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

Patent metadata

Field	Value
Publication number	US-2018327877-A1
Application number	US-201715800500-A
Country	US
Kind code	A1
Filing date	Nov 1, 2017
Priority date	May 10, 2017
Publication date	Nov 15, 2018
Grant date	—

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.

First claim

What is claimed is:

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, 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.

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 is plated with a plating raw material.

7 . The low-alloy and corrosion-resistant steel of claim 6 , wherein the low-alloy and corrosion-resistant steel has a plating thickness of about 1 μm to about 50 μm.

8 . The low-alloy and corrosion-resistant steel of claim 6 , wherein the plating raw material comprises more than 0 wt % and less than about 3 wt % of Mg and about 5 wt % to about 15 wt % of Si, and the balance Al and inevitable impurities.

9 . The low-alloy and corrosion-resistant steel of claim 8 , wherein an amount of plating raw material plated onto the low-alloy and corrosion-resistant steel is about 10 g/m 2 to about 800 g/m 2 .

10 . 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.

11 . The method of claim 10 , wherein a structure in the hot-rolling step is ferrite pearlite (FP).

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

13 . The method of claim 10 , wherein a hydrochloric acid concentration in the acid pickling step is about 17% or more.

14 . The method of claim 10 , wherein a temperature in the acid pickling step is about 75° C. to about 85° C.

15 . The method of claim 10 , wherein an annealing temperature in the cold-rolling step is about 600° C. to about 860° C.

16 . The method of claim 10 , wherein a heat treatment method in the cold-rolling step is a batch annealing furnace (BAF) or a continuous annealing furnace (CAF).

17 . The method of claim 10 , further comprising: a plating step of plating the low-alloy and corrosion-resistant steel after the cold-rolling step.

18 . The method of claim 17 , wherein a plating temperature in the plating step is about 650° C. to about 670° C.

19 . The method of claim 17 , 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.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp
• Hyundai Steel Co

Inventors

• Choi Jae-Woong
• Yang Won-Seok

Classifications

• C21D8/00 Primary

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• Y10T428/12757

  Fe · CPC title

• C25D3/66

  from melts · CPC title

• C23C2/12

  Aluminium or alloys based thereon · CPC title

• C25D7/04

  Tubes; Rings; Hollow bodies · CPC title