Wang Hui,Huang Haoran,Li Yang.Effect of Cs2O-bearing Refining Slag on the Cleanliness of High-Strength Valve Spring Steel[J].Special Steel,DOI:. DOI: 10.20057/j.1003-8620.N260126.
Wang Hui,Huang Haoran,Li Yang.Effect of Cs2O-bearing Refining Slag on the Cleanliness of High-Strength Valve Spring Steel[J].Special Steel,DOI:. DOI: 10.20057/j.1003-8620.N260126.DOI:
Effect of Cs2O-bearing Refining Slag on the Cleanliness of High-Strength Valve Spring Steel
High-strength valve spring steel has exceptionally high requirements for fatigue performance and service reliability, and non-metallic inclusions in steel are a key factor affecting its overall performance. The effects of Cs
2
O on the physicochemical properties of CaO-SiO
2
-Al
2
O
3
-MgO refining slag and the cleanliness of molten steel were systematically studied with 65Si2CrV high-strength valve spring steel as the research object and the mechanism of action was revealed by combining the changes in viscosity and surface tension of refining slag. The results show that Cs
2
O, as a typical network modifier, can produce free oxygen ions (O
2-
) at high temperatures by ionization, which can promote the depolymerization of silicate network structure, and transform the high degree of polymerization structural units (Q
2
, Q
3
) into low degree of polymerization units (Q
0
, Q
1
). It causes the decrease in the viscosity and surface tension of refining slag, thereby improving the fluidity of slag and the wettability of slag-steel interface.With the addition of 5%
w
[Cs
2
O] to the refining slag, the cleanliness of the molten steel is significantly improved. The total oxygen mass fractions of
the two steels are 0.004 0% and 0.002 3%, respectively, representing a reduction of 42.5% for the latter compared with the former; the numbers of inclusions per unit area are 40/mm
2
and 16/mm
2
, respectively, corresponding to a decrease of 60% in the latter compared with the former. At the same time, the average composition point of inclusions migrates to the low-melting-point region at 1 400 ℃, the large-size brittle inclusions are effectively controlled, and the inclusion removal efficiency is significantly improved. This study provides theoretical guidance for the design of new alkali metal oxide refining slag and the production of high-cleanliness valve spring steel.
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