Non-metallic inclusion and total oxygen in 50Cr5MoV

The total amount of oxygen content and the category of inclusions in 50Cr5 Mo V forged steel roll by the route of EBT→LF→VD were analyzed. The results show the average w(T[O]) was 0.004 7% after LF refining and 0.001 4% after VD refining,and 0.001 55% in tundish,0.001 8% in billet and 0.001 0% in rolled steel on average. During the initial stage of LF refining,the inclusions in steel mainly are irregular forms of Al2O3. 96.75% of the inclusions have the diameters less than 10 μm.After the LF refining,most of the inclusions are 0-10 μm diameters of compound oxide inclusions,predominantly containing CaO-Al2O3-SiO2.During the transfer of steel from VD treatment to tundish,the protective casting is awful,and the severe reoxidation contributes to the growing amount of inclusions,mainly containing spherical mCaO·nAl2O3compound oxide inclusions 99.65% of the inclusions in the steel slab are less than 10 μm. Most of them are spherical calcium-aluminate compound inclusion,with a few spherical calcium aluminosilicate compound inclusion.And 98.77% of the inclusions in rolled steel have diameters less than 10 μm Therefore,the process optimization of every process of iron making,could contribute to the effective control of inclusions and ensure the quality of 50Cr5 Mo V forged steel roll.