US2870903A - Metal drawing lubricant - Google Patents

Description

Jan. 27, '1959 Filed April 8, 1955 J. A. M. LEDUC METAL DRAWING LUBRICANT IWIREI SURFACE CLEANINGI IMOLTEN cAusTlcl {EEO-LIE; I .J

T Y MOLTEN FATTY SUBSTANCE f HEAT SURFACE TO ELEVATED TEMPERATURE Y ICOATED WlREI I T L 1 I L JQ EQ |T r [WIRE DRAWINGI WATER OR 7 A ME! I .q --1 I FINISHED WIREI FIG. 2

4 Sheets-Sheet 2 INVENTOR JOSEPH ADRIEN M. LEDUC ATTORNEY Jan. 27, 1959 ,1. A. M. LEDUC METAL DRAWING LUBRICANT 4 Sheets-Sheet 3 Filed A ril 8, 1955 INVENTOR JOSEPH ADRIEN M. LEDUC ATTORNEY J. A. M. LEDUC METAL DRAWING LUBRICANT Jan. 27, 1959 4 Sheets-Sheet 4 Filed April 8, 1955 INVENTOR JOSEPH ADRIEN M. LEDUC ATTORNEY erations.

2, 19. METAL DRAWING U CANT .5 1 Ad ifll M. Leduc, Palnesville, vQh i 3 m 19 Diemond'Allreli (lompanyffileveland, Ohio, a corPGEai n o P ilaw r i Application AprilS, 1955, Serial No. 500,058

2 c aims. (c1. 2.05172 ing. Processes of this type, while'used'commercially,

involve a relatively large number of operations andhave certain inherent disadvantages, including the additional process control required and costs involved. Addition ally, in many processes of-this type, organicsplvents are employed as carriers for any lubricant coating applied.

These solvents generally must be removed" and often leave an objectionable greasy residue on the metal.

Another prior process involves passing wire, or other metal to be treated, through a molten salt, for example, molten caustic, followed by either aqueous Washing, without further treatment, or by aqueous washing together with additional rnetal treatments. Such processes, in some instances, are satisfactory. However, any coating or film thereby formed on the metal is but a surface layer which can be relati vely easily removed, Moreover, the intermediate aqueous washings remeve much of any such surface coating.

A third type of metal treatment contemplates passing wire or other metal through a molten bath comprising the reaction product of caustic; soda and a fatty aei'd. This procedure thus involves passing the metal through a molten soap, generally in, the, presence of gaps-tie. Again, while a soap film is applied to the surfaceofthe metal by this technique, the'coating comprises a pre f ormed soap which may be relatively easilyremgyed from the metal surface. H

S n h r m a of n m mqus of. su fac coating in wire drawing may seriously impair the quality of the drawn wire, or injure the drawing dies, it will be appreciated that while the prior art metal treating processes do provide various types of lubricant films, the

heretofore proposed processes have not been a completely satisfactory solution to the'problem of preparing metal for drawing operations.

Accordingly, the present invention has for its. principal object the provision of a new, and improved metaltreating process which avoids the difficulties heretofore enu er n c ndit on n m ta pr or deep. dr win operations.

A f h r b ec f h nventio i he: p ovision o a n d mprov d adherent. Pr tective. ubr canta metals.

Unitrd sates PM 0 w A t l furt q birst of ha a r sn isle. arqv sle a 2,870,903 Patented Jan. 27, 1,959

new and improved rnetal treating process of eonditiontion will appear more fully from the following description.

Generally, the present invention is based upon the discovery that an improved, uniform, adherent and durable surface diffusion'layer can be provided on metal by contacting such metal successively with a first bath cornprisingat least one molten alkali metal hydroxide and a second bath comprising at least one molten fatty substance, such as a molten fatty acid, capable of chemical reaction withsaid hydroxide to form a strongly adherent, protective, lubricant surface diffusion zone at and beneath the metal surface and thereafter subjecting; this surface diffusion zone to an elevated temperature.

