200 t LD-LBAr-CC流程生产低碳铝镇静钢的洁净度

钢厂试验的低碳铝镇静钢(/%:0.036～0.037C、0.009Si、0.173～0.176Mn、0.012～0.013P、0.005～0.006S)生产流程为200 t LD转炉-钢包吹Ar精炼(LBAr)-230 mm×1 300 mm板坯连铸工艺。通过LD转炉挡渣出钢,并加入Mn-Fe、铝丸进行预脱氧和合金化3 min,钢水TO]和N]分别为91.8×10^-6和19.4×10^-6,在氩站经10～12 min 25～45 m³/h流量吹氩和3～5 min 15～25 m³/h的软吹氩后,TO]降至42.3×10^-6,N]为22.0×10^-6,中间包和铸坯TO]分别为38.3×10^-6和28.9×10^-6,N]分别为23.6×10^-6和26.5×10^-6。该流程生产的铸坯满足TO]≤30×10^-6的内控要求。经氩站精炼后,显微夹杂物去除率为30.0%,而大型夹杂物去除率达58.7%;显微夹杂物主要为脱氧产物Al₂O₃;大型夹杂物主要为SiO₂、Al₂O₃、SiO₂-Al₂O₃、CaO-SiO₂-Al₂O₃。

Cleanliness of Low Carbon Al-Killed Steel Produced by 200 t LD-LBAr-CC Flow Sheet

The production flow sheet for test low carbon Al-killed steel (/% : 0.036-0.037C, 0.009Si, 0.173-0.176Mn, 0.012-0.013P, 0.005-0.006S) at steel works is 200 t LD converter-ladle blowing argon (LB Ar) -230 mm x 1 300 mm slab casting process. With slag stopping at LD converter tapping, adding Mn-Fe and aluminium bullet to deoxidizing and alloying for 3 min, the liquid TO] and N] are respectively 91.8 x 10^-6 and 19.4 x 10^-6, blowing argon with flow rate 25-45 m³/h for 10-12 min then soft blowing argon with 15-25 m³/h for 3-5 min in ladle at argon station, the TO] decreases to 42.3 x 10^-6 and the N] is 22.0 x 10^-6, in tundish liquid and in slab the TOJ is respectively 38.3 x 10^-6 and 28.9 x 10^-6 and the N] is respectively 23.6 x 10^-6 and 26.5 x 10^-6. The slab produced by this flow sheet meets the internal control requirement i. e. TO] ≤ 30 x 10^-6. After refining at argon station the amount of micro-inclusions in steel decreases by 30.0%, while the amount of large inclusions decreases by 58.7% ； the micro-inclusions in steel are mainly deoxidation product A1₂O₃, while the large inclusions in steel are mainly SiO₂, Al₂O₃, SiO₂-Al₂O₃ and CaO-SiO₂-Al₂O₃.