if necessary however, the thin, fully bonded sweeping layer material can also be subjected to a further process

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and possibly also a heating after the renewed Rolling, in order to bring the multilayer material to the desired final thickness without compromising the quality of the bond between. Metal layers is reduced. Such re-rolling and annealing can also be performed v / ground to the grain size of the layers of sweeping material if necessary to influence »As such a re-rolling and annealing in any known This can not be done in any more detail.

According to the method according to the invention, thermostat metals Can be made from a wide variety of materials. For example, any of the iron or iron alloy materials listed in Table I below can be included any other materials of this Table I can be combined by the method according to the invention to form a Manufacture thermostat material, provided, of course, that the selected materials make a corresponding difference have in their coefficient of thermal expansion and thus the so-produced sweeping layer thermostat metal has the desired flexibility.

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Table I 'rv

Alloy Nickel Chromium Iron Manganese Aluminum Molybdenum Cobalt Carbon

tion '. . .

B 22.0 3.0 remainder - - - - · 0.5

C 19.4 2.25 remainder

D 14.65 - remainder 9.5 _t 5.1

E 25.0 8.5 remainder

G 18.0 11.5 remainder '- - -. _-

g GA 18.0 10.0 remainder - - 3.0

to GB 19.0 7.0 remainder - - - __ _Y

S H 14.0 - remainder 5.0 - - - 0.5

ί Κ - rest

- * I «25.0 - remainder 4.0

-j M 8.0 18.0 remainder

'15 32.0 - remainder - - 1.0 1.0

71 - 16.5 remainder - 4.5

10 36.0 - remainder - - - __

11 38.65 - remainder - - - »_

12 31.0 8.0 balance - - - 8.0 -

13 32.0 - remainder - -, 1.0 15.0 -

As usual, small amounts of additives can be added to the alloys mentioned in the table borrowed constituents may be present in the form of impurities. cn

Legie nickel tion 14th 38.0 15th 32.0 20th 40.0 30th 42.0 40 45.0 00 98 26 50
70 50.0

- rest

- remainder 17.0 remainder

"** As usual, in the alloys mentioned in the table, small amounts of additional * ° borrowed constituents may be present in the form of impurities.

Table I (port setting) ■

Chromium Iron Manganese Aluminum Molybdenum Cobalt Carbon up

_. ■ .___ M,, —— U - ———- _ο

ff

7.0 remainder

Remainder - - 1.0 1.0

cn

cn cn ro

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If thermostat metals are formed from two or more iron or iron alloy materials, the temperature, in which the initially connected high layer material, v / ie mentioned above, is treated, preferably selected so that the treatment temperature is greater than 0.5 x the absolute Melting temperature of that iron or iron alloy material which has the highest melting temperature, such that the oxide films on the contacting interfaces of the layers dispersed into both materials.

Furthermore, one or more of the W alloys listed in Table I can be combined with any other alloys having a higher melting temperature above the final treatment temperature in accordance with the method of the invention. For example, alloys of Table I can be combined with alloys of Table II to form thermostat metals in accordance with the invention.

Table II

Alloy Nickel Manganese Iron Copper Cobalt Chromium

rest

18.0 10.0 remainder - 57.0 9.0

As usual, the alloys mentioned in the table may contain small or small additional components in the form of impurities. . . _;

If an alloy from Table I is used with an alloy from Table II is combined, the one with a high Iem-

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treatment carried out at the temperature, the initially connected !, teaching layer material is subjected, preferably so controlled that the treatment temperature is at least the same 0.5 of the absolute melting temperature of the iron or iron alloy material of the multilayer body is.

