US 12,378,628 B2
Wire rod and steel wire for spring, having enhanced toughness and corrosion fatigue properties, and respective manufacturing methods therefor
Kwan Ho Kim, Pohang-si (KR)
Assigned to POSCO CO., LTD, Pohang-si (KR)
Appl. No. 17/269,793
Filed by POSCO, Pohang-si (KR)
PCT Filed Feb. 22, 2019, PCT No. PCT/KR2019/002209
§ 371(c)(1), (2) Date Feb. 19, 2021,
PCT Pub. No. WO2020/040388, PCT Pub. Date Feb. 27, 2020.
Claims priority of application No. 10-2018-0097262 (KR), filed on Aug. 21, 2018.
Prior Publication US 2021/0180152 A1, Jun. 17, 2021
Int. Cl. C21D 9/52 (2006.01); C21D 6/00 (2006.01); C21D 8/06 (2006.01); C21D 9/02 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (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); F16F 1/02 (2006.01)
CPC C21D 9/525 (2013.01) [C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/065 (2013.01); C21D 9/02 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (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); F16F 1/021 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A wire rod for springs with improved toughness and corrosion fatigue properties, the wire rod comprising, by weight percent:
carbon (C): 0.4 to 0.7%,
silicon (Si): 1.2 to 2.3%,
manganese (Mn): 0.2 to 0.69%,
chromium (Cr): 0.2 to 0.8%, and
a balance of iron (Fe) and inevitable impurities, and
wherein a grain size of ferrite and colony is 13.2 μm or less,
wherein a grain size of the colony is 8.0 μm or less, and
wherein a Charpy impact energy is 38 J/cm2 or more.