The production flow sheet of non-quenched and tempered steel S38MnSiV (/%: 0.41 ~0.45C

0.55 ~ 0.70Si

1.40~1.55Mn

≤0.025P

≤0.025S

0.10 ~ 0.20Cr

0.11 ~ 0.15V

0.012 0 ~ 0.020 ON) is 40% hot metal + scrap-100 t EAF-LF-VD-160 mm x 160 mm ~260 mm x 340 mm CC process. With controlling arc furnace tap end [C

]

0.15% ~ 0.30%

tapping [P

]

≤0. 012%

tapping temperature 1 640 ~ 1 680 °C

refining by high basicity slag

controlling aluminum content in liquid

after VD feeding manganese-nitride wire to control nitrogen content in liquid etc. process measure

the 8 heat steelmaking results show that oxygen content in steel- [O

]

 x 10

-6

-11 x

10

-6

[H

]

1.2 x 10

-6

1. 5 x 10

-6

and [N

]

135 x 10

-6

- 180 x 10

-6

for the Φ140 mm round bar products rolled from 260 mm x 340 mm casting bloom with normalizing at 880℃ for 120 min

airflow cooling and tempered at 580℃ for 240 min air cooling

the tensile strength Rm is 870 ~925 MPa and the yield strength Re

]

is 560 - 605 MPa

its metallurgy quality all meets the requirement of standard.