Abstract: The oxygen content in IF steel (/% ：≤0.005C, ≤0.04Si, 0.05~0.20Mn, ≤0.015P, ≤0.015S, 0.03~0.06Als) before adding aluminium in RH refining process is 340 x 10^-6~467 x 10^-6, and the types, size and number of inclusions in steel after adding aluminium for 2~10 min have been studied by ASPEX scanning electron microscope. Results show that the main type of inclusions in IF steel alter deoxidation by adding aluminium in RH refining process is alumina, with increasing circulation time of RH refining the number of inclusions in liquid decreases ； with after adding aluminium for 6 min it is available to alloying operation and further prolonging circulation time the removing rate of inclusions in liquid slows down； as the initial oxygen content in IF liquid before adding aluminium is rather higher, it may be appropriate to extend circulation time to 8 min then to alloying.

Key words: IF Steel, 300 t RH Circulation Time, Deoxidation, Al₂O₃ Inclusions

摘要： RH精炼过程加铝前IF钢（/%:≤0.005C,≤0.04Si,0.05~0.20Mn,≤0.015P,≤0.015S,0.03~0.06Als）中的氧含量为340×10^-6~467×10^-6，用Aspex扫描电镜研究了加铝后210 min钢中夹杂物类型、尺寸和数量，结果表明，IF钢在RH工序加铝脱氧后钢液中夹杂物的类型主要为氧化铝，随着RH循环时间的增加，钢液中夹杂物数量减少；加铝真空循环6 min后可进行合金化，进一步延长循环时间，钢液中夹杂物的去除速度减缓；加铝前IF钢液中的初始氧含量偏高时，可适当延长循环时间至8 min，再进行合金化。

关键词: IF钢, 300t RH循环时间, 脱氧, Al₂O₃夹杂