The effect of 300 t converter-RH refining calcium treatment on inclusions in non-oriented silicon steel sheet (%： ≤0.005C

1. 2 ~2. 2Si

0. 2 ~0. 6Mn

≤0. 20P

≤0. 005S

0. 2 ~0. 6 Al

0 ~0. OlCa) has been studied by electrolysis and scanning electron microscope. Results show that with 0. 25% and 0. 35% Al content in steel

all the dissolved oxygen in liquid is less than 1 X 10

-4

%

and the CaS inclusions are produced after calcium treatment

especial for the liquid containing 0. 35% Al； the amount of inclusions in steel is sharply decreased by calcium treatment process especially for less than 0. 5 μm tiny inclusions; the main inclusions after calcium treatment are AIN and CaS with minor oxide inclusions and AlN-CaS compound inclusions

and the size of most inclusions is 1. 5 ~5. 0 μm .