Abstract: With using 120 t top and bottom combined blown converter-LF refining-VD-Φ150 ~ Φ200 mm round billet casting flow sheet, the development and production for casting round billet of J55 (37Mn5) , L80 ( TC80, 0.24% ~ 0. 28%C, 1.40% ~ 1. 55Mn) , N80 (36Mn2V) and Pl 10 (26CrMn4) grade oil case steel have been completed at Tiansteel by the measures including controlling residual deleterious elements content in metal； intensifying converter dephosphorizing in early phase, controlling end [C] ≥0. 10% and after tapping slag layer thickness in ladle W50 mm； controlling ingredient of refining slag and end slag ( FeO + MnO) ≤ 1.0% ； increasing bottom argon flow rate to 200 ~ 300 L/min in VD process ； and shielding casting in whole casting process. Production results show that for J 55 grade steel the total oxygen content is ≤25 x 10^-6 and P ≤0. 020% ； for L80, N80 and P110 grade steels the total oxygen content ≤20 x 10^-6 and P≤0. 015% ； the residual deleterious elements ( Pb + Sn + As + Sb + Bi) ≤ 140 x 10^-6 ; the rating of total inclusions in steel ≤2. 5 and the ratings of central porosity and shrinkage cavity are respectively ≤1.0.

摘要： 采用120 t顶底复吹转炉-LF-VD-Φ150～Φ200 mm圆坯连铸流程,通过控制铁水有害残余元素含量,强化转炉前期脱磷,控制终点[C]≥0.10%,出钢钢包渣厚≤50 mm,控制精炼终渣(FeO+MnO)≤1.0%,提高VD过程底吹氩流量至200～300 L/min,连铸全程保护浇注等措施,天钢完成J55(37Mn5),L80(TC80,0.24%～0.28%C,1.40%～1.55Mn),N 80(36Mn2V)和P 110(26CrMo4)级石油套管钢连铸圆坯的开发生产。生产结果表明,J55钢级的全氧含量≤25×10-6,P≤0.020%;N80、LS0和P110级别的全氧含量≤20×10^-6,P≤0.015%;残余有害元素(Pb+Sn+As+Sb+Bi)≤140×10^-6,夹杂物总量≤2.5级,圆管坯的中心疏松和缩孔等分别≤1.0级。

关键词: 石油套管钢, 120 t转炉-LF-VD-圆坯连铸流程, 质量控制