Cold-rolled steel plate for hot forming, having excellent corrosion-resistance and spot-weldability, hot-formed member, and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-12467111-B2
Application number	US-202418666200-A
Country	US
Kind code	B2
Filing date	May 16, 2024
Priority date	Sep 26, 2016
Publication date	Nov 11, 2025
Grant date	Nov 11, 2025

Abstract

An aspect of the present invention relates to a cold-rolled steel plate for hot forming, which is excellent in corrosion-resistance and spot-weldability, contains, by weight %, C: 0.1-0.4%, Si: 0.5-2.0%, Mn: 0.01-4.0%, Al: 0.001-0.4%, P: 0.001-0.05%, S: 0.0001-0.02%, Cr: 0.5% to less than 3.0%, N: 0.001-0.02%, and a balance of Fe and inevitable impurities, satisfying formula (1) below, and includes an Si amorphous oxidation layer continuously or discontinuously formed at a thickness of 1 nm-100 nm on the surface thereof. Formula (1): 1.4≤ 0.4*Cr+Si≤3.2 (wherein element symbols denote measurements of respective element contents by weight %).

First claim

The invention claimed is:

1 . A hot-formed product, comprising:
a base steel; a first oxide layer comprising Si on the base steel; and a second oxide layer comprising Fe on the first oxide layer; wherein a first thickness of the first oxide layer is smaller than a first thickness of the second oxide layer.

2 . The hot-formed product of claim 1 ,
wherein the first oxide layer comprises Mn.

3 . The hot-formed product of claim 1 ,
wherein the first oxide layer comprises Cr.

4 . The hot-formed product of claim 1 ,
wherein the first oxide layer comprises Fe.

5 . The hot-formed product of claim 1 ,
wherein the second oxide layer comprises Mn.

6 . The hot-formed product of claim 1 ,
wherein the second oxide layer comprises Cr.

7 . The hot-formed product of claim 1 ,
wherein the second oxide layer comprises Si.

8 . The hot-formed product of claim 1 ,
wherein the first thickness of the first oxide layer is smaller than a second thickness of the first oxide layer.

9 . The hot-formed product of claim 1 ,
wherein the first thickness of the second oxide layer is smaller than a second thickness of the second oxide layer.

10 . The hot-formed product of claim 1 ,
wherein an amount of Cr of the first oxide layer is greater than an amount of Cr of the second oxide layer.

11 . A hot-formed product, comprising:
a base steel; a first oxide layer comprising Si on the base steel; and a second oxide layer comprising Fe on the first oxide layer; wherein the first oxide layer is continuously or discontinuously formed on the base steel.

12 . The hot-formed product of claim 11 ,
wherein the first oxide layer comprises Mn.

13 . The hot-formed product of claim 11 ,
wherein the first oxide layer comprises Cr.

14 . The hot-formed product of claim 11 ,
wherein the first oxide layer comprises Fe.

15 . The hot-formed product of claim 11 ,
wherein the second oxide layer comprises Mn.

16 . The hot-formed product of claim 11 ,
wherein the second oxide layer comprises Cr.

17 . The hot-formed product of claim 11 ,
wherein the second oxide layer comprises Si.

18 . The hot-formed product of claim 11 ,
wherein a first thickness of the first oxide layer is smaller than a second thickness of the first oxide region.

19 . The hot-formed product of claim 11 ,
wherein a first thickness of the second oxide layer is smaller than a second thickness of the second oxide region.

20 . The hot-formed product of claim 11 ,
wherein an amount of Cr of the first oxide layer is greater than an amount of Cr of the second oxide region.

Assignees

• Posco Co Ltd

Inventors

• Oh Jin-Keun
• Cho Yeol-Rae
• Cho A-Ra
• Cha Jin-Ho
• Heo Si-Myoung
• Seo Jeong-Won
• Kim Seong-Woo

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C22C38/54

  with boron · CPC title

• C22C38/50

  with titanium or zirconium · CPC title

• C22C38/26

  with niobium or tantalum · CPC title

• C22C38/24

  with vanadium · CPC title