USRE17385E - Pierre bebthxlemy and henry de montby - Google Patents

Description

Reissued July 30, 1929.

UNITED STATES PATENT OFFICE.

ALUMINUM ALLOY AND METHOD OF MANUFACTURING THE SAIME.

No Drawing. Original No. 1,599,869, dated September 14, 1926, Serial Np. 37,573, filed June 16, 1925, and

in France May 11, 1925. Application for reissue filed September 15, 1927, Serial No. 219,811.

The present invention has for its subject a new aluminum alloy of which the density is Substantially equal to that of aluminum itself but whose mechanical strength is much higher than that of aluminum. This alloy is essentially characterized by the fact that its composition includes copper, manganese, iron and siliconemployed in the form of ferro-silicon, tungsten, magnesium, also cadmium, and aluminum, in suitable determined proportions, yielding an alloy which may be subjected to any mechanical treatment such as rolling, drawing, hammering, wire drawing and so fort-h. Our improved alloy may 15, be even used for casting to produce a superior cast product.

The invention also relates to the process of manufacture of, the saidalloy, according to which process there is first prepared a rich in a plumb-ago crucible lined with magnesia and containing a certain quantity of a mix ture of wood charcoal, calcium fluoride, oxide of magnesium and arseneous acid, the molten rich alloy thus produced being freed from floating slag and-being then run into ingot moulds for subsequent alloying with aluminum in the proportion (variable according to the usesfor which the metal is adapted) of. 10 to 15 parts by weight of rich alloyito 90.

to 85 parts by weight of aluminum. The purpose of using the rich alloy is to facilitate the production of a light and homogeneous alloy in which ingredients are incorporat.

35, ed having a melting point, much higher than that of aluminum. We have discovered thatif all the different elements .or ingredients appearing in our alloys are melted and mixed together in-a single crucible that the alloy the ingredients have not been properly intermixed with the others, and other ingredients have completely failed to impart their desirable qualities to the'alloy, because of the differences in the melting points of the various ingredients. 1 I

Finally the invention has for its object a modification of the process, which modification is more particularlyapplicablein the case of alloys adapted to be fused, and in which the magnesium and cadmium (t-his latter body-may be replaced by sodium) are only incorporated at the moment when the alloy of the body above specified by fusion thus produced is not homogeneous, certain of rich alloy is mixed with the aluminum, this lncorporation being'made at a temperature not higher than 725 C. As later set forth more fully herein, the incorporation of cadmium substantially increases the resistance of the alloys to oxidation, and this applies to all the alloys set forth in ,the various formulas incorporated in this specification. However, experience has shown that if cadmium is first introduced into the fused mass, that the cadmium falls to the bottom of the fused mass. If magnesium is added to the fused mass subsequent to the addition of the cadmium, then no direct contact takes place with the magnesium and the cadmium because the magnesium tends to remain upon the top of the fused mass of the bath. Under such aircumstances, namely, if the cadmium and the magnesium do not contact, the cadmium is not incorporated uniformly in the alloy because this 1s produced by the action of the magnesium. Hence, it is highly advantageous to add the cadmium and the magnesium to the fused mass as part of a single step of the method, and under conditions which cause the magnesium to exert the desired action upon the cadmium. Y

With reference 119 examples which are given solely as examples of the methods of carrying the invention into effect, there will be described the method of preparation of alloys suitable for various uses. In all cases the rich alloy is prepared by fusing the constituents in a lumbago crucible lined with magnesia and in the bottom of which there are first placed 25 grammes of the following mixture: Grammes. Pulverized beech charcoal 1000 Natural calcium fluoride 1000 Oxide of magnesium k 250 Arseneous acid 10 above referred to and consisting of charcoal,

calcium fluoride, magnesium oxide and'arseneous acid, is. used to provide a sufiiciently powerful reducing action. Although these four ingredients are eliminated from the final I enables a regular and constant temperature to be secured. This may be a heavy oil furtion) nace or a furnace for heat recuperatlon of the Bigot system, for example. IVhen the fusion has been effected, the alloy is agitated for a very long time by means of a rod of carbon in the said retort lined with magnesia (a rod of iron should never be used for this opera- Then the floating powder and slag are removedfrom the surface of the molten mass, which is then run in small ingots in an ingot mould made of iron lined with magnesla.

The composition of the rich alloy thus prepared varies according to the use to which the final alloy is adapted to be applied.

E sample [.For obtaining an alloy adapted to form plates, rods, tubes, Wires, sections and so forth, the rich alloy is prepared from the following substances: copper, grammes; manganese, 2 grammes; ferrosilicon, 5.35 grammes, having 55% iron and silicon (i. e. iron 2.95 gms. silicon 2.40

gins.) tungsten, 2 grammes; magnesium, 15

grammes; aluminum, 35.65 grammes.