In general, the elevated temperature to which the surface diffusion zone is heated, and the length of time it isexposed to such a temperature, may be varied, depending on the particular application. However, it is, .of course, desirable that the metal itself not be appreciablyheated}, at least not heated to the extent that the metal surface diffusion layer bond is impaired. On thecontrary, it is preferable only briefly to exposethe surface of the diffusion layer to a relatively high temperature atmosphere, e. g., WON-1 500 F., as by passing the metal through a furnace maintained at such a temperature. r

In practice, excellent results have been obtained by passing metal, treated with molten alkali metal hydroxide and a molten. fatty substance, through a furnace maintained at a temperature within the range from the melting. point of the molten fatty substance to a higher temperature dictated by the application intended and the speed at which the treated metal will be passed through the furnace. In certain applications, temperatures as high. as 2000" F; may be used. At present, in treating wire it is preferred to expose the surface diffusion zone to an atmosphere maintained at a temperature within the-range from about 10009 -1I500 F. by passingthe treated: wire through such an atmosphere at: a rate of from 10 to 20 feet per minute. Those skilled in the art Will recognize that by. increasing the speed at which treated wire is passed through a high temperature atmosphere; a corresponding increase in the temperature employed is. required in order to accomplish the same amount of heating.

By the practice of this invention the molten alkali metal hydroxide provides a penetrating. and cleansing action on the metal; being treated; Further, this beneficial action of the alkali metal hydroxide establishes the alkali metal hydroxide in highly reactive form, both at the metal surface and deep vvi t he pores of the metal. Hence, when a thus-treated rnetal is contacted with a molten fatty substance, such a, fatty acid, a chemical reaction occurs not only at .the surface of the metal, but after penetrating or diffusing into. the metal Within the metal pores as well to establish, what is herein referred to as a surface diffusion. sorrel The subsequent elevated temperature treatmentror baking further enhances the desirable features-ref the surface by removing unreacted fatty bstance and. ro id n smoo her-mars uniform surface. Accordingly, the resultant reaction product surface diffusionzone is'extremely diflicult to remove byabrasion, as Well asibysuch handling metal receives in industry prior to further treatment.

Another inherent advantage is realized since the heat treated reaction product cgr npning the improved surface diffusion zone essent'ially isa soap or other lubricant soap-likc material; not enly, are excellent lubricant characteristics provided, butremoylal of this surface life fusion zone when desired may be accomplished readily by washing with water or steam without an elaborate or costly cleaning procedure. I

The preferred practice of-the invention at present contemplates first preheating metal to an elevated temperature, above the temperature of the molten alkali metal hydroxide employed, quenching the thus-heated metal in the first molten bath comprising molten alkali metal hydroxide," and passing the metal into a second molten bath, containing a fatty acid or other substance capable of reacting with the molten hydroxide, as indicatedabove. The thus-treated metal is then subjected to an elevated temperature for a short time, the, temperature being high enough substantially completely to remove unreacted fatty acid or other'unreacted fatty substance and the exposure time being sufliciently brief so that the surface diffusion layer itself is not injured, nor, in most instances, is the metal appreciably heated.

Those skilled in the art will appreciate that the foregoing sequence is particularly advantageous where it is desired-first to anneal or otherwise heat treat wire or other metal to be processed, since such metal can advantageously be transported directly from the heating furnace, preferably through an inert or reducing atmosphere, such as hydrogen, cracked petroleum gas, argon, nitrogen, carbon dioxide, mixtures thereof, or the like, into the molten alkali metal hydroxide of this invention without intermediate treatment.

As used throughout the specification and claims, the

expression alkali metal hydroxide is intended to include hydroxides of the various alkali metals, e. g., sodium, potassium, rubidium, cesium, and lithium. However, sodium and potassium hydroxides are, of course,

