100t BOF-LF-CC流程冶炼10B21钢的工艺优化

Process Optimization for Steel 10B21 Steelmaking by100 t BOF-LF-CC Flowsheet

针对10821钢（％：0．19～0．22C，≤0．08Si，0．8～1．0Mn，≤0．020P，≤0．020S，0．010～0．040A1，0．001～0．005B）冶炼过程中钢液硅含量超标、可浇性差、铸坯角裂的问题，通过生产数据和夹杂物分析、铸坯低倍检验得出，LF白渣后，渣中SiO：被Al还原，造成[Si]超标；钢中A2O3在水口蓄积降低10821钢的可浇性，凝固过程氮化硼和氧化硼在晶界析出，易使铸坯产生角裂。通过提高转炉终点[C]为0．10％～0．14％，出钢温度1640～1660℃，转炉铝铁加入量由1．82kg／t降至1．36kg／t，LF精炼铝铁加入量由2．8kg／t降至1．6kg／t，喂钙量由1．23kg／t增至2．05kg／t，添加微量固氮元素Ti，优化连铸工艺等措施后，钢液中si含量-[si]≤0．08％比例从65．62％提高到89．50％；单个中间包连浇炉数从4炉提高到12炉；铸坯角裂得到有效控制，正品铸坯收得率由88．23％提高至97．64％。

According to the issues for the steel 10B21 （/% ： 0. 19 -0. 22C, ≤0. 08Si, 0. 8 - 1.0Mn, ≤0. 020P, ≤0. 020S, 0. 010-0. 040A;, 0. 001 -0. 005B） during steelmaking process including silicon content in liquid going beyond the limit of standard, poor castability and exiting cracked comer of cast billet, with analysis on production data and inclusions in steel, and cast billet macro-examination, it is obtained that after LF white slagging, the SiO2 in slag is reduced by Al led to [ Si] going beyond the limit; the castability of steel 10B21 decreases by Al2O3 in liquid depositing in nozzle, and during casting solidification process the boron nitride and oxide precipitate at grain boundary causing cast billet cracked comer. With using the process measures including increasing BOF end [ C] to 0. 10% -0. 14% , controlling tap- ping liquid temperature 1 640 - 1 660 ℃, decreasing BOF aluminium iron adding amount from 1.82 kg/t to 1.36 kg/t, decreasing LF refining aluminium iron adding amount from 2. 8 kg/t to 1.6 kg/t, increasing feeding calcium amount from 1.23 kg/t to 2. 05 kg/t, adding micro fixed nitrogen element Ti and optimizing casting process, the ratio of [ Si] ≤0.08% increases from 65.62% to 89.50%, single tundish continuous-continuous casting heats in crease from 4 heats to 12 heats and the casting bloom cracked comer is effectively controlled, and the yield of qualified cast billet increases from 88.23% to 97.44%.