微孔MgO耐火材料对钢液洁净度的影响

Effect of microporous MgO refractories on steel cleanliness

通过浸泡实验研究了3种镁质(致密镁质、微孔MgO质、镁碳质)耐火材料与超低碳钢液(1560℃)的相互作用,考察了不同浸泡时间(0~35 min)钢中O、N、C和Al、Si、Mn含量及钢中夹杂物的成分、数量、分布等特征的变化,并对耐火材料与钢的界面层进行了观测和分析。结果表明,随着浸泡时间的延长,3组钢中氧含量均先升高再降低,均对钢液有一定的污染,钢中夹杂物的数量增加,夹杂物种类由Al2O3-MnO夹杂逐渐转变为Al-Mg-Si-Mn-O复合夹杂。与致密镁质耐火材料相比,微孔MgO质和镁碳质耐火材料与钢的界面处分别能形成连续的镁铝尖晶石层和致密的MgO层,有助于降低耐火材料的侵蚀以及对钢液的污染。此外,与不含碳的镁质耐火材料相比,镁碳质耐火材料对钢液增碳严重。因此,微孔MgO质耐火材料不仅对钢液的二次污染小、不会向钢液增碳,而且还可以吸附钢中氧化铝夹杂,更有利于超低碳洁净钢的生产。

Interaction between three kinds of magnesia-based refractories(compact magnesia,microporous MgO,and magnesia-carbon)and ultra-low-carbon steel(1560℃)was investigated by immersion experiments.The changes of O,N,C and Al,Si,Mn content and the composition,quantity and distribution of inclusions in steel at different immersion time(0-35 min)were investigated,and observation and analysis of the interface layer between refractory and steel were carried out.The results show that with the extension of the immersion time,the oxygen content in the three kinds of steels first increases and then decreases,which causes some pollution to the molten steel,the number of inclusions in the steel increases,and the type of inclusions gradually changes from Al2O3-MnO to Al-Mg-Si-Mn-O composite inclusions.Compared with dense magnesium refractory materials,a continuous MgO spinel layer and a dense MgO layer can be formed at the interface between microporous MgO and magnesium carbon refractory materials and steel,which helps reduce the erosion of the refractory material and contamination of molten steel.In addition,compared with magnesium-free refractory materials without carbon,magnesium-carbon refractory materials have severe carbon addition to molten steel.Therefore,the microporous MgO refractory material not only has little secondary pollution to the molten steel and does not add carbon to the molten steel,but also can absorb alumina inclusions in the steel,which is more conducive to the production of ultra-low carbon clean steel.