Abstract:Based on the measured surface temperature of the bloom, mathematical model for solidification heat transfer is presented according to modifying the heat transfer coefficient of different cooling zone and the calculating results of the model are applied to the static soft reduction well. The following results are obtained: the best casting condition for soft reduction is liquid steel overheat 10~30℃、secondary intensity 0.28L/kg、casting speed 0.85m/min and reduction amount 8mm; using soft reduction technology can decrease the grade of center porosity from 2.0~2.5 to 1.0~1.5, improve the V-shape segregation and center shrinkage cavity, and also decrease the center average carbon segregation index of the bloom from 1.17~1.26 to 1.07~1.13.