US1352322A - Metallic alloy and method of making same - Google Patents

Description

and useful Improvements in stair THERON D. STAY, OF CLEVELAND, OHIO, ASSIGNOR TO THE ALUMINUM CASTINGS COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

METALLIC ALLOY AND METHOD OF MAKING SAME.

No Drawing. v i

To all whom it may concern:

Be it known that I, THERON D. STAY, a citizen of the United States, residing at Cleveland, in the county ofCuyahoga and State of Ohio, have invented certain new Metallic Alloys and Methods of Making Same, of which the following is a specification This invention relates more especially to an aluminum alloy and the method of making it.

One object of the invention is to produce an aluminum alloy having the low specific gravity characteristic of aluminum and at the same time possessing certain characteristics, not possessed by-that metal, which especially adapt the alloy for the production of castings and particularly castings in which the constituent material is irregularly distributedvas to bulk and which must lend themselves to machining bearing qualities.

To these ends I have produced an aluminum alloy containing aluminum, copper and titanium. These'metals have melting points that differ widely from each other; and this fact, and other factors as well, give rise to certain difliculties in the'production of the alloy.

Therefore, a tion has been to further object of my invendevelop' a process by which the improved alloy can be produced econo'mically with respect to time and the labor and apparatus employed, and which at the same time permits of close technical control.

At the outset it may be briefly explained that the process erably dividedinto four distinct stages, as

follows: (I) The production of a copper alloy cont'aming'copper, aluminum and titanium, with the copper largely predominant; (2)- the production of an aluminum alloy containing aluminum, copper and titanium, in which the major constituents are aluminum and copper, with the amount of aluminum somewhat greater than that of copper; the production of an aluminumcopper alloy in which the two'metals are present in substantially equal amounts; and (4) the production of the final alloy containing aluminum, copper and titanium in the desired proportions.

The alloy produced in the first stage of i the process preferably has a composition, by

and have good Specification of Letters Patent. Patented SEEN]. 7, 192(1 Applicationifiled March 6, 1917. Serial No. 152,791.

6% titanium. To produce this alloy there of making the alloy is prefv u'id, any excess over may be placed in an electric furnace titanium oxid and enough alumlnum to, reduce the titanium plus ten or twelve per cent.

excess, together with the proper amount of I copper, and allowance for volatilization of the copper, due to the high temperature, being made. The alloy which is thus produced in an electric furnace is very tough and should be cast into relatively thin plates so that it can be cut into pieces suitable for charging in crucibles. In passing, it is observed that this alloy has a melting point very materially lower than the melting point of titanium, thus affording the latter metal in a form in which it can be handled at lower temperatures.

In the second stage of the process I produce an alloy which preferably has a composition substantially as follows: 52.1% aluminum; 46.5% copper; and 1.4% titanium. In producing this latter alloy I take 100 lbs. of pure lake copper or electrolytic copper and 100 lbs. of the copper-aluminumtitanium alloy produced in the electric furnace and melt them down preferably in an oil-fired furnace of the tilting type, using crucible with constant stirring; and at this.

stage the molten alloy turns from a red color to white and becomes more liquid. It seems that the "addition of the solid aluminumcopper alloy to the mixture prodiices an alloy having a lower melting point; and at there appears to be a rise in temperature, indicating that an exothermic the same time reaction-is taking place.

If the aluminum-copper chill is added at the proper time the entire 50'lbs. may be used. However, if the metal in the crugible is allowed to become too cold, only enough of the should be added to make it thoroughly liqthis amount causing the aluminum-copper alloy.

whole mixture to become pasty so it could not be readily separated from the slag and dross.

