Abstract: The variation of cold heading steel cleanliness from LF end to continuous casting was investigated. The results showed that，Due to severe reoxidation from LF end to casting starts, the mass fraction of T.O and \[N\] in steel increased by 39×10^-6 and 21×10^-6 respectively, and the w(CaO)/w(Al2O3) of inclusions decreased. At steady casting period, the T.O and \[N\] content decreased and stabilized at 30×10^-6 and 65×10^-6 respectively, while the ratio of w(CaO)/w(Al2O3) of inclusions fluctuated and located in the low melting point area of CaO-Al2O3-MgO-CaS diagram. Thermodynamic calculation indicated that with current steel composition, a 3.5×10^-6 nitrogen pickup would generate solid inclusions. The first three meters of the head billet was suggested to be cut off to assure a good steel cleanliness.

Key words: cold heading steel, head billet, cleanliness, inclusions