Development of high productivity casting of conventional and thin slabs

The final industrial goal of this project was to allow conventional and thin slab casters to reach the highest quality at the maximum casting speed, compatible with their metallurgical lengths. For this goal, the proposal was to reach regular solidification at high speed in a round billet and conservation of such regularity in a rectangular product, avoiding soliciting support of a thin shell below the mould. Round billets (Ø 85 mm) and thin slab (250*50 mm2) casting trials performed on Arcelor Research pilot casters raised the possibility of casting medium carbon-like high carbon grades at 4 m/min in a short mould. Such in-mould residence time is equivalent to a casting at 10 m/min with a classical mould length. Surface quality is good, thanks to meniscus-free casting technology. The main conclusion reached is that it is possible to achieve good surface quality at high casting speed, even for medium carbon steels, providing that solidification progresses evenly along the product perimeter, the mould taper is adapted and extraction is regular. Some new systems for strand support and cooling were studied at CRM. A new hydraulic bearing system to avoid strand strains was finally stopped due to overriding operational constraints. A new cooling system aimed at intensive and homogeneous cooling was tested successfully at lab scale. The main conclusion of the project is that there is a process now known to be able to cast peritectic steels at high speed, similar to other steels, with round bar-like thin slab applications. The answers now available show that this process is viable and the knowledge acquired is sufficient to design an industrial thin slab strand using the MFC principle.