DE1521113A1 - Process for coating metal bars with molten metal - Google Patents

Description

Dr. Gertrud Hauser tooo Monek «n.pafin ₉ ,

Dlpl.-Ing. Gottfried Leiter Er ", b., ₀ .r., Ra". 19 ^ 5

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Anaco Steel Corporation 703 Curtis Street Middletown, Ohio / USA

Process for coating metal strands with molten

metal

The invention relates generally to a method of coating iron rod-like articles with molten metal Metal, in particular it relates to a process by which aluminum-coated iron or steel strands are produced that are characterized by very high tensile strength. To this end, the invention is based on continuous coating described by steel wire with practically pure aluminum. However, beer is to be understood that the teaching of the invention does not is limited to this and the method is equally limited to the covering of wire * * tape or tubing with any of the common, customary coating metals can be used «

the

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The fundamental meaning of the invention can perhaps be best understood if one refers to a specific object that can be manufactured according to the present method economically higher than has been possible up to now.For example, AC3R consists of high tensile strength cables (Aluminum Conductors Steel Reinforced) a number of aluminum wires wrapped around a central steel reinforcement wire. This Stahlsttttsdraht must have a minimum tensile strength of 116üO kg / cm bie 13000 kg / ca;} © '* u the strength own, and must miniaale Dehsiuigsanforderuzi4 * fe er-Tillen. Au3serdem is e * highly wttusehetiawert that "ί" τ verse ** .ageatahldraht ei new high 9rad to Korroeionsf estigkei t aufeist, usually by a .. jrta & ± .- * ⁴ ^ r # s Ubersuge ei *!; * ^ ird. The Predominant M & length of Stahldrahtjeelen in derΒβit manufactured ACSR is made by eineis iBatmuc'Hgalvmnieierverfahren that "under a Ansah! of calibration points and ~! is not right, not; auletat, well the I «^ - u * duration In the corrosive a-teosphere shortens v ± r4.

It was recognized for a long time that <ts "would be a wish, one with pure aluminum coated 8 steel wire that : By a very high tensile strength auegeseloliiiet 1st, which · was But not possible according to the previously known methods. In First and foremost, it is clear that 3ae Baslesetftll is usually id the coating process is subjected to a thermal operation

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which greatly reduces its original tensile strength, down to a value below the specified minimum. One part it has been proposed to obtain a satisfactory product by coating aluminum with a second coating metal Metal, such as silicon, is alloyed. It is known that aluminum-silicon alloys have a lower melting point than pure aluminum and it was therefore believed that the plating process could be carried out at considerably lower temperatures so that it would be possible to maintain the desired physical properties. Unfortunately, however, alloying aluminum with silicon diminishes the lorroBionexeatigkeit of the coated product is essential.

A second solution to the problem discussed above was to restore the lost mechanical properties a λ drawing process to restore Jen plating. This drawing process is then followed by a stress-relieving afterglow to meet the minimum tendon requirements. It is well known that the tensile strength of a steel wire is greatly increased when it is used subject to a considerable reduction in cross-sectional area · However, for various reasons, the drawing of a coated Wire is not entirely satisfactory. Apart from the » The main problem after re-drawing is required is that the soft aluminum tends to * stick to it Collect drawing form entrance and pinch off the wire.

at

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Another previously proposed solution used complex salts as fluxes which, by eliminating the need for oven cleaning, made it possible to achieve a maintain a high degree of the original mechanical properties of the wire. The problem here is that it is extremely difficult to prepare the flux completely removed after the coating and a regular flux on the wire after plating the corrosion resistance of the product deteriorated

In view of the above explanations, the specific Express the objectives of the invention as follows «

The main aim of the invention is to create a method with which a stick-like bite object with predetermined physical properties can be coated with practically pure aluminum, while maintaining the original Tensile strength in an acceptable level.

Another object of the invention is to provide one Process, like a high-tensile aluminum-coated one Steel wire can be manufactured, which is characterized by superior corrosion resistance.

Another object of the invention is to provide a method to cover an otrang-like egg object with

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practically pure aluminum, which does not require any prior flux treatment.

Hoche: Another object of the invention is to provide one Veri'iihrena, represent the manufacture of an aluminum coated Steel-based wire that meets the ACSR standard requirements fulfilled and in which no renewed pulling angow "clet will.

