The effect of electromagnetic stirring on the crystallization of concast billets

článek v časopise ve Web of Science, Jimp

angličtina

Electromagnetic stirring (EMS) applied on the steel caster (concasting machine) is basically a magneto-hydraulic process that influences the crystallisation processes and solidification of billet steel. From the viewpoint of physics and chemistry, the course of the process is co-determined by a number of relevant parameters, physical and thermokinetic characteristics of the concast steel and also electrical and magnetic quantities. 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-alloyed steel. As part of these tests, certain parts of the billets had been cast without the use of stirrers, while, 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, fine-ground and etched to make the dendritic structure visible. The mode with the highest efficiency was when both stirrers ran simultaneously. The growth of the columnar crystals, which pointed inward, was limited to 0,25 to 0,33 of the width of the billet when there was no stirring. Experimental research was also confronted with results acquired from the application of the models of the temperature field and chemical heterogeneity and the physical-similarity theory.

concasting, electromagnetic stirring, dendritic structure, quality of billets, defects.

KAVIČKA, F.; STRÁNSKÝ, K.; SEKANINA, B.; ŠTĚTINA, J.; DOBROVSKÁ, J.

2011

15. 2. 2011

Ljubljana, Slovenija

1580-2949

Materiali in tehnologije

45

2

Slovinská republika

163

166

4