Composite body of magnesium and steel and method of making same

867,693. Making composite sheets; welding by pressure; jointing by rolling. CRANE CO. Nov. 3, 1959, No. 37251/59. Classes 83 (2) and 83 (4). A method of bonding ferrous articles to magnesium or magnesium base alloy articles in the solid state, e.g. to make composite sheets or strips, comprises providing the ferrous article with a thin surface of a coating metal which is soluble in magnesium, e.g. nickel, copper, silver, cadmium, aluminium, tin, zinc, berylium, cobalt, lead or silicon, placing a solid article of magnesium against the surface of said ferrous article having said coating metal, heating said assembly to cause the coating metal to diffuse into the magnesium in an atmosphere of an inert gas, e.g. helium, neon, argon, crypton, zenon or mixtures thereof and at a temperature below the melting-point of magnesium and urging the articles together to achieve solid phase bonding at the interface. The surface of the ferrous article is cleaned by wire brushing, sandblasting or pickling by dipping in a 15% aqueous solution of hydrochloric acid. The metal coating is applied by an electroplating step and the thickness of the coating may range from 0.0001 to 0.0010 inches. The magnesium article is cleaned by dipping in hydrochloric acid, washing in water and air drying and its surface is scratched with a wire brush. In an example a sheet of steel is degreased and plated with copper to a depth of 0.0002 inches by immersion for 10 minutes in a copper cyanide solution. A sheet of magnesium cleaned and scratched is placed against the copper coating. The sheets are clamped together and heated in a chamber containing an inert gas to a temperature within the range 600‹ to 1200‹ F. The assembly is allowed to cool within the chamber. The method may be carried out continuously in which case the articles are passed between rolls in an inert atmosphere at a temperature within the above range.