The flowsheet for steelmaking of 280 mm x 325 mm casting bloom of steel 55SiCr (/% : 0.55C

1. 42Si

0. 67Mn

0. 008S

0. 67Cr) is 80 t BOF-LF-RH-CC process. With during BOF tapping adding Al

ferrosilicon and refining slag

controlling slag basicity R (CaO/SiO

2

) about 2. 0

RH refining for ≥ 20 min

soft blowing stirring for ≥15 min to control the transformation of inclusions in steel

the clean spring steel 55SiCr is gotten. Analysis results show that during LF refining process the inclusions in liquid transformfrom earlier period Al

3

O

3

-SiO

2

-MnO and Al

2

O

3

inclusions to inclusion Al

2

O

3

-CaO-SiO

2

after RH vacuum treatment the inclusions in liquid all transform to inclusion Al

2

O

3

-CaO-SiO

2

the T[0

]

and [N

]

at beginning LF refining are respectively 36 x 10

-6

and 26 x 10

-6

and the T[0

]

and [N

]

in casting bloom are respectively 7 x 10

-6

and 43 x 10

-6

and the inclusions in casting bloom are mainly Al

2

O

3

-CaO-SiO

3

and Al

2

O

3

with size≤10μm