含Ti铝镇静超低碳钢连铸过程水口堵塞控制实践

分析水口堵塞物组成及其堵塞发生的机理得出,含Ti铝镇静超低碳钢连铸过程水口堵塞物呈分层结构,由反应层和粘结层组成,其中反应层为耐材酸性物质与钢水中Al反应以及钢水因与堵塞壁面接触温度降低、夹杂物析出反应所致,粘结层由夹杂物伴随冷钢堆积所致,且粘结层中Al含量由内至外呈增加的趋势,Ti含量则呈减少的趋势。通过顶渣改质将(FeO+MnO)控制在8%以下、RH脱碳终点[O]控制在0.030%以内,以及采用开浇前中间包充氩置换工艺等优化措施,含Ti铝镇静超低碳钢连浇炉数由原来的3炉提升至5炉,水口堵塞率由原来的80%降低至30%。

Practice on Control of Nozzle Clogging in Casting Process of Ti-Bearing Al-Killed Ultra-Low Carbon Steel

By analyzing on ingredient of nozzle clogging and mechanism of clogging-forming it is obtained, that the nozzle clogging in casting process of Ti-bearing Al-killed ultra-low carbon steel has a hierarchical structure, consisting of a reaction layer and a bonding layer; inside, the reaction layer is caused by the reaction of the acid material in refractory with Al in the steel and the precipitation of inclusions caused by the temperature of molten steel decreasing due to contact with the wall surface of the clogging, while the bonding layer is caused by the accumulation of inclusions accompanied by cold steel； the mass percentage of Al in the bonding layer increases from the inner to the outer layer, and the mass percentage of Ti decreases. By taking such measures as (FeO + MnO) is controlled below 8% by modifying top slags, the mass percent [0] after RH decarburization is controlled within 0. 030% , the tundish argon replacement process before casting is implemented and so on, the number of continuous casting heats of Ti-bearing Al-killed ultra-low carbon steel increases from original 3 to 5, and the nozzle clogging rate has been reduced from original 80% to 30%.