The production flow sheet for test low carbon Al-killed steel (/% : 0.036-0.037C

0.009Si

0.173-0.176Mn

0.012-0.013P

0.005-0.006S) at steel works is 200 t LD converter-ladle blowing argon (LB Ar) -230 mm x 1 300 mm slab casting process. With slag stopping at LD converter tapping

adding Mn-Fe and aluminium bullet to deoxidizing and alloying for 3 min

the liquid T[O

]

and [N

]

are respectively 91.8 x 10

-6

and 19.4 x 10

-6

blowing argon with flow rate 25

-45 m

3

/h for 10-12 min then soft blowing argon with 15-25 m

3

/h for 3-5 min in ladle at argon station

the T[O

]

decreases to 42.3 x 10

-6

and the [N

]

is 22.0 x 10

-6

in tundish liquid and in slab the T[OJ is respectively 38.3 x 10

-6

and 28.9 x 10

-6

and the [N

]

is respectively 23.6 x 10

-6

and 26.5 x 10

-6

. The slab produced by this flow sheet meets the internal control requirement i. e. T[O

]

≤ 30 x 10

-6

. After refining at argon station the amount of micro-inclusions in steel decreases by 30.0%

while the amount of large inclusions decreases by 58.7% ； the micro-inclusions in steel are mainly deoxidation product A1

2

O

3

while the large inclusions in steel are mainly SiO

2

Al

2

O

3

SiO

2

-Al

2

O

3

and CaO-SiO

2

-Al

2

O

3

.