US 12,221,680 B2
Cryogenic austenitic high-manganese steel having excellent corrosion resistance, and manufacturing method therefor
Un-Hae Lee, Gwangyang-si (KR); Dong-Ho Lee, Gwangyang-si (KR); Sang-Deok Kang, Gwangyang-si (KR); and Sung-Kyu Kim, Gwangyang-si (KR)
Assigned to POSCO CO., LTD, Pohang-si (KR)
Appl. No. 17/283,884
Filed by POSCO, Pohang-si (KR)
PCT Filed Oct. 25, 2019, PCT No. PCT/KR2019/014197
§ 371(c)(1), (2) Date Apr. 8, 2021,
PCT Pub. No. WO2020/085864, PCT Pub. Date Apr. 30, 2020.
Claims priority of application No. 10-2018-0128505 (KR), filed on Oct. 25, 2018; and application No. 10-2019-0133780 (KR), filed on Oct. 25, 2019.
Prior Publication US 2021/0388475 A1, Dec. 16, 2021
Int. Cl. C22C 38/38 (2006.01); C21D 8/02 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/20 (2006.01); C22C 38/32 (2006.01)
CPC C22C 38/38 (2013.01) [C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/20 (2013.01); C22C 38/32 (2013.01); C21D 2211/001 (2013.01)] 13 Claims
 
1. A cryogenic austenitic high-manganese steel material having excellent corrosion resistance, comprising:
by weight %, 0.2-0.5% of C, 23-28% of Mn, 0.05-0.5% of Si, 0.03% or less of P, 0.005% or less of S, 0.5% or less of Al, 3-4% of Cr, and a balance of Fe and inevitable impurities;
95 area % or more of austenite as a microstructure; and
a Cr concentration section continuously formed in an area within 50 μm from a surface in a thickness direction,
wherein the Cr concentration section includes a high Cr concentration section in which Cr is concentrated in a relatively high concentration and a low Cr concentration section in which Cr is concentrated in a relatively low concentration, and
wherein the high Cr concentration section is distributed in a fraction of 30 area % or less (excluding 0%) relative to an entire surface area of the Cr concentration section.