US 11,939,651 B2
Al—Fe-alloy plated steel sheet for hot forming, having excellent TWB welding characteristics, hot forming member, and manufacturing methods therefor
Seong-Woo Kim, Gwangyang-si (KR); Jin-Keun Oh, Gwangyang-si (KR); Yeol-Rae Cho, Gwangyang-si (KR); and Hyeon-Jeong Shin, Incheon (KR)
Assigned to POSCO CO., LTD, Pohang-si (KR)
Appl. No. 17/059,641
Filed by POSCO, Pohang-si (KR)
PCT Filed May 31, 2018, PCT No. PCT/KR2018/006244
§ 371(c)(1), (2) Date Nov. 30, 2020,
PCT Pub. No. WO2019/231023, PCT Pub. Date Dec. 5, 2019.
Prior Publication US 2021/0222276 A1, Jul. 22, 2021
Int. Cl. C22C 38/32 (2006.01); B23K 35/02 (2006.01); B23K 35/30 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C23C 2/02 (2006.01); C23C 2/12 (2006.01); C23C 2/26 (2006.01); C23C 2/28 (2006.01); C23C 2/40 (2006.01); B23K 103/16 (2006.01); B23K 103/20 (2006.01)
CPC C22C 38/32 (2013.01) [B23K 35/0238 (2013.01); B23K 35/3086 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 9/46 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C23C 2/02 (2013.01); C23C 2/0224 (2022.08); C23C 2/12 (2013.01); C23C 2/261 (2022.08); C23C 2/28 (2013.01); C23C 2/29 (2022.08); C23C 2/40 (2013.01); B23K 2103/166 (2018.08); B23K 2103/20 (2018.08); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An Al—Fe alloy plated steel sheet for hot press forming, the Al—Fe alloy plated steel sheet comprising:
a base steel sheet comprising, by weight percentage (wt %), carbon (C): 0.1 to 0.5%, silicon (Si): 0.01 to 2.0%, manganese (Mn): 0.1 to 10%, phosphorus (P): 0.001 to 0.05%, sulfur (S): 0.0001 to 0.02%, aluminum (Al): 0.001 to 1.0%, nitrogen (N): 0.001 to 0.02%, and a balance of iron (Fe) and unavoidable impurities;
an Al—Fe alloy layer disposed on the base steel sheet; and
an oxide layer formed on the Al—Fe alloy layer, the oxide layer having a thickness of 2 μm or less, wherein the thickness of 2 μm or less refers to a thickness to a point having 10 wt % of oxygen concentration in an oxygen concentration profile obtained through glow discharge spectrometer (GDS) analysis,
wherein the Al—Fe alloy layer comprises, by wt %, aluminum (Al): 40 to 60%, silicon (Si): 2 to 10%, and a balance of iron (Fe) and unavoidable impurities, and a fraction of an unalloyed phase is 1 area % or less, and
wherein the Al—Fe alloy layer comprises:
a diffusion layer disposed on the base steel sheet and constituting a layer while including Si in an amount of 0.5 to 12.0 wt %; and
an intermediate layer disposed in the Al—Fe alloy layer and constituting a layer while including Si in an amount of 3.0 to 20.0 wt %, and
wherein a sum of average thicknesses of the diffusion layer and the intermediate layer is 1.0 to 10 μm.