T[O] and [N] Content and their Controlling Measurement in Molten Steel and Slab of Steel Grade 45

Steel grade 45 was produced bythe process of LD converter-LF refining-continuous casting in an iron and steel corporation.T[O] and [N]content in molten steel and slab were investigated in this paper.The results show that T[O] content in molten steel after LF refining decreased 40.3%,while the variation of [N] content was small.When the molten steel was transferred into tundish,there was reoxidation of molten steel and melting of oxides in refractory material.Consequently,T[O] and [N] contents in molten steel in tundish increased 55.9% and 20.5% respectively.[N]content in slab increased 21.6% because lots of air inhaled during casting.On the other hand,part of oxidative inclusions could be removed from molten steel during casting.Then the T[O] content in slab declined 12.8%.It was suggested that the molten steel should be prevented from reoxidation during refining and casting to improve the quantity of steel grade 45.