中碳铝镇静钢开浇阶段中间包钢水洁净度的变化规律研究

Cleanliness Variation of Molten Steel in Tundish at the Opening Stage of Continuous Casting of Medium Carbon Aluminum Killed Steel

对中碳铝镇静钢单开第一炉浇注过程中的中间包钢水系统取样,用ASPEX扫描电镜分析了钢中夹杂物数量、成分等特征的变化规律。结果表明,开浇初期,中间包钢水的二次氧化现象严重。与RH终点的钢水相比,开浇初期中间包钢水的T.O含量增加了160%,N含量增加了39.7%,夹杂物的数量密度增加了118%,大颗粒夹杂物的数量密度增加了185%。随着浇注的进行,氧氮含量和夹杂物的数量密度下降;夹杂物成分向Al2O3含量增加的方向移动,且分布逐渐集中。开浇过程中钢水不仅受空气的氧化作用,还受中包耐材、卷渣等因素的影响。开浇初期钢液二次氧化生成的固态夹杂物更易聚合为大颗粒夹杂物。

Steel samples were taken from tundish at the initial teeming stage of the first heat of medium carbon aluminum killed steel and analyzed with ASPEX for variation of inclusion quantity and composition in the steel.Results showed that at the initial stage of casting,reoxidation of steel in the tundish is severe.Compared with the steel at the end of RH refining,the total oxygen content in the steel at the tundish increased by 160%,nitrogen content increased by 39.7%,quantity density of inclusions increased by 118% and large inclusions increased by 185% at the initial stage of casting.With the casting going on,the oxygen and nitrogen content and quantity density of inclusions decreased,while the composition of inclusions moved towards the direction of increasing Al2O3 content with gradually concentrating distribution.The steel is not only affected by oxidation of the air,but also affected by factors such as tundish refractory and slag entrapment.The solid inclusions formed by reoxidation at the initial stage of casting tend to aggregate into large inclusions.