Abstract: The evolution of inclusions in a typical titanium-containing ultra-pure ferritic stainless steel (/% ： ≤ 0.01C,17.5 ~ 18.5Cr, 0.40 ~0. 55Nb, 0. 10～0.25Ti) during 80 t K-OBM-S-VOD-LF-200 mm x 1 240 mm CCM process is systematically studied by means of thermodynamic analysis, scanning electron microscopy analysis and EDS (Energy Dispersive Spectum) analysis. The results show that while Si-Al composite deoxidization is used in VOD reduction period, the main types of inclusions are Al2O3 -CaO-SiO2 -MgO and Al2O3 -CaO-MgO； after titanium alloying, the inclusions are transformed into Al2O3 -CaO-TiOx -MgO. Because of the high melting point and large size of such inclusions, it is difficult to be modified by calcium treatment, and easy to cause nozzle clogging. By increasing Al/Ti ratio more than 0.11, reducing T[0] in steel to below 25 x 10-6 before titanium alloying and using pure ferrotitanium alloy, the large-size inclusions containing titanium can be avoided.

Key words: Ultra-Pure Ferritic Stainless Steel, Inclusions, Titanium Alloying, Al/Ti Ratio, T[0], Cleanliness

摘要： 通过热力学分析、扫描电镜和EDS能谱分析等方法,系统研究了一种典型含钛超纯铁素体不锈钢（/%:≤0.01C,17.5～18.5Cr,0.40～0.55Nb,0.10～0.25Ti）80 t K-OBM-S-VOD-LF-200 mm×1 240 mm CCM过程夹杂物的衍变。结果表明,VOD还原期采用Si-Al复合脱氧,夹杂物类型以Al2O3-CaO-SiO2-MgO和Al2O3-CaO-MgO为主,钛合金化后夹杂物转变为Al2O3-CaO-TiOx-MgO,由于此类夹杂物熔点高、尺寸大,且很难通过钙处理变性,容易聚集造成水口堵塞。通过提高铝钛比至0.11以上,降低钛合金化前钢中全氧含量至25×10-6以下,使用纯净的钛铁合金可以避免形成大尺寸的含TiOx夹杂物。

关键词: 超纯铁素体不锈钢, 夹杂物, 钛合金化, 铝钛比, T[O], 纯净度,