Although the treatment at high temperature according to the method according to the invention has been described above in connection with a batch process, the initially bonded multilayer material can also be subjected to a treatment at high temperature by being transported through a conventional strip annealing device, the treatment temperature in relation to on the throughput speed is selected so that the double purpose already mentioned is achieved, namely to dissolve and disperse the oxides present at the intermediate surfaces of this initially connected multilayer material and also to bring about a diffusion of the strip materials in order to achieve the most complete possible connection of the layers of the multilayer material reach. In order to transport the initially connected Mehrechichtmaterials to facilitate by a Streifenglüheinrichtung as it passes, the initially connected Ltehrschichtmaterial a batch pre-treatment in a conventional Glockenglühofen or the like is preferably. subjected to at least to a limited extent to achieve a diffusion or a sintering within the strip material and thus to increase the strength of the initial bond of the layers. As shown in Pig. 2, after cleaning and the achievement of an initial bond, the multilayer material is introduced into a conventional G-lock annealing furnace and brought to a temperature of the order of magnitude of

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815 C / I heated for 5 minutes to 1 hour to increase the bond strength of the multilayer material that at least limited diffusion of the strip materials occurs. This multilayer material with a something The bond is then improved by means of a strip annealing device or the like. moved through, in which the material of the desired, a high temperature treatment is subjected to the oxide films from the contacting To disperse interfaces of the layers away and to further provide additional diffusion of the strip materials so long to carry out until the strip materials are essentially are fully interconnected.

If, for example, a thermostat metal is formed from alloys B and 10, as described above, according to the method of the invention, the main surfaces of the strips are rubbed in air with a wire brush in order to remove the coarse contaminants from the main surfaces. After the cleaned surfaces of the strips are brought into contact with one another, the strips are passed through a roller mill in which the strips are compressed at approximately a 70% reduction in thickness to form a prebonded multilayer material. This multilayer material is ann a Sihtervor- · transition in "a Glockenglühofen at a temperature of un-) ferry 815 ° C subjected to about one hour. Diese'Zwischenbehandlung increases the bond strength of the multilayer material. After this material from the Glockenglühofen initially connected and sintered iat removed , the multilayer material is then sent through a conventional strip annealing device with a dwell time of 5 to 60 minutes at a temperature of approximately 1093 C,

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so as to achieve essentially complete dispersion of the
Oxide films from the "touching interfaces" of the strips and a substantially complete bond between the layers of multilayer material, thereby creating a thermostat material.

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Claims (8)

ή ^ \ Process for the production of a thermostatic Hehrschichtmetalles, in which the pure surfaces of at least two different thermal expansion coefficients exhibiting metal layers, of which at least one consists of an oxidizable metal, are brought into contact with each other, and in which further these metal layers to reduce their thickness are pressed together to form a partial metallurgical bond in the solid phase, characterized in that the metal layers are heated to a temperature below their melting temperature from a level "at which the oxides from the contacting interface of the oxidizable metal layer into this or both metal layers dispersed therein and in which a diffusion is carried out in order to bring about an essentially complete bond of the contacting intermediate surfaces of the layers in the solid phase. 2. The method according to claim 1, characterized in that the metal layers to a temperature of 0.5 to 0.7 the absolute melting temperature of the oxidizable metal layer are heated. 3. The method according to claim 1 or 2, characterized in that iron or an iron alloy is used for at least one layer. _y - 2 - 009826 / U72 A 37 690 h October 9, 1969 _Λ 1 9 5 A 5 5 2 4. The method according to any one of the preceding claims, characterized in that the partially connected metal layers first heated to a relatively lower temperature in order to have a limited diffusion in the metal layers to increase the bond strength of the metal layers. 5. The method according to any one of the preceding claims, characterized in that characterized in that for the at least one oxidizable Metal layer a material of Table I is selected. 6. The method according to any one of the preceding claims, characterized marked that for all metal layers materials of table I. 7. The method according to any one of claims 1 to 5, characterized in that that for at least one of the ketal layers Material of Table II is selected. 8. The method in which elongated thin metal strips are used as starting materials, according to one of the preceding claims, characterized in that the metal strips are continuously moved in the longitudinal direction and brought into contact with their clean surfaces, and that the metal strips under '■ reduction of their Starch are preferably pressed together by Y / alzen to form the partially metallurgical bond. 009826/1472 Blank page