HOT PRESS FORMED ARTICLE HAVING GOOD ANTI-DELAMINATION, AND PREPARATION METHOD FOR SAME

• US 20180142337A1
• Filed: 04/05/2016
• Published: 05/24/2018
• Est. Priority Date: 05/26/2015
• Status: Active Grant

• Current Assignee: POSCO Co. Ltd. (Posco Holdings Incorporated)
• Original Assignee: Posco Holdings Incorporated
• Inventors: KIM, Heung-Yun
• Granted Patent: US 10,655,204 B2
• Time in Patent Office: Days
• CPC Class Codes: B21B 1/38 for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rollingB21B1/40 takes precedence; folding sheets before, or separating layers after, rolling B21B47/00
• CPC Class Codes: B32B 15/012 one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy
• CPC Class Codes: C21D 1/673 for die quenching
• CPC Class Codes: C21D 8/0205 of ferrous alloys
• CPC Class Codes: C21D 8/0273 Final recrystallisation annealing
• CPC Class Codes: C21D 9/46 for sheet metals
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C22C 38/28 with titanium or zirconium
• CPC Class Codes: C22C 38/32 with boron
• CPC Class Codes: C22C 38/38 with more than 1.5% by weight of manganese
• CPC Class Codes: C23C 10/22 Metal melt containing the element to be diffused
• CPC Class Codes: C23C 2/12 Aluminium or alloys based thereon
• CPC Class Codes: C23C 2/20 Strips; Plates
• CPC Class Codes: C23C 2/28 Thermal after-treatment, e.g. treatment in oil bath
• CPC Class Codes: C23C 2/29 Cooling or quenching
• CPC Class Codes: Y10T 428/12757 Fe

Abstract

Provided is a hot press formed article having good anti-delamination and having a hot dip aluminized layer formed on the surface of a base steel sheet. The base steel sheet comprises 0.18-0.25 wt % of C, 0.1-0.5 wt % of Si, 0.9-1.5 wt % of Mn, 0.03 wt % or less of P, 0.01 wt % or less of S, 0.01-0.05 wt % of Al, 0.05-0.5 wt % of Cr, 0.01-0.05 wt % of Ti, 0.001-0.005 wt % of B, 0.009 wt % or less of N and the balance of Fe and other impurities. The aluminized layer comprises a single soft diffusion layer comprising α-Fe with solid-solubilized Al, and the hardness of the diffusion layer is 300-600 (Hv).

Claims

1. A hot press formed (HPF) article, having good delamination resistance and having a hot-dip aluminum plated layer formed on a surface of a base steel sheet,

wherein the base steel sheet comprises carbon (C):

0.18 wt % to 0.25 wt %, silicon (Si);

0.1 wt % to 0.5 wt %, manganese (Mn);

0.9 wt % to 1.5 wt %, phosphorous (P);

0.03 wt % or less, sulfur (S);

0.01 wt % or less, aluminum (Al);

0.01 wt % to 0.05 wt %, chromium (Cr);

0.05 wt % to 0.5 wt %, titanium (Ti);

0.01 wt % to 0.05 wt %, boron (B);

0.001 wt % to 0.005 wt %, nitrogen (N);

0.009 wt % or less, a balance of iron (Fe) and other impurities;

the plated layer only comprises a single soft diffusion layer comprising α

-Fe with solid-solubilized Al; and

hardness of the diffusion layer is 300 (Hv) to 600 (Hv).

2. The hot press formed article having good delamination resistance of claim 1, wherein a thickness of the diffusion layer is within a range of 2 μ

m to 40 μ

m.

3. The hot press formed article having good delamination resistance of claim 2, wherein the thickness of the diffusion layer is within a range of 2 μ

m to 10 μ

m.

4. The hot press formed article having good delamination resistance of claim 1, wherein the diffusion layer includes 1.0 wt % to 5.0 wt % of at least one of Si, Mn, or Al based on the diffusion layer.

5. The hot press formed article having good delamination resistance of claim 1, wherein the diffusion layer includes 0.2 wt % to 1.0 wt % of at least one of Cr, molybdenum (Mo), or Ti based on the diffusion layer.

6. A method of manufacturing a hot press formed article having good delamination resistance, comprising:

preparing a steel sheet having the same steel composition as in claim 1;

hot-dip aluminum plating the steel sheet, as the steel sheet is heated at a temperature of 550°

C. to 850°

C. and is maintained at 640°

C. to 680°

C., and the steel sheet is then immersed in a hot-dip aluminum plating bath in which a composition includes Si;

1 wt % to 11 wt %, Fe;

less than 3 wt %, the balance of Al and other impurities;

alloying a hot-dip aluminum plated layer on a surface, as the hot-dip aluminum plated steel sheet is heated at a temperature of 900°

C. to 990°

C. and is maintained for 20 minutes to 30 minutes; and

manufacturing a HPF product by hot forming the hot-dip aluminum plated steel sheet having been alloyed while quenching the hot-dip aluminum plated steel sheet to a temperature range of 300°

C. or less.

7. The method of manufacturing a hot press formed article having good delamination resistance of claim 6, wherein the plated layer having been alloyed only comprises a single soft diffusion layer comprising α

-Fe with solid-solubilized Al; and

hardness of the diffusion layer is 300 (Hv) to 600 (Hv).

8. The method of manufacturing a hot press formed article having good delamination resistance of claim 7, wherein a thickness of the diffusion layer is within a range of 2 μ

m to 40 μ

m.

9. The method of manufacturing a hot press formed article having good delamination resistance of claim 8, wherein the thickness of the diffusion layer is within a range of 2 μ

m to 10 μ

m.

10. The method of manufacturing a hot press formed article having good delamination resistance of claim 7, wherein the diffusion layer includes 1.0 wt % to 5.0 wt % of at least one of Si, Mn, or Al based on the diffusion layer

11. The method of manufacturing a hot press formed article having good delamination resistance of claim 7, wherein the diffusion layer includes 0.2 wt % to 1.0 wt % of at least one of Cr, Mo, or Ti based on the diffusion layer.