120 t BOF-LF-CC流程生产20CrMo齿轮钢的工艺实践

Φ12~32 mm 20CrMo齿轮钢(/%:0.19~0.23C,0.48~0.58Mn,0.24~0.28Si,0.009~0.015P,0.003~0.012S,0.87~1.08Cr,0.17~0.18Mo,0.024~0.046Als)的生产流程为铁水脱硫-120 t顶底复吹转炉-LF-软吹-200 mm×200 mm方坯连铸-连轧工艺。结果表明,通过控制铁水S]≤0.030%,BOF终点C]≥0.08%,终点P]≤0.012%,转炉出钢加0.6~1.0 kg/t铝块预脱氧控制LF精炼渣碱度3.5~5.0,连铸钢水过热度20~30℃,拉速1.1~1.4 m/min,开轧温度1 060~1 100℃,终轧≤900℃等工艺措施,钢中全氧含量为12.5×10^-6~22.5×10^-6,氮含量33×10^-6~40×10^-6,热轧材中心和一般疏松0.5~1.0级,热顶锻和力学性能满足标准要求,淬透性带宽△J₉ HRC值3.0,△J₁₅HRC值4.2。

Process Practice on Gear Steel 20CrMo Produced by 120 t BOF-LF-CC Flowsheet

The production flowsheet for 012 ~ 32 mm bars of gear steel 20CrMo (/%:0.19 ?0.23C, 0.48 ~ 0.58Mn, 0.24 ?0.28Si, 0.009 -0.015P, 0.003?0.012S, 0.87 ~1.08Cr, 0.17 ~0.18Mo, 0.024 ~ 0.046Als) is desulphurizing hot metal-120 t top and bottom combined blowing converter-LF-soft argon blowing-200 mm x 200 mm billet concasting-continuous rolling process. Results show that with using the process measures including controlling hot metal S]≤0.030% , BOF end C] 5:0.08% and end P]≤0.012% , adding 0.6 ~ 1.0kg/t aluminium pig for pre-deoxidizing at BOF tapping, controlling LF refining slag basicity 3.5 ?5.0, casting liquid overheating extent 20 ~30 ℃, casting rate 1. 1 ~ 1. 4 m/min, beginning rolling at 1 060 ~ 1 100 °C and finishing rolling at ≤900 ℃，the total oxygen content and the nitrogen content in steel are respectively 12. 5 x 10^-6?22. 5 x 10^-6 and 33 x 10^-6 ~40 x 10^-6, the rating of central and general porosity in rolled products is 0. 5 ~ 1. 0, the hot upset test and the mechanical properties of steel meet the requirement of standard, and the hardenability band width △J₉ HRC value is 3. 0 and the △J₁₅  HRC value is 4. 2.