US 12,331,408 B2
Surface-treated steel sheet
Atsuo Shimizu, Tokyo (JP); Yoshikatsu Nishida, Tokyo (JP); Shin Ueno, Tokyo (JP); and Hiromasa Shoji, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 18/841,582
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Sep. 28, 2022, PCT No. PCT/JP2022/036111
§ 371(c)(1), (2) Date Aug. 26, 2024,
PCT Pub. No. WO2023/166772, PCT Pub. Date Sep. 7, 2023.
Claims priority of application No. 2022-032606 (JP), filed on Mar. 3, 2022.
Prior Publication US 2025/0109500 A1, Apr. 3, 2025
Int. Cl. C23C 28/00 (2006.01); C21D 9/46 (2006.01); C23C 2/06 (2006.01); C23C 2/28 (2006.01); C23C 22/36 (2006.01)
CPC C23C 28/32 (2013.01) [C21D 9/46 (2013.01); C23C 2/06 (2013.01); C23C 2/29 (2022.08); C23C 22/36 (2013.01); C23C 2222/20 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A surface-treated steel sheet, comprising:
a base steel sheet;
a plated layer formed on the base steel sheet and containing 50 mass % or more of Zn and 0.3 mass % or more of Mg; and
a chemical conversion coating formed on the plated layer,
wherein the chemical conversion coating contains a silicon compound, P and F, and Mg,
an average Si concentration of the chemical conversion coating is 10 mass % or more,
the chemical conversion coating includes an F—Mg concentrated layer having an Mg concentration of 1.50 mass % or more and 40.00 mass % or less and an F concentration of 0.50 mass % or more and 5.00 mass % or less in a region in contact with an interface between the chemical conversion coating and the plated layer,
a thickness of the F—Mg concentrated layer is 1.0 nm or more, and
an average Mg concentration is less than 0.50 mass % and an average F concentration is less than 0.50 mass % in a region of the chemical conversion coating excluding the F—Mg concentrated layer.