The production flow sheet of Φ110 〜Φ280 mm hot rolled round steel 12Crl MoVG for boiler tube (/%: 0. 08 〜0. 15C

0. 17~0. 35Si

0. 40 -0. 70Mn

≤0.015P

≤0.010S

0. 90 〜1. 20Cr

0. 25 ~0. 35Mo

0. 15 -0. 30V

≤0. 015 [Alt]) is 120 t top and bottom combined blown con verter-LF-RH-CC-Rolling process. With the process measures including to control hot metal [ As]

[ Sn]

[ Sb]

[ Pb] and [ Bi]

control converter end point [C]0. 04% 〜0. 080%

[P] ≤0. 010% and [ S] ≤0. 010%

deoxidize by aluminum iron during tapping

feed Al wire in ladle to control [ Alt] ≤0. 015%

refine by compound refining slag and some aluminum shot in LF process

control tundish liquid superheating extent 20 ~ 35 ℃

whole-shielding-cast etc

the [As] + [ Sn] + [ Sb] + [ Pb] + [ Bi] is W 0. 029%

the [P]

[ S] and [Als] are respectively ≤0.011%

≤0. 008% and ≤0. 010%

and the rating of each series inclusion is ≤1.0 to meet the technical requirement of user.