US 12,392,005 B2
Ferritic stainless steel with improved high temperature creep resistance and manufacturing method therefor
Il Chan Jung, Pohang-si (KR); Hoi Hun Kim, Pohang-si (KR); and Han Jin Ryu, Pohang-si (KR)
Assigned to POSCO, Pohang-si (KR)
Appl. No. 17/632,926
Filed by POSCO, Pohang-si (KR)
PCT Filed Feb. 6, 2020, PCT No. PCT/KR2020/001718
§ 371(c)(1), (2) Date Feb. 4, 2022,
PCT Pub. No. WO2021/025248, PCT Pub. Date Feb. 11, 2021.
Claims priority of application No. 10-2019-0095077 (KR), filed on Aug. 5, 2019.
Prior Publication US 2022/0356542 A1, Nov. 10, 2022
Int. Cl. C21D 9/46 (2006.01); C21D 6/00 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/20 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01)
CPC C21D 9/46 (2013.01) [C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0205 (2013.01); C21D 8/0236 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/20 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C21D 2211/004 (2013.01); C21D 2211/005 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A ferritic stainless steel with improved high temperature creep resistance comprising, in percent by weight (wt %), 0.005 to 0.03% of carbon (C), 0.005 to 0.03% of nitrogen (N), 0.05 to 0.9% of silicon (Si), 0.05 to 0.9% of manganese (Mn), 14.0 to 19.0% of chromium (Cr), 0.1 to 0.6% of titanium (Ti), 0.1 to 0.6% of niobium (Nb), 0.1 to 0.6% of copper (Cu), 0.01 to 0.04% of phosphorus (P), 0.01% or less of sulfur (S, except for 0), and the balance of iron (Fe) and inevitable impurities, and
satisfying Expressions (1) and (2) below,
wherein 7*105/mm2 or more of precipitates including Nb, Fe, and Cr are distributed in a region of the ferritic stainless steel from T/3 to T/5 based on thickness T:
0.5≤Nb/Cu≤3  Expression (1):
20≤[2Nb+Ti]/[C+N]  Expression (2):
wherein Nb, Cu, Ti, C, and N denote contents (wt %) of the elements.