the commonly used alkali metal hydroxides. Because of its availability andlow cost, sodium hydroxide is the' form an adherent, protective, lubricant surface difiusion zone may comprise a variety of materials capable of forming an adherent reaction product upon chemical combination with an alkali metal hydroxide. Such materials include oils, greases, fats, fatty oils, fatty acids, and fatty acid derivatives, such as fatty acid esters, amides, and the like, and are generally termed fatty substances herein. At present, it is preferred to employ one or a mixture of fatty acids of commercial purity. Superior results are obtained using a fatty acid or fatty acid mixture which solidifies at a temperature well above room temperature, i. e., 70 F. Typical fatty acids which may be employed, either alone or in admixture, include such saturated fatty acids as caproic caprylic capric lauric myristic palmitic stearic arachidic behenic, and lignoceric acids as well as unsaturated fatty acids, such as myristoleic palmitoleic oleic linoleic linolenic elaeostearic licanic ricinoleic, and erucic acids In some instances, natural oils and fats containing substantial proportions of one or more of such fatty acids also may be employed. Illustrative of such materials are tallow or lard, fish oils, such as whale, menhaden, sardine, and herring, plant oils, such as coconut, palm kernel, babassu, murumuru, palm, rape seed, mustard seed, olive, peanut, sesame, corn, cottonseed, soybean, sunflower, walnut, linseed, perilla, castor, tung, and oiticica oils, as well as certain halogenated derivatives thereof. However, aspointed out hereinbefore, it is preferable to utilize a fatty substance which, upon reaction with the alkali metal hydroxide, forms a continuous solid reaction product layer and'which has a relatively high flash point in order to minimize danger of fire caused by contact with hot metal. Any danger from such flash fires can also be prevented, of course, by blanketing the molten baths with an inert atmosphere.

In some instances it is desirable to incorporate one or more additives in the molten baths of this invention.

Suitable additives for the molten alkali metal hydroxide bath include substances to lower the melting point of the caustic and/ or to improve the cleansing action of the caustic. Additives for the molten fatty substance may include sulfur-containing substances, such as molybdenum disulfide, sodium sulfide, sodium sulfite, as well as other lubricant-type materials, e. g., mica, graphite, and the like.

Referring now to the drawings,

Fig. -l is aschematic flow diagram illustrating one embodiment of the method of this invention;

Fig. 2 is a schematic flow diagram illustrating another embodiment of the method of this invention;

Fig. 3 is a schematic representation of one form of apparatus which may be used in the treatment of wire in accordance with this invention; and

Fig. 4 illustraties schematically another type of apparatus for the treatment of wire in accordance with this invention.

Referring to Fig. 1, wire first is passed into molten caustic and then into a molten fatty acid, thereby to form, in situ, a surface diffusion zone of a lubricant soap coating. As indicated in Fig. 1, the wire may be, and at present preferably is, subjected to a heat treatment, such as annealing at 1600l850 F., the temperature depending on the type of wire being processed prior to immersion in the molten caustic. Optimum results are obtained when the wire is heated to a temperature in excess of the temperature of the molten caustic ,thereby to obtain a quenching effect when the wire is contacted with the molten caustic. In this heat treatment there preferably is provided an inert atmosphere, e. g., nitrogen, carbon dioxide, or the like, surrounding the wire. In practice, it is frequently advantageous to extend the furnace exit tube beneath the surface of the molten caustic to insure maintenance of the desired inert atmosphere.

The wire is then passed from the molten caustic directly into the molten fatty acid without intermediate treatment, although in some instances, it is desirable to accomplish a predetermined amount of cooling interme-' diate the first and second molten baths, as by passage of the wireover one or more pulleys or spools intermediate the molten baths. Such cooling is only required when it is necessary to minimize danger of igniting the second molten bath, e. g., fatty acid, upon contact with the heated metal.

After removal from the second bath, the wire is sub jected to an elevated temperature in a baking or-other heat treatment operation. Such a heat treatment is not intended appreciably to heat thewire itself but, on the contrary, briefly to expose the surface of the lubricant layer to an elevated temperature. The singular improvement obtained by such heat treatment, or baking, is that any unreacted excess fatty substance mechanically car- 9f time i p t is r i m a smoother,:ntore uniformcon V W surface is obtain ed l f H The resultant coated Wire may then either be stored 9 shipped w out fur he tre tment, o p ss d ire t y through wiredrawing dies. The drawn wire still retains an appreciable thickness of a continuous uniform, protective and lubricating surface layer. In some instances, it is desirable to remove this layer by treatment withwater, or, preferably, by steam treatment. In othercases, since this layer is extremelyadh'e're'nt and offers continued protection against rust, corrosion, and abrasion, it is advantageous to ship or store the .wire without removal of this layer.

