9th ECCC European Continuous Casting Conference – ECCC 2017

Over the last 50 years, continuous slab casting processes have been widely installed over the world taking advantage of their enhanced productivity, yield, energy consumption and labor efficiency. Nowadays, the continuous slab casting can be divided into four categories as casting thickness: strip casting, thin slab casting, thick slab casting and ultra-thick slab casting processes. Strip casting processes which directly produce thin strips (less than 5mm) from molten steel are being improved to cover more steel grades with 30-100 m/min casting speed. Thin slab casting processes with slab thickness less than 100 mm begins to be connected with a subsequent endless-rolling process in order to easily produce the ultra-thin gauge products by increasing the casting speed to 5-8 m/min. For the conventional thick slab casting with 200-300 mm slab thickness, higher casting speed is interested in a view point of the balance of converter, caster and hot rolling mill capacity. In order to guarantee the slab quality of heavy gauge plate as the energy and shipbuilding materials, ultra-thick slab casters with 400-700 mm slab thickness are designed. In this case, the casting speed is seriously limited less than 0.4m/min because of metallurgincal length limit. In the case of thick slab casting at a low casting speed, the control of meniscus freezing, centerline segregation and bending/unbending within caster are the key technologies. For thin slab casting at a high casting speed, the control of mold level hunting, molten flow in the mold, high frequency mold oscillation and surface quality are important problems. In this article, the inevitable reason why the range of casting speed has been spread out is discussed. The above continuous casting processes are briefly introduced and the related key technologies based on POSCO’s experience are reviewed in the view point of casting speed depending on slab thickness.