HIGH-STRENGTH ZINC-PLATED STEEL SHEET HAVING TENSILE STRENGTH OF 1180 MPa OR MORE AND METHOD FOR MANUFACTURING SAME, AND SURFACE TREATMENT SOLUTION

WIPO Patent Application WO/2020/121899

A1

Provided is a high-strength zinc-plated steel sheet having excellent delayed fracture resistance.　A high-strength zinc-plated steel sheet having a coating film (x) on a surface thereof, wherein the coating film (x) contains an organic resin (a) and a metal salt (b) containing at least one group selected from a phosphate group, a phosphite group, a silicate group and a molybdate group, and does not contain a particulate component other than the metal salt (b) and having a largest particle diameter equal to or larger than the film thickness of the coating film (x). The metal salt (b) and Zn together form a chelate complex and, as the result, a dense passive coating film is formed on the surface of the steel sheet; the pH value falls within the range from 8 to 11 steadily due to the pH buffering effect of an ion containing the metal salt (b) and, as the result, the dissolution of Zn can be prevented and the generation of hydrogen on the base metal can be suppressed; and the coating layer (x) does not contain a microparticulate component other than the metal salt (b) and having a larger particle diameter and, therefore, it is possible to prevent the interface between each of the particles and the coating film (x) from becoming the point of origin of corrosion. As a result, the invasion of hydrogen into the inside of the steel sheet can be prevented and excellent delayed fracture resistance can be achieved.

WO/2008/044299	BRAKE DISCS EXCELLENT IN RESISTANCE TO TEMPER SOFTENING AND TOUGHNESS
JPS5841326	[Title of the Invention] A manufacturing method of a high tension hot-rolled steel product for processing
JP3536776	MAGNESIA FOR ANNEALING AND SEPARATING AGENT OF GRAIN ORIENTED SILICON STEEL SHEET AND METHOD FOR MANUFACTURING GRAIN ORIENTED SILICON STEEL SHEET HAVING EXCELLENT MAGNETIC CHARACTERISTIC AND FILM CHARACTERISTIC

HATA KENTARO (JP)
MATSUDA TAKESHI (JP)
YOSHIDA MASAHIRO (JP)

PCT/JP2019/047285

June 18, 2020

December 03, 2019

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JFE STEEL CORP (JP)

C21D9/46; C23C2/06; C23C2/28; C23C28/00; C22C38/00; C22C38/04; C22C38/38

JP2009120947A	2009-06-04
JP2011219791A	2011-11-04
JP2013193273A	2013-09-30

KUMASAKA Akira et al. (JP)

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