Method for the manufacturing of liquid metal embrittlement resistant galvannealed steel sheet

Patent metadata

Field	Value
Publication number	US-11654653-B2
Application number	US-201816605473-A
Country	US
Kind code	B2
Filing date	Apr 25, 2018
Priority date	May 5, 2017
Publication date	May 23, 2023
Grant date	May 23, 2023

Abstract

The present invention relates to a method for the manufacture of a galvannealed steel sheet including the steps of A.) coating of the steel sheet with a first coating consisting of nickel and having a thickness between 150 nm and 650 nm, the 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 on a purely optional basis, one or more elements such as Nb≤0.5%, B≤0.010%, Cr≤1.0%, Mo≤0.50%, Ni≤1.0%, Ti≤0.5%, the remainder of the composition is made up of iron and inevitable impurities resulting from the elaboration, B.) annealing of the coated steel sheet being annealed at a temperature between 600 to 1200° C., C.) coating of the steel sheet obtained in step B.) with a second coating based on zinc and D.) an alloying heat treatment to form a galvannealed steel sheet.

First claim

The invention claimed is:

1. A method for the manufacture of a galvannealed steel sheet comprising the following successive steps:
A) coating a steel sheet with a first coating consisting of nickel and having a thickness between 200 nm and 500 nm, said steel sheet having a composition including in weight percentage:
0.10<C<0.40%,
1.5<Mn<3.0%,
0.7<Si<3.0%,
0≤Nb≤0.5%,
0≤B≤0.010%,
0≤Cr≤1.0%,
0≤Mo≤0.50%,
0≤Ni≤1.0%,
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. in an atmosphere comprising from 1 to 10% of H 2 at a dew point between −60 and −30° 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.

2. The method according to claim 1 , wherein in step A), the steel sheet further comprises 0.05<Al<1.0% and 0.75<(Si+Al)<3.0%.

3. The method according to claim 2 , wherein in step A), the first coating has a thickness between 250 and 450 nm.

4. The method according to claim 1 , wherein in step B), the annealing is a continuous annealing.

5. The method according to claim 1 , wherein in step C), the second coating comprises above 50% of zinc.

6. The method according to claim 5 , wherein in step C), the second coating comprises above 75% of zinc.

7. The method according to claim 6 , wherein in step C), the second coating comprises above 90% of zinc.

8. The method according to claim 1 , wherein the second coating does not comprise nickel.

9. The method according to claim 8 , wherein in step C), the second coating consists of zinc.

10. The method according to claim 1 , wherein in step D) the alloying treatment is performed by heating the coated steel sheet obtained in step C) at a temperature between 470 and 550° C.

11. The method according to claim 1 , wherein the steel sheet obtained in step B) is cooled prior to step C).

12. The method according to claim 1 , wherein the steel sheet obtained in step B) is cooled to quench temperature of 210° C.

13. The method according to claim 1 , wherein the steel sheet obtained in step B) is cooled to room temperature.

Assignees

• Arcelormittal

Inventors

• Allely Christian
• Bertho Pascal
• Chakraborty Anirban
• Ghassemi-Armaki Hassan

Classifications

• C22C38/02

  containing silicon · CPC title

• C25D5/50

  by heat-treatment · CPC title

• C25D3/12

  of nickel or cobalt · CPC title

• C25D7/0614

  Strips or foils · CPC title

• C23C10/28

  using solids, e.g. powders, pastes · CPC title