Optimisation of final electromagnetic stirring installation position in 800 mm round bloom based on liquid core radius ratio and feeding ability

Final electromagnetic stirring (F-EMS) is an effective technique for improving the internal quality of large size round blooms, but its metallurgical performance strongly depends on the installation position. In the present study, the liquid core radius ratio (LCRR) is introduced as a new parameter to characterise the installation position, and its relationship with the feeding ability at the final solidification is established. The results show that variations in the LCRR have little influence on the electromagnetic distribution. When F-EMS is installed at an LCRR of about 30%, the solidification end is extended, the feeding channel is widened, and the Niyama value at the strand centre increases by nearly 20% compared with the no electromagnetic stirring (EMS) case, indicating a significant improvement in feeding ability. Plant trials further confirmed this conclusion, at an LCRR of 31.3%, the width of the central porosity zone was reduced by 90 mm compared with that at 25.5%, and by 101 mm compared with that at 44.9%. These findings demonstrate that the LCRR provides a more effective criterion than simple distance coordinates for characterising the installation position, offering both theoretical and guidance for the rational application of F-EMS.