钢球用钢Φ380mm连铸圆坯表面裂纹原因分析及工艺改进

Cause Analysis on Surface Crack of Steel Ball Steel Φ380mm Continuous Casting Round Bloom and Process Improvement

对Φ380mm高碳钢球钢连铸圆坯轧成钢材出现的表面裂纹进行了统计分析结果表明:抛丸检查后的连铸圆坯表面存在纵向裂纹,主要原因是钢液在结晶器中凝固时冷却不均产生的。通过将结晶器铜管锥度由0.45%/m调整为0.63%/m,1300℃保护渣粘度由0.60 Pa·s降到0.50 Pa·s,1300℃保护渣熔速由36 s调整到49 s,二冷比水量由0.30 L/kg降到0.25 L/kg,二冷段四面冷却改为八面冷却等措施,有效降低了大规格钢球钢铸坯及轧材的表面纵裂纹,轧材表面探伤合格率提高到95%以上。

The occurred surface crack of products rolled from Φ380mm high carbon steel ball steel continuous casting round bloom has been statistcally analyzed.The results show that there is a longitudinal crack on the surface of the continuous casting round bloom after shot peening,which is mainly caused by the uneven cooling of the molten steel in the mold.By adjusting the taper of the crystallizer copper tube from 0.45%/m to 0.63%/m,the 1300℃viscosity of mold slag is reduced from 0.60 Pa·s to 0.50 Pa·s,and the flux rate of the mold shield slag at 1300℃is adjusted from 36 s to 49 s,secondary cooling water ratio decreasing from 0.30 L/kg to 0.25 L/kg,the four-sided cooling of the second cooling section is changed to eight-sided cooling,the surface longitudinal cracks of the large-size steel ball steel billets and rolled materials are effectviely reduced,and the surface inspection qualified rate of the rolled material increases to more than 95%.