The molten'alloy in the crucible is next fiuxed with zinc chlorid which causes the dross and slag to be easily separated from the molten metal. After the slag has been carefully skimmed off with an iron skimmer the molten metal is poured slowly into a bath of 150 lbs. of molten alummum-copper alloy containing threeper cent. copper, this latter alloy having been heated in a suitable holding or mixing furnace.- This furnace is preferably placed so that the metal in the crucible can be poured directly into it so thatdissipation of heat from the molten mass is reduced to a minimum, it being necessary to avoid any freezing of the metal in the crucible before it is alloyed-with the material in the mixing furnace. The bath must be constantly stirred while the crucible metal is being poured to keep the heavier elements from settling to the bottom of the pot before theyhave opportunity to ziial'loy with the lighter aluminum. At this point any of the -aluminum-copper chill which was not used in the crucible may be added to the bath. After fluxing with zinc chlorid and skimming off the dross the alloy may be poured into ingot molds.

I I prefer to addthe aluminum-copper al- .loy in solid form, as described above, be-

cause the solid-metal gives the molten bath.

In the third stage, above referred to, of the process I produce an aluminum-copper .alloy containing equal parts, by wei ht, of

the two metals. For this purpose melt 200 lbs. of lake copper or electrolytic copper in a tilting furnace under a cliarcoal cover, in a manner familiar to all acquainted with the art. In the meantime I melt 100 lbs. of a three. per cent. copper alloy of aluminum and introduce into it lO6'lbs; of ingot aluminum. Into this latter metal I then pour the moltencopper, stirring, with an iron skimmer, to insure a uniform mixture. The aluminum is added in' ingot form, as above stated, to cool the alloyand prevent it from attacking the iron pot. .After fluxing with zinc chlorid the metal may be poured into ingot molds.

I come now to the fourth stage of my complete the charge.

poses.

However, the important process in which I produce the final alloy,.;

which preferably has a composition, by weight, as follows:

Aluminum 88.00% to 90. 00% Copper 12. 00% to 10. 00% Titanium 0.10% or under.

In producing this final alloy I take eight pounds of the aluminumcopper-titanium alloy producedin the second stage, above referred to, of the process; sixteen pounds of the,aluminum-copper alloy produced in the third stage; and seventy-six pounds of pure aluminum; and these metals I place in a molten bath of 100 pounds of scrap alloy. of the same composition as that which is to be produced. Enough of the scrap is added to Then when this has been melted down, and reaches a temperature not to exceed1550 F., and the mass thoroughly stirred it is ready for casting pur- On a consideration of the several stages in which the process is preferably carried out,

as above set forth, it will be observed that the amount of metal handled in the electric furnace at its high temperatures; may be, and in practice is,

to minimize the amount of metal heated to the comparatively high temperature necessary to melt the copper, and to correspondingly reduce the amount of time consumed and the capacity of the cruciblemelting furnaces which, as will readily be understood, are much more expensive than the iron furnaces which can be used with the lower working temperatures of the fourth stage where the bulk of metal employed is much larger. In addition, by dividing the process into the stages as set forth, the constituent materials for the final stage are produced in the-form of pigs which can be analyzed, Weighed and proportioned con"- veniently and in a manner to effectively contro the composition of. the final product.

I prefer, in casting my improved alloy, to pour it at a temperature of about 1350 F. When the metal is poured at the right temperature the casting has a speckled or mottled appearance, while if it is poured too hot, this. speckled appearance gives'way to a solid white aspect and the casting is usually-found to be porous.

When the process, above described. is carefully followed an alloy is secured which has remarkable characteristics. In particular it has a low crystallization shrinkage, and this makes it especially useful in producing castings in which the material is unevenly distributed, with relatively thin parts adjacent thick parts, and in castings of intricate shapes. can be made of thisalloy' having a fine- Furthermore, castings relatively small. Furthermore, by following the procedure in the secondand third stages, I am enabled grained structure and-a degree of hardness that produce excellent machining qualities; and these castings, when machined, have remarkably good bearing qualities.

I have found that the alloy is especially adapted for the production of piston castings. Such castings, when machined,-arc capable of taking a high polish, are sufficiently hard to withstand abnormal wear when in contact with other metallic surfaces, such .as the cast iron cylinder walls of internal combustion engines, and will not score the iron surfaces like other aluminum alloys with which I am familiar. Furthermore, my improved alloy will not soften at temperatures encountered in internal combustion engine cylinders. Again this alloy can by heat treatment be given a permanentexpansion to, obviate difiiculties incident to the so-called growth which is characteristic of most aluminum alloys.

