0.12%~0.16%C铬钼钢连铸板坯表面纵裂的控制

12Cr2Mo,14CrMo和15CrMo钢的生产流程为铁水-110t BOF—LF—VD-300 mm×（1700~2400）mm板坯CC工艺。分析了钢中碳含量,Mn/S,结晶器倒锥度,结晶器冷却工艺和保护渣,浸入式水口插入深度等因素对连铸板坯表面纵裂的影响。通过将优化前3种钢的结晶器倒锥度1.10优化成12Cr2Mo钢1.20,14CrMo钢1.15,15CrMo钢1.10,浸入式水口的插入深度由原先的170~180 mm调整到140~150 mm,使用粘度较低的保护渣（碱度1.25,1300℃粘度0.129 Pa·s）,以增加渣液的流动性,连铸板坯表面纵裂缺陷得到了有效的控制,纵裂率由原先的8.9%降低到优化后的3.2%。

Control of Casting Slab Surface Longitudinal Cracks of 0.12%-0.16% C Chromium Molybdenum Steel

The Production flowsheet for steel 12Cr2Mo, 14CrMo and 15CrMo is metal-110t BOF-LF-VD-300 mm x (1700-2400) mm slab CC process. The effect of factors including carbon content in steel, Mn/S, mold inverted taper and immersion nozzle insertion depth on casting slab longitudinal cracks is analyzed. By optimizing the mold inverted taper from before optimization 1.10 for three kinds of steel to 1.20 for steel 12Cr2Mo, 1.15 for steel 14CrMo and 1.10 for steel 15CrMo, adjusting the immersion nozzle insertion depth from original 170-180 mm to 140-150 mm, and using lower viscosity mold powder (basicity 1.25, viscosity 0.129 at 1300℃) to increase the flux flowability, the casting slab surface longitudinal cracks defect is effectively controlled, the longitudinal cracks occurred rate decreases from original 8.9% to 3.2% after optimization.