Nkk Corporation

Masahiro Iwabuchi

Shoji Yoshikawa

Mitsuaki Uesugi

Tsutomu Kawamura

Akira Kazama

Takahiko Oshige

Masaichi Inomata

Shinichi Tomonaga

Shuji Kaneto

Hajime Tanaka

Osamu Uehara

Shigemi Fukuda

Shuichi Harada

Yasuo Kushida

Tsuneo Suyama

Hiroyuki Sugiura

Fusato Kitano

Akira Gamou

Takeshi Fujita

Kaoru Sato

Masaaki Yamashita

Tadashi Inoue

Yasunobu Nagataki

Kentaro Sato

Masayasu Nagoshi

Yoshihiro Hosoya

Junichi Inagaki

Yoshiharu Sugimoto

Michitaka Sakurai

Shoichiro Taira

Masaya Morita

Toru Imokawa

Yoichi Miyakawa

Shuji Nomura

Shunsaku Node

Takeo Ishii

A defect marking device includes a flaw inspection device which has a plurality of light-receiving parts that identify reflected lights coming from an inspection plane of a metal strip under two or more of optical conditions different from each other; a signal processing section that judges the presence/absence of surface flaw on the inspection plane based on a combination of reflected light components identified under these optical conditions different from each other; and a marking device which applies marking that indicates information relating to the flaw on the surface of the metal strip.

Method for marking defect and device therefor

The defect marking method comprises the steps of: installing a surface defect tester to detect surface flaw and a marker device to apply marking at defect position, in a continuous processing line of steel sheet; detecting the surface flaw on the steel sheet using the surface defect tester; determining defect name, defect grade, defect length, and defect position in the width direction of the steel sheet, on the basis of thus detected flaw information, further identifying the defect in terms of harmful defect, injudgicable defect, and harmless defect; applying tracking of the defect position for each of the harmful defect and the injudgicable defect; and applying marking to the defect position. The defect marking device comprises a defect inspection means having plurality of light-receiving parts and a signal processing section, and a marking means.

The invention relates to a high strength hot-dip galvanized steel sheet consisting essentially of 0.03 to 0.25% C, 0.7% or less Si, 1.4 to 3.5% Mn, 0.05% or less P, 0.01% or less S, 0.05 to 1% Cr, 0.005 to 0.1% Nb, by mass, and balance of Fe, and being made of a composite structure of ferrite and secondary phase, and having an average grain size of the composite structure of 10 &#x3bc;m or smaller. Since the high strength hot-dip galvanized steel sheet of the present invention hardly induces softening at HAZ during welding, it is applicable to structural members of automobiles for 'Tailor Welded Blanks' (TWB).

High strength hot-dip galvanized steel sheet and method for manufacturing the same

The invention provides a galvannealed steel sheet which has an oxide layer having 10 nm or larger thickness on the plateau of the coating layer flattened by temper rolling. With the use of the galvannealed steel sheet, no powdering occurs during press-forming, and stable and excellent sliding performance is attained. By selecting the area percentage of the plateau of the flattened coating layer to a range from 20 to 80%, making the coating layer single layer of &dgr; phase, and letting &zgr; phase exist in the &dgr; phase, further improved sliding performance and anti-powdering property are obtained.

Galvannealed steel sheet and method for manufacturing the same

Cold-rolled steel sheet and galvanized steel sheet, which are excellent in formability, panel shapeability, and dent-resistance, and method of manufacturing the same

Growing community of inventors

Fukuyama, Japan

Masahiro Iwabuchi