US1261987A - Method of making aluminum-alloy articles. - Google Patents

Description

UNITED STATES PATENT OFFICE.

ALFRED WILM, OF gIIAGHTENSEIli-BERLIN, GERMANY.

HE lHUD O1" MAKING ALUMINUMAI|LOY ARTICLES.

Patented Apr. 9, 1918.

No Drawing. Application filed Bay 24, 1812, Serial 110. 698,658. Renewed August 23, 1917. Serial No. 187,887.

To all whom it may concern:

Be it known that I, ALFnuo WILM, a subject of the King of Prussia, Emperor of Germany, residing in Schlachtensee-Berhn, Germany, have invented certain new and useful Improvements in Methods of Making Aluminum-Alloy Articles; and I do hereby declare the followir to be a full, clear, and exact description ot the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to aluminum-alloy articles, and to a method of making the same which is directed to obtaining a. uniform close-grained texture of the metal of the articles, of such a character as to imart thereto increased strength, rigidity, and mertness to electrolysis. The departure from the known procedure which characterizes this invention lies in bringing about a close-grained texture of the metal of al-uminum-alloy articles with a uniform distribution of the metallic constituents through the mass, by selecting such metals and in such proportional quantities as will admit of the formation of an article from a molten admixture thereof, which will subsequently become intimately and uniformly associated throughout the mass of the article under the influence'of a degree of heat less than would be required to destroy the form of the article, and which will ultimatelv be fixed in such intimate and uniform association in the mass bythe withdrawal of heat at a rate which will not allow time for their loss intimate or less uniform redistribution therein.

The correlation of the admixture of chosen meta-ls with the particular treatment to which it is subjected can be varied to some extent to effect differing degrees of hardness, ductility and strength in the metal of the article produced, butthe limits of permissible variation in the quantities of the metals used to efl'ect advantageous results are well defined, as will appear from the foL lowing description.

In order to produce an aluminum-alloy article havin the desirable characteristics enumerated 9. ve, it has been necessary to discover what metals and what proportions of said. metals, when admixed with amajor quantity of. aluminum, would as ume an in:- tmlate association and. uniform distribution in. a mass at some temperature below the congealing point of the mass. Thus I have found that when approximately one-half of one per cent. of magnesium is added to a molten admixture of aluminum with approximately from 3 to 6 per cent. of copper and a quantity of manganese approximating one-seventh of the copper content, an article formed from said admixture can be given the required texture, resulting in a marked increase in strength and rigidity and resistivity to electrolytic decomposition, by cooling it from a temperature of substantially 500 C. with sufiicient rapidity to in When the aluminum is meltedand the crucible charge is at a red heat it is stirred for a short time with an iron rod, whereupon the temperature of the charge will rise to white heat owing to the heat generated by the reduction of the metallic oxids of oopper and manganese in the aluminum. The aluminum oxid thus ormed rises readily to the surface of the charge and may be removed as a scum by a rod. Another quantity of foul-kilograms of aluminumis now added, stirred u and the molten admixture thereupon quickly poured out into a shallow iron mold to chill. This rich alloy contains a relatively large quantity of manganese which would settle out if the charge were allowed to cool slowly. Q

The rich alloy is melted with an added amount of aluminum to bring the copper content to from 3 to 6 per cent. of the mass, as the requirements of the product may call for. Approximately one-half of one per cent. of metallic magnesium is now added to the molten mass, preferably after it. has been removed from the smeltin furnace, and the charge is formed into t e article, congcaling in the form required for the article which may be an ingot, a bar, or a cast shape of any other kind.

As it is usually diflicultto coola cast piece in the mold. to a predetermined temperature throughout, I prefer to reheat the piece throughout, when it is desired to effect the uniform distribution of the metals, to a temperature lyin between 420 C. and 560 C. and preferab? closely approximating 500 C. and therea ter cool itto the normal temperature with sufficient rapidity to revent substantial separation of the metal ic constituents from the uniformly distributed condition to which they have been brought by the heat treatment, as, for example, by quenching it in water. i

The presence of copper in the alloy in excess of six per cent. will generally revent the obtaining of a fine-grained uni ormlydistributed texture, by the application of any temperature below the congealing point, while the addition of magnesium in quantities above two per cent. or much below .5 per cent. will prevent the attainment of the requisite hardness.

While I prefer to add magnesium in the proportion of approximately one two-hundredth part of the aluminum content of each particular alloy, the diflerence is so trifling that for commercial practice I add .5 per cent. of the entire mass for any alloy within the limits herein given.

Heretofore, articles made of aluminumalloys containing a large ercentage of aluminum have not possessed uniform distribution of theconstituent metals through the mass, and have consequently suffered from electrolytic decomposition when exposed to air and moisture and were of little or no value as fittings exposed to salt water.

as in marine construction.

The treated alloys herein described resist the action of salt water to a remarkable degree.

Among other metals which may be used in the aluminum alloys herein described and permit uniformity of distribution with the aluminum, are .silver, vanadium, nickel, chromium, tungsten, molybdenum and titanium, vany of which will produce advantag eo us characteristics as to strength and rigidity in the treated allo -article.

