The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 22, 1993
Filed:
May. 15, 1991
Koji Yamaguchi, Chiba, JP;
Yasuo Kishimoto, Chiba, JP;
Toshikazu Sakuraya, Chiba, JP;
Masaru Washio, Chiba, JP;
Kazuhisa Hamagami, Chiba, JP;
Hiroshi Nishikawa, Chiba, JP;
Kawasaki Steel Corporation, Kobe, JP;
Abstract
A method of producing an ultra-low-carbon steel by conducting vacuum-decarburization of a molten steel by means of a vacuum degasifier of the type having recirculation pipes and a vacuum chamber. When the carbon content of the molten steel has come down to a level of 50 ppm or less, hydrogen gas is introduced together with an inert gas into the molten steel either by directly injecting a hydrogen-containing gas into the molten steel in the vacuum chamber through a tuyere provided in the wall of the vacuum chamber or by blowing the hydrogen-containing gas onto the surface of the molten steel in the vacuum chamber through a lance provided in the vacuum chamber. In order to enhance the effect produced by the method of the present invention, it is possible to take an additional measure such as blowing of hydrogen gas through a tuyere provided in the wall of the recirculation pipe or injection of hydrogen or hydrogen-containing gas through an injection lance immersed in the molten steel held in, a ladle.