The production process of 0. 88% Si non-oriented silicon steel is adding 300 kg lime in tapping of 100 t BOF

controlling end [C

]

0.035%-0.05% and tapping liquid temperature 1640-1650 °C

RH blowing oxygen to decarburize

adding 99.0% Al-Fe alloy 6.69 kg/t and adding 70%Si-Fe alloy 15.70 kg/t in RH refining process

in whole process shield-atmosphere casting 70 mm slab

and using magnesia basic tundish shielding agent. Analysis results show that RH end [O

]

is 28 x 10

-6

slab [O

]

is 22 x 10

-6

RH beginning [N

]

is 16 x 10

-6

nitrogen content in liquid increases

by 4 x 10

-6

during RH process and the nitrogen content in steel increases by 6 x 10

-6

during end RH to slab casting process ； at end RH decarburization the main inclusions in steel are spherical

MnO·Al

2

O

3

after RH Refining the main inclusions in steel are irregular

Al

2

O

3

accompanied by a small amount CaS inclusions ； the main inclusions in liquid of tundish are irregular

Al

2

O

3

in casting slab the most inclusions are irregular

Al

2

O

3

with a small amount of AIN and minor composite inclusions containing Na caused by slag enclosure in mold.