120t BOF-LF-CC流程生产20CrMo齿轮钢的工艺实践

Process Practice on Gear Steel 20CrMo Produced by120 t BOF-LF-CC Flowsheet

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△J_9 HRC值3.0,△J_(15)HRC值4.2。

The production flowsheet for O12 ～ 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 de- sulphurizing 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 ] I〉 0.08% and end [ P]≤0. 012%, adding 0. 6 ～ 1.0 kg/t alumininm pig for pre-deoxidi- zing 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/rain, beginning rolling at 1 060 ～ 1 100 ℃ and finishing rolling at ≤900 ℃ , the total oxygen content and the nitrogen content in steel are respectively 12. 5 × 10 -6 - 22. 5 × 10 -6 and 33 ×10 -6 - 40 ×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 re- quirement of standard, and the hardenability band width AJ9 HRC value is 3.0 and the AJl5 HRC value is 4. 2.