The central crack ratio of the Φ600 mm 50CrMo steel continuous casting round bloom produced by 90 t LD-LF- VD-CC flow sheet at steel plant reaches up to 30% . It is obtained by analysis that the central cracks of the continuous casting round bloom all appear on the inner arc side. The main reason is that developed columnar crystal of the steel

the inner arc columnar crystals basically extend to the center of the round bloom

leading to the round bloom center cracking and expanding to the inner arc side during straightening. By increasing the electromagnetic stirring current of the crystallizer from 260 A to 400 A

the superheat of the tundish liquid reducing from 30-50 to 15-30 ℃

and the casting speed lowering from 0.34 m/min to 0.28 m/min

and the accuracy of the roller table of the tension leveling machine reducing from 0.40-1.00 mm to below 0.20 mm

etc

the center crack of the Φ600 mm 50CrMo steel continuous casting round bloom is completely eliminated.