US944371A - Process of making and casting alloys. - Google Patents

Description

J. F. MONN OT. PROGESS OF MAKING AND CASTING ALLOYS.

APPLICATION FILED JULY 16, 1908.

Patented Dec. 28, 1909.

. ing Alloys; and

UNITED STATES PATENT. onrion.

JOHN F. MONNOT, OF

NEW YORK, N. Y., ASSIGNOR TO MONNO'I. METALLURGICAL COM:-

PANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK;

PROCESS OF MAKING AND CASTING ALLOY S.-'

Specification of Letters fatent.

malted neazs, 1909.

Application filed July 16, 1908. Serial No. 443,?95.

To all whom it may concern:

Be it known that I, JOHN F. MoN Nor, a citizen of the United States, residing at Ne York, in the county of New York and one .or more of the constituent metals is sealing molten readilyvolatilizable or oxidizable, and of casting such metallic mixtures or alloys.

According to my invention, the alloy to be cast is formed, or else brought to a molten condition, under the protection of a deep operating both to exclude air volatiliza-tion, and-is drawn off from a point beneath such layer and passed into and through a substantial or deep layer of molten 'flux or slag contained in a suitable mold,

such tapping operation being preferably so conducted as to prevent or minimize any intermediate contact with air.

In many metallic mixtures and alloys where precise composition is of great importance, as in the various brasses, bronzes, alloy steels, etc., under the present practice it is a matter of somedifiiculty to maintain this precise composition during long treatments or during remelting since volatilizable or oxidizable components tend to disappear. In brass, for instance, since the boiling point of zinc is comparatively low, being about the melting point of copper, in making, melting, casting, and remelting brass, there is a steady loss of zinc which tends to volatilize from exposed surfaces of the melted metal and, since zinc vapors are readily infiammable,to burn out. In handling brass in the melted state steadyloss of zinc and the composition of the alloy steadily varies. As fairly precise ratios between the copper and the zinc are desirable are often necessary in making alloys for special purposes, this represents a grave inconveniencein the art, and the princlpal method of obviating 'it now in use is layer of floating flux or slag and to prevent.

'zinc vapor and air cannot coexist.

there. is, therefore, a-

to add more zinc from time: to time as the zmc burns out, or to use an excess of zinc. in. making the brass or other alloy, These-y methods are obviously disadvantageous,

Similar difficulties are met with in. handling on other alloys. The tin of bronze, though not very volatile at bronze-casting temperatures, is very oxidizable, and burns out, not

only changing the composition of the alloy.

but injuring itby leaving infusi-ble particles of oxid. Nickel, cobalt, lead, iron and other metals also tend to burn out of copper alloys. In the manufacture of the modernalloy steels, the alloying bodies, such as vanadium, y, titanium, chromium, etc., are generally more oxidizable than the iron and readily burn out, and, from their usual small quantity, any such loss seriously afiects the quali-= ties of the alloy. In' casting these mixed metals, the stream of molten metal passing through or in contact with the air, in addition to taking up or entrai-ning more or less air by occlusion or adsorption, tends to oxidize, becoming covered withoxid pellicl'es which prevent good contact with the moldand accurate shaping. Intthe case of brass and other zinc-alloys, the loss of zinc in casting is quite serious.- Inthe evaporation of any liquid, such as the zinc from the molten alloy, the amount evaporated in a time unit-1s directly proportional to the surface exposed and inversely proportional to the amount of its vapor already presentin the space into which evaporation proceeds As the melting-point of brass is not far'be low the boiling point ofzinc, so that the tension of zinc vapor from molten brass is quite large, it follows that, irrespective of the oxidizing effect of air, the conditions for the loss of zinc are nearly ideal in pouring a thin stream of molten brass through free" air into a mold, a maximum surface of hightemperature metal being exposed to an atmosphere which is free of zinc vapors, since more, apart from changes in composition, of the alloys incident to melting and pouring-,- in pouring much air is generally carried for.- ward by entrainment, and adsorption into the mold where it continues the oxidation 10-5 and where it leads to sponginess of the metal. In the mold itself, the walls are with a thin layer or film of always covered etc., adsorbed or condensedv air, moisture, I thereon, and it is Furtherdiflicult to displace this film by the molten metal, such metal generally having no real wetting action on the mold walls. In producing a casting, this air, etc., as it is slowly dlsplaced accumulate's to form blowholes, blebs, pits, etc., in the surface of the casting.

