US1871607A - Aluminium alloy - Google Patents

Description

Patented Aug. 16, 1932 UNITED STATES PATENT OFFICES- EOBACE CAMPBELL HALL, OF LITTLEOYER DERBY, AND TENNYSON FRASER BRAD- BURY, OF DERBY, ENGLAND, ASSIGNORS '10 ROLLS ROYCE LIMITED, OF DERBY,

I ENGLAND ALUMINIUM ALLOY No Drawing. Application filed October 16, 1930, Serial No. 489,224, and in Great Britain October 24,1929.

It is common knowledge that aluminium and aluminium alloys are liable to corrosion when exposed to the air.

The object of this inventionis to make a light aluminium alloy having a higher resistance to corrosionthan any such alloy previously known which can be satisfactorily cast, forged or extruded, and this without sacrificing hardness and strength orby sacrificing but little of these qualities.

According to this invention we make an alloy by compounding the elements and that in the relative quantlties within the ranges set out below.

Magnesium'from 0.1 to 4 per cent of the whole.

Nickel from 0.5 to 2.5 per cent of the whole.

"Iron from 0.3 to 1.5 per cent of the whole.

Silicon from 0.5 to 5.0 per cent of the whole.

Titanium up to 0.5 per cent of the whole.

anganese up to 0.2 per cent of the whole.

Chromium from .01 to 0.2 per cent of the whole.

Copper up to 0.5 per centof the whole.

Aluminium the remainder except for traces only of other elements.

An alloy compounded as above has a greater resistance to corrosion than for example, that claimed in our application for Letters Patent No. 401,970 now United States Patent No. 1,7 82,300 but at the same timepossesses about 80 per cent of the hardness and strength of that alloy.

Further this alloy has a higher resistance to corrosion than any previously known light allo of aluminium that it is possible to cast to orce and to extrude satisfactorily due largely to the presence of chromium and to the small copper content associated with the chromium, it is lighter than the aluminium alloys commonly in use which contain copper or zinc with or without other constituents, it

so The alloy is made in manner common in is capable of being cast, forged or extruded foundry practice, that is to say,'to molten commercial aluminium are added alloys rich in one or more of the other constituents other than magnesium, which is last added in the metallic state.

Preferably the alloy is cleaned and deoxidised prior to being cast by the addition of sodium. Such sodium may be added by wrapping a piece of metallic sodium (preferably) not exceeding- 0.1 per cent of the alloy to be treated in a piece of sheet aluminium or aluminium foil the whole being plunged below and held below the surface of the molten alloy until the sodium is diffused.

What we claim is V f 'An aluminium alloy formed by compounding the elements and that in the relative quan- Igitlies respectively within the ranges set out e ow 1lllagnesium from 0.1 to 0.4 per cent of the w ole. Nickel from 0.5 to 2.5 per cent of the whole.

Iron from 0.3 to 1.5 per cent of the whole.

Silicon from 0.5 to 5 per cent of the whole.

Titanium up to 0.5 per cent of the whole.

Manganese up to 0.2 per cent of the whole.

Chromium from ;01 to 0.2 per cent of the whole.

Copper up to 0.5 per cent of the whole.

Aluminium the remainder except for traces only of other elements,

In testimony whereof we have hereto affixed our signatures.

HORACE CAMPBELL HALL.

TENNYSON FRASER BRADBURY. 7