The steelmaking flowsheet of tested bearing steel GCr15 (/%: 1.00C

0.20Si

0.39Mn

0.015P

0.005S

1.50Cr

0.003Ti

0.015Als) is pre-desulphurized hot metal-100t BOF-LF-RH-200mmX200mm billet casting. The main process characteristics are adding 1.2kg/t aluminium for pre-deoxidation in BOF tapping

using white slag operation in LF refining with initial slag main ingredient (/%: 22Al

2

O

3

56CaO

10SiO

2

5MgO)

RH 67Pa for 25min and shield casting in cast process. Analysis results of two heats malting sho

w that the oxygen and nitrogen content in liquid at end RH are lowest respectively  7X10

-6

~8x10

-6

and 24x10

-6

~26x10

-6

the size of majority inclusions in steel is 3~8μm

and the number of inclusions in steel at unit area is lowest at end RH

and the main nonmetallic inclusions in cast billet are Al

2

O

3

-CaO; with condition of high basicity refining slag the calcium aluminate easily reacts with magnesiumaluminum spinel

with slag basicity 2~3 the small amount of MgO-Al

2

O

3

occurs and with slag basicity more than 4 the MgO-Al

2

O

3

series inclusions don't occur

besides with condition of high basicity the MgO content in MgO-Al

2

O

3

-CaO series inclusions is able to decrease.