Method for manufacturing black plated steel sheet, apparatus for manufacturing black plated steel sheet, and system for manufacturing black plated steel sheet

Patent metadata

Field	Value
Publication number	US-10697053-B2
Application number	US-201616081962-A
Country	US
Kind code	B2
Filing date	Aug 9, 2016
Priority date	Mar 1, 2016
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

The purpose of the present invention is to provides a method for manufacturing a black plated steel sheet that is capable of more evenly blackening the area of the plated steel sheet to be blackened. The present invention relates to a method for manufacturing a black plated steel sheet by bringing a plated steel sheet with an Al- and Mg-containing hot-dip galvanized layer into contact with water vapor inside a sealed vessel. This method performs, in the following order: a first step for heating a plated steel sheet disposed inside a sealed vessel in the presence of a gas, the dew point of which is always less than the plated steel sheet temperature; a second step for evacuating the heated ambient gas inside the sealed vessel to make the pressure of the gas inside the sealed vessel to be 70 kPa or less; and a third step for introducing water vapor inside the sealed vessel in which the pressure of the gas therein has been reduced to 70 kPa or less to blacken the galvanized layer.

First claim

The invention claimed is:

1. A method for producing a black-plated steel sheet by contacting a plated steel sheet with water vapor in a closed vessel, the plated steel sheet including a base steel sheet and a plating layer, the plating layer including a hot-dip Al and Mg-containing Zn-plating layer formed on a surface of the base steel sheet, the method comprising:
heating the plated steel sheet disposed in the closed vessel filled with a first gas having a dew point which is always lower than a temperature of the plated steel sheet;
after the heating of the plated steel sheet, reducing a gas pressure in the closed vessel to 70 kPa or less by exhausting a first atmospheric gas heated in the closed vessel;
after the reducing of the gas pressure by exhausting the first atmospheric gas, blackening the plating layer by introducing the water vapor into the closed vessel;
after the blackening of the plating layer, reducing the gas pressure in the closed vessel to 70 kPa or less by exhausting a second atmospheric gas in the closed vessel where the black-plated steel sheet having the plating layer blackened is disposed; and
after the reducing of the gas pressure by exhausting the second atmospheric gas, cooling the plated steel sheet by introducing a second gas having a dew point which is always lower than the temperature of the plated steel sheet into the closed vessel.

2. The method according to claim 1 , wherein the plated steel sheet is a coil-shaped plated steel sheet.

3. The method according to claim 2 , wherein the coil-shaped plated steel sheet is disposed with the coil end facing upward in the closed vessel.

4. The method according to claim 2 , wherein two or more of the coil-shaped plated steel sheets are each disposed with eyes vertical in the closed vessel, and the coil-shaped plated steel sheets are stacked.

5. The method according to claim 1 , wherein the plated steel sheet is a processed plated steel sheet.

6. The method according to claim 1 , wherein, in the heating, the first gas is air.

7. The method according to claim 5 , wherein, in the heating, the plated steel sheet is heated while the first gas is stirred in the closed vessel.

8. The method according to claim 1 , wherein, in the blackening, the inside of the closed vessel has an atmospheric temperature of 105° C. or more, and relative humidity of 80% or more.

9. The method according to claim 1 , wherein, in the blackening, the inside of the closed vessel is heated.

10. The method according to claim 1 , wherein, in the blackening after the introducing the water vapor into the closed vessel, a predetermined amount of the first atmospheric gas is expelled from the inside of the closed vessel, and another water vapor is further introduced into the closed vessel.

11. The method according to claim 1 , wherein, in the blackening after the introducing the water vapor into the closed vessel, the first atmospheric gas in the closed vessel is stirred.

12. The method according to claim 1 , wherein the hot-dip Al and Mg-containing Zn-plating layer contains 0.1 mass % or more and 60 mass % or less of Al, and 0.01 mass % or more and 10 mass % or less of Mg.

Assignees

• Nisshin Steel Co Ltd

Inventors

• Nakano Tadashi
• Ueno Shin
• Yamamoto Masaya

Classifications

• C23C2/06 Primary

  Zinc or cadmium or alloys based thereon · CPC title

• C23C2/40

  Plates; Strips · CPC title

• C22C21/10

  with zinc as the next major constituent · CPC title

• C22C18/04

  with aluminium as the next major constituent · CPC title

• C22C18/00 Primary

  Alloys based on zinc · CPC title