10 heats of non-quenched-tempered steel 49MnVS3 (/% : 0.46 ~ 0.48C

0

30 ~ 0.40Si

0.88〜0.92Mn

0.001~0. 014P

0.004 ~ 0.005S

0.09~ 0.10V

0.19 ~ 0.22Cr) are produced by 100 t EBT DC EAF-LF- VD-260 mm x 340 mm bloom casting-Φ140 〜150 mm round bar rolling process flowsheet. With using the process measures including charging 75% hot metal

in EAF earlier period dephosphorizing to ≤0.015%P

before tapping controlling 0.20% ~0. 30% [C

]

in refining adding 150 ~200 kg silicon carbide

controlling LF refining slag basicity 2. 80 ~2. 95 and ( CaO)/( Al

2

O

3

) = 1.2 ~ 1. 6

after VD feeding 1. 5 m/t calcium-iron wire and soft argon blowing for ≥15 min

the [N

]

[H

]

and [O

]

of steel 49MnVS3 are respectively 130 x 10

-6

- 220 x 10

-6

1.2 x 10

-6

- 1.5 x 10

-6

and 5 x 10

-6

~ 11 x 10

-6

finished products grain size is N5 rating

nonmetallic inclusions and macrostructure are all ≤ 1. 5 rating

the structure (banded orientation ≤1 rating) and the mechanical properties (R

m

803 ~883 MPa

R

el

517 〜590 MPa

A 16% ~21%

A

ku

39~59J) all meet the requirement of standard.