Nippon Steel Corporation

Hiroshi Sugano

Kenichiro Miyamoto

Masayuki Abe

Takashi Morohoshi

Masaharu Oka

Katsuhiko Kato

Masafumi Zeze

Shinya Kitamura

Yuji Koyama

Keiichi Katahira

Takayuki Kaneyasu

Yasuhiro Kinari

Akio Shinkai

Shintaro Kusunoki

Ryuzou Hayakawa

Ryusuke Miura

Hiroyuki Ishimatsu

A cast steel with excellent workability, characterized in that not less than 60% of the total cross section thereof is occupied by equiaxed crystals, the diameters (mm) of which satisfy the following formula:&#x3c;1.2+0.75,wherein D designates each diameter (mm) of equiaxed crystals in terms of internal structure in which the crystal orientations are identical, and X the distance (mm) from the surface of the cast steel. The cast steel and the steel material obtained by processing the cast steel have very few surface flaws and internal defects.

Cast steel and steel material with excellent workability, method for processing molten steel therefor and method for manufacturing the cast steel and steel material

Cast steel piece and steel product excellent in forming characteristics and method for treatment of molted steel therefor and method for production thereof

In a straight barrel type vacuum refining apparatus, use is made of a combination of: a decarburization method wherein the flow rate of oxygen fed into a vacuum tank and the flow rate of an inert gas fed into the vacuum tank are regulated and, at the same time, the flow rate of oxygen gas blown is reduced at a rate of 0.5 to 12.5 Nm /h/t/min in a low carbon concentration region having a carbon concentration of not more than the critical carbon concentration; and a vacuum refining apparatus provided with dust accumulation preventing means.

Method and apparatus for vacuum decarburization refining of molten steel

Method of vacuum decarburization/refining of molten steel

Growing community of inventors

Kitakyushu, Japan

Hiroshi Sugano