Based on statistics of process data of IF steel (/% : ≤ 0.002 5C

≤ 0. 005Si

0. 01 ~0

12Mn

≤ 0. 020P

≤ 0. 010S

0. 02 ~0. 04Als

0. 03 ~0. 05Ti) in steelmaking process

the effect of oxygen content in liquid at Ar station and amount of adding aluminium in RH decarburization period on T[O

]

and the effect of alloys adding procedure

top slag modified treatment and shielding casting process on cleanliness of liquid are analyzed. Research results show that the measures including proper increasing the BOF end oxygen content in liquid and temperature of liquid

extending the interval time between Al and Fe-Ti addition

top slag modifying treating and shielding casting process are available to increase the cleanliness of liquid. It is obtain

ed by commercial production that with the average temperature of liquid at initial RH refining increasing by 2. 4 °C

controlling BOF tapping slag amount to decrease the thickness of top slag layer from original 。80 mm to 60 ~75 mm as a result during RH decarburization process the adding aluminium heats decreasing by original 36% to 3%

and with top slag modification to decrease the (FeO + MnO) from original 22% to 17% and increase the continuous-continuous casting heats from 8 heats to 10 heats

the T[O

]

in liquid in tundish decreases form 37. 4 x 10

-6

to 21. 6 x 10

-6

to obviously increase the cleanliness of liquid.