The single-strand, thin-slab caster at Severstal Columbus is coupled directly via a tunnel furnace with the 6-stand hot strip mill. The caster has a 74-inch wide mold, the widest unit currently in operation for a thin-slab caster. Electromagnetic braking produces a quiet, liquid metal surface in the mold, and decreases the standing wave which helps eliminate the entrapment of mold powder in the steel. The caster can produce slabs 2.36 or 2.56 inches (60 or 65 mm) thick, 36 to 74 inches wide, and 50 to 180 feet long.
Based on a 165-ton heat size, it has an annual rated capacity of 1.7 million tons with a production rate of 200 to 300 tons/hr. A typical casting time is 25–45 minutes, with an average of 40 minutes. Machine turnaround time is 20 minutes. A typical casting speed is 200 ipm (160 minimum, 236 maximum).
This vertical-type caster has a machine height of 35 ft. (10.68 m), a metallurgical length of 28 ft. 4.5 in. (8.065 m) and a bend radius of 10 ft. 8 in. (3.25 m).
Heats are delivered to the dual-arm caster turret by a 450 ton crane. Metal flow from the ladle is controlled by a slidegate nozzle into the tundish. The tundish is equipped with an electrically controlled stopper rod that delivers metal to the mold through a single alumina-graphite submerged entry nozzle. Typically, the caster is operated with a tundish capacity of 46 tons and a metal depth of 43 inches (1,100 mm).
There are two natural gas–fired tundish preheat stations that raise the tundish temperature to 1,850°F prior to being placed in operation. The plant has eight tundishes and two tundish cars. Tundish life varies between 10 and 12 heats.
Metal level in the mold is controlled to within 1.5 mm by a radiation–type sensor inputs data to the tundish stopper rod. A direct-drive hydraulic mold oscillator that can provide a stroke in either a nonsinusoidal or sinusoidal mode, depending on product and casting speed.
There are four slab containment segments with four secondary hydraulic cooling zones. Slab containment ends with a pinch roll unit followed by a pendulum-type shear that cuts the slab sections to length prior to entering the tunnel furnace. Slabs are transferred directly into the tunnel furnace. The melting and casting operations are supported by a metallographic laboratory.
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