Abstract: Based on simulation of molten steel flow field in mold for 150 mm×150 mm billet and analysis on slag inclusion mechanism, the relative process parameters for concasting have been improved including increasing immersion depth of submerged nozzle to 120～135 mm from original 70～80 mm, enlarging lower vent diameter of submerged noazle to 32 mm from 25 mm, increasing viscosity of mold flux to0.40 Pa · s from 0.38 Pa · s, and mold molten steel level fluctuation decreased to ±3.0 mm from ±5.0 mm,as a result the qualified rate for inclusion rating in steel C72DA increased from 92. 10% to 99.51%.

Key words: Steel C72DA, , Mold, , Entrapped Slag Inclusion