Through the sampling analysis in the production process of U75V heavy rail steel

the inclusions evolution and control of large scale inclusions in heavy rail steel are investigated base on the samples taken during steelmaking process. The results show that the total oxygen content in molten steel can be reduced to less than 10 x 10

-6

by controlling the aluminium content ≤20x10

-6

the binary basicity of refining slag 1.8 ~ 2.2

the white slag holding time 15 min

and the RH vacuum 100 Pa 15 min. The coarse inclusions of B and D are basically eliminated and the inclusions of C are completely plasticized in finished product

aluminium content less than 20 x 10

-6

With the overheat of tundish 25 ~35℃

the average residence time of tundish steel (750 ±30) s

the depth of nozzle insertion 90 ~ 110 mm

and the fluctuation of mould

liquid level ≤ ±3 mm

the inclusion in molten steel can be removed.