Abstract: The process characteristics and steel cleanness of lowcarbon aluminum killed steel under different RH process routes were discussed. The results showed that: the w(T.Fe+MnO)of route 1 was 5 %-12 %, while route 2 was under 2 %, besides the lost of acidsoluble aluminium for route 1 was 54×10-6 more than route 2. Effective removal time of inclusion under route 2 was 64 min more than 45 min of route 1, and the total oxygen at mold through process route 1 was 13×10-6 higher than that of route 2. The total inclusion ratio of route 1 was higher than that of the route 2, and for rout 1, it has 10.6 % of the inclusions bigger than 5 μm,while only 3.6 % for route 2.The optimization measures were put forward respectively according to the different RH refining process.

Key words: low carbon Al-killed steel, RH refining process, inclusion