ALUMINIUM BRONZE

Ashburton Guardian, Volume VII, Issue 1738, 12 January 1888, Page 3

ALUMINIUM BRONZE

According to one of the Inventors of the Oowles system of electric smelting, In are m the production of the aluminium alloys that are attracting so much at ention, aluminium broi)z» is deatluad to revolution's* the art of gun making. For a gun made of aluminium broiza Mr Cowles claims, according to the results of very careful teats a tensile strength, 70,000 pounds to the square inch ; elastic limit, 23,000 pounda to the square inch ; etaistio extension 0,0018, per unit length ; redaction of area, 30 per cent, r v. innate elongation, 40 per cent. ; hardness, about 13. Mr CowJea says : "By mandrellog, the streng'h of this metal In the bore could be increased to over one hundred thousand pounds to the square inch, and the elaat 0 limit raised to sixty or seventy pounds. The itrotoh within the elastic limit would be increased, and, as other tests than thoae given enow, would far snrpass that of gun steel. The outer portion of the walls, where the strain Is not as great at the moment of explosion, would have a great raserve of ductility. It would be impoa-lble to burst soon a gun with four times the powder preuure now nsed In the steel ' built up" gun The walls would be solid. There would be no danger of crystallization. No rust or verdigris oan form on aluminium brorz , The finished gun would have the color and lustre of gold. It would not be affected by salt water. The fabrication of such guns would not require a great outlay of oapital Invested m plant, and the mineral resources of onr country are capable of supplying m inexhaustible quantities the raw material necessary for the production of aluminium alloys. Were oar Government enabled to make a great advance m the art of gun fabrication before equipping itself with the guns now needed, it would render valueless, against as, the present armaments of Europe The cost of the finished aluminium bronzo guns Is estimated at fifty-nine cents a pound, and a finished gun need weigh no more, if as much, as a eel gun of a like calibre. The cost of the fabrication would be abont the same as with cast iron, With an abundance of aluminium alloys on hand, there are two well-tried methods of fabrication that might be employed to give us solid guns to jjrai.t destructive powers and endurance ; First, the Rodman method of casting a gun and cooling it from the centre during the eolldifioation of the metal. Were this employed, wa might > adopt the A bronze, having a tensile 1 strength of about one hundred thousand pounds to the square inch, a bardnßea greater than cast iron, and an elastic limit four times as high. But the preference is given to the method of oaating invented by the late Samuel B. Dean, of Boston, and now used exclusively by the Austrian artillery The gun In firat cast solid ia aohill mould. It Is then bored, and conical chilled steel mandrels of gradually Increasing diameters, are successively driven through the bore by hydraullo pressure. The metal around the bore ia thereby given greater strength and hardness, a higher elastic limit, and a greater elastic extension. These properties gradually vary till the outer circumference of the gun is reached, where the metal has its normal oondition of great toughness. " Australasian and South American." The population of Queensland is estimated to have increased during the past year by 15,698 per3one.