400系易切削不锈钢硫铁加入方式优化

邢钢一步法(脱磷站+60t AOD+60t LF)生产400系易切削不锈钢过程中,前期采用硫铁全部在AOD出钢时加入配S],AOD出钢至上机浇铸过程中钢渣碱度始终处于低碱度范围(R=1.40～1.95),硫铁消耗较大,钢液氧含量偏高,随着冶炼炉数的增加,炉衬侵蚀严重,影响AOD炉龄和钢坯质量,且钢渣较长时间处于低碱度状态,极易造成钢中C]含量的上升(尤其是430F、430FR低碳类钢种),很难实现多炉连浇。后期通过优化硫铁加入方式,在LF后期加硫铁,AOD炉渣碱度2.0～2.3,LF炉渣碱度1.6～2.0,缩短低碱度渣处理时间,降低S]损耗和钢液氧含量及对炉衬侵蚀。使易切削不锈钢S]的收得率由62%提高到75%,吨钢硫铁消耗下降2.12 kg,铸坯皮下气泡等缺陷得到控制。

Optimization of Sulphure Iron Addition Mode of 400 Series Free-Cutting Stainless Steel

Xinggang one-step method (dephosphorization station +60 t AOD furnace +60 t LF furnace) is used in the production of 400 series free cutting stainless steel, in the early stage, in all the sulphur iron was added to the steel in the AOD to fit S]. The alkalinity of steel slag during the AOD tapping to the upper casting process is always in the low alkalinity range (R = 1.40 ~ 1.95). The consumption of sulphur iron is large, oxygen content in molten steel is high, with the increase of the number of smelting furnaces, the lining erosion is serious, effecting AOD furnace life and billet quality and the steel slag is in a low alkalinity state for a long time, which is easy to cause the increase of C] content in the steel (especially 430F, 430FR low carbon steel) , which is difficult to achieve multi-furnace continuous pouring. In the later stage, by optimizing the method of adding iron sulphide and the alkalinity of slag at different stages, including iron sulphide in LF late period, AOD slag basicity 2.0 ~ 2.3 and LF slag basicity 1.6 ~ 2.0, the treatment time of low alkalinity slag is shortened, the S] element loss and the oxygen content of molten steel and the erosion of the furnace lining are reduced. The sulfur element absorption rate was increased from 62% to 75% , the sulphur iron consumption per ton of steel decreased by 2.12 kg, and defects such as subcutaneous bubbles in the slab were controlled.