Method of manufacturing leaded free-cutting steel by continuous casting process

A method of manufacturing steel containing an effective amount of lead, comprising introducing molten steel into a tundish;

• continuously pouring said molten steel, at a selected rate, from said tundish through downwardly extending passage means of said tundish into the upper portion of an upright continuous casting mold associated with said tundish, which mold is substantially filled near the top thereof with molten steel, and which passage means extends beneath the upper surface of said molten steel in said mold, while simultaneously adding to the upper surface of said molten steel in said upper portion of said casting mold, at a selected rate, above and laterally offset from said molten steel being poured into said mold through said passage means from said tundish, a lead feed material selected from the group consisting of lead, lead alloys, lead surface coated with a metallic material, and lead alloys coated with said metallic material, said metallic material being essentially free of lead and being composed of one or more suitable metals which do not adversely affect the properties of said steel, which lead feed material melts in contact with said molten steel to form a molten mixture in said upper portion of said mold, while simultaneously uniformly horizontally stirring said mixture in said upper portion of said mold by means of electromagnetic stirring force of a strength sufficient to cause said steel, when hardened, to have a higher lead content in peripheral portions thereof than in central portions thereof, whereby said lead feed material is mixed throughout said molten steel in said upper portion of said mold.

A method of manufacturing a steel casting containing an effective, uniformly distributed amount of lead, comprising the steps of:

• feeding molten, refined steel from a ladle through a downwardly extending nozzle of said ladle into a tundish, which tundish is substantially filled with molten steel, said nozzle extending beneath the surface of said molten steel in said tundish;
• simultaneously pouring molten steel, at a selected rate, from said tundish through downwardly extending passage means of said tundish into the upper end of a continuous casting mold, which mold is substantially filled with molten steel, which passage means extends beneath the upper surface of said molten steel in said mold and opens at the downward end thereof, so that said molten steel is poured in the form of a downwardly moving stream into said molten steel within said mold;
• simultaneously adding a solid lead feed material consisting essentially of lead at a selected rate through a guide pipe directly to the upper surface of said molten steel in the upper end of said mold, which lead feed material melts upon contact with said molten steel to form a molten mixture of steel and lead in an upper portion of said mold, said lead feed material being added at a position above and laterally offset from said molten steel stream so that said molten steel stream from said tundish does not substantially carry molten lead therewith downwardly in said mold, the rate of feeding of said lead feed material being controlled in proportion to the amount of molten steel poured into said mold to maintain a predetermined weight ratio of said lead feed material to said molten steel;
• simultaneously, uniformly and horizontally rotating said mixture in said upper portion of said mold by means of electromagnetic stirring force whereby said lead feed material is stirred and mixed throughout said molten steel in said upper portion of said mold;
• simultaneously withdrawing lead-containing vapors by suction through a duct communicating with a hood interposed between the bottom of said tundish and the upper end of said mold, said guide pipe extending through said hood into the interior thereof, said passage means of said tundish extending downwardly through the interior of said hood, a lower end portion of said hood being flexible to allow vibration of said mold during stirring;
• and
• simultaneously continuously moving said molten steel downwardly in said mold and solidifying same to form a casting.