Perrior has an aim of the invention in the creation of a Process in which the above objectives are obtained in an economically and commercially feasible manner,

Broadly speaking, in practicing the invention, a continuous, char strand of cold drawn wire having the desired physical properties is subjected to a series of cleaning steps which thoroughly clean the strand surface. The cleaned strand is then fed into a furnace which has a reducing atmosphere and is operated at a fairly tight and precisely controlled temperature range, which will be discussed in more detail below. Without exposing the strand to the outside atmosphere again, the servant is then passed through a (-'- eiraB ¹ * with a molten metal overhang. Mo the temperature of the overlying metal and the janity of the strand in this, are very important aspects do.v iJrfinrlun "; dar * So

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as soon as possible after leaving the cover bacJec eubb the wire can be cooled to reduce the coating, and the desired physical strength in the coated product maintain.

The invention will now be described in detail with reference to the attached drawing, in which the single figure shows a description and form of a wire coating method according to the invention.

The starting material for practicing the invention is preferably a high carbon steel that has been cold drawn ^{to a tensile strength of about 18,300 kg / cm 4 *.} The brewery;, .. re area for the. The carbon content of the starting material appears to be rather narrowly limited. It has been found that steel wire with a carbon content between 0.60 and 0.90 # is completely satisfactory. however, it is clear that the height of the strand material can be varied outside of this range with the addition of suitable alloying elements. The strength of the base metal atranga before coating can naturally " fluctuate in a relatively wide range and in order to ensure the above-mentioned postigkVitberelch in the coated state", the initial sweeping is not very critical.

KJ II

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A steel wire 10 that fully meets the above requirements met, is from a delivery roller 11 through the various Deputy of the invention.

The first stage of the invention is generally used for thorough cleaning of the surface of the wire strands. In the first step of cleaning, for example, carbon-like drawn connections are removed from the wire surface. This is done by passing the wire through a Mar-Temp-salt bath 12 (consisting essentially of HatriUTmitrat and Hatriunmitrit is) is conducted, welohes is maintained at a sufficiently high temperature to the wire to a temperature in Dereich 370-540 ⁰ C. to heat. Various conventional steps, such as a bieoxidation bath or simply heating the strand in an oxidizing furnace, can be used so long as these temperature conditions are met.

After leaving the salt bath 12, the wire runs under the Varmspülfcrauee 13 and into the acid pickling bath 14, which removes adhesive bonds that were pressed into the surface of the wire during drawing. The exact strength and temperature aei? acidic solutions are not absolutely critical to the invention. A solution containing 8 # HOl and maintained at 54 ⁰ C provides satisfactory results. The acidic pickling bath does not remove drawing compound particles that are in the surface

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of the Stahldraliteu inkrußöiert Bind, but also dao surface oxide, the calibration after leaving the salt bath results and delivers a light drape surface.

Before introducing it into the reduction furnace, it is necessary to remove any residues Remove from Braht 10 * This can be done by taking cold water 15, the Burstsn cleaner 16 and a hot waoser flush as shown at 17. The hot water rinse 17 takes place largely »self-drying. In some cases it can the buret cleaner 16 can be omitted, with residual acid is then removed by an alkaline high pressure spray. Palis the scrubber 16 is used, 1st the one used at 17 Rinsing solution, preferably very slightly alkaline, so that a very thin film of alkaline material remains on the wire, which enters the dryer in order to keep the rust as low as possible, while the surface of the wire dries.

It is obvious that there are many other methods to perform these Vorreinigungeschritte, einschlieeelich the use of an aqueous alkaline solution of Ifatritiahydrid, a sand blasting or the like or Granaliengebläee _e opoziellen The above-mentioned steps are ale such is not critical to the invention.

The wire 10 is next over a suitable guide disk 18 and in the heat-resistant tube 19, which is in the furnace 20

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g.

attached isc, led »Sin suitable GaH, e.g. ated ammonia, is fed into the tube 18 through one in the drawing inlet not shown fed to a reducing « Create atmosphere.

In the tube 19 the wire is heated to a temperature which approaches 660 ⁰ G, but does not exceed it. It is well known that the temperature is below the melting point of practically pure / luninii ~ u, so that at this point the wire heat is insufficient "To finish the coating properly" ^11. This means that the coating metal temperature does not have enough margin to provide a sufficiently flowable film of molten metal around the wire. 3 bands such that a smooth, smooth, conentric coating of the desired thickness is formed.

