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

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 fO2 is a volume fraction of oxygen in the wiping gas.