The flow sheet for production of gear steel 20CrMnTiH at Jiyuan Iron and Steel Co is 601 top and combined blown converter-LF (VD) -150 mm x 150 mm billet concasting process. With controlling BOF end [ C

]

≥0. 08%

using silicon-calcium-barium

ferro-aluminium and aluminium shot combined deoxidizing in ladle

LF refining by SiO

2

-Al

2

O

3

- CaO slag series and micro adjusting Ti content in liquid by feeding Ti-Fe wire during LF refining

soft argon blowing N15 min after VD vacuum treatment

auto controlling liquid surface in tundish

whole shielding casting and M-EMS and F-EMS stirring

the analysis of finished gear steel 20CrMnTiH is (%) 0. 19 ~0. 21C

0

23 ~ 0. 27Si

0. 86 〜0. 90Mn

1.11 〜 1. 1

5Cr

0.057 ~ 0.063Ti

≤0.020P

≤0.010S

(5.6-19.3) x10

-6

(40.6 -65.2) x10

-6

and the J9 HRC value of 032 ~40 mm steel products is 34. 42 -39. 10

△HRC≤6

and all examination indexes meet the requirement of standard.