US1518321A - Aluminum alloy - Google Patents

Description

' Be it "known .that I, ANDRE Patented Dec. 9 1924.

UNITED STATES 1,518,321 PATENT OFFICE.

Arizona seven, or rARIs'FRANoE.

1T0 Drawing in Aluminum Alloys; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable. others skilled in the art to which I it appertains to make and use the same.

This invention relates to aluminum alloys and processes for the manufacture thereof, and has for its object the manufacture ofa li ht alloy, the basis of which is aluminum, which possesses superior qualities of resistance to rupture, of elasticity and of extensibility, together with practically negligible coefficients of dilation and contraction, and a lowdensity. This alloy which consists essentially of the combination of the following constituents: aluminum, copper, manganese, magnesium, lead and carbon, is free from the striae or filaments of oxide of aluminum that form lines of rupture and lends itself very well to machining and to autogenous welding; it is unoxidable and susceptible of acquiring a beautiful polish. According to this invention the process of manufacturing this alloy consists essentially in combining carbon with the metallic constituents-of the alloy in the bath, while preventing the oxidation of the metal by shielding the surface of the bath from the effects of the contact of the air. The combination of the carbon in raphitic form is advantageously obtaine by incorporating with the bath finely powdered carbon, derived, for example, from charcoal and assisted by stirring; the surface of the bath being shielded from the action of air during this carbon treatment by means of at protecting layer, for example of charcoal floating on the surface of the bath, or by any other suitable or knownmethod.

In practice, theoperati'on is performed as follows The cupro-manganese mixture is first prepared with the required proportion, the greatest portion of the' aluminum intended to constitute the alloy is then melted, and powdered and broken'charcoal is introduced in the aluminum bath from the beginning of the melting. The previously pre ared cupro-manganese mixture is then ad ed to the bath, and the temperature is raised. The

- ALUMINUM 'ALLoY.

Application filed September 11, 1922. Serial No. 587,582.

remainder of the aluminum is subse uently added and the temperature is then a lowed to fall somewhat. Finally the magnesium and the lead are added and the metallic alloy so obtained is cast into moulds.

The operation isadvantageously effectuated in a covered crucible or thelike, which is only uncovered during the time necessary for the successive additions of the materials and for the mixing. The latter must be frequent, and care must be taken to add to the bath new quantities of powdered charcoal at each. open ng of the crucible or the like,

so as to ensure the proper combination of the carbon with the alloy. As it has been stated above, all oxidation of the metal of the bath will be prevented by the layer of broken-up charcoal floating on its surface. Finally, the metal is suitably reheated before use. 7

The following typical. composition of a rupture resisting alloy is given as a particular example of an alloy according to this invention Aluminum 93.92 Copper 4.25 Magnesium 0.79 ifanganese 0.80 'ead Carbon} The alloy comprises also traces o'f,silico11 and, it may be, of iron, which may be con- 'tained as impurities in the metals used s constituents.-

Once reheated and rolled, for instance in the shape of plates of 20 mm. in thickness, the metal obtained gives approximately the following characteristic coefficients Kg. Resistance to rupture 43.5 Coefficient of elasticity 25 Coefficient of extension 20.3 Coefficient of constriction 0.38 Density (about) 2.78

It will be understood that by suitable reheating and rolling, the above mentioned coefficients may be somewhat varied.

The particular process of manufacture, of this alloy willnow be described, as an example The cupro-manganese mixture is prepared in the proportions of-425-of copper to'0.80 of manganese. .About three-quarters of the whole aluminum are melted, powdered and broken coal being-introduced into the mass, and the said previously prepared cupromanganese mixture is added. The temperature of the bath is raised to about 950 C.

for nearly two hours. The remaining aluminum is then added and the temperature is allowed to fall to about 800 C. The mixture is well stirred and the heating continued at the same temperature. Finally the lead and themagnesium are added, tak- 'ing care that the magnesium does not rise to the surface of thebath. The metal is stirred and skimmed and the alloy obtained is cast into ingots or pigs, withthe usual precautions for casting aluminum. The metal is finally reheated during about 2 to 3 hours.

The alloy so manufactured lends itself to direct machining by rolling, drawing, etc.,

the metal having obtained its characteristic properties without quenching or other particular heat treatment:

I claim:

1. A process of manufacturing an aluminum alloy containing copper, manganese, magnesium and lead which com rises maintaining the mixture molten whl e protected on its surface by a layer of finely divided carbon containing material and stirring the -metal while so protected to cause the carbon to enter the metal. v p

2. A strong, ductile alloy of light weight composed of about 93.92% aluminum, 4.25% copper 0.79% magnesium, 0.80% manganese and 0.24% lead and carbon.

In testimony that I claim the foregoing as my invention, I have si nedm name.

. t ANTRE EYER.