In another application, Serial No. 391,67 4, filed Sept. 6 1907, I have disclosed methods and means of counteracting the difiiculties due to adsorbed air and moisture in the cast metal and the mold, the invention, broadly stated, consisting in pouring the molten metal down through a layer of molten wiping material ofsubstantialdepth, whereby its surfaces are wiped free of entrained or adsorbed air and also of adhering oxids, the heavy molten metal itself passing down through the wiping material as clean metallic-surfaced metal, the several drops or portions of which are as ready for mutual -union as drops of clean mercury. For this purpose and to accomplish this end,the layer of wiping material must be qu through free air in transit. The stated method I regard as particularly adapted tobrass or bronze and other alloys of copper comprising zinc or tin,but it may also be used for a variety of other metallic mixtures containing volatile or oxidizable components. V

The flux or slag used may be one having oxid-dissolving properties, as borax or Waterglass ortheir mixtures, or a high sllica slag, or it may be substantially neutral toward oxids, like borax or water glass neutralized with soda, since in the described method of operation little chance for oxidation is afforded. a

In melting or making brass under a cover of flux or slag since there is, if the cover be thick, no exposure of the surface'of the alloy to a free atmosphere into which zinc vapors can expand, nor any absorption of such vapors, nor 1s there any opportunity for oxidation, the composition of the alloy remains substantially constant. If the flux cover be relatively thin on the other hand, exposure of bare metal and oxidation and evaporation will occur during stirring and mixin The flux cover therefore should be quite deep. In tapping off the molten alloy into a deep body of flux or slag, evaporation and oxidation are similarly precluded if the metal be taped from a low point in the mass thereo and sentinto the flux through ite deep. 7 I pre erably 7 determined and a closed conduit. In this method of operation, thewiping function of the flux or slagj in the mold upon the molten metal itself is not so important asin the processof said application Sr. No. 391,674, slnce such metal does not come into substantial contact with air and cannotentrain it or be oxidized thereby, though the wiping function remains important as far as the mold walls are concerned; for as, the molten metal accumulates in the mold, the wiping material,

being lighter, rises, progressivelywiping the wiping material has an important effect on: the strength of the cast metal; for the several particles of the cast molten metal being clean, are in good condition to unite one with another during solidification and-produce sound metal.

It is a familiar fact that superheated liquids introduced into vessels having walls which are not f chemically clean tend to evolve vapors at localized oints or nuclei on said walls, and, simi arly, that liquids containing crystalhzable components tend to a localized crystallization on similar foci or nuclei. In vessels with f chemically clean walls neither of these segregations takes place. of the presence of a large body of molten flux or wiping liquid in the molds in the present invention is that such flux causes 'the mold walls to become chemically clean. In molten brass the vapor tension of the zinc is ve high, the casting temperature of brass ein very near the boiling point of zinc, an in castinginto the ordinary molds nuclei in the walls 'tend to cause evolution of zinc vapors whereas in castin into molds "having walls kept terlal this phenomenon does not occur and the castings are sound and homogeneous. Furthermore, since-many of the valuable alloy compositions are not eutectics but tend to segregation or crystallization of alloys or meta s of different composition from that desired, the absence of crystallization-aiding nuclei in the walls in the flux-filled molds of the present invention aids-materially in securing sound, homogeneous castings of such compositions.

. The described method, it will be er- One 'of the valuable features -chemica ly clean by flux or wiping maceived, gives means of producing soun ingots or castings, free from oxid, blow-holes, sponginess or orosity, from alloys of refi'ecise composition. particularly app 'cable to brass and-other ile ' fused wiping material, or. a solid'la er of alloys containing the readily volatile and oxidizable metal zinc, it-is also advantageous for use with bronzes and other alloys containing tin, and for ferrous metals containing such oxidizable components as chromium, aluminum, vanadium, tantalum, titanium, manganese, nickel, cobalt, etc., and for steels containing precise amounts of carbon. The molten metal being shielded from contact with air, these substances do not burn out.

In the accompanying illustration, I have shown,'more or less diagrammatically, certain .typical arrangements of apparatus adapted for use in the described method.

