硅镇静钢Q235B精炼渣系优化及工业试验

Optimization and industrial testing of refining slag system for silicon killed steel Q235B

为提高硅镇静钢Q235B的洁净度,寻求合适硅镇静钢的精炼渣系,开展了热力学计算和实验室试验,确定了合适的硅镇静钢Q235B精炼渣成分,降低了原工艺渣系的碱度。优化后的渣系碱度控制在1.70~2.0,w(Al 2 O 3)控制在7.0%~10.0%。将优化的渣系成功用于工业试验,结果表明:渣系优化后硅镇静钢Q235B工业试验炉次LF出站钢中平均w(T.O)可降至42×10-6,最低26×10-6,铸坯中平均w(T.O)可降至35×10-6以下;中间包夹杂物最大直径可控制在20μm以下,轧材中夹杂物数密度可控制15个/mm 2以下,轧材夹杂物面积分数可控制在35×10-6以下,显著降低了钢中夹杂物的评级,提高了钢水洁净度。

In order to improve the cleanliness of silicon-killed steel Q235B and find a suitable refining slag system,thermodynamic calculations and laboratory experiments were carried out to determine the appropriate composition of refining slag and reduce the basicity of the original process slag system.The basicity of the optimized slag system was controlled between 1.70 and 2.0,and the mass fraction of Al 2 O 3 was controlled between 7.0%and 10.0%.The optimized slag system were successfully used in industrial tests.The results showed that after optimizing the slag system,the mass fraction of T.O in Q235B silicon killed steel after LF refining in the industrial test furnace could be reduced to 42×10-6 on average,with a minimum of 26×10-6.The average mass fraction of T.O in the slab can be reduced to less than 35×10-6.The maximum diameter of the inclusions in the tundish can be controlled below 20μm,the number density of inclusions in the rolled material can be controlled below 15/mm 2,and the area fraction of inclusions in the rolled material can be controlled below 35×10-6.The grade of inclusions in steel was significantly reduced and the cleanliness of molten steel was improved.