Coated steel material

Patent metadata

Field	Value
Publication number	US-11787156-B2
Application number	US-202017771012-A
Country	US
Kind code	B2
Filing date	Oct 16, 2020
Priority date	Nov 14, 2019
Publication date	Oct 17, 2023
Grant date	Oct 17, 2023

Abstract

A coated steel material including: a base steel, and a coating layer containing a Zn—Al—Mg alloy layer disposed on a surface of the base steel, wherein the coating layer has a predetermined chemical composition, and, in a backscattered electron image of the Zn—Al—Mg alloy layer that is obtained at a time of observing the surface of the Zn—Al—Mg alloy layer after polishing to ½ of the layer thickness, under a scanning electron microscope at a magnification of 100×, Al crystals are present, and the average value of the cumulative circumferential length of the Al crystals is 88 to 195 mm/mm 2 .

First claim

The invention claimed is:

1. A coated steel material comprising a base steel, and a coating layer containing a Zn—Al—Mg alloy layer disposed on a surface of the base steel,
wherein the coating layer has a chemical composition formed from, in % by mass:
Zn: greater than 65.0%,
Al: greater than 5.0% to less than 25.0%,
Mg: greater than 3.0% to less than 12.5%,
Sn: 0 to 0.20%,
Bi: 0% to less than 5.0%,
In: 0% to less than 2.0%,
Ca: 0% to 3.0%,
Y: 0% to 0.5%,
La: 0% to less than 0.5%,
Ce: 0% to less than 0.5%,
Si: 0% to less than 2.5%,
Cr: 0% to 0.25%,
Ti: 0% to 0.25%,
Ni: 0% to 0.25%,
Co: 0% to 0.25%,
V: 0% to 0.25%,
Nb: 0% to 0.25%,
Cu: 0% to 0.25%,
Mn: 0% to 0.25%,
Fe: 0% to 5.0%,
Sr: 0% to less than 0.5%,
Sb: 0% to less than 0.5%,
Pb: 0% to less than 0.5%,
B: 0% to less than 0.5%, and
impurities, and
wherein, in a backscattered electron image of the Zn—Al—Mg alloy layer that is obtained at a time of observing a surface of the Zn—Al—Mg alloy layer, after polishing the Zn—Al—Mg alloy layer such that a layer thickness thereof is reduced by one-half, under a scanning electron microscope at a magnification of 100×, Al crystals are present, and an average value of a cumulative circumferential length of the Al crystals, as determined by binarization image processing and shape characterization measurement, is 88 to 195 mm/mm 2 .

2. The coated steel material of claim 1 , wherein a content of the Sn is 0 to less than 0.10%, in % by mass.

3. The coated steel material of claim 2 , wherein the coating layer has an Al—Fe alloy layer of a thickness of 0.05 to 5 μm, between the base steel and the Zn—Al—Mg alloy layer.

4. The coated steel material of claim 1 , wherein the coating layer has an Al—Fe alloy layer of a thickness of 0.05 to 5 μm, between the base steel and the Zn—Al—Mg alloy layer.

Assignees

• Nippon Steel Corp

Inventors

• Saito Mamoru
• Goto Yasuto
• Ishizuka Kiyokazu

Classifications

• C23C28/021

  including at least one metal alloy layer · CPC title

• C22C18/00

  Alloys based on zinc · CPC title

• C22C18/04

  with aluminium as the next major constituent · CPC title

• C23C2/06 Primary

  Zinc or cadmium or alloys based thereon · CPC title

• C22C21/00

  Alloys based on aluminium · CPC title