	US 12,134,245 B2
	Method for the manufacturing of liquid metal embrittlement resistant galvannealed steel sheet
Christian Allely, Metz (FR); Pascal Bertho, Yutz (FR); Anirban Chakraborty, Chesterton, IN (US); and Hassan Ghassemi-Armaki, Schererville, IN (US)
Assigned to ArcelorMittal, Luxembourg (LU)
Filed by ArcelorMittal, Luxembourg (LU)
Filed on Apr. 6, 2023, as Appl. No. 18/131,622.
Application 18/131,622 is a division of application No. 16/605,473, granted, now 11,654,653, previously published as PCT/IB2018/000429, filed on Apr. 25, 2018.
Claims priority of application No. PCT/IB2017/000520 (WO), filed on May 5, 2017.
Prior Publication US 2023/0241865 A1, Aug. 3, 2023
Int. Cl. B32B 15/01 (2006.01); B23K 11/11 (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 2/28 (2006.01); C23C 10/28 (2006.01); C25D 3/12 (2006.01); C25D 3/22 (2006.01); C25D 5/12 (2006.01); C25D 5/50 (2006.01)

CPC B32B 15/011 (2013.01) [B23K 11/11 (2013.01); C21D 8/0273 (2013.01); C21D 9/46 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C23C 2/0224 (2022.08); C23C 2/28 (2013.01); C23C 10/28 (2013.01); C25D 3/12 (2013.01); C25D 3/22 (2013.01); C25D 5/12 (2013.01); C25D 5/50 (2013.01)]

17 Claims

1. A galvannealed steel sheet obtainable from a method for the manufacture of a galvannealed steel sheet having the following successive steps:

A) coating a steel sheet with a first coating consisting of nickel and having a thickness between 150 nm and 650 nm, said steel sheet having the following composition in weight percentage:

0.10<C<0.40%,

1.5<Mn<3.0%,

0.7<Si<3.0%,

0.05<Al<1.0%,

0.75<(Si+Al)<3.0%,

and optionally one or more of the following elements:

Nb≤0.5%,

B≤0.010%,

Cr≤1.0%,

Mo≤0.50%,

Ni≤1.0%,

Ti≤0.5%,

a remainder of the composition being iron and inevitable impurities resulting from the processing;

B) annealing the coated steel sheet at a temperature between 600 to 1200° C.;

C) coating the steel sheet obtained in step B) with a second coating based on zinc; and

D) subjecting the steel sheet obtained in step C) to an alloying heat treatment to form a galvannealed steel sheet,

the galvannealed steel sheet comprising:

a first layer comprising nickel directly topped by a second layer based on zinc, the first and second layers being alloyed through diffusion such that the second alloy layer comprises from 8 to 50 wt. % of iron, from 0 to 25 wt. % of nickel, and a balance being zinc.