优化55t LD-60t LF-CC工艺提高钢的洁净度

Optimization of 55 t LD-60 t LF-CC Process to Upgrade Cleanliness of Steel

控制LD（氧气顶吹转炉）吹炼终点C-低碳钢0．08％～0．10％C、中碳钢0．10％～0．15％C、高碳钢≥0．20％c；通过LD出钢时强化预脱氧，控制出渣钢下渣率达98％，控制LF精炼Als为0．020％～0．035％，保证精炼渣中（FeO）≤0．5％，喂CaSi线，50～80L/min软吹氩时间≥7min以及全程保护浇注；中间包采用高效保温吸渣剂及稳定连铸操作等工艺措施，使石钢55t转炉-60tLF冶炼流程在不进行真空处理的工艺条件下，连铸坯中氧含量控制在20×10^-6以下。

The oxygen contem in concasting billet has been controlled less than 20 ×10^-6 in condition of non-vacuum treatment with 55 t LD-60 t LF melting flow sheet at Shijiazhuang Iron and Steel by the operation measures such as control- ling LD blowing end-point carbon： low carbon steel 0.08%～0.10%C; medium carbon steel 0.10% ～ 0.15%C and high carbon steel ≥0.20%C, strengthening pre-deoxidation at steel tapping of LD, controlling slag tapping rate up to 98%, controlling Als 0.020% ～ 0.035% during LF refining, to ensure refining （FeO） ≤0.5%, feeding CaSi wire, 50 ～80 L/ min soft blowing argon time ≥ 7min, protective casting in whole process, using high efficiency holding and absorbing slag agent, and constant casting operation.