If desired, 20 grammes of cadmium could be incorporated into the final alloy secured, when this rich alloy is added to aluminum in the proportions later described herein. The addition of the cadmium is particularly advantageous in preparing an alloy intended for casting.

The effect is the same as though the rich alloy above mentioned in Example I had had 20 grammes of cadmium added thereto.

We have discovered that it is highly advantageous to'incorporate iron into the alloy by employing ferro-silicon and in particular, ferro-silicon containing more than of iron. The ferro-silicon forms a chemical combination with the other ingredients of the alloy to eliminate the disadvantages lesulting when it is attempted to directly unite aluminum with iron.- When it is attempted to directly alloy aluminum -with iron, the iron often separates in the final alloy. Likewise, we prefer to use ferro-silicon containing more than 50% of iron, because we have "discovered that if the silicon is present in excess that this is injurious to the quality of the completed product.

The quantity of rich alloy obtained by fusing the preceding substances in the manner indicated above is alloyed with 900 grammes of pure aluminum (i. e. 99 to 99.5%

pure), by melting the hundred grammes of rich alloy and the nine hundred grammes of aluminum and inte'rmixing them.

Example I I .-The rich alloy for the pre a- ,ration of a metal adapted for the manu acture of castings of any nature, is obtained -mium, this addition being for the purpose of decreasing cracks and flaws in the castings. The effect is the same as though the 20 grammes of magnesium had been omitted in preparing a rich alloy according to Examplev II, and 20 grammes of magnesium and 20 grammes of cadmium had been added when the rich alloy made according to Example II was combined with 900 grammes of pure aluminum. Of course, the cadmium and the magnesium are added under the conditions above mentioned to increase the resistance to oxidation and to facilitate the casting operation.

p The magnesium which enters into the formulae of the rich alloys which have been indicated above (and also in the formula of the third example hereinafter set forth) may be simultaneously melted with the other constituents of. the rich alloy, or it may be 'subsequently added tothe alloy, like the cadmium and at the same time that the cadmium is added, namely, at the moment when the rich allow is melted together with the aluminum mass. Although the addition of cadmium to an aluminum alloy imparts various desirable properties to the alloy such as high resistance to oxidation, we have discovered that it is diflicult to uniformly incorporate the cadmium in an aluminum alloy, especially in an aluminum alloy of the type specified herein. We have also discovered that the addition of magnesium to an aluminum alloy increases its susceptibility to oxidation. However, by simultaneously adding the magnesium and the cadmium to an aluminum alloy, the ma nesium causes the cadmium to be uniformIy incorporated throughout the alloy so as to render it homogeneous, to increase its resistance to oxidation, etc. The amount of magnesium thus added simultaneously with the them as V sion of the pure aluminum, with the incorto the alloy under such conditions that it poration a'of the appropriate rich ally,-is

preferably effected in a plumbago crucible lined with magnesia and'heated in an ordinary coke furnace.

The cadmium, may be replaced by an equivalent quantity of sodium. However, for

making a .non-oxidizable alloy it is preferable to simultaneously add cadmium and magnesia um to the alloy.

Emample.Ill.-A formula similar to the preceding is particularly suitable for the manufacture of engine pistons: copper, 52.50 grammes; manganese, 5 grammes; ferro-silicon, 5.50 grammes, having 1ron 55% and s11- icon 45% (i. e. iron 3.03 gms., and silicon 2A7 grns.); tungsten, l gramme; magnesium,

grammes; aluminum, 46 grammes.

This quantity of rich alloy is incorporated in 850 grammes of pureahiminum with the addition, under the condition specified above, of 20 grammes, of cadmium. The 20 grammes of magnesium called for by the formula of the rich alloy may be added to the alloy simultaneously with the cadmium instead of being previously fused with the other constituents of the rich alloy.

Irrespective of the formula adopted,'it is important, in order to obtain products of good quality and constant characteristics, to use only pure metals and start with cupros,

that is, copper alloys of the various ingredients, in thepreparationof the rich alloys. The metal intended to berolledshould be previously heated for one hour at a temperature between 400 and 450 C. After two or three rollin'gs, the-sheet'should be re-heated under the same conditions, and this treatment is repeated until the required thickness is obto which 5% of glycerine has been added.

Annealing can then be effected at a temperature of L50 to 47 5 (1., and then the plate is allowed to cool slowly in air.

The manufacture of tubes, wires, rods, sections, is effected in the same manner.

Once the mechanical treatment has been completed, it is advisable to allow the metal to mature for from eight to ten days; and from this moment on it possesses all its permanent and desirable qualities.

