Method for manufacturing a metal sheet with a ZnAl coating and with optimized wiping, corresponding metal sheet, part and vehicle

Patent metadata

Field	Value
Publication number	US-10745790-B2
Application number	US-201715826037-A
Country	US
Kind code	B2
Filing date	Nov 29, 2017
Priority date	Mar 6, 2013
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

The present invention provides a method for manufacturing a metal sheet. In this method, at least one of the following equations is satisfied:
Z d + 18 ⁢ ⁢ ln ⁡ ( Z d ) < 8 ⁢ ⁢ ln ⁡ ( P V ) - 27.52 ( A ) f ⁢ ⁢ O 2 < 2.304 · 10 - 3 ( 27.52 + Z d + 8 ⁢ ⁢ ln ⁡ ( V P ⁢ ( Z d ) 2.25 ) ) 2 ( B )
wherein:
Z is the distance between the metal sheet and the nozzle along the main ejection direction (E), Z being expressed in mm, d is the average height of the outlet of the nozzle along with the running direction of the metal sheet in front of the nozzle, d being expressed in mm, V is the running speed of the metal sheet in front of the nozzle, V being expressed in m·s −1 , P is the pressure of the wiping gas in the nozzle, P being expressed in N·m −2 , and fO 2 is the volume fraction of oxygen in the wiping gas. A metal sheet, part and land motor vehicle are also provided.

First claim

What is claimed is:

1. A method for manufacturing a coated meta sheet comprising a steel substrate, at least one face of which is coated, the method comprising the steps of:
providing the steel substrate,
depositing a metal coating on the at least one face of the steel substrate by dipping the steel substrate in a bath to obtain the coated metal sheet,
wiping the metal coating with a wiping gas, the wiping gas being ejected from at least one nozzle through at least one outlet of the at least one nozzle, the coated metal sheet running in front of the at least one nozzle, the wiping gas being ejected from the at least one nozzle along a main ejection direction E, the wiping gas having a pressure F in the at least one nozzle, the at least one outlet of the at least one nozzle being a slot having an average height d along a running direction S of the coated metal sheet in front of the at least one nozzle,
solidifying the metal coating, an outer surface of the metal coating having, after solidification and before any skin-pass operation, a waviness Wa0.8 of less than or equal to 0.55 μm, the metal coating comprising Al, a remainder of the metal coating being Zn and inevitable impurities, the metal coating having a weight content of aluminum from 0.2 to 0.7%; and
satisfying at least one of the following equations:

Z
d

+

18
⁢

⁢

ln
⁡

(

Z
d

)

<

8
⁢

⁢

ln
⁡

(

P
V

)

-
27.52

(
A
)

f
⁢

⁢

O
2

<

2.304
·

10

-
3

(

27.52
+

Z
d

+

8
⁢

⁢

ln
⁡

(

V
P

⁢

(

Z
d

)

2.25

)

)

2

(
B
)

wherein:
Z is a distance between the coated metal sheet and the at least one outlet of the at least one nozzle along the main ejection direction E, Z being expressed in mm,
d is the average height of the at least one outlet of the at least one nozzle along the running direction S of the coated metal sheet in front of the at least one nozzle, d being expressed in mm,
V is a running speed of the coated metal sheet in front of the at least one nozzle, V being expressed in m·s −1 ,
P is the pressure of the wiping gas in the at least one nozzle, P being expressed in N·m −2 , and fO 2 is a volume fraction of oxygen in the wiping gas.

2. The method according to claim 1 , wherein the metal coating further includes one or more additional elements selected from the following: Si, Sb, Pb, Ti, Ca, Mn, Sn, La, Ce, Cr, Zr or Bi, a weight content of each additional element in the metal coating being less than 0.3%.

3. The method according to claim 1 , wherein the waviness Wa 0.8 of the outer surface of the metal coating after solidification and before any skin-pass operation is less than or equal to 0.35 μm.

4. The method according to claim 1 , further comprising the step of: skin-pass rolling the coated metal sheet with Electron Discharge Texture (EDT) work rolls, the EDT work rolls having a working surface having a roughness Ra 2.5 from 2.05 to 2.95 μm.

5. The method according to claim 1 , further comprising the step of: skin-pass rolling the coated metal sheet with Electron Beam Texture (EBT) work rolls, the EBT work rolls having a working surface having a roughness Ra 2.5 from 2.90 to 4.10 μm.

6. The method according to claim 1 , wherein at least one of the following equations is verified:

Z
d

+

18

Assignees

• Arcelormittal

Inventors

• Mataigne Jean-Michel
• Dauchelle Didier
• Bertrand Florence

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C21D8/04

  to produce plates or strips for drawing, e.g. for deep-drawing · CPC title

• C23C2/0222

  in a reactive atmosphere, e.g. oxidising or reducing atmosphere (C23C2/024 takes precedence) · CPC title

• C21D8/0452

  with application of tension · CPC title