US 12,312,663 B2
Chromium steel having excellent high-temperature oxidation resistance and high-temperature strength, and method of manufacturing same
Hyun-Je Sung, Pohang-si (KR)
Assigned to POSCO, Pohang-si (KR)
Appl. No. 17/769,087
Filed by POSCO, Pohang-si (KR)
PCT Filed Sep. 25, 2020, PCT No. PCT/KR2020/013144
§ 371(c)(1), (2) Date Apr. 14, 2022,
PCT Pub. No. WO2021/080205, PCT Pub. Date Apr. 29, 2021.
Claims priority of application No. 10-2019-0131380 (KR), filed on Oct. 22, 2019.
Prior Publication US 2024/0102136 A1, Mar. 28, 2024
Int. Cl. C22C 38/22 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01)
CPC C22C 38/22 (2013.01) [C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0263 (2013.01); C21D 9/46 (2013.01); C22C 38/001 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C21D 2211/005 (2013.01)] 2 Claims
OG exemplary drawing
 
1. A chromium steel, comprising: by weight %, 0.1% or less of C (not including 0%), 0.7% or less of Si (not including 0%), 0.1% or less of Mn (not including 0%), 0.01% or less of S (not including 0%), 0.03% or less of P (not including 0%), 27-33% of Cr, 3.5% or less of Al (not including 0%), 2.5% or less of Nb (not including 0%), 6.5% or less of W (not including 0%), 0.5% or less of Mo (not including 0%), 0.3% or less of Ti (not including 0%), 0.015% or less of N (not including 0%) and the remainder being Fe and unavoidable impurities, the chromium steel satisfying the following relational expression (1),
wherein the steel has a microstructure including ferrite, and
wherein in the microstructure of the steel, the number of precipitates having a diameter of 500 nm or less and including Laves phase and carbonitride are present in a range of 10/μm2 or
(Cr−SUM)(Al−SUM)≥45,  [Relational Expression 1]
where SUM is a formula related to contents of specific elements and impurity elements, and specifically indicates a total content of Cu+Co+V+La+Ce+Zr+Ta+Hf+Re+Pt+Ir+Pd+Sb+100N.