Hydrogen pick-up after vacuum degassing

Abstract

The present work aimed at determining the major source for hydrogen pick-up of the steel after vacuum degassing but before casting. Samples of slag and metal were taken at different stages during ladle treatment at SSAB. Hydrogen increase after vacuum treatment was observed. Moisture contents of the industrial slags were analysed and their water capacities were calculated. It could be seen that the hydrogen increase was correlated to the amount of moisture in the slag and the water capacity. The study showed that the slag containing most water was also the heat having the largest hydrogen increase. The slag with most water had the highest water capacity. It could be concluded that the major source for hydrogen increase after degassing was due to the slag-metal reaction.

Effect of carbon on the solubility of nitrogen in slag

“…It has been reported that the slag having the highest water capacity is also the heat having the largest hydrogen increase aftervacuum treatment [1]. The authors have concluded that the major source for hydrogen coming back into the steel is due to the slag-metal reaction [1]. It would be valuable to investigate whether this mechanism also applies to nitrogen pickup.…”

“…This has been of special interest for the steelmaking industrysince nitrogen has been proven difficult to remove withconventional degassing methods. It has been reported that the slag having the highest water capacity is also the heat having the largest hydrogen increase aftervacuum treatment [1]. The authors have concluded that the major source for hydrogen coming back into the steel is due to the slag-metal reaction [1].…”