Abstract: 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%.

摘要： Φ13 mm 55SiCrA-1钢(0.55%C)的生产流程为脱S铁水-80 t BOF-LF-RH-280 mm×325 mm坯连铸-轧制。所生产的Φ13 mm55SiCrA-1钢在冷拉过程中出现异常断裂,金相分析结果表明,盘条心部存在明显的黑点,且中心相邻区域出现负偏析现象。通过优化钢水过热度(15～25℃),二冷比水量(0.25 L/kg),结晶器电磁搅拌电流(300 A)和轻压下量(辊Ⅰ-1 mm,Ⅱ-2.5 mm,Ⅲ-3.5 mm,Ⅳ-3.5 mm和V-2 mm)使碳在铸坯横截面上分布趋于均匀,碳含量范围由原来0.49%～0.63%降至0.52%～0.60%,使冷拔断丝率由原7%降至0.5%。