A concast billet caster and electromagnetic stirring of the melt

Electromagnetic stirring (EMS) suppresses the growth of columnar crystals of billets and reduces the tendency to cracking during casting and at low temperatures. A caster was used for the testing of two induction stirrers – one on the actual mould and the other beneath the mould – to determine the effect of EMS on the formation of the structure of non-alloy steel. As part of these tests, certain parts of the billets had been cast without the use of stirrers and other parts underwent alternate switching on and off of the stirrers for as many as nine combinations of modes. Samples were taken from the sections of these billets, fi ne-ground and etched in order to make the dendritic structure visible. The mode with the highest effi ciency was when both stirrers ran simultaneously. The growth of the columnar crystals, which pointed inward, was limited to 1 4-to1 3of the length of the case when there was no stirring. Experimental research was also confronted with results acquired from the application of the models of the temperature fi eld and chemical heterogeneity and the physical-similarity theory. Statistical monitoring of the quality of concast billets has proven that stirring signifi cantly reduces the occurrence of defects – in this case cracks.