Fig. 2 illustrates amodification of the process of this invention which does not involve heat treatment of the wire priorto contact with molten caustic. In'the process shown in Fig. 2, wire is subjectedto surface cleaning prior to caustic treatment. Typicaliof the surface cleaning treatments contemplated are such conventional metal cleaning procedures ssana blasting,'ac id picklihgfa cid etching, and/or other abrasive orchemical treat ent, including electrolytic metalsurface cleaning operations. It should be emphasized that in many applications no pretreatment of the metal isnec'essary at all, the molten caustic 'acco'rding a thoroughirust removing and surface cleansingaction". Thewire'is then s ubjected-to the same sequence of operations illustrated in Fig. 1, which operations, of course, may or may not include cooling intermediate the molten baths.

Fig. 3 illustrates, in schematic form, apparatus partic ularly adapted in the treating of hard'drayvn wirein accordance with this invention. The apparatus shown in Fig. 3 for treating a wire 10 comprises a storage reel 12, a feed pulley 14,afirst tubular heat treating furnace 1,6, ,amolten caustic container 13 a guide pulley 20, a fatty acid fit'a'iner'zg, a second tubular heat neat Ient furnace 24,anischarge n gy 26, and takeup pulley Z8driven. through belt 30 by a rn'otor 32.

Those skilled in the art willre alize that a variety of types of supporting structures (notshown) maybe employed in utilizing theapparatus in lig 3. To provide an inert or redu cinglatmosphere when desire dgthere may be provided tubular extension 17 having a gas'inlet "19 for countercurrently introducing the desired atmosphereproviding gas, e. g., nitrogen. Alternatively, the outlet of the furnace 16 and the molten caustic container may be juxtaposed to eliminate exposure of. the wire .prior to contact with the caustic.

The molten caustic container 18 and themolten fatty acid container 22 may be fabricated from nickel, steel, Monel, or o-ther c'hemicaland temperature-resistant metal of alloy. Each of theicontainers 18 and 22 preferably comprises a curved tubular member, e. g., 12 inch radius,

having an inlet intermediate its ends, and .a radius of curvature dictated by the minimum bending radius the wire to be processed can Withstand. Hence, it Will be appreciated that the containers 18 and 22, having a relatively large radius of curvature, permit the processing of hard drawn wire which is capable of only a slight degree of bending without rupture. Moreover, containers of this type have the additional advantage of permitting the use of relatively small quantities of molten caustic and molten fatty acid.

In order to provide. the desired elevated. temperature within the containers 18 and 22, each container is pro- .vided with suitable heating means, such as a longitudinally extending heating coil comprising an electrical resistance heating element (not shown). In order to minimize heat loss the containers 18 and 22 preferably are suitably covered with asbestos or other insulation.

In operation, using the apparatus of Fig. 3, wire 10 is passed continuously from the storage reel 12 over feed pulley 14 through the heat treatment furnace 16 'wherein any desired heat treatment in advanc gf fi;

(f ty acid c nt n 58, 'a

apparatus which fnay be used in treating wire 10" in the practice of this invention, there is -prdvided a storage spool 34, a first heat treatmcntfurnace 36, guide spools -5 and lea m t n au .c aia 56 p av c wi h hea msim n (not she. a).

. some. W than. a aq d the tre tm nt t raa s 4.8. an it aken? $1 1 550 mamma be 5 a s mi ra T ere is in t ate s hra sti all 'iihb a s nl n s 5 n embodiment of apparatus permitting the "use of a special atmosphere, e. g., inert or reducing, in the furnace 36 without exposure of the wire 10 to the outside atmosphere prior to contact with the molten caustic. There is ralso provided an inlet39 for introduction of'the desired atmosphere providing gas. e. g., nitrogen. The operation of the;apparatns illustrated in Fig.4 is similar to that previously described. The sequence of .operations is as follows: Wire 10' is taken continuously from storage reel 34, passed successively through the first heat treatm a qrna r 36. thro gh molten F na ic n QFIlil 56, nia a at ri in q' i aifi 55. ihw h the ec n heat treatment furnace and onto ta e np spool 56'.

