120 t BOF-LF-CC流程生产20CrMnTi齿轮钢的工艺实践

武钢条材总厂采用铁水脱硫-120 t BOF-LF-200 mm×200 mm方坯连铸-热轧工艺生产窄淬透性带20CrMnTi齿轮钢。生产结果表明,通过转炉高拉碳工艺,控制终点[C]≥0.08%,出钢时加0.8 kg/t铝块预脱氧、钢包吹氩喂氩喂铝线150 m,LF精炼时喂0.4 kg/t铝线和控制精炼渣碱度3.0~4.0,并采用精确调整合金成分,氩封长水口连铸等工艺措施,生产122炉20CrMnTi齿轮钢成分为(%):0.19~0.21C，0.22~0.31Si，0.85~1.04Mn，1.01~1.19Cr，0.04~0.09Ti，0.02~0.06Cu，≤24×10-6[O]，≤55×10-6[N]；疏松和偏析级别均≤1.0,晶粒度级别≥9.0;淬透性带宽△HRC≤5.9,满足标准要求。

Process Practice for Gear Steel 20CrMnTi Produced by 120 t BOF-LF-CC Flow Sheet

The gear steel 20CrMnTi with narrow hardenability band is produced by hot metal desulphurizing-120 t BOF-LF-200 mm x 200 mm billet casting-hot rolling process at Long Products General Plant, Wuhan Iron and Steel. Production results show that with the process measures including using BOF catch carbon practice to control end [C] ≥ 0.08% , adding 0.8 kg/t aluminium during tapping for pre-deoxidizing, than argon blowing and feeding aluminium wire 150 m in ladle, during LF refining feeding 0.4 kg/t aluminium wire and controlling refining slag basicity 3.0-4.0, microadjusting alloying element content and argon shielding long nozzle casting process, the results of analysis of 122 heats gear steel 20CrMnTi are (/% ) 0.19-0.21C, 0.22-0.31Si, 0.85-1.04Mn, 1.01-1.19Cr, 0.04-0.09Ti, 0.02-0.06Cu, ≤ 24 X 10^-6[O] and ≤ 55 x 10^-6[N]; the rating of porosity and segregation ≤ l.0 and the rating of grain size ≥ 9.0; and the width of hardenability band △HRC of products ≤ 5.9 to meet the requirement of standard.