Possibilities of S-EMS utilization for the improvement of central segregation in continuously cast billets in conditions of TŽ

Purpose: The aim of the paper is to investigate practical possibilities of the strand stirrer (S-EMS) for the improvement of inner quality and central segregation in high carbon billets. An optimal S-EMS setting was proposed for the billet caster producing billets 150x150 mm. Design/methodology/approach: Impact of different S-EMS settings on central segregation and inner quality of as-cast billets was investigated. A set of longitudinal and transverse samples were analysed including evaluation of baumann prints and central segregation by means of LECO method. Samples of wires for segregation survey in rolled products were picked up as well. Findings: It was observed that application of the strand stirrer (S-EMS) is capable to suppress central segregation. However, its impact is visible just to a certain stirring level. Subsequent increasing of stirring intensity does not cause further improvement of segregation in the analyzed central part. On the contrary, stronger white band can be seen in the solidification line. Moreover, concentration gradient between the central part and surrounding ring of negative central segregation is lowered. These two effects can play a significant role in the evaluation of segregation level in rolled wires. Research limitations/implications: Analysis of central segregation in a lower size than used 6 mm. Practical implications: Optimal S-EMS setting seems to be 300 A/14 Hz. Originality/value: Impact of S-EMS setting on changes in central segregation of as-cast billets, relationship between central segregation level in wires and cast structure.