Steel sheet for cans, and production method therefor

Patent metadata

Field	Value
Publication number	US-11339491-B2
Application number	US-201816619147-A
Country	US
Kind code	B2
Filing date	Jun 5, 2018
Priority date	Jun 9, 2017
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

A steel sheet for cans which exhibits excellent weldability; and a production method therefor include a steel sheet for cans with the surface of a steel sheet in order from the steel sheet side, a chromium metal layer and a hydrous chromium oxide layer. The deposited amount of the chromium metal layer is 65-200 mg/m2. The deposited amount of the hydrous chromium oxide layer in terms of chromium is 3-30 mg/m2. The chromium metal layer includes: a base part having a thickness of 7.0 nm or higher; and granular protrusions which are on the base part, have a maximum grain size of 100 nm or lower, and have a number density per unit area of at least 200 per μm2.

First claim

The invention claimed is:

1. A tin mill black plate comprising, on a surface of a steel sheet, a chromium metal layer and a hydrated chromium oxide layer stacked in this order from a steel sheet side,
wherein the chromium metal layer has a coating weight in a range of 65 to 200 mg/m 2 ,
the hydrated chromium oxide layer has a coating weight in a range of 3 to 30 mg/m 2 in terms of chromium amount, and
the chromium metal layer includes a base portion with a thickness of not less than 7.0 nm and granular protrusions provided on the base portion and having a maximum diameter of not more than 100 nm and a number density per unit area of not less than 1,000 protrusions/μm 2 .

2. The tin mill black plate according to claim 1 , wherein the hydrated chromium oxide layer has a coating weight in a range of more than 15 mg/m 2 but not more than 30 mg/m 2 in terms of chromium amount.

3. A tin mill black plate manufacturing method for obtaining the tin mill black plate according to claim 1 by use of an aqueous solution that contains Cr in an amount of not less than 0.50 mol/L and F in an amount of more than 0.10 mol/L and is free of sulfuric acid except for sulfuric acid inevitably incorporated therein, the method comprising:
a step of subjecting a steel sheet to treatment 1 including cathodic electrolysis treatment C 1 using the aqueous solution; and
a step of subjecting the steel sheet having undergone the cathodic electrolysis treatment C 1 to treatment 2 including anodic electrolysis treatment A 1 and cathodic electrolysis treatment C 2 following the anodic electrolysis treatment A 1 , using the aqueous solution, at least two times.

4. The tin mill black plate manufacturing method according to claim 3 , wherein a current density of the anodic electrolysis treatment A 1 is in a range of not less than 0.1 A/dm 2 but less than 5.0 A/dm 2 , and
an electric quantity density of the anodic electrolysis treatment A 1 is in a range of not less than 0.1 C/dm 2 but less than 5.0 C/dm 2 .

5. The tin mill black plate manufacturing method according to claim 3 , wherein the aqueous solution used in the cathodic electrolysis treatment C 1 , the anodic electrolysis treatment A 1 , and the cathodic electrolysis treatment C 2 comprises only one type of aqueous solution.

6. The tin mill black plate manufacturing method according to claim 4 , wherein the aqueous solution used in the cathodic electrolysis treatment C 1 , the anodic electrolysis treatment A 1 , and the cathodic electrolysis treatment C 2 comprises only one type of aqueous solution.

Assignees

• Jfe Steel Corp

Inventors

• Nakagawa Yusuke
• Suzuki Takeshi
• Suto Mikito
• Kojima Katsumi
• Baba Yuya
• SOU Hanyou
• Yamanaka Yoichiro
• Tokui Shunsuke

Classifications

• C25D5/627

  Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance · CPC title

• C25D9/06

  by anodic processes · CPC title

• C25D9/10

  on iron or steel · CPC title

• C25D5/18

  Electroplating using modulated, pulsed or reversing current · CPC title

• C25D7/00

  Electroplating characterised by the article coated · CPC title