包晶钢15CrMoG方坯表面缺陷分析与改进

针对包晶钢15CrMoG的200 mm×200 mm连铸坯存在表面凹陷及纵裂漏钢问题，对铸坯表面检查进行分析及试验对比。结果表明，结晶器铜管和保护渣传热不均及二冷强度低导致表面产生凹陷缺陷及漏钢问题。通过将结晶器铜管锥度从0.72%/m提到1.10%/m、保护渣碱度从0.72提到1.05、黏度从0.44 Pa·s提到0.74 Pa·s、熔化温度由1 170℃提高到1 191℃及二冷比水量从0.30 L/kg提高到0.45 L/kg等措施，改善结晶器冷却传热和二冷段喷淋冷却效果，提高铸坯冷却均匀性，使得铸坯缺陷明显改善。

Analysis and improvement of surface defects of peritectic steel 15CrMoG billet

Facing the quality problems of surface sag and longitudinal crack of steel leakage of 200 mm×200 mm continuous casting billet of peritectic steel 15CrMoG, the surface sag and breakout defects of casting billet are analyzed by surface inspection and test comparison. The result indicates that surface sag and longitudinal crack of steel leakage are caused by the uneven heat transfer between the crystallizer copper tube and the slag and the low intensity of secondary cooling. By changing the crystallizer copper tube taper from 0.72%/m to 1.10%/m and the basicity of slag from 0.72 to 1.05 and the viscosity from 0.44 Pa·s to 0.74 Pa·s and the melting temperature from 1 170 ℃ to 1 191 ℃ and the secondary cooling ratio water quantity from 0.30 L/kg to 0.45 L/kg,it improves the cooling heat transfer of the crystallizer and the cooling effect of the secondary cooling section and the cooling uniformity of casting billet. The result shows the defects of casting billet have been effective controlled.