' In this showing :.-Figure 1 shows a veris pivoted to a lever tending downward some distance;

heat ofthe metal cast,

tical section of an ingot casting apparatus;

and Fig. 2 shows a section of a modified, Fig. 8 shows a form of such apparatus. section of a pouring ladle and of an ingot mold in connection therewith, both contaming deep layers of molten flux, as described.

In Flg. 1, 1 designates a crucible or heating chamber, closed by cover 2, mounted on a hollow pedestal or support 3, against which plays the flame from-an oil burner 4:.

The crucible and support arecontained in a casing 5, having a steel jacket .6. In the bottom of the crucible is an opening 7 normally closed by stopper 8, carried by rod 9, said rod being protected by an encircling annulus 10 of fireclay or other refractory and indifi'erent cruciblematerial. Therod 11 by which it can be moved up or down, thereby permitting or preventing discharge of molten metal through the opening at" the bottom of the crucible. Within the crucible, as shown, are a layer of brass or other alloy 12, and a layer of fused covering material or flux 13. Below thecrucible and communicating with the hole in its bottom, is a conduit 14 ex- In casting an ingot of brass or other alloy, a suitable mold 15, containing a deep layer of such material adapted to be melted y the is placed below the crucible with this conduit. dipping into the wiping material in the mold. The mold may be completely filled with the wiping material if desired. As molten metal enters and this wiping material'is displaced, the latter flows over edge 16 to any suitable receptacle. I

' In making an alloy which it is desired to have precise in composition, for example, in making brass, one or more of the ingredients may be melted in the crucible 1, under cover of the flux orslag 13, and the other ingredient added thereto. For example, in making brass, copper may "be melted in said crucible, under the coating 13, or may be introducedtherein in molten condition,

and solid or molten through such cover,

' nor will any material amount zinc introduced into the molten copper; or

oreferably, the zinc may be melted in the crucible under cover of the flux coating 13, which prevent-s evaporation and oxidation and maintains the metal with a clean surface, and the molten copper poured through the flux or slag 13 into the zinc, or the copper may be poured through such cover '13 into contact with the zinc while the latter is still solid, the heat of themolten copper melting the zinc but the thick cover 13 preventing oxidation of the zinc below such cover and preventing material volatilization of the zinc. In these ways alloys or,mixtures of very recise composition may be made, there bemg'practically no escape of either metal prior to the min ling of the metals. Or, the brass, already ormed,-may be placed in the crucible 1 and melted under cover of the material 13, or it may be melted elsewhere and poured through such cover into the crucible. By whichever of the above described ways the alloy is formed or melted or heated to the desired condition for pouring, it will be preserved practically free from oxid and will maintain for a long period of time practically its original composition. The thick cover of flux or slag 13 permits free stirring, if such be needed, as is frequently the case, without exposure of metallic surfaces for oxidation or for volat-ilization of volatile components. In the case of molten brass, the zinc being at a temperature below its boilingpoint though at one where it has a high vapor tension, cannot form any material amount of Vapor under the thick flux layer, the molten brass in this respect behaving like very hot water under a thick layer of floating oil. The brass therefore remains of substantially constant composition during this operation. With a thin flux'coating, stirring exposes bare metal and zinc .flashe's into vapor form therefrom. After the desired casting temperature is obtained, the rod 9 is raised and the A molten metal allowed to flow down through conduit 14 to a point below the surface of the flux layer in the mold. The small amount of air in the short conduit does not have any material oxidizing power he entrained, but any oxid which may be formed or any air which may be entrained will be removed,

- by the wiping material, and 'a sound, solid ngot formed.

11 the modified apparatus of Fig. 2, the pedestal 3 carrying the crucible is hollow and the conduit 14 of Fig. 1 is omitted, the mold in use 'being placed near or against the bottom of the crucible, thereby minimizing the contact of metal with-air.

