120 t BOF-LF-VD-CC流程高品质重轨钢U75V的生产实践

通过对重轨钢U75V的生产过程进行取样分析,研究了实际冶炼过程中重轨钢夹杂物的演变规律和大型夹杂物的控制。研究结果表明:控制铝含量≤20×10^-6,精炼渣二元碱度1.8～2.2,白渣保持时间≥15 min,RH真空度在100 Pa以下保持高真空时间≥15 min,可使钢液中全氧含量降至10×10^-6以下,且铝含量不超过20×10^-6,轧材中基本消除B类和D类粗系夹杂,C类夹杂完全塑性化;中间包钢水过热度按25～35℃控制,中间包钢水平均停留时间(750±30)s、水口插入深度控制在90～110 mm,结晶器液面波动≤±3 mm等措施,可去除钢水中的夹杂物。

Production Practice of High Quality U75V Heavy Rail Steel by 120 t BOF-LF-VD-CC Flowsheet

Through the sampling analysis in the production process of U75V heavy rail steel, the inclusions evolution and control of large scale inclusions in heavy rail steel are investigated base on the samples taken during steelmaking process. The results show that the total oxygen content in molten steel can be reduced to less than 10 x 10^-6 by controlling the aluminium content ≤20x10^-6 ,the binary basicity of refining slag 1.8 ~ 2.2,the white slag holding time 15 min,and the RH vacuum 100 Pa 15 min. The coarse inclusions of B and D are basically eliminated and the inclusions of C are completely plasticized in finished product, aluminium content less than 20 x 10^-6 With the overheat of tundish 25 ~35℃ ,the average residence time of tundish steel (750 ±30) s,the depth of nozzle insertion 90 ~ 110 mm,and the fluctuation of mould liquid level ≤ ±3 mm,the inclusion in molten steel can be removed.