What is Strip Casting? Steel Foundations
Cast strip is the product produced by the continuous cast rolling process, also known as a strip caster.
A cast strip is the thinnest continuously cast flat product with a thickness of approximately 0.40” (10 mm) before being hot rolled in-line to its final strip thickness. In other words, the strip casting process casts steel directly into a hot rolled coil (HRC).
The strip casting process begins with a ladle full of liquid steel suspended over a tundish. The tundish provides a buffer during ladle changes, which enables the casting process to be continuous. The tundish also provides the last opportunity for any inclusions (impurities) to float out of the steel into the slag prior to entering the solidification mold. The molten steel in the tundish flows to the nozzle which is suspended over an additional reservoir called a “bathtub,” which controls the flow of molten steel to the solidification step.
The strip casting process does not utilize an oscillating caster mold for solidification, such as traditional thin or thick slab casters. It uses two counter-rotating, water-cooled drums or rolls that draw the molten steel down between the rolls and solidifies it prior to the steel exiting the gap between the rolls. The gap between the rolls is known as the “bite” of the rolls.
The metallurgical length of a caster is how far down into the caster the strand goes before it is completely solidified. When compared to slab casting processes, the strip casting process has almost no metallurgical length, which allows the overall height of a strip caster to be very small.
Eventually, the solidified cast strip is bent from vertical to horizontal, where it goes through a descaler, to remove any oxide surface scale, and rolling stands, to hot roll the strip to its required thickness. The cast steel strip is thin enough that only a single or double finishing stand is necessary to produce the hot rolled coil.
Finally, the hot rolled coil is cooled by water sprays, sheared to individual coil lengths, and coiled at the coiling stand at the end. When compared to traditional slab casting, this process conserves energy by eliminating the need reheat the steel prior to the hot rolling process.
The smaller overall size of the strip caster along with being constructed in line with the hot rolling equipment, gives this process a much smaller overall footprint and allows it to be built almost anywhere.