Austenitic, lightweight, high-strength steel sheet having high yield ratio and ductility, and method for producing the same

Patent metadata

Field	Value
Publication number	US-9738958-B2
Application number	US-201113993452-A
Country	US
Kind code	B2
Filing date	Dec 12, 2011
Priority date	Dec 13, 2010
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

Provided is an austenitic, lightweight, high-strength steel sheet having a high yield ratio and ductility and a method for producing the same, and more particularly, to a high-strength steel sheet for automotive interior panels, exterior panels, and structural parts, and a method for producing the steel sheet. The steel sheet may be a hot-rolled steel sheet, a cold-rolled steel sheet, or a plated steel sheet. The steel sheet includes, by weight %, C: 0.6% to 1.0%, Si: 0.1% to 2.5%, Mn: 10% to 15%, P: 0.02% or less, S: 0.015% or less, Al: 5% to 8%, Ti: 0.01% to 0.20%, N: 0.02% or less, and the balance of Fe and inevitable impurities, wherein the steel sheet has a specific gravity of 7.4 g/cm 3 and a Mn/Al ratio of 2 to 3.

First claim

The invention claimed is:

1. An austenitic, lightweight, high-strength steel sheet having a high yield ratio and ductility, the steel sheet comprising, by weight %, C: 0.6% to 1.0%, Si: 0.1% to 2.5%, Mn: 10% to 14.8%, P: 0.02% or less, S: 0.015% or less, Al: 5% to 8%, Ti:0.01% to 0.20%, N: 0.02% or less, Ca: 0.001% to 0.02%, and the balance of Fe and inevitable impurities, wherein the steel sheet has a specific gravity of 7.4 g/cm 3 , a Mn/Al ratio of 2 to 3, and a single-phase austenite microstructure, and wherein the steel sheet has a yield ratio of 60% or more.

2. The steel sheet of claim 1 , wherein the steel sheet is one of a hot-rolled steel sheet, a cold-rolled steel sheet, and a plated steel sheet.

3. The steel sheet of claim 2 , further comprising at least one selected from the group consisting of Cr: 0.1% to 3.0%, Ni: 0.05% to 2.0%, Cu: 0.1% to 2.0%, and Mo: 0.05% to 0.5%.

4. The steel sheet of claim 2 , further comprising at least one selected from the group consisting of V: 0.005% to 0.5%, Nb: 0.005% to 0.2%, Zr: 0.005% to 0.2%, and B: 0.0005% to 0.0030%.

5. The steel sheet of claim 2 , further comprising Sb: 0.005% to 0.2%.

6. The steel sheet of claim 2 , wherein the steel sheet has a tensile strength of 800 MPa to 1200 MPa and elongation of 30% or more.

7. The steel sheet of claim 4 , further comprising Sb: 0.005% to 0.2%.

8. The steel sheet of claim 3 , further comprising Sb: 0.005% to 0.2%.

9. The steel sheet of claim 3 , further comprising at least one selected from the group consisting of V: 0.005% to 0.5%, Nb: 0.005% to 0.2%, Zr: 0.005% to 0.2%, and B: 0.0005% to 0.0030%.

10. The steel sheet of claim 9 , further comprising Sb: 0.005% to 0.2%.

11. The steel sheet of claim 1 , wherein the steel sheet has a tensile strength of 800 MPa to 1200 MPa and elongation of 30% or more.

Assignees

• Chin Kwang-Geun
• Han Sang-Ho
• Kwak Jai-Hyun
• Posco

Inventors

• Chin Kwang-Geun
• Han Sang-Ho
• Kwak Jai-Hyun

Classifications

• C21D8/02

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

• C22C38/28

  with titanium or zirconium · CPC title

• C21D8/0247

  characterised by the heat treatment · CPC title

• C22C38/001

  containing N · CPC title

• C23C2/28

  Thermal after-treatment, e.g. treatment in oil bath · CPC title