Speaker
Mr
Wataru Todo
(JFE Steel Corporation, Steelmaking Dept., East Japan Works(Chiba))
Description
JFE Steel Corporation produces around 0.6 million tons of Cr base ferrite stainless steel per year at the Chiba Works. Recently, the demand of ultra-low carbon grade of Cr base ferrite stainless steel is increasing for using automotive exhaust system parts and so on. In the case of producing ultra-low carbon Cr base ferrite stainless steel, the bottle neck of the production line is Vacuum Oxygen Decarburization (VOD) process as secondary refining facility.
In order to increase its productivity, we improve the method for decarburizing molten Cr base stainless steel by the following measures: (1) Optimizing the ratio of mixing oxygen and argon through the blowing top lance under vacuum to accelerate a decarburizing speed by reducing CO partial pressure and (2) Changing a materials-feeding process to keep higher temperature of molten Cr base stainless steel in VOD process than before.
As a result, the decarburization time in the improved VOD process is reduced by 25% as compared with the conventional one and also the productivity is increased by 35%.
Author
Mr
Wataru Todo
(JFE Steel Corporation, Steelmaking Dept., East Japan Works(Chiba))
Co-authors
Mr
Futoshi Ogasawara
(JFE Steel Corporation, Steelmaking Research Dept.)
Mr
Tomomichi Terabatake
(JFE Steel Corporation, Steelmaking Dept., East Japan Works(Chiba))