The metallurgical flow sheet for steel 20CrMnTiH (TS) is 60 t top and bottom combined blowing converter- LF- VD- 150 mm X 150 mm billet casting. The unqualified rate of inclusions in steel 20CrMnTi H(TS) at first examination at steelworks is up to 2% main inclusions are B series ( compound calcium aluminate + magnesia-alumina spinel

and partial alumina) and D series ( calcium aluminate

and partial compound calcium aluminate + magnesia-alumina + titanium nitride)

that size is more than 20 μm. With the process measures including using low phosphorus hot metal and high quality scrap

converter end [C

]

≥0

09%

adding 40 kg silicon-calcium and 40 kg aluminium cladding steel to replace original only adding 80 kg aluminium cladding steel for pre-deoxidation in converter tapping

using SiC70 t

o replace SiC45 to diffusion-deoxidize in LF refining

feeding Ti wire after VD

insuring refining end slag basicity 3. 0

and controlling heel liquid more than 2 t

the T[O

]

decreases from original 12 X 10

-6

to 8 x 10

-6

and the unqualified rate of inclusions in steel at first examination decreases to 0.5%