The various heat treatment furnaces indicated in the drawings may comprise different types of apparatus, including flame heated devices, depending upon the par ticular application. However, it has been found practicable in most instances to employ a tubular heating chamber having a relatively small diameter, e. g, /2 to 1 /2" 011'1685, the size, of course, being dictated by the size of wire or other metal processed, and providing ade- .quate heating :by a spirally disposed electrical resistance heating element about the tubular heating chamber. Those skilled in the art will realize, of course, that a suitable electrical resistance heating element may comprise Nichrome wire, and the tubular heating chamber may be formed from a heat resistant metal, such as nickel, steel,,or other suitable metal or alloy, or, if desired, from a heat-resistant metallic or non-metallic refractory substance, such as glass or other refractory. It is desirable to provide heat-resistant insulation about the heating chamber and heating element, a typically practicable in; sulation being fibrous asbestos or other mineral substance, with or without a heat-resistant binder.

In order that those skilled in the art may more completely understand the present invention and the preferred methods by which the same may be carried into effect, the following specific examples are o-ffere Example I A non-annealed steel wire 0.081" in diameter, moving at a speedof 10 feet per minute, is first passed through a 3-foot long, 4" diameter, electrically heated tubularfurnace at a temperature of l835- P. The wire emerging from the furnace is at red heat and has an approximate temperature of 1475 This preheated wire passes co ntinuoualy into molten sodiumhydro-xide, which has a temperature of 6 The wire then immerspd in molten stearic acid maintained at a temperature of 300 F. The continuously moving wire is then passed through an 18" long 1 diameter tubular furnace maintained at a temperature of1205 4 1 i The thus-treated wire is then passed through wiredrawing dies wherein, in one pass, it is subjected to a substantial reduction, i. e., 30%, in diameter. The wire draws readily without injury to the die or accumulation .Of excess coating thereon. The drawn wire retains. an adherent B and sat a d 'fiiu sa 9. wh stles/ s w lish ma t-tn {any either removed by water or steam washing, ormay be allowed to remain on the wire for protective purposes.

Example 11 The procedure of Example I is repeated using palmitic acid instead of stearic acid. Substantially the same results are obtained.

Example Ill Employing apparatus of the type illustrated in Fig. 3, using a tubular furnace having a temperature of 1475 F. and provided with a nitrogen atmosphere, iron wire is heated to red heat and passed successively through molten sodium hydroxide at 680 F. and stearic acid at 212 F. There is obtained a durable, protective and lubricant surface on the wire.

Example IV The procedure of Example III is repeated and the trated wire is passed at a speed of 10 feet per minute through a second tubular furnace maintained at 1475 F. to obtain a harder, more uniform surface and to facilitate removal of unreacted stearic acid.

Example V The procedure of Example IV is repeated, using potassium hydroxide instead of sodium hydroxide. Substantially identical results are obtained.

Example VI To illustrate the use of molten alkali metal hydroxide in combination with other fatty substances, a series of experiments are conducted in the following manner. Iron wire is pickled in 50% hydrochloric acid for minutes, rinsed in water, and then heated to 1350 F. in a quartz tube by gas burners. A nitrogen atmosphere is provided in the furnace.

The thus-treated wire is then dipped for 5 seconds in molten sodium hydroxide maintained at a temperature of 680 F. and thereafter immediately dipped into a second molten bath for 5 seconds, the second bath being maintained at a temperature of 300 F. The thus-treated wires are then passed rapidly through the heated quartz tube to obtain an improved coating surface. The following table indicates the compositions of the second molten bath and the type of reaction observed:

Fatty Substance Reaction Observed Tung Oil l Mild Reaction.

Do. Vigorous Reaction. Mild Reaction.

Vigorous Reaction.

Although, as indicated in the above table, a reaction is noted in each instance, the adherency and surface characteristics of the resultant coating vary, depending on the composition of the second molten bath.

Example VII The procedure according to Example VI is repeated using somewhat different temperature conditions. In this set of experiments the tubular furnace temperature is maintained at 1832 F., the molten sodium hydroxide temperature is 932 F., and the fatty substance temperature is 302 F., the coated wire samples being passed through the tubular furnace after immersion in the molten fatty substance in addition to an initial pass through for O ll Fatty Substance Reaction Observed Mild Reaction-Short Duration. Mild Reaction.

