	US 11,725,255 B2
	Press hardened part with high resistance to delayed fracture and a manufacturing process thereof
Blandine Remy, Sanry les Vigy (FR); Thierry Sturel, Le Ban Saint Martin (FR); Emmanuel Lucas, Metz (FR); and Gianni Boi, Rombas (FR)
Assigned to ArcelorMittal, Luxembourg (LU)
Appl. No. 17/311,677
Filed by ArcelorMittal, Luxembourg (LU)
PCT Filed Dec. 18, 2018, PCT No. PCT/IB2018/060219 § 371(c)(1), (2) Date Jun. 7, 2021, PCT Pub. No. WO2020/128571, PCT Pub. Date Jun. 25, 2020.
Prior Publication US 2022/0025480 A1, Jan. 27, 2022
Int. Cl. B21D 22/02 (2006.01); B32B 15/01 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/50 (2006.01); C22C 38/54 (2006.01); C21D 9/46 (2006.01); C21D 6/00 (2006.01); C21D 8/02 (2006.01)

CPC C21D 9/46 (2013.01) [B21D 22/02 (2013.01); B32B 15/012 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0263 (2013.01); C22C 38/001 (2013.01); C22C 38/004 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/50 (2013.01); C22C 38/54 (2013.01); C21D 2211/002 (2013.01); C21D 2211/004 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01)]

18 Claims

1. A press hardened coated steel part, comprising a base of steel and a coating, the coating containing (Fex-Aly) intermetallic compounds resulting from the diffusion of iron into an aluminum or an aluminum-based alloy, or an aluminum alloy of a precoating, wherein the chemical composition of the steel comprises, in weight:

0.16%≤C≤0.42%

0.1%≤Mn≤3%

0.07%≤Si≤1.60%

0.002%≤Al≤0.070%

0.02%≤Cr≤1.0%,

0.0005≤B≤0.005%

0.002%≤Mg≤0.007%

0.002%≤Ti≤0.11%

0.0008%≤0≤0.005%

wherein (Ti)×(0)²×107≤2

0.001%≤N≤0.007%

0.001%≤S≤0.005%

0.001%≤P≤0.025%

and optionally one or more elements selected from:

0.005%≤Ni≤0.23%, and

0.005%≤Nb≤0.060%,

a remainder being Fe and unavoidable impurities,

and wherein a microstructure of the steel includes at least 95% martensite, by area or volume fraction;

wherein a tensile strength of the press hardened steel part is between 1400 and 2000 MPa;

and wherein, the press hardened steel part has a resistance to delayed fracture greater than or equal to 3×10¹⁶×TS^−4.345+100, wherein TS is said tensile strength.