Multi-layered zinc alloy plated steel having excellent spot weldability and corrosion resistance

Patent metadata

Field	Value
Publication number	US-11208716-B2
Application number	US-201716471943-A
Country	US
Kind code	B2
Filing date	Dec 22, 2017
Priority date	Dec 26, 2016
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

Provided is a multilayer zinc alloy plated steel material comprising a base steel material and multiple plating layers formed on the base steel material, wherein each of the multiple plating layers includes one of a Zn plating layer, a Mg plating layer, and a Zn—Mg alloy plating layer, and the ratio of the weight of Mg contained in the multiple plating layers to the total weight of the multiple plating layers is from 0.13 to 0.24.

First claim

The invention claimed is:

1. A multilayer zinc alloy plated steel material comprising:
a base steel material having a thickness; and
multiple plating layers formed on the base steel material,
wherein a ratio of a total Mg content in the multiple plating layers to a total weight of the multiple plating layers is from 0.13 to 0.24,
wherein the multiple plating layers comprise: a first plating layer formed on the base steel material and having a Mg content of 7 wt % or less; and a second plating layer formed on the first plating layer, and
wherein the first plating layer comprises: a Zn single phase, and the second plating layer comprises: a Zn—Mg alloy phase, or
wherein the first plating layer comprises: a Zn single phase and a Zn—Mg alloy phase, and the second plating layer comprises: a Zn—Mg alloy phase, and
wherein grains of the multiple plating layers have an average diameter of 100 nm or less (excluding 0 nm).

2. The multilayer zinc alloy plated steel material of claim 1 , wherein, when a GDS profile is measured at a thicknesswise center portion of the each of the multiple plating layers, a Mg content in the each of the multiple plating layers deviates within a range of ±5%.

3. The multilayer zinc alloy plated steel material of claim 1 , wherein a total plating amount of the multiple plating layers is 40 g/m 2 or less (excluding 0 g/m 2 ).

4. The multilayer zinc alloy plated steel material of claim 1 , wherein, when spot welding is performed on the multilayer zinc alloy plated steel material, the multiple plating layers are configured to be changed to a single alloy layer in a weld zone, and the single alloy layer comprises: a MgZn 2 alloy phase in an area fraction of 90% or greater (including 100%).

5. The multilayer zinc alloy plated steel material of claim 1 , wherein, when spot welding is performed in accordance with SEP 1220-2, an average length of type B cracks is equal to or less than 0.1 times the thickness of the base steel material.

6. The multilayer zinc alloy plated steel material of claim 1 , wherein the base steel material comprises, by wt %, C: 0.10% to 1.0%, Si: 0.5% to 3%, Mn: 1.0% to 25%, Al: 0.01% to 10%, P: 0.1% or less (excluding 0%), S: 0.01% or less (excluding 0%), and a balance of Fe and inevitable impurities, and
wherein the contents of C, Si, Mn, P, and S satisfy Condition 1 below:
[C]+[Mn]/20+[Si]/30+2[P]+4[S]≥0.3  Condition 1:

where each of [C], [Mn], [Si], [P], and [S] refers to a content (wt %) of a corresponding element.

7. The multilayer zinc alloy plated steel material of claim 6 , wherein the base steel material comprises: a microstructure including at least one of austenite and retained austenite.

8. The multilayer zinc alloy plated steel material of claim 1 , wherein a total plating amount of the first laying layer and the second plating layer is 40 g/m 2 or less (excluding 0 g/m 2 ), and a plating amount of the first plating layer is 3 g/m 2 or greater.

9. The multilayer zinc alloy plated steel material of claim 1 , wherein, in the first plating layer comprising the Zn single phase and the Zn—Mg alloy phase, the Zn—Mg alloy phase comprises: a Mg 2 Zn 11 alloy phase.

10. The multilayer zinc alloy plated steel material of claim 1 , wherein the multiple plating layers further comprise: a third plating layer formed on the second plating layer and having a Mg content of 2 wt % or less, and
wherein the third plating layer comprises: a Zn single phase, or a Zn single phase and a Zn—Mg alloy phase.

11. The multilayer zinc alloy plated steel material of claim 10 , wherein a total plating amount of the first playing layer, the second plating layer and the third plating layer is 40 g/m 2 or less (excluding 0 g/m 2 ), a plating amount of the first plating layer is 3 g/m 2 or greater, and a plating amount of the third plating layer is 2 g/m 2 or greater.

12. A multilayer zinc alloy plated steel material comprising:
a base steel material having a thickness; and
multiple plating layers formed on the base steel material,
wherein a ratio of a total Mg content in the multiple plating layers to a total weight of the multiple plating layers is from 0.13 to 0.24,
wherein the multiple plating layers comprise: a first plating layer formed on the base steel material and having a Mg content of 7 wt % or less; and a second plating layer formed on the first plating layer, and
wherein the first plating layer comprises: a Zn single phase, and the second plating layer comprises: a Zn—Mg alloy phase, or
wherein the first plating layer comprises: a Zn single phase and a Zn—Mg alloy phase, and the second plating layer comprises: a Zn—Mg alloy phase, and
wherein, when spot welding is performed on the multilayer zinc alloy plated steel material, the multiple plating layers are configured to be changed to a single alloy layer in a weld zone, and the single alloy layer comprises: a MgZn 2 alloy phase in an area fraction of 90% or greater (including 100%).

13. A multilayer zinc alloy plated steel material comprising:
a base steel material having a thickness; and
multiple plating layers formed on the base steel material,
wherein a ratio of a total Mg content in the multiple plating layers to a total weight of the multiple plating layers is from 0.13 to 0.24,
wherein the multiple plating layers comprise: a first plating layer formed on the base steel material and having a Mg content of 7 wt % or less; and a second plating layer formed on the first plating layer, and
wherein the first plating layer comprises: a Zn single phase, and the second plating layer comprises: a Zn—Mg alloy phase, or
wherein the first plating layer comprises: a Zn single phase and a Zn—Mg alloy phase, and the second plating layer comprises: a Zn—Mg alloy phase, and
wherein, when spot welding is performed in accordance with SEP 1220-2, an average length of type B cracks is equal to or less than 0.1 times the thickness of the base steel material.

Assignees

• Posco

Inventors

• Kwak Young-Jin
• Kim Goo-Hwa
• Eom Mun-Jong
• Hong Seok-Jun
• Ko Kyoung-Pil
• Jung Yong-Hwa
• Lee Dong-Yoeul
• Kim Tae-Yeob
• Nam Kyung-Hoon

Classifications

• C22C38/02

  containing silicon · CPC title

• Y10T428/12979

  Containing more than 10% nonferrous elements [e.g., high alloy, stainless] · CPC title

• C23C14/16 Primary

  on metallic substrates or on substrates of boron or silicon · CPC title

• C23C28/023 Primary

  only coatings of metal elements only · CPC title

• C23C2/06

  Zinc or cadmium or alloys based thereon · CPC title