Continuous silver float casting of steel sheet or plate

Abstract

An improvement in systems for continuous casting steel to near net shape sheet or plate directly from molten metal. This is accomplished by floating the liquid steel on a liquid substrate of silver, allowing it to solidify and withdrawing a continuous section of thin, wide steel. Liquid to liquid casting, by eliminating the mechanical problems of thin sheet casting with wheels or belts, allows for increased tonnage rates. For example, aiming at a thickness of 3 mm. by a width of 1500 mm., a liquid steel to liquid silver caster in continuous production at 200 feet per minute will produce 750,000 tons per annum. Increased cast speeds and/or multiple lines due to simple construction seem practicable for greater tonnage. Only liquid silver, as a float medium, makes high quality float casting of molten steel possible. The present invention combines the superior qualities of silver as a float medium for steel with an apparatus for introducing molten steel uniformly across a wide, thin section onto a U-shaped surface of molten silver so that the steel may freeze without bath turbulence to form a flat sheet or plate free of shape distortion and surface defects. Cooling of the bottom surface of the molten steel by heat transfer through the liquid silver and the subsequent heat exhaustion by means of a water cooled base--coupled with cooling the upper surface of the steel at high rates by recirculating heat exhausted inert atmosphere gas and by water spray cooling the casting chamber top--result in a casting speed which produces steel in a commercially viable tonnage range for continuous operation.

Dependencies are inferred from the claim text.