.Rapid artificial maturing of the castings (Examples II and III)c an be promoted by subjecting them for one hour to annealing at a temperatureof 200 to 250 C, which annealing is followed by immersion in a bath of boiling water to which 5% of glycerine has been added. The same result is obtained by allowing the furnace to cool after annealing for one hour.

The aluminum alloy in the'form of castings obtained according to the'invention can be readily tempered.

It will be noted that the cadmium is added ticular process for making said alloy.

forms what may be termed a sub-alloy with magnesium to facilitate its uniform intermixture with the other ingredients of the al loy. We prefer to use magnesium for caus ing the cadmium to be uniformlyincorporated in the alloy, because magnesium has a much lower specific gravity than cadmium and has a much higher melting point. Hence, the magnesium tends to remain at the top of the bath so that the cadmium melts at the top of the bath and is intermixed with the magnesium before it becomes uniformly 1nttfi'mixed with the other ingredients ofthe a oy.

It will be noted that in the specific exam- ,ples previously mentioned, that the percent-I is three per cent or less, alight alloy is ob tained whose density is equal to or less than three, and the cadmium is present in the form of a solid solution in such an alloy.

In order to have the alloy substantially resistant to oxidation, the minimum quantity of cadmium should be between one-half .per cent andone per cent and it is preferred to have V the percentage of cadmium at least two per 10 cent, or between two and three per cent for this purpose. If a greater per cent of cadmium is utilized, that is, proportions between three per cent and five per cent, the density of the alloy substantially increases although the alloy still resists corrosion or oxidation. Larger proportions of cadmium can be employed without lowering the resistance to corrosion, but this has the effect of substantially increasing the density of the alloy, because if seven per cent of cadmium is employed, the density is 4.48. The alloys having the higher percentages of cadmium, namely between three per cent and twelve per cent, can be eas ily cast, have a low co-efiicient of friction and resist oxidation.

We have described a preferred embodiment of our invention but it is obvious that numerous changes and omissions could be made therein without departing from the spirit, In particular the claims for the improved alloy hereunto annexed are independent of any par- We claim I p 1. A process for the manufacture of an 12 aluminum alloy comprising fusing in a plumbago crucible lined with magnesia and containing a mixture of woodcharcoal, calcium fluoride, oxide of magnesium, and arseneous acid, a mixture of copper, manganese, fer'rosilicon, tungsten, magnesium, and aluminum, so asto produce a rich alloy, runmng the rich alloy into ingot moulds, and subsequently mixing the rich alloy with pure aluminum.

Subsequently mixing the rich alloy with pure aluminum, in the proportion of to parts by weight of rich alloy to 90 to 85 parts by weight of aluminum.

3. A process for theproduction of an aluminum alloy for the production oi castin gs compris ng tu'smg copper, manganese, i'erro-;

silicon, tungsten, magnesium, and aluminum, 1n a plumbago cruc ble lined w th magnesia and containing a mixture of wood charcoal, calcium fluor'icle,joxide of .magnesi um, and arseneous acid, removing the floating impurities from the rich molten alloy thus obtained,

molding the rich, alloy, and thenniixing it ,with aluminum, and Whilst mixing with the aluminum, adding magnesium and cadmium,

this addition being made at a temperature not higher than 725 C; t.

4; A process for the production of an aluminum alloy for the production of castingscomprismg fus ng copper, manganese, .ferrosilicon, tungsten, magnesium, and aluminum,

in a plumbago crucible lined with magnesia and containing a mixture of wood charcoal, calcium fluoride, oxide of magnesium, and arseneous acid, removing the floating impuri ties from the rich molten alloy, molding the rich alloy, and then mixing it with aluminum, and Whilst mixing with the aluminum, adding made at a temperature not higher than 725 C 5. In the art of making an aluminum alloy containing cadmium, that step in the art which consists in adding the cadmium to the other constituents of the alloy while simultaneously adding magnesium to cause the cadilnium to be uniformly incorporated in the al- 0y.

' 6. In the art of making an aluminum alloy containing cadmium, that step in the art which consists in adding cadmium to the other constituents of the alloy while they are in themolten condition, while simultaneously adding to the molten mass a substantially equal quantity of magnesium to cause the cadmium tubeuniformly incorporated in the alloy. e

7. An aluminum alloy compr ing copper, manganese, iron, silicon, tungsten, magnesium, aluminum, cadmium being also present in the alloycj n the form of a solid solute uni- "t'orn' ly incorporated-in the said alloy, the proportion of cadmium in the said alloy being equal to'or greater than one-half per cent.

7 In. testimony whereof we afiix our signatures,

-PI ERRE BERTHELEMY. -VTE. HENRY DE MONTBY.

magnesium and sodium, this'addition being