Without exposing the wire 10 to the atmosphere again, it is transferred from the tube 19 in the furnace to a bath of molten aluminum 21 led. The preferred coating apparatus will be discussed in detail

in the German patent specification. (Patent application

), As already at the beginning of the

Description was found is a superior Korro sionsbestä nd accuracy

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oioiiGbentändigkeifc get a bath of commercially pure aluminum by use and, therefore dag pure Überi'.ugometßll is preferred * The term "technically pure Ali" ΐnium "refers Aich on an aluminum containing only insignificant Mtmgen of impurities. Fai is of course possible Ίηπ Λΐιΐϊηΐ— η! Umbau zu alloy «in order to obtain a greater scope for compliance with the ACSR-B standard requirements.

From the attached chemical drawing it can be seen that the wire 10 directly ″ and without any support from the reducing Atmosphere in the pipe "9 do the coating. This int wlclitigi to ensure that the wire temperature is continuous is increased from the point in time in dom rUea «r Reduction furnace offered, am he there about:; ugsbad verläse md there a very simple over-the-top process, wolchoo through the Absence of puhrungee disks and the like, at this stage noted, causing bends of deo tape, F.eiesen and bedlenunge difficulties be eliminated.

The time / temperature ratio during immersion of the FHahltrimgQS in aluminum is also critical for the invention. As ej.'klurb above, the exit temperature of the wire from the reduction furnace is below 66O ⁰ C, that is below the melting point of technically pure aluminum. Boron wire nut therefore by dta geechmolrjcne aluminum cmi dia final ...- ,. in

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Completion temperatures (660 to 677 ⁰ C) are heated,

The time-temperature ratio required during the actual coating step is such that the surface temperature of the wire is increased to over 660 ° C. so that the completion can take place.Optimal conditions occur when the wire is heated ^{to a temperature just above 660 ° C.} , but under technical conditions this would be practically impossible. Therefore, for the technical operation of practical wire surface temperature range from 660 to 677 ⁰ C. Higher temperatures are possible, but quite unfit to obtain high tensile strength in coated condition as agent missing for a sufficiently rapid cooling or quenching "

In a nutshell, the wire surface temperature is a Puncture of the temperature reached before entering the coating bath, the temperature of the bath and the Bintauohzeit in this. In other words, the temperature of the wire must be when it enters in the Überzagobad plus the tfberhitee recorded in the bathroom itself sufficient to bring the surface of the wire to the finishing temperature at which the wire at the point in time at which it leaves the coating bath contains sufficient warnings to do so on the surface of the wire a metal film that is capable of being applied for anschliesoenöo finish exists. These factors

can

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can be changed as desired, as long as a wire top surface temperature in the above range during the coating period is obtained.

To effectively solidify the aluminum coating and the wire To cool immediately after leaving the bath 21, means must be provided, which is essential in order to obtain sufficient strength in the coated state. For this the drawing shows a short gas preparation chamber 22, the a quenching with water 23 immediately follows.

The coated wire can then be taken up by a take-up roll 24 for storage or further processing «

To show a specific embodiment of this procedure, the following values from a laboratory test are given. A wire with a diameter of 0.101 eyes and the following composition was used as the outer material:

Carbon 0.80 #

Manganese 0.68 #

Phosphorus $ 0.009

Sulfur 0.030 #

Copper 0.14 i »

Silicon 0.19 #

Aluminum 0.004 #

The wire was cold drawn to an initial tensile strength of 18700 kg / cm ² »

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The cleaning steps were carried out as generally explained above, including immersion in a lead oxidation bath at a temperature of 54O ⁰ C for a period of about 4 seconds.

The wire reached a Oberflächenteraperatur of 621 ⁰ C in the reduction furnace directly before entry into the coating. The bath (pure aluminum) was maintained at 682 ° C and the immersion time was limited to 1 1/4 seconds under these conditions the wire temperature rose slightly above 660 ⁰ C to obtain a good coating. Of course, as mentioned above, this critical wire temperature can be achieved with a shorter immersion time using a higher bath temperature.

