	US 12,435,402 B2
	Austenitic stainless steel material
Masaharu Hatano, Tokyo (JP); Kazuhisa Matsumoto, Tokyo (JP); and Mitsuki Matsumoto, Tokyo (JP)
Assigned to NIPPON STEEL STAINLESS STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/787,972
Filed by NIPPON STEEL STAINLESS STEEL CORPORATION, Tokyo (JP)
PCT Filed Jan. 8, 2021, PCT No. PCT/JP2021/000422 § 371(c)(1), (2) Date Jun. 22, 2022, PCT Pub. No. WO2021/141099, PCT Pub. Date Jul. 15, 2021.
Claims priority of application No. 2020-001834 (JP), filed on Jan. 9, 2020.
Prior Publication US 2023/0047414 A1, Feb. 16, 2023
Int. Cl. C22C 38/58 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (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)

CPC C22C 38/58 (2013.01) [C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/02 (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)]

9 Claims

1. An austenitic stainless steel material, which has a passivation film on a surface, comprising:

a chemical composition consisting of, in mass %,

C: 0.10% or less,

Si: 1.0% or less,

Mn: 8.0 to 10.0%,

P: 0.030% or less,

S: 0.0030% or less,

Cr: 15.0 to 18.0%,

Ni: 7.0 to 9.0%,

N: 0.15 to 0.25%,

Al: 0.005 to 0.20%,

Ca: 0.0005 to 0.01%,

Cu: less than 1.0%,

Mo: less than 1.0%,

B: 0 to 0.0050%,

Nb: 0 to 0.50%,

Ti: 0 to 0.50%,

V: 0 to 0.50%,

W: 0 to 0.50%,

Zr: 0 to 0.50%,

Co: 0 to 0.50%,

Mg: 0 to 0.005%,

Ga: 0 to 0.010%,

Hf: 0 to 0.10%,

REM: 0 to 0.10%, and

the balance: Fe and impurities,

wherein:

an f value calculated by Formula (i) below is more than 29.5 and less than 32.5;

cation fractions of a chemical composition in the passivation film satisfy Formula (ii) below:

f value=Ni+0.72Cr+0.88Mo+1.11Mn−0.27Si+0.53Cu+12.93C+7.55N (i)

4.5≤(Mn+Fe)/Cr<9.0 (ii)

where, each symbol of an element in Formula (i) above represents a content (mass %) of the corresponding element contained in the steel, with a value of a symbol being taken as zero if the corresponding element is not contained, and each symbol of an element in Formula (ii) above represents a cation fraction (atomic percent) of the corresponding element contained in the passivation film, with a value of a symbol being taken as zero if the corresponding element is not contained.