Cleanliness and inclusion evolution of GCr15 bearing steel produced in EAF—LF—VD—CC process
In order to understand the evolution law of inclusions in GCr15 bearing steel,full process sampling analysis was processed based on EAF—LF—VD—CC process in a domestic steel mill.The variation of impurity elements and the evolution of inclusions in the whole process were systematically studied.The analysis results show that the mass fraction of impurity elements Ca and Ti in the rolled steel sample is relatively high,reaching 0.0016% and 0.001 7% respectively,and the mass fraction of total oxygen(T.O)is 0.0007%.The main types of inclusions are Mg-Al spinel,calcium aluminate and silicate composite inclusion.The larger size inclusions appear at LF and VD stations,and the maximum size of inclusions exceeds 30 μm.After the vacuum condition breaking,a large number of CaO-MgO-Al2O3-SiO2 complex appear,with uniform composition distribution and individual size exceeding 45 μm.The proportion of MnS and TiN inclusions in casting billet and rolling material is relatively high.