Highly corrosion-resistant plated steel sheet having excellent plating adhesion and resistance to liquid metal embrittlement

Patent metadata

Field	Value
Publication number	US-11530470-B2
Application number	US-201917280509-A
Country	US
Kind code	B2
Filing date	Sep 20, 2019
Priority date	Sep 27, 2018
Publication date	Dec 20, 2022
Grant date	Dec 20, 2022

Abstract

Provided is a highly corrosion-resistant plated steel sheet having plating adhesion and resistance to liquid metal embrittlement. A highly corrosion-resistant plated steel sheet comprises a base steel sheet and a plated layer, which sequentially comprises an Fe—Al alloy layer and an MgZn2 layer from an interface with the base steel sheet.

First claim

The invention claimed is:

1. A highly corrosion-resistant plated steel sheet comprising:
a base steel sheet; and
an aluminum based plating layer formed on the base steel sheet, the plating layer having a composition including, by weight, 5 to 10% of Si, 5 to 30% of Zn, and 1 to 7% of Mg,
wherein the plating layer comprises: an Fe—Al alloy layer formed on the base steel sheet; an MgZn 2 layer formed on the Fe—Al alloy layer; and an Al alloy layer formed on the MgZn 2 layer,
wherein a total content of Fe and Al in the Fe—Al alloy layer is 70% by weight or more,
wherein a proportion of the MgZn 2 phase directly on an Fe—Al alloy phase in the plating layer is 90% or more, and
wherein the proportion is determined as a ratio of an area of the MgZn 2 phase to an overall area when observed after a layer formed to be higher than MgZn 2 is removed.

2. The highly corrosion-resistant plated steel sheet of claim 1 , wherein the plating layer includes an Mg 2 Si phase with an area ratio of 10% or less with respect to a total cross-sectional area of the plating layer.

3. The highly corrosion-resistant plated steel sheet of claim 2 , wherein an area ratio of an Mg 2 Si phase in contact with the Fe—Al alloy layer is 2% or less, and
wherein the area ratio of the Mg 2 Si phase in contact with the Fe—Al alloy layer is determined as a ratio of an area of the Mg 2 Si phase to an overall area when observed after a layer, formed to be higher than Mg 2 Si contacting with the Fe—Al alloy layer, is removed.

4. The highly corrosion-resistant plated steel sheet of claim 1 , wherein the composition of the plating layer further includes, by weight, 0.5% or less (excluding 0%) of Be and Sr in total.

5. The highly corrosion-resistant plated steel sheet of claim 1 , wherein the Fe—Al alloy layer has a thickness of 1 μm to 8 μm.

6. The highly corrosion-resistant plated steel sheet of claim 5 , wherein the plating layer includes an Mg 2 Si phase with an area ratio of 10% or less with respect to a total cross-sectional area of the plating layer.

7. The highly corrosion-resistant plated steel sheet of claim 6 , wherein an area ratio of an Mg 2 Si phase in contact with the Fe—Al alloy layer is 2% or less, and
wherein the area ratio of the Mg 2 Si phase in contact with the Fe—Al alloy layer is determined as a ratio of an area of the Mg 2 Si phase to an overall area when observed after a layer, formed to be higher than Mg 2 Si contacting with the Fe—Al alloy layer, is removed.

8. The highly corrosion-resistant plated steel sheet of claim 1 , wherein the MgZn 2 layer has a thickness of 0.5 μm or more.

9. The highly corrosion-resistant plated steel sheet of claim 8 , wherein the plating layer includes an Mg 2 Si phase with an area ratio of 10% or less with respect to a total cross-sectional area of the plating layer.

10. The highly corrosion-resistant plated steel sheet of claim 9 , wherein an area ratio of an Mg 2 Si phase in contact with the Fe—Al alloy layer is 2% or less, and
wherein the area ratio of the Mg 2 Si phase in contact with the Fe—Al alloy layer is determined as a ratio of an area of the Mg 2 Si phase to an overall area when observed after a layer, formed to be higher than Mg 2 Si contacting with the Fe—Al alloy layer, is removed.

Assignees

• Posco
• Posco Co Ltd

Inventors

• Park Il-Jeong
• Kim Myung-Soo
• Lee Suk-Kyu

Classifications

• B32B15/012

  one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy · CPC title

• C22C21/10

  with zinc as the next major constituent · CPC title

• C23C2/18

  Removing excess of molten coatings from elongated material · CPC title

• Y10T428/2495

  Thickness [relative or absolute] · CPC title

• C23C30/005

  on hard metal substrates · CPC title