Abstract: The distribution of over 50 μm bubbles in slab surface layer with or without EMS was studied by using metallographic analysis method. The results show that the bubbles of the two processes cluster at a certain distance from the inner arc of the slab as the accumulation zone, but the bubbles distribution with EMS has no obvious symmetry about the centerline of the broad face. Numerical results from a flow analysis in the mold show that the main difference between the two processes is that EMS can improve flow distribution of the nozzle impact area. A more stable transverse flow appears the nozzle impacting area with EMS, which is helpful to the removal of the bubbles; while without EMS, there is a large longitudinal vortex area at the quarter of the broad face, which leads to the bubbles clustering and easily to be captured by the shell. The influence on the bubbles distribution with or without EMS was studied by combining the experiment with the simulation, it's important for the purity of the IF steel casting slab.

Key words: slab, bubble, distribution rule, EMS