The examination of the coated wire showed the following physical properties! 1 # yield strength - 11650 kg / cm; Tensile strength - 1,560 kg / o » ² ; Elongation over 25.4 em - 4.5 * ♦

In another beispieleweieen approach using practically the same of the previous example Ausgangematerial a Mar-Temp-salt bath was used in place of the Blaibades, the aluminum bath was maintained at 704 ⁰ C and the immersion time was limited to 0.04 seconds. The examination of this wire revealed the following physical properties:

1 ft yield point

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1 i> yield strength - 11760 jrg / om ² ; Tensile strength 134-00 kg / era ² ; Stretch over 25.4 cm - 5 #.

to the thermal treatment to repeat short, the Were you exposed to the wire This is first heated to a temperature in the range of 370 to 54O ⁰ C in a salt bath, then cooled to a low temperature verhältnisr.iässig, BEV 'it is heated continuously eo that while it is in a molten coating metal bath, it reaches the required coating temperature. It is assumed that the first heating step is a pre-tempering or batepenning treatment, and it has been found that this pre-temperature very clearly and substantially affects the elongation or ductility of the coated wire and helps to maintain the cold tensile strength during the second heating stage.

The invention has been described above on the basis of an exemplary embodiment. It is obvious, however, that daae numerous changes and modifications are possible without departing from the scope of the invention.

Claims

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Claims (10)

Claims 1.) Continuous process for coating a metal - strand with molten metal, characterized de.se a) the surface of the strand is thoroughly cleaned, b) the cleaned strand in a protective atmosphere on a Temperature is heated below the temperature of the plating metal bath, c) passing the strand through a bath of molten metal being the speed of the Durohtrittee of the strand through the pad with the temperature of the bath in Beeiohung it means that the surface of the strand is essentially heated to the production temperature of the coating metal and d) the coating solidifies and the strand is cooled " 2.) The method according to claim 1, characterized in that the thorough cleaning of the strand surface is carried out by heating the strand to a temperature in the range from 370 to 540 ⁰ C and then cooling the strand before heating the cooled strand in a protective atmosphere. 3.) The method according to claim 1, characterized in that the strand surface is thoroughly cleaned by first heating the strand to a temperature in the range of 370 to 3 540 ⁰ C in order to remove carbon-like material from its surface 9 0 9 8 3 0/05: 7 BATH burn area, the train then an acid pickle * unt-r - will throw · χη Ziehverbindungeteilchen that are incrusted in the Stra.gcberfläche, rinsed to remove and then the train i-ur Enti'Hrnung restlioher Iteisssäure and dirt 'ird · 4.) Method according to claim 3? characterized in that d ιββ dnr strand n & oh the acid pickling and before rinsing the strand being scrubbed. 5j) Method according to claim 4, characterized in that nozzle 41 · solidification of the coating and the cooling of the strand by means of a liquid quenching agent. 6 ") Method according to claim 1, characterized in that this dl · The maximum temperature obtained in the heating step is 1 bar before the strand enters the molten metal bath. 7.) Continuous process for coating metalütechee strand material with technically pure aluminum, daduroh £> - indicates that a) the surface of the strand is thoroughly cleaned, b) the cleaned strand is heated to a maximum age in a reducing atmosphere, dl 56O ⁰ O, the melting point of aluminum, does not exceed the maximum temperature practically at the brew of the Brhitzungsehrli tea reached 909830/0557 SAD ORIGINAL is achieved, ο) immediately afterwards the strand is passed through a bath of techniaoh pure molten aluminum »whereby the speed of passage of the strand through the bath is related to the temperature of the bath in such a way that the surface of the strand is at a temperature in the range from 660 to 677 ⁰ C is heated and d) the coating solidifies and the strand is cooled. 8.) The method according to claim 7, characterized in that the strand passes directly and without support or carrier from the HeIs reduction stage into the bath of molten aluminum. Method according to Claim 8, characterized in that the strand surface is thoroughly cleaned by heating the strand to a temperature in the range from 370 to 54O ⁰ C and includes cooling the strand before it is heated in a reducing atmosphere. 10.) A method according to claim 7, characterized in that the thorough cleaning of the surface of the strand is accomplished by the strand is heated to a temperature in the range 370-340 ⁰ C at first, burn, inter alia, carbon-like material from its surface and the strand then an acid pickle is subjected to remove pulling bond particles encrusted in the strand surface and the strand is then rinsed to remove residual pickling acid and dirt. 909930/0557 BATH Blank page - 1Ϋ-