Do. Vigorous Reaction. Mild Reaction.

Vigorous Reaction. Do.

7 Example VIII A further series of experiments are conducted according to the procedure of Example VI, except that after the wire is washed with water, following acid pickling, it is placed in an oven maintained at 212 F. for 15 minutes. The tubular furnace temperature is maintained at 1562 F., the molten sodium hydroxide temperature is 932 F., and the molten fatty substance temperature is 302 F. The results of such runs using the fatty substances, wherein the coated surfaces are subjected to an elevated temperature following immersion in the second molten bath, are set forth in the table below:

Fatty Substance Reaction Observed Beet Tallow Mild Reaction. L d D o. Vig r us Reaction.

Mild Reaction.

Example IX To illustrate the effect of removal of surface diffusion layers formed in accordance with the present invention, a 12" length of 7 diameter iron wire which had been coated by successive immersion in molten sodium hydroxide and stearic acid and passed through an 18" x 1%" diameter tubular furnace maintained at 1475 F. is placed in a jet of 250 p. s. i. g. steam. By such treatment the coating is substantially all removed.

Example X A further experiment is conducted by placing a drop of room temperature water on a length of wire treated with molten sodium hydroxide and molten stearic acid. Examination under a microscope reveals that the surface diffusion layer softens under the influence of water and can then readily be removed by wiping. Toluene and carbon tetrachloride are applied in the same manner as the drop of water to an identical coating without appreciable solvent effect.

Example XI A 40-foot length of iron wire previously conditioned in accordance with the process of this invention by successive immersion in molten sodium hydroxide and molten stearic acid and baking at an elevated temperature is given a 54% reduction from 0.0915" diameter to 0.062" diameter in four passes through wire drawing dies at a speed of feet per minute. The intermediate die sizes and the percent reduction for each pass are as follows:

Percent The appearance of the surface of the wire coating improved after each draw and the finished 0.062" diameter wire retained a uniform coating.

Example XII To illustrate the use of lubricant additives to the molten fatty substance, the following series of experiments are conducted. Samples of iron wire are pickled in HCl at room temperature, rinsed, dried, heated to dull red heat in a nitrogen atmosphere and immersed in molten sodium hydroxide maintained at a temperature of 932 F. The samples of the thus-treated wires are then separately immersed in a second molten bath comprising stearic acid and one 'of the following additives, the indicated percentage being by weight of the stearic acid, and thereafter passed through a tubular furnace maintained at 1832" F. at a rate sufiicient to cause only the removal of unreacted stearic acid and an improvement in the surface of the diffusion layer without appreciable heating of the wire itself. 1

5% mica powder (160 mesh) 50% powdered graphite (Acheson Electric Furnace Graphite grade 38-National Carbon Co., Inc.)

5% powdered graphite (Acheson Electric Furnace Graphite grade 38-National Carbon Co., Inc.)

In each instance, no apparent reaction of the additive with the stearic acid was noted and the resultant coating was smooth and homogenous. The baking treatment provided a hard, thin, adherent surface diffusion layer. It will be appreciated, thus, that in addition to the other advantages hereinbefore set forth, the present invention affords an excellent means for binding graphite, even a large amount of graphite, on a wire prior to drawing.

Throughout the specification and claims, in stating that the alkali metal hydroxide is employed in the molten state, it is meant that its temperature may range from the temperature at which the particular alkali metal hydroxide or mixtures thereof become molten, to a temperature limited by the boiling point of such hydroxides. However, as a practical matter, the temperature, which, of course, may be varied within this range, depending upon the particular application, is the lowest which provides the desired effect on the metal being treated. Typically practicable temperatures, using sodium hydroxide, are within the range from its melting temperature, i. e., 318.4" C. (606.1 E), to about 510 C. Similarly, the temperature of the second molten bath also may range from the melting point to the boiling point of the substance or mixture employed, or higher if a vapor phase reaction is desired, although generally temperatures as low as possible within this range are employed. Using stearic acid, typically practicable temperatures within the range from 250-310 R, although temperatures as high as 375 F. have been used.

