The production flowsheet of Φ13 mm 55SiCrA-l steel (0.55% C) is desulphurized metal-80 t BOF-LF- RH-280 mm x325 mm bloom casting- rolling. The abnormal fracture of produced 613 mm 55SiCrA-l steel occurs during cold-drawn process

and the metallographic analysis results show that there are obvious black spots in center of coil and the negative segregation occurs at the zone near center. With the process measures including optimizing liquid overheating extent (15 ~25 ℃)

secondary water ratio (0.25 L/kg)

mold electromagnetic stirring current (300 A) and light reduction amount ( roller I- 1 mm

Ⅱ- 2.5 mm

Ⅲ - 3.5 mm

Ⅳ- 3. 5 mm and V-2 mm)

the distribution of carbon at cross section of casting bloom tends to uniform i. e. the carbon content range decreases from original 0.49% ~0. 63% to 0.52% ~ 0.60%

and the cold-drawn fracture ratio decreases form original 7% to 0. 5%.