'In Fig. 3 I show an ordinary ladle 17 containing a body of molten metal 18 covered by a deep layer of flux er slag 19; and adjacent to said ladle I show a mold 20 concover 18, and when an alloy of the desired composition has been produced, the molten metal maybe poured into the mold. Or the ladle may be filled with molten brass or other alloy from any suitable source, and then the molten metal poured thence into the mold, the contact of the molten metal with the air during pouring being too brief to permit-material oxidation or volatiliza- ,tion. As is well known, a relatively heavy liquid may bepoured otffrom beneath a relatively light liquid or. floating mass, with very little, if any, escapeof the lighter subin permanent molds of any of any other special form.

stance,'hence, as will bereadily understood, it is easy to pour ofl the'ffmolten metal from beneath the layer 19 with practically no loss of material from said layer. However, ,there is-no objection to the passing of more or less of this material 19 into'the mold, as it merely adds to the amount of such material inthe mold.

The mold into which the molten alloy is cast may be a mold of special configuration; that is to say, a mold of some machine part, a gear wheel, for example, or of'statuary, or My process lends itself particularly to the casting of alloys desired shape.

hat I claim 1s:- y 1 i 1. Inthe production of castings, the process which comprises producing a mass of molten metal under a deep layer of molten covering material and tapping metal from a point below such layer and flowing it through a deep layer of wiping material into a suitable mold.

2. In the production of castings, the process which comprises producing a molten mass of an alloy containing easily oxidizable or volatilizable components under a deep layer of molten covering material and tapping the metal from a point below such layer and flowing it through a deep layer of wiping material into a'suitable mold.

3. In the production of castings, the procwhich comprises producing a molten mass of a metal comprising zinc under a deep layer of molten covering material and a metal "tapping metal from a point below such layer and flowing it through adeep layer oflwiping material into a suitable mold 4;. In the production of castings, the process which comprises producing a molten mass of brass under a deep layer of molten covering material and tapping the molten ess which comprises flowing a molten alloy rom a point below such layer and" flowing it through a deep layer of fusible through a deep layerof fusible wiping material contained in said mold, without substantial contact with air.

6. In the productionof brass castings, the process which comprises flowing a molten alloy or mixture containing a readily oxidizable or volatilizable ingredient into a mold through a deep layer of fusible wiping material contained 1n said mold.

7. A process of formin and casting .alloys of .precise' compositlon, which comprises melting one of the constituents of the alloy under a deep layer of molten covering material and adding the other constituent or constituents thereto while suchfirstconstituent is molten, and then casting the re-, sulting alloy from beneath such covering material into a suitable receptacle.

. 8. A process of forming and casting alloys of precise composition, which comprises melting one of .the constituents of the alloy undera deep layer of molten covering material and adding the other constituent orconstituents thereto while such first constituent is molt-en, thoroughly mingling the constituents and then casting the resulting alloy from beneath such covering material into a suitable receptacle.

9. A process of forming and. casting alloys of precise composition, which comprises melting one of theconstituents ofthe alloy under a deep layer of molten covering material and adding the other constituent or constituents thereto while such first "constituent is molten andcasting the alloyso produced through a deeplayer of wiping material into a suitable receptacle.

10'. A process of forming and casting alloys of precise composition, which comprises melting one of the constituents of the alloy under a deep layer of molten covering material and adding the other constituent or -constituents thereto while such first constituent is molten,- thoroughly mingling the constituents and then casting the alloy so produced through a deep layer of wiping material into a suitable receptacle.

11. A process of'produoing alloys such as brass, bronze, etc., containing one or more readily volatilizable constituents which-consists in melting such volatilizable 'constituout or constituentsunder a deep layer of molten covering material and thereby reducing loss of such constituents, and mixing the so melted metal with the other constituent or constituents of the alloy and then pouring the alloy so produced from beneath such covering material into a suitable receptacle.

12. A process of producing alloys such as brass, bronze, etc., containing one or more readily volatilizable constituents which consists in melting such Volatilizable constituent or constituents under a deep layer of 130 molten coverifig material 'and thereby reducing'loss of such constituents, and mixing the so melted metal with the other constituent or constituents of the alloy and then pouring the alloy so produced from beneath such covering material through a deep layer of wiping material into a suitable receptacle.

13. A process of producing brass of pre-' cise composition which comprises covering zinc with a deep layer of fusible covering material and pouring molten copper through such covering material into contact with the gling zinc and thereby melting the zinc and minit with the co per and then pouring the molten alloy so" produced from beneath said layer of covering material into a suitable receptacle.

In testimony whereof I aflix my signature, in the presence of two witnesses.

JOHN F. MONNOTQ V Witnesses:

H, M. MARBLE, FRANK E. RAFFMAN.

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