	US 12,227,826 B2
	Steel plate for pressure vessel having excellent hydrogen induced cracking resistance and method of manufacturing same
Dae-Woo Kim, Pohang-si (KR)
Assigned to POSCO CO., LTD, Pohang-si (KR)
Appl. No. 17/296,456
Filed by POSCO, Pohang-si (KR)
PCT Filed Nov. 29, 2019, PCT No. PCT/KR2019/016697 § 371(c)(1), (2) Date May 24, 2021, PCT Pub. No. WO2020/111858, PCT Pub. Date Jun. 4, 2020.
Claims priority of application No. 10-2018-0153076 (KR), filed on Nov. 30, 2018.
Prior Publication US 2021/0395867 A1, Dec. 23, 2021
Int. Cl. C22C 38/46 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01)

CPC C22C 38/50 (2013.01) [C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C21D 2211/005 (2013.01)]

4 Claims

1. A steel plate for a pressure vessel having excellent hydrogen induced cracking resistance, the steel plate comprising, by wt %, 0.2 to 0.3% of carbon (C), 0.05 to 0.50% of silicon (Si), 0.1% or more to less than 0.5% of manganese (Mn), 0.005 to 0.1% of aluminum (Al), 0.010% or less of phosphorus (P), 0.0015% or less of sulfur(S), 0.001 to 0.03% of niobium (Nb), 0.001 to 0.03% of vanadium (V), 0.001 to 0.03% of titanium (Ti), 0.01 to 0.20% of chromium (Cr), 0.01 to 0.15% of molybdenum (Mo), 0.01 to 0.50% of copper (Cu), 0.05 to 0.50% of nickel (Ni), 0.0005 to 0.0040% of calcium (Ca), and a balance of Fe and other unavoidable impurities,

wherein an average ferrite grain size is 5 to 20 μm, and

wherein the steel plate contains 0.01 to 0.02 wt % of Nb (C,N) or V (C,N) carbonitrides having an average diameter of 5 to 20 nm after post weld heat treatment (PWHT).