Alloys having certain peculiar advantages forcommereial purposes may, for example, be compounded as follows With alleys of very great hardness which are obtaine by the use of an increased proportion pf copper and magnesium, that is to say, with copper up to 5% and magnesium up to 2%, an addition of nickel in suitable proportions will serve to reduce the brittleness of the product without interfering with the uniform distribution of the con stituents. Thus an alloy of about 93.25 aluminum, 6% co per, 5% magnesium and 25% nickel has t e characteristic qualities above referred to, with increased ductility. Ora-particularly good alloy is formed by alloying wmd "treating as above described 94.5 parts aluminum, 4 parts copper, nesium and 1 part nickel.

By employing chromium in about the proportions 94.5 parts aluminum, 4 parts copper, .5 parts magnesium and 1 part chromium, the capacity to take and retain a polish is increased.

For friction surfaces it is of advantage to use titanium in about the proportions 94.5 parts aluminum, 4 parts copper, .5 parts magnesium and 1 part titanium.

In using an alloy containing iron, I have found the following composition particularly suitable for practising my invention, viz.: aluminum 94.25 parts, copper 4 parts, magnesium .25 and iron 1.5 parts. V

In fact a material of great value for certain well-defined purposes'may be produced by adding magnesium alone to the aluminum in about the proportion of 200 parts of aluminum to 1 part of magnesium and then subjecting the material to the heat treatment above described. The result is to in- .5 magcrease the tensile strength and particularly to make the material easier to work or shape. For purposes such as the manufacture of cooking utensils and the like, where ease of working is more important than tensile strength the magnesium is added in less amount, as for example, about 2% to .3%.

It is to be understood that where the material is to undergo machining operations, such as rolling, drawing, turning, swaging and .the like, the heat treatment should follow such operations, though slight changes in shape, such as flanging or bending, are

permissible immediately after the heat treatment.

Having thus described my invention, what I claim is:

1. The method of manufacturing artlcles of aluminum alloys which comprises forming the article from an admixtureof aluminum and one or more other metals m quantities which will assume an adequately umform proportional distribution throughout the mass within a range of tem erature lying' below the fusing point 0 the alloy, maintaining the formed article at a temperature within said range until said uniform proportional distribution of the metals is attained, and cooling the article at a rate which will insure fixation of the uniformly low-the congealing point of-themutinno taining the formed article at a temperature within said ranlge until said uniform proportional distri ution of the constituents of the admixture is attained, and cooling the article at a rate. which will insure fixation of the uniformly distributed alloy; substantially as described.

3. The method of manufacturing articles of aluminum alloys which comprises the making of a molten admixture of suitable proportions of aluminum and one or more other metals, adding to said molten admixture a quantity of ma esium approximately equal to one-two-hun redth part of the aluminum content of said admixture, subjecting an article formedjrom said admixture to a temperature somewhat below the congealing point of said admixture until an adequately uniform proportional distribution of the metals is attained throughout the mass and cooling the article to the normal temperature at a rate which will insure fixation of the uniformly distributed proportions; substantially as described.

4. The'method of manufacturing articles 'of aluminum alloys which comprises the making of a molten admixture of suitable proportions of aluminum, copper and manganese, the quantity of manganese being approximately equal to one-seventh of the copper content of the admixture, adding to said admixture a quantity of magnesium approximately equal to one-two-hundredth part of the aluminum content of the admixture, subjecting an article formed from said admixture to a temperature somewhat below the congealing point of said admixture until an adequately uniform proportional distribution of the metals is attained throughout the mass and cooling the article to the normal temperature at a rate which will insure fixation of the uniformly distributed proportions; substantially as. described.

5. The method of manufacturing articles of aluminum alloys which comprises the making of a molten admixture of aluminum, copper and manganese, the copper content of which is limited to from 3 to 6 per cent. and the manganese content being proportional to the amount of copper in the ratio of one art manganese to seven parts copper adding to said admixture ap roximately .5 per cent. of magnesium, su jecting an article formed from said admixture to a temperature lying above 420 C. until an adequate uniform proportional distribution of the metals is attained throughout the mass and cooling the article at a rate which will insure fixation of the uniformly distributed proportions; substantially as described.

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

ALFRED WILM.

Witnesses HENRY Hasrnn,

Wownmm Ham.

It is hereby certified that in Letters Patent No. 1,261,987. granted April 9, 1918, upon the application (if Alfred Wilm, of Schluclitvnscv-Beriin, Gvrrmmy, for an improvement in Mcthmis of Making Alumimim-Alioy Artic lns," an errur appears in the printed specification requiring correction as foilowei: Page 2, line (51, for the nunn'ml and character 5% read 5%; and that the said Letters Patent shonld be mm! with this correction therein that the same may conform to the record of the case in the Patent Ollice.

Sig 'ned and sealed this 30th day of April, A. D., 1918.

[SEAL] F. W. H. CLAY,

Acting C'omm'iss'ioner of Patents. C1. 75--1