The spring steel SK5 (/% : 0.75 ~0. 84C

≤ 0. 35Si

≤0.40Mn

≤0. 035P

≤0.030S) is produced by 100 t EAF-LF-VD-CC flow sheet. With using the process measures including pre-deoxidizing at EAF tapping by adding silicon-manganese and ferroaluminium

compound-deoxi dizing during LF refining process by adding 80 ~ 150 kg aluminium- manganese-calcium alloy and small amount silicon manganese alloy with refining slag basicity 11.13 and ( CaO) / ( Al

2

0

3

) =4. 98

the deoxidizing effect is obvious

the average total oxygen content is 11 X 10

-6

in casting billet and the nitrogen content in billet is 35 x 10

-6

. During steelmaking process the change sequence of inclusions i

n steel is pure A1

2

O

3

- sulfide- MgO  •A1

2

O

3

• CaO- MgO • A1

2

O

3

• CaO • SiO

2

and the main inclusions in billet is CaO • Al

2

O

3

・ SiO

2

・ MgO series

its plasticization level could be optimized future by adjusting refining ingredient and reducing melting point of refining slag.