Abstract: In order to quantitative analyse weather the inclusions in ULC steel slab can meet the requirements of coldrolled sheet，the ULC slab inclusions distribution, composition, size and area ratio was quantitative analysed using Aspex SEM. The inclusions were evenly distributed on the slab section, very few size range were 50～100 μm. Some cluster inclusions larger than 100 μm were existed in slab butts and tail. It was shown that werather oxygen blowing or not in RH,but the same activity oxygen after RH decarbonrization in different heats, the total inclusion number and area ratio were also same. The exicted production was stable, but the slab butts and tail can't use thin plate cold rolling.

Key words: ULC steel, slab, inclusions, quantitative analysis