US 12,416,058 B2
Hot formed pre-coated steel part
Tiago Machado Amorim, Longeville les Metz (FR); Christian Allely, Metz (FR); Raisa Grigorieva, Metz (FR); and David Dussaussois, Homecourt (FR)
Assigned to ArcelorMittal, Luxembourg (LU)
Filed by ArcelorMittal, Luxembourg (LU)
Filed on Aug. 31, 2021, as Appl. No. 17/463,128.
Application 17/463,128 is a continuation of application No. 15/748,395, granted, now 11,162,153, previously published as PCT/IB2016/000983, filed on Jul. 11, 2016.
Claims priority of application No. PCT/IB2015/001284 (WO), filed on Jul. 30, 2015.
Prior Publication US 2021/0395853 A1, Dec. 23, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. C21D 9/46 (2006.01); B21D 22/02 (2006.01); B32B 15/01 (2006.01); C21D 1/673 (2006.01); C21D 6/00 (2006.01); C21D 8/00 (2006.01); C22C 21/02 (2006.01); C22C 21/10 (2006.01); C23C 2/12 (2006.01); C23C 2/26 (2006.01); C23C 2/28 (2006.01); C23C 2/40 (2006.01)
CPC C21D 9/46 (2013.01) [B21D 22/022 (2013.01); B32B 15/012 (2013.01); C21D 1/673 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/005 (2013.01); C22C 21/02 (2013.01); C22C 21/10 (2013.01); C23C 2/12 (2013.01); C23C 2/26 (2013.01); C23C 2/261 (2022.08); C23C 2/28 (2013.01); C23C 2/29 (2022.08); C23C 2/40 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01)] 57 Claims
 
1. A hot formed pre-coated steel part, comprising a steel sheet precoated with a metallic coating and then hot formed into the hot formed pre-coated steel part, the coating including:
2.0 to 24.0% by weight of zinc;
1.1 to 7.0% by weight of silicon;
and optionally additional elements chosen from Pb, Ni, Zr or Hf, a content by weight of each additional element being less than 0.3% by weight,
a balance being aluminum, unavoidable impurities and residual elements resulting from feeding ingots or from a passage of the steel sheet in a molten bath;
a ratio Al/Zn by weight greater than 2.9; and
a ratio Zn/Si by weight between 2.9 and 8;
a microstructure in the steel sheet after hot forming being martensitic or martensitic-bainitic or made of at least 75% of equiaxed ferrite, 5 to 20% of martensite and bainite in an amount less than or equal to 10%,
wherein a thickness of the coating is between 10 and 50 μm, and the coating is free from magnesium.