Variations of nitrogen with silicon content of electrical steels

The nitrogen content of commercial heats of electrical steels has been observed to increase with decreasing silicon content prior to teeming despite a constant nitrogen content prior to addition of alloying silicon to molten steel. This behavior can be qualitatively described by a nitrogen transfer model which predicts: the rate of absorption of nitrogen by the metal is greater at lower silicon contents; a final nitrogen level increasing with decreasing silicon; the thermodynamic activity of nitrogen is approximately constant regardless of silicon content at teem time; the nitrogen level increases with longer holding times; and ladle practice will affect nitrogen levels.