VOD底吹氮精炼高氮钢P91的工艺实践

Practice of Process for VOD Nitrogen Bottom-Blown Refining High Nitrogen Steel P91

锅炉用铁素体耐热钢P91(%:0.08～0.12C、8.0～9.5Cr、0.85～1.05Mo、0.18～0.25V、0.06～0.10Nb、0.030～0.070N)的冶炼工艺流程为20 t EBT EAF+10 t感应炉混炼-LF-VOD(吹氮)-3 t锭模铸。通过低真空(～26 000 Pa)底吹N气搅拌使脱氧剂、造渣材料充分快速与钢液反应,使[N]从(80～90)×10^(-6)增至(120～140)×10^(-6),然后底吹氮以(9～15)×10^(-6)/min的增氮速率将[N]增至620×10^(-6),钢材中的N含量约为500×10^(-6),达到标准要求。

The steelmaking process flow sheet of ferrite heat resisting steel P91 for boiler （ %;0.08 - 0.12C, 8.0 9.5Cr, 0. 85-1.05Mo, 0. 18 N0. 25V, 0. 06 -0. 10Nb, 0. 030 -0. 070N） is 20tEBT EAF ＋10tinduction furnace mixing melting- LF-VOD （ nitrogen blowing） - 3 t ingot mold casting. With bottom blowing nitrogen gas stirring in low vacuum （-26 000 Pa） to make sufficient and quick reaction between deoxidizer, slag-making materials and liquid, the [N] increases from （80 - 90）×10^-6 to （120 - 140）×10^-6, then by nitrogen bottom-blowing with （9-15 ）×10^-6/min increasing rate of N content in liquid, the [ N] shall increases to 620 ×10^-6, and the nitrogen content in steel products is about 500×10^-6 to meet the requirement of standard.