The production flow sheet for Φ500 mm casting bloom of 0.20% C steel (0.19% ~ 0.23% C) is 70 t BOF-LF-VD-Φ500 mm heavy round caster. The study and optimization work on mechanical equipment and process parameters including secondary water cooling parameter have been carried out. In first pilot production with continuous casting 8 heats of 0.20% C steel

the optimizing parameters including using special mold powder

controlling liquid overheating extent 25 ~35 °C

casting speed 0.30 m/min

secondary water rate 0.14 L/kg

mold electromagnetic stirring 400 A/1.5 Hz are used. The examination results show that the bloom surface has not visible defects including bulging

feather defect； the rating of center line shrinkage is 0.5 and the rating of center porosity is 1

the carbon segregation is ≤1.12

and the oxygen content in steel ≤15 x 10

-6

nitrogen content in steel ≤65 x 10

-6

to meet the requirement

of design.