	US 12,281,392 B2
	Hot dip galvanized steel sheet and method for producing same
Takafumi Yokoyama, Tokyo (JP); Hiroyuki Kawata, Tokyo (JP); Kunio Hayashi, Tokyo (JP); Yuji Yamaguchi, Tokyo (JP); and Satoshi Uchida, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/427,680
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Feb. 6, 2020, PCT No. PCT/JP2020/004638 § 371(c)(1), (2) Date Aug. 2, 2021, PCT Pub. No. WO2020/162560, PCT Pub. Date Aug. 13, 2020.
Claims priority of application No. 2019-020090 (JP), filed on Feb. 6, 2019.
Prior Publication US 2022/0127709 A1, Apr. 28, 2022
Int. Cl. C21D 9/46 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C22C 38/52 (2006.01); C22C 38/54 (2006.01); C22C 38/60 (2006.01); C23C 2/02 (2006.01); C23C 2/06 (2006.01); C23C 2/28 (2006.01); C23C 2/40 (2006.01)

CPC C23C 2/40 (2013.01) [C21D 8/0226 (2013.01); C21D 8/0263 (2013.01); C21D 9/46 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/008 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/52 (2013.01); C22C 38/54 (2013.01); C22C 38/60 (2013.01); C23C 2/02 (2013.01); C23C 2/0224 (2022.08); C23C 2/024 (2022.08); C23C 2/06 (2013.01); C23C 2/28 (2013.01); C23C 2/29 (2022.08); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/003 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01); C21D 2211/009 (2013.01)]

3 Claims

1. A hot dip galvanized steel sheet comprising a base steel sheet and a hot dip galvanized layer on at least one surface of the base steel sheet, wherein the base steel sheet has a chemical composition comprising, by mass %,

C: 0.050% to 0.350%,

Si: 0.10% to 2.50%,

Mn: 1.00% to 3.50%,

P: 0.050% or less,

S: 0.0100% or less,

Al: 0.001% to 1.500%,

N: 0.0100% or less,

O: 0.0100% or less,

Ti: 0% to 0.200%,

B: 0% to 0.0100%,

V: 0% to 1.00%,

Nb: 0% to 0.100%,

Cr: 0% to 2.00%,

Ni: 0% to 1.00%,

Cu: 0% to 1.00%,

Co: 0% to 1.00%,

Mo: 0% to 1.00%,

W: 0% to 1.00%,

Sn: 0% to 1.00%,

Sb: 0% to 1.00%,

Ca: 0% to 0.0100%,

Mg: 0% to 0.0100%,

Ce: 0% to 0.0100%,

Zr: 0% to 0.0100%,

La: 0% to 0.0100%,

Hf: 0% to 0.0100%,

Bi: 0% to 0.0100%,

REM other than Ce and La: 0% to 0.0100% and

a balance of Fe and impurities,

a steel microstructure at a range of ⅛ thickness to ⅜ thickness centered about a position of ¼ thickness from a surface of the base steel sheet contains, by volume fraction,

ferrite: 0% to 50%,

retained austenite: 0% to 30%,

tempered martensite: 5% or more,

fresh martensite: 0% to 10%, and

pearlite and cementite in total: 0% to 5%,

when there are remaining structures, the remaining structures consist of bainite, and

a number ratio of tempered martensite with a Mn concentration profile satisfying the following formulas (1) and (2) is 0.2 or more with respect to the total number of the tempered martensite:

[Mn]_b/[Mn]_a>1.2 (1)

[Mn]_a/[Mn]<2.0 (2)

where [Mn] is the Mn content in mass % in the base steel sheet, [Mn]_ais the average Mn concentration in mass % in the tempered martensite, and [Mn]b is the Mn concentration in mass % at the interfaces of different phases of the tempered martensite and at least one of the ferrite phase and the bainite phase.