The speed at which wire is passed through the molten baths and heat treating furnaces can be varied widely and is dictated by the type of wire being processed and the particular application intended. However, in small-scale installations employing temperatures of the order indicated hereinbefore, lineal speeds within the range from to 20 feet per minute are typical. It is appreciated that commercial wire drawing operations involve wire speeds often as high as several hundred feet per minute. For example, stainless steel wire drawing speeds generally range from about 80 to 200 feet per minute, while carbon steel wire is often drawn at speeds as high as 500 to 600 feet per minute. Hence, it is generally more practicable to treat wire in accordance with this invention and then separately to draw the treated wire. However, in certain instances, continuous drawing operations wherein wire is first treated by the technique of the present invention can be achieved by proper selection of bath compositions, temperatures, and wire drawing speeds.

Metals which can advantageously be treated in accordance with this invention include both ferrous and nonferrous metals and alloys. Illustrative are various irons, steels, including stainless steels, titanium, copper, nickel, cobalt, as well as various alloys containing these or other metals or alloys. Moreover, while the invention has been described with particular reference to wire drawing, it will be understood, of course, that other metal operations are contemplated as well, e. g., tube drawing, pressing and stamping in suitable dies, deep drawing of sheet metals, wire rollingQand the like.

While this invention is applicable in a. variety of metal treating operations, those skilled in the art will recognize that it provides an improved method for wire patenting, i. e., heat treating of wire, generally medium or high carbon steel wire, before drawing or between draws, whereby the wire is heated above its transformation temperature range and then cooled to a temperature above this range. Wire patenting operations heretofore generally have involved successively passing wire through molten lead, acid pickling, lime slurry soaking, lime baking, and subsequent application of a lubricant. In accordance with the method of the present invention, the patenting can be accomplished directly by successive immersion of the wire in molten caustic and a molten fatty acid or other fatty substance as indicated hereinbefore, without resort to a multiplicity of elaborate and relatively costly operations as heretofore required.

While particular reference has been made herein to the conditioning of wire continually passing as individual strands or filaments through the molten baths, it will be appreciated that the practice of this invention is particularly advantageous in the treatment of coils of wire, tubing and the like. In many instances, depending on the application, such coils need not be unwound but may be treated in cell form.

It is to be understood that although the invention has been described with specific reference to particular embodiments thereof, it is not to be so limited, since changes and alterations therein may be made which are Within the full intended scope of this invention as defined by the appended claims.

What is claimed is:

1. A metal treating process comprising the steps of successively immersing the metal in molten alkali metal hydroxide, immersing said metal in a molten fatty substance which reacts with said hydroxide in situ to form a lubricant layer, and subsequently subjecting the thustreated metal to heating at an elevated temperature sufficient to remove excess unreacted molten fatty substance without removing said lubricant layer.

2. The process of claim 1 wherein said metal is subjected to drawing following removal of the excess molten fatty substance.

References Cited in the file of this patent UNITED STATES PATENTS 1,547,539 Antropoff July 28, 1925 2,076,793 Salender Apr. 13, 1937 2,127,497 Webster Aug. 23, 1938 2,132,557 Bobrov Oct. 11, 1938 2,218,557 Shoemaker -2 Oct. 22, 1940 2,432,784 Miller Dec. 16, 1947 2,632,347 Sproule Mar. 24, 1953

Claims (2)

1. A METAL TREATING PROCESS COMPRISING THE STEPS OF SUCCESSIVELY IMMERSING THE METAL IN MOLTEN ALKALI METAL HYDROXIDE, IMMERSING SAID METAL IN A MOLTEN FATTY SUBSTANCE WHICH REACTS WITH SAID HYDROXIDE IN SITU TO FORM A LUBRICANT LAYER, AND SUBSEQUENTLY SUBJECTING THE THUSTREATED METAL TO HEATING AT AN ELEVATED TEMPERATURE SUFFICIENT TO REMOVE AXCESS UNREACTED MOLTEN FATTLY SUBSTANCE WITHOUT REMOVING SAID LUBRICANT LAYER.

2. THE PROCESS OF CLAIM 1 WHEREIN SAID METAL IS SUBJECTED TO DRAWING FOLLOWING REMOVAL OF THE EXCESS MOLTEN FATTY SUBSTANCE.

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