Posco

Noroo Coil Coatings Co., Ltd.

Chang-Hyun Park

Soo-Hyoun Cho

Dae-Chul Bae

Dong-Yun Kim

Ju-Seung Lee

Ki-Jang Oh

Shin-Hwan Kang

Sang-Woo Choi

Ho-Moon Bae

Geon Shin

Eun-Kyeong Kim

Myung-Hee Choi

Young-Sam Park

Provided is a solution composition for steel sheet surface treatment, comprising 30 wt % to 60 wt % of a trivalent chromium compound containing chromium phosphate (A) and chromium nitrate (B); 0.2 wt % to 0.4 wt % of a rust-inhibiting and corrosion-resisting agent; 0.1 wt % to 0.3 wt % of a molybdenum-based compound; 5 wt % to 10 wt % of a water-soluble cationic urethane resin; 0.5 wt % to 2.0 wt % of a silane coupling agent; and 27.3 wt % to 64.2 wt % of water, a zinc-based plated steel sheet surface-treated with the same, and a manufacturing method therefor, the zinc-based plated steel sheet surface-treated with the solution composition for steel sheet surface treatment containing trivalent chromium may have an excellent effect on corrosion resistance, blackening resistance, fingerprint resistance, oil resistance, and alkali resistance.

Solution composition for steel sheet surface treatment, zinc-based plated steel sheet surface-treated with same, and manufacturing method therefor

An aspect of the present disclosure may provide a defect detection apparatus and method for a steel plate, in which a defect in a steel plate may be detected, and particularly, only an inner defect in the steel plate may be detected, even with a relatively low amplification rate.

Apparatus and method of detecting defect of steel plate

Growing community of inventors

Ansan-si, South Korea

Chang-Hyun Park