	US 12,338,516 B2
	Damper spring
Shinya Teramoto, Tokyo (JP); Yutaka Neishi, Tokyo (JP); Michimasa Aono, Tokyo (JP); Shoichi Suzuki, Tokyo (JP); and Tatsuro Ochi, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP); and NIPPON STEEL SG WIRE CO., LTD., Tokyo (JP)
Appl. No. 17/904,445
Filed by NIPPON STEEL CORPORATION, Tokyo (JP); and NIPPON STEEL SG WIRE CO., LTD., Tokyo (JP)
PCT Filed Feb. 19, 2021, PCT No. PCT/JP2021/006398 § 371(c)(1), (2) Date Aug. 17, 2022, PCT Pub. No. WO2021/167072, PCT Pub. Date Aug. 26, 2021.
Claims priority of application No. 2020-027779 (JP), filed on Feb. 21, 2020.
Prior Publication US 2023/0081462 A1, Mar. 16, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. C22C 38/34 (2006.01); C22C 38/04 (2006.01); C22C 38/22 (2006.01); C22C 38/24 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/30 (2006.01); C22C 38/32 (2006.01); C22C 38/42 (2006.01)

CPC C22C 38/34 (2013.01) [C22C 38/04 (2013.01); C22C 38/22 (2013.01); C22C 38/24 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/30 (2013.01); C22C 38/32 (2013.01)]

4 Claims

1. A damper spring, wherein:

when a wire diameter is defined as d (mm), a chemical composition at a d/4 depth position from a surface contains, in mass %,

C: 0.50 to 0.80%,

Si: 1.20 to less than 2.50%,

Mn: 0.25 to 1.00%,

P: 0.020% or less,

S: 0.020% or less,

Cr: 0.40 to 1.90%,

V: 0.05 to 0.60%,

N: 0.0100% or less,

Mo: 0 to 0.50%,

Nb: 0 to 0.050%,

W: 0 to 0.60%,

Ni: 0 to 0.500%,

Co: 0 to 0.30%,

B: 0 to 0.0050%,

Cu: 0 to 0.050%,

Al: 0 to 0.0050%, and

Ti: 0 to 0.050%,

with the balance being Fe and impurities,

and wherein:

in a microstructure of the damper spring, an area fraction of martensite is 90.0% or more, and

a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 5000 to 80000 pieces/μm³.