| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.32 ( March 1995 ) Ironmaking Technology, Secondary Refining, and Center-Segregation Control with Forging in CC ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Development of Hydrogen Gas Injection Method for Promoting Decarburization of Ultra-low Carbon Steel in RH Degasser Koji Yamaguchi, Toshikazu Sakuraya, Kazuhisa Hamagami |
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Synopsis : Kawasaki Steel has developed a hydrogen gas injection method at the RH degasser for promoting the decarburization reaction of the ultra-low carbon steel in the range of a carbon content of less than 20 ppm. Hydrogen gas is blown into the molten steel in the snokel of 260-t RH at Chiba Works in the later period of decarburization treatment at a flow rate of up to 4 m3-norm/min. Part of the hydrogen gas is dissolved in the molten steel to raise the hydrogen concentration of the molten steel up to about 3 ppm, which promotes the evolution of gas bubbles in the molten steel in the vacuum vessel and increases the interfacial area between the gas and metal. The apparent rate constant of decarburization in the range of carbon content from 20 ppm to 10 ppm is increased from 0.05 min-1 to 0.1 min-1 by this method. The carbon content can be decreased to 7 ppm in average in 25 min of decarburization treatment. Ultra-low carbon steel of [C]10 ppm can be obtained with certainty in 25 min of decarburization treatment. |
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