Behaviour of Hydrogen in Industrial Scale Steel Melts

The behaviour of hydrogen during controlled industrial scale secondary steel making process has been examined in a variety of low alloy steels, sensitive to hydrogen flaking. The study examines the role played by the moisture in input raw materials such as the ferro-alloys, type of carbon additive and fluxes in enhancing the hydrogen content in the ladle furnace. Post alloying, the influence of vacuum degassing parameters such as the vacuum level, vacuum holding time, Ar flow rate, type of porous plug used, slag chemistry and the steel grade was examined. The vacuum degassing process was analysed using a kinetic model, which could justify the trends seen in the vacuum level, holding time and Ar gas flow rate. Finally, the hydrogen pick-up post vacuum degassing through slag cover and the casting tundish was found to be influenced by parameters such as the quality of the tundish spray mass, and casting sequence. The influence of steel grade in hydrogen removal was also examined.