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:
Mar. 03, 2009
Filed:
Feb. 28, 2007
Kosuke Yamashita, Futtsu, JP;
Ryuji Nakao, Hikari, JP;
Tomoaki Tanaka, Hikari, JP;
Masao Igarashi, Hikari, JP;
Koichiro Yoshino, Hikari, JP;
Makoto Sumi, Kitakyushu, JP;
Kosuke Yamashita, Futtsu, JP;
Ryuji Nakao, Hikari, JP;
Tomoaki Tanaka, Hikari, JP;
Masao Igarashi, Hikari, JP;
Koichiro Yoshino, Hikari, JP;
Makoto Sumi, Kitakyushu, JP;
Nippon Steel Corporation, Tokyo, JP;
Nittetsu Plant Designing Corporation, Fukuoka, JP;
Abstract
A refining method and apparatus for decarburization refining of chromium containing molten steel in a vessel having a first step of blowing oxygen while the inside of the vessel is at a pressure of between 400 Torr and atmospheric pressure, a second step of blowing oxygen while evacuation the inside of the vessel to 250 to 400 Torr and a third step of blowing gas while evacuating the vessel to not more than 250 Torr. Further, a refining method and apparatus for ultra-low carbon chrome melt by performing a first vacuum refining until the third step, then restoring the pressure in the vessel to at least 400 Torr, then performing second vacuum refining while making the bottom blowing gas blow rate at least 0.4 Nmper to steel.