Low-alloy and corrosion-resistant steel for vehicle, having improved corrosion resistance under corrosive environment, and preparation method thereof

• US 10,640,839 B2
• Filed: 11/01/2017
• Issued: 05/05/2020
• Est. Priority Date: 05/10/2017
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group), Hyundai Steel Company, Kia Motors Corporation (Kia Corp.)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Inventors: Choi, Jae-Woong, Yang, Won-Seok
• Primary Examiner(s): Schleis, Daniel J.
• Application Number:
  US15/800,500
• Publication Number:
  US 20180327877A1
• Time in Patent Office: 916 Days
• Field of Search: None
• 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 2211/005 Ferrite
• CPC Class Codes: C21D 6/004 containing Cr and Ni
• CPC Class Codes: C21D 6/005 containing Mn
• CPC Class Codes: C21D 6/008 containing Si
• CPC Class Codes: C21D 8/005 of ferrous alloys C21D8/02 - C21D8/12 take precedence
• CPC Class Codes: C22C 21/02 with silicon as the next major constituent
• 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 38/008 containing tin
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/42 with copper
• CPC Class Codes: C22C 38/48 with niobium or tantalum
• CPC Class Codes: C23C 18/1637 metallic substrate
• CPC Class Codes: C23C 18/1692 Heat-treatment
• CPC Class Codes: C23C 18/48 Coating with alloys
• CPC Class Codes: C23C 2/12 Aluminium or alloys based thereon
• CPC Class Codes: C23G 1/08 Iron or steel
• CPC Class Codes: C25D 3/66 from melts
• CPC Class Codes: C25D 7/04 Tubes; Rings; Hollow bodies
• CPC Class Codes: Y10T 428/12757 : Fe

Abstract

A low-alloy and corrosion-resistant steel for a vehicle, may include about 0.001 wt % to about 0.1 wt % of C, about 0.01 wt % to about 0.5 wt % of Si, about 0.1 wt % to about 0.6 wt % of Mn, more than 0 wt % and about 0.18 wt % or less of P, more than 0 wt % and less than about 0.02 wt % of S, about 0.001 wt % to about 0.03 wt % of Nb, more than 0 wt % and about 0.03 wt % or less of Cr, about 0.05 wt % to about 0.3 wt % of Cu, about 0.05 wt % to about 0.2 wt % of Ni, and more than 0 wt % and about 0.2 wt % or less of a combined weight of Sn and Sb, and the balance iron and inevitable impurities.

Claims

1. A low-alloy and corrosion-resistant steel for a vehicle, comprising:

about 0.001 wt % to about 0.1 wt % of C, about 0.01 wt % to about 0.5 wt % of Si, about 0.1 wt % to about 0.6 wt % of Mn, more than 0 wt % and about 0.18 wt % or less of P, more than 0 wt % and less than about 0.02 wt % of S, about 0.001 wt % to about 0.03 wt % of Nb, more than 0 wt % and about 0.03 wt % or less of Cr, about 0.05 wt % to about 0.3 wt % of Cu, about 0.05 wt % to about 0.2 wt % of Ni, about 0.05 wt % to about 0.1 wt % of Sn and about 0.05 wt % to about 0.15 wt % of Sb, and the balance iron and inevitable impurities,

wherein the low-alloy and corrosion-resistant steel includes Cu-Sb layer,

wherein the low-alloy and corrosion-resistant steel is plated with a Al based material, and

wherein the Al based material comprises more than 0 wt % and less than about 3 wt % of Mg, about 5 wt % to about 15 wt % of Si, and the balance Al and inevitable impurities.

2. The low-alloy and corrosion-resistant steel of claim 1, wherein the low-alloy and corrosion-resistant steel has a tensile strength of about 350 MPa to about 450 MPa.

3. The low-alloy and corrosion-resistant steel of claim 1, wherein the low-alloy and corrosion-resistant steel has a yield point of about 200 MPa to about 400 MPa.

4. The low-alloy and corrosion-resistant steel of claim 1, wherein the low-alloy and corrosion-resistant steel has an elongation of about 30% to about 45%.

5. The low-alloy and corrosion-resistant steel of claim 1, wherein a microstructure of the low-alloy and corrosion-resistant steel is ferrite.

6. The low-alloy and corrosion-resistant steel of claim 1, wherein the low-alloy and corrosion-resistant steel has a plating thickness of about 1 μ

m to about 50 μ

m.

7. The low-alloy and corrosion-resistant steel of claim 1, wherein an amount of the Al based material plated onto the low-alloy and corrosion-resistant steel is about 10 g/m² to about 800 g/m².

8. A method for preparing a low-alloy and corrosion-resistant steel for a vehicle, the method comprising:

a hot-rolling step of hot-rolling the low-alloy and corrosion-resistant steel of claim 1;

an acid pickling step of removing iron oxides from the hot-rolled low-alloy and corrosion-resistant steel; and

a cold-rolling step of cold-rolling the acid pickled low-alloy and corrosion-resistant steel.

9. The method of claim 8, wherein a structure in the hot-rolling step is ferrite pearlite (FP).

10. The method of claim 8, wherein a thickness in the hot-rolling step is about 3 mm to about 4 mm.

11. The method of claim 8, wherein a hydrochloric acid concentration in the acid pickling step is about 17% or more.

12. The method of claim 8, wherein a temperature in the acid pickling step is about 75°

C. to about 85°

C.

13. The method of claim 8, wherein an annealing temperature in the cold-rolling step is about 600°

C. to about 860°

C.

14. The method of claim 8, wherein a heat treatment method in the cold-rolling step is a batch annealing furnace (BAF) or a continuous annealing furnace (CAF).

15. The method of claim 8, further comprising:

a plating step of plating the low-alloy and corrosion-resistant steel after the cold-rolling step.

16. The method of claim 15, wherein a plating temperature in the plating step is about 650°

C. to about 670°

C.

17. The method of claim 15, further comprising:

an alloying heat treatment step of heat-treating the plated low-alloy and corrosion-resistant steel at a temperature of about 690°

C. to about 790°

C. after the plating step.