The evolution behavior of total oxygen content and amount

size

ingredient and type of inclusions in steel during steelmaking process of stainless steel 304 by 160 t EAF-180 t AOD-LF-CC flowsheet has been studied by nitrogen oxygen analyzer

optical and scanning electron microscope. The AOD refining process main operation data are initial [C

]

2.0% 〜3.0%

[Si

]

0.2% 〜0.4%

end [C

]

0.04% 〜0.06%

end AOD slag ingredient (/

%)： 53.9CaO

30. 1 SiO

2

1. 34Al

2

O

3

5. 22MgO

8. 74CaF

2

0. 39Cr

2

O

3

0. 53TFe

0. 62MnO

and end LF slag ingredient (/%)： 57.9CaO

21.6SiO2

1.70Al

2

O

3

6. 30MgO

0. 03Cr

2

O

3

11.9CaF

2

0. 26TFe

0.31MnO. Results show that in AOD- LF-CC process the oxygen content in steel decreases gradually

the deoxidized ratio is up to 71. 0% and the oxygen content in casting slab is 25 x 10

-6

the amount of large inclusions decreases obviously in refining process

and there is no ≥20μm inclusion occurring in casting bloom ； during refining process the main inclusions in steel are low-melting silicate

and from end LF to cast slab the MgO and Al

2

O

3

content in inclusions increase respectively by 12% and 17. 5%

due to temperature decreasing

in cast slab the residual Mg

Al continuously combined with 0 to precipitate MgO-Al

2

O

3

Aspinel and residual Mg and Al reacting with low-melting siHcate to form high-melting silicate

therefore the inclusions in cast slab are mainly magnesium-aluminium spinel and high-melting silicate.