Microstructure Formation in Thin Slab Casting

New processes have been developed in the last years to produce near net shape steel products by continuous casting. This work deals with the analysis of the effects of liquid core reduction during the solidification in the microstructure of thin slabs obtained by continuous cast process. An equipment able to simulate the liquid core reduction during the solidification was projected and constructed. This instrumented simulator consists of a watercooled mould with a moveable side wall driven by a hydraulic piston. Experiences were carried out using steels with different compositions, with and without liquid core reduction, in order to analyze the influence of the solidification parameters in the microstructure formation. The alloy temperature during solidification was monitored by thermocouples positioned within the slab. From experimental results of temperature variation close to metal/mould interface and numerical simulation, the variation of heat transfer coefficient at this interface was estimated. Samples from the as cast slabs were examined after polishing and etching to characterize the microstructure. Comparisons between microstructures of slabs obtained under different solidification conditions were carried out. A numerical method based on finite difference was applied to simulate the solidification process and the results were compared with the experimental data.