In describing the composition of my improved alloy and the method of producing it, 1 have indicated approximately the relative amounts of the various materials which I prefer to employ. It is to be understood, however, that the relative amounts of the constituent materials may be varied to some extent without seriously affecting the quality of the product. Again, in the first stage of the process, the excess aluminum may be cut down as much as desired, providing, of course, a correspondingly larger amount is added in one of the later stages of the process. And, again, where I have specified the use, as constituent material, of an aluminum alloy containing 3% copper, I believe that pure aluminum might be used, or an alloy containing more or less than 3% of copper. Of course it will be understood that the apparatus employed in carrying out the process may be varied widely to suit conditions in particular cases without materially affecting the product secured.

/Vliat I claim is: V,

1. An aluminum alloy composedof aluminum in a predominating amount, copper in appreciable amounts and titanium.

2. An aluminum alloy composed of aluminum in a predominating amount, copper in appreciable amounts and titanium up to 10%.

An aluminum alloy containing aluminum, copper and titanium in approximately the following proportion by weight: alumi- Hum 88% to 90%, copper 12% to 10%, and titanium 0.10% approximately.

"4:. An alloy of aluminum, copper ant titanium, in which the aluminum largely predominates, which is characterized by low crystallization shrinkage, and, in the solid state, by relatively great hardness and a fine-grained structure having good bearing qualities.

5 The method of forming an alloy containing a metal of relatively high melting point and a metal of relatively low melting point which consists in first forming an alloy whose constituents include the said high melting point metal and a metal having a melting point between those of the other two metals, and then combining with the last named alloy said low melting point metal.

6. The method of forming an alloy containing a metal of relatively high melting point and a metal of relatively low melting.

point which consists in first forming an alloy whose constituents include the said high melting point metal and a metal having a melting point between those of the other two metals, combining with the last named al loy a mixture of the medium and low melting point metals, and thereafter combining with the resultant alloy additional amounts ing said alloy with copper and aluminum in proportions to increase the percentage of aluminum.

8. The method of producing an alloy of aluminum, copper and titanium which consists in forming an alloy of copper, aluminum and titanium in which the copper largely predominates, combining said alloy with copper and aluminum in proportions to increase the percentage of aluminum,

and melting the alloy resulting from the last step with copper and aluminum in proportions to still further increase the percentage of aluminum, thereby producing an alloy of aluminum, copper and titanium in which the aluminum largely predominates.

9. The method of forming an alloy of aluminum, copper and titanium in which the aluminum largely predominates, which consists in melting together copper and an alloycontaining copper, aluminum and titanium in which the copper largely predominates, adding to the molten product metal in the solid state consisting predomi-' nantly of aluminum, and thereafter comof copper and aluminum in proportions to 'bining with the alloy thus obtained amounts increase the percentage of aluminum in the alloy. I 10. The method of forming an alloy of aluminum, copper and titanium in which the aluminum largely predominates, which consists in melting together copper and analloy containing copper, aluminum and titanium in which the copper largely predominates, adding to the molten product metalin the solid state consisting predominantly of aluminum, combining the resultpredominantly of aluminum to a moltenant product with a molten alloyof aluminum and copper in which the aluminum predominates, and combining with the last resulting alloy aluminum and copper in proportion to increase the percentage ofaluminum in the alloy.

11. The steps in the production of an alloy of aluminum, copper'and titanium in which the aluminum largely predominates, which consist in adding a metal consisting mixture of copper, aluminum and titanium in' which the copper predominates, and then pouring the resultant product into a bath of molten metal consisting predominantly of aluminum.

- melting point and a metal of relatively low melting point in which the latter largely predominates, which consist in adding a 9 metal consisting predominantly of the low melting point metal to a molten mixture of the high and low melting point metals with a metal of intermediate melting point in which the latter metal predominates, and then pouring the resultant product into a bath of molten metal consisting predominantly of the low melting point metal.

In testimony whereof, I aflix my signa- 30 ture.

THERON D. STAY.