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

Patent metadata

Field	Value
Publication number	US-2020002803-A1
Application number	US-201716471943-A
Country	US
Kind code	A1
Filing date	Dec 22, 2017
Priority date	Dec 26, 2016
Publication date	Jan 2, 2020
Grant date	—

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

1 . A multilayer zinc alloy plated steel material comprising a base steel material and multiple plating layers formed on the base steel material,
wherein 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, and each of the multiple plating layers comprises at least one of a Zn single phase, a Mg single phase, and a Zn—Mg alloy phase, and has a phase structure different from phase structures of adjacent plating layers.

2 . (canceled)

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

4 . The multilayer zinc alloy plated steel material of claim 1 , wherein grains of the multiple plating layers have an average diameter within a range of 100 nm or less (excluding 0 nm).

5 . The multilayer zinc alloy plated steel material of claim 1 , wherein the sum of plating amounts of the multiple plating layers is within a range of 40 g/m 2 or less (excluding 0 g/m 2 ).

6 . (canceled)

7 . 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 changed to a single alloy layer in a weld zone, and the single alloy layer in the weld zone comprises a MgZn 2 alloy phase in an area fraction of 90% or greater (including 100%).

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

9 . The multilayer zinc alloy plated steel material of claim 1 , wherein each of the multiple plating layers is formed by levitating and heating a coating material in a vacuum chamber by electromagnetic force to produce a deposition vapor and inducing and spraying the deposition vapor onto a surface of the base steel material.

10 . The multilayer zinc alloy plated steel material of claim 9 , wherein the levitated coating material has a temperature of 700° C. or greater.

11 . 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 the balance of Fe and inevitable impurities, and
wherein the contents of C, Si, Mn, P, and S contained in the base steel material 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 the content (wt %) of a corresponding element.

12 . (canceled)

13 . The multilayer zinc alloy plated steel material of claim 11 , wherein the base steel material comprises at least one of austenite and retained austenite as a microstructure.

14 . The multilayer zinc alloy plated steel material of claim 1 , wherein the multiple plating layers comprise a first plating layer formed on the base steel material and a second plating layer formed on the first plating layer, the first plating layer comprises a Zn single phase or a Zn single phase and a Zn—Mg alloy phase and has a Mg content within a range of 7 wt % or less, and the second plating layer comprises a Zn—Mg alloy phase.

15 . The multilayer zinc alloy plated steel material of claim 14 , wherein the first or second plating layer further comprises an additional alloy phase other than a Zn single phase, a Mg single phase, and a Zn—Mg alloy phase.

16 . The multilayer zinc alloy plated steel material of claim 15 , wherein the sum of plating amounts of the first and second plating layers is within a range of 40 g/m 2 or less (excluding 0 g/m 2 ), and the plating amount of the first plating layer is within a range of 3 g/m 2 or greater.

17 . The multilayer zinc alloy plated steel material of claim 15 , wherein the first plating layer is a Zn—Mg alloy plating layer and has a composite phase comprising a Zn single phase and a Mg 2 Zn 11 alloy phase.

18 . (canceled)

19 . The multilayer zinc alloy plated steel material of claim 1 , wherein the multiple plating layers comprise a first plating layer formed on the base steel material and a second plating layer formed on the first plating layer, the first plating layer comprises a Zn—Mg alloy phase, and the second plating layer comprises a Zn single phase or a Zn single phase and a Zn—Mg alloy phase and has a Mg content within a range of 2 wt % or less.

20 . The multilayer zinc alloy plated steel material of claim 19 , wherein the first or second plating layer further comprises an additional alloy phase other than a Zn single phase, a Mg single phase, and a Zn—Mg alloy phase.

21 . The multilayer zinc alloy plated steel material of claim 19 , wherein the sum of plating amounts of the first and second plating layers is within a range of 40 g/m 2 or less (excluding 0 g/m 2 ), and the plating amount of the second plating layer is within a range of 2 g/m 2 or greater.

22 . The multilayer zinc alloy plated steel material of claim 1 , wherein the multiple plating layers comprise first to third plating layers sequentially formed on the base steel material, the first plating layer comprises a Zn single phase or a Zn single phase and a Zn—Mg alloy phase and has a Mg content within a range of 7 wt % or less, the second plating layer comprises a Zn—Mg alloy phase, and the third plating layer comprises a Zn single phase or a Zn single phase and a Zn—Mg alloy phase and has a Mg content within a range of 2 wt % or less.

23 . The multilayer zinc alloy plated steel material of claim 22 , wherein at least one of the first to third plating layers further comprises an additional alloy phase other than a Zn single phase, a Mg single phase, and a Zn—Mg alloy phase.

24 . The multilayer zinc alloy plated steel material of claim 22 , wherein the sum of plating amounts of the first to third plating layers is within a range of 40 g/m 2 or less (excluding 0 g/m 2 ), the plating amount of the first plating layer is within a range of 3 g/m 2 or greater, and the plating amount of the third plating layer is within a range of 2 g/m 2 or greater.

25 . (canceled)

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

• C23C28/025

  with at least one zinc-based layer · CPC title

• C22C18/00

  Alloys based on zinc · CPC title

• C23C14/24

  Vacuum evaporation · CPC title

• C23C30/00

  Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process (C23C26/00, C23C28/00 take precedence) · CPC title