Φ50 mm 35MnB steel bar ( 0. 35% C

0. 28% Si

1. 25% Mn

0. 002 0% B

0. 030% Ti ) for track link is produced by 60 t BOF-LF-VD-220 mm x 220 mm CC-rolling process. By optimizing the technical parameters of BOF tapping

including [ C

]

≥ 0. 10% and [P

]

≤ 0.015%

basicity of refining slag R =3.87 ~ 5. 73

soft blowing time for、15min

20 ~32 ℃ superheat of tundish liquid

rolling heating temperature at 1 100 ~ 1 200 °C

starting rolling at 1 000 ~ 1 070 ℃

and finishing rolling at，850 °C

of the finished 35MnB steel bar

the [O

]

≤15 x 10

-6

[ N

]

≤50 x 10

-6

rating of macrostructure and nonmetal inclusion ≤1.5

hardenability JI. 5 HRC number：53 ~ 55

J19 HRC number:34 ~ 38

TS 960 ~ 1 050 MPa

YS 765 ~ 810 MPa

IE 80 ~ 100 J

to meet the requirement of each performance index.