US 11,814,696 B2
Steel for press hardening and press hardened part manufactured from such steel
Pascal Drillet, Rozerieulles (FR); Maria Poirier, Villers Saint-Paul (FR); and Sujay Sarkar, Metz (FR)
Assigned to ArcelorMittal, Luxembourg (LU)
Filed by ArcelorMittal, Luxembourg (LU)
Filed on Oct. 1, 2021, as Appl. No. 17/491,785.
Application 17/491,785 is a division of application No. 15/741,290, granted, now 11,319,610, previously published as PCT/IB2016/000788, filed on Jun. 10, 2016.
Claims priority of application No. PCT/IB2015/001156 (WO), filed on Jul. 9, 2015.
Prior Publication US 2022/0017987 A1, Jan. 20, 2022
Int. Cl. C21D 9/46 (2006.01); B32B 15/01 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/32 (2006.01); C22C 38/38 (2006.01); B21D 22/02 (2006.01); C21D 1/673 (2006.01); C21D 8/02 (2006.01); C22C 38/46 (2006.01); C22C 38/44 (2006.01); C22C 38/50 (2006.01); C22C 38/54 (2006.01); C22C 38/48 (2006.01); C22C 21/02 (2006.01); B23K 26/02 (2014.01); B21B 1/22 (2006.01); C21D 6/00 (2006.01); C22C 38/22 (2006.01); C23C 2/12 (2006.01)
CPC C21D 9/46 (2013.01) [B21B 1/22 (2013.01); B21D 22/022 (2013.01); B23K 26/02 (2013.01); B32B 15/012 (2013.01); C21D 1/673 (2013.01); C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0263 (2013.01); C21D 8/0278 (2013.01); C22C 21/02 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/22 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/32 (2013.01); C22C 38/38 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/54 (2013.01); C23C 2/12 (2013.01); B21B 2001/225 (2013.01); B32B 2605/00 (2013.01); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01)] 24 Claims
 
1. A press hardened steel part comprising:
a chemical composition including, by weight:
0.062≤C≤0.095%;
1.4%≤Mn≤1.9%;
0.2%≤Si≤0.5%;
0.020%≤Al≤0.070%;
0.02%≤Cr≤0.1%;
wherein: 1.5%≤(C+Mn+Si+Cr)≤2.7%;
0.040%≤Nb≤0.060%;
3.4×N≤Ti≤8×N;
wherein: 0.044%≤(Nb+Ti)≤0.090%;
0.0005≤B≤0.004%;
0.001%≤N≤0.009%;
0.0005%≤S≤0.003%;
0.001%≤P≤0.020%;
a remainder being Fe and unavoidable impurities; and
a microstructure including, in a majority of the part, in surface fractions: less than 40% of bainite, less than 5% of austenite, less than 5% of ferrite, and more than 50% martensite, the martensite consisting of fresh martensite and self-tempered martensite;
the press hardened steel part comprising at least one hot deformed zone (A) with a deformation quantity εc higher than 0.15, and at least one zone (B) with the deformation quantity εc of less than 0.05, the at least one hot deformed zone (A) and the at least one zone (B) experienced the same cooling cycle in press hardening,
wherein an average lath width of a martensitic-bainitic structure in the at least one hot deformed zone (A) is reduced by more than 50% as compared to a lath width of a martensitic-bainitic structure in the at least one zone (B).