Abstract: The surface of 300 mm x 360 mm low carbon steel casting bloom produced by using original mold powder [/%: 25. 64 CaO, 22. 72SiO₂, 5. 69MgO, 8.29Al₂O₃, 11. 87 (Na₂O + K₂O), 5. 49CaF₂, 5. 10BaO] easily produces network cracks at steel work. With analysis on 由e relativity between mold powder lubricating property and metallurgical quality of casting bloom and study on the influence of basicity, MgO and Al2 03 on melting point of mold powder and the influence of Ca₂F and alkali-earth oxide content on viscosity of mold powder, the optimum ingredient of mold powder [/%: 22. 06CaO, 23. 63SiO₂,4. 76MgO, 8. 29Al₂O₃, 11. 90 (Na₂O + K₂O), 2. 32CaF₂,4. 18BaO] is defined. The application results show that as the thickness of liquid slag layer increases to 7 ~ 10 mm from original slag 6 ~ 7. 5 mm, the casting bloom surface network is completely eliminated.

摘要： 钢厂使用原保护渣[/%:25.64CaO,22.72SiO₂,5.69MgO,8.29Al₂O₃,11.87(Na₂O+K₂O),5.49CaF₂,5.10BaO]生产的300mm×360 mm低碳钢连铸坯表面易产生网状裂纹。通过分析保护渣润滑性能与铸坯冶金质量之相关性和研究碱度、MgO和Al₂O₃对保护渣熔点的影响,CaF₂和碱土金属化合物含量对保护渣粘度影响,优化了保护渣的成分[/%:22.06CaO,23.63SiO₂,4.76MgO,8.29Al₂O₃,11.90(Na₂O+K₂O),2.32CaF₂,4.18BaO],应用结果表明,使保护渣液层的厚度由原保护渣的6~7.5 mm提高到7~10 mm,完全消除了连铸坯的网状裂纹。