High-strength steel sheet and manufacturing method therefor

Patent metadata

Field	Value
Publication number	US-2016145706-A1
Application number	US-201414392119-A
Country	US
Kind code	A1
Filing date	Jun 27, 2014
Priority date	Jun 27, 2013
Publication date	May 26, 2016
Grant date	—

Abstract

A high-strength steel sheet according to the present invention comprises, by weight, 10.0-15.0% Mn, 6.0-9.0% Al, 0.5-2.0% Cr, 0.8-1.6% C, and 0.001-0.01% N, and further comprises, by weight, 0.02-0.1% V, 0.005-0.015% Nb, and 0.005-0.02% Mo, or further comprises 0.1-0.5 wt % TiAl particles. The high-strength steel sheet has a mixed structure comprising austenite and a fine k-carbide having a mean particle diameter of 10-500 nm.

First claim

1 . A high-strength steel sheet comprising, by weight, 10.0-15.0% manganese (Mn), 6.0-9.0% aluminum (Al), 0.5-2.0% chromium (Cr), 0.8-1.6% carbon (C), 0.001-0.01% nitrogen (N), 0.02-0.1% vanadium (V), 0.005-0.015% niobium (Nb), and 0.005-0.02% molybdenum (Mo), with the remainder being iron (Fe) and inevitable impurities, and the steel sheet having a mixed structure comprising austenite and a fine k-carbide ((Fe,Mn) 3 AlC) having a mean grain size of 10-500 nm.

2 . The high-strength steel sheet of claim 1 , wherein a density of the high-strength steel sheet is 7.1 g/cm 3 or lower.

3 . The high-strength steel sheet of claim 1 , wherein the high-strength steel sheet is a cold-rolled steel sheet, the high-strength steel sheet having a tensile strength of 1000 MPa or higher and an elongation of 20% or higher.

4 . The high-strength steel sheet of claim 1 , further comprising, by weight, 11.0-13.0% manganese (Mn), 6.0-7.5% aluminum (Al), 1.0-2.0% chromium (Cr), and 1.0-1.2% carbon (C).

5 . A high-strength steel sheet comprising, by weight, 10.0-15.0% manganese (Mn), 6.0-9.0% aluminum (Al), 0.5-2.0% chromium (Cr), 0.8-1.6% carbon (C), 0.001-0.01% nitrogen (N), and 0.1-0.5% TiAl particles, with the remainder being iron (Fe) and inevitable impurities, the steel sheet having a mixed structure comprising austenite and a fine k-carbide ((Fe,Mn) 3 AlC) having a mean grain size of 10-500 nm.

6 . The high-strength steel sheet of claim 5 , wherein the high-strength steel sheet has a density of 7.1 g/cm 3 or lower.

7 . The high-strength steel sheet of claim 5 , wherein the high-strength steel sheet is a hot-rolled steel sheet, the high-strength steel sheet having a tensile strength of 1200 MPa or higher and a product of tensile strength and elongation being 35,000 MPa-% or higher.

8 . The high-strength steel sheet of claim 5 , further comprising, by weight, 11.0-13.0% manganese (Mn), 6.0-7.5% aluminum (Al), 1.0-2.0% chromium (Cr), and 1.0-1.2% carbon (C).

9 . A method for producing a high-strength steel sheet, comprising:
hot-rolling a steel slab comprising, by weight, 10.0-15.0% manganese (Mn), 6.0-9.0% aluminum (Al), 0.5-2.0% chromium (Cr), 0.8-1.6% carbon (C), 0.001-0.01% nitrogen (N), 0.02-0.1% vanadium (V), 0.005-0.015% niobium (Nb), and 0.005-0.02% molybdenum (Mo), with the remainder being iron (Fe) and inevitable impurities, at a finish-rolling temperature equal to or higher than an Ar3 point of the steel slab to obtain hot-rolled steel sheet; and coiling the hot-rolled steel sheet at a temperature between 300° C. and 700° C.

10 . The method of claim 9 , further comprising:
cold-rolling the hot-rolled steel sheet to obtain a cold-rolled steel sheet; and annealing the cold-rolled steel sheet at an austenite single-phase region temperature equal to or higher than the Ac3 point for about 100 to 300 seconds.

11 . A method for producing a high-strength steel sheet, comprising:
hot-rolling a steel slab comprising, by weight, 10.0-15.0% manganese (Mn), 6.0-9.0% aluminum (Al), 0.5-2.0% chromium (Cr), 0.8-1.6% carbon (C), 0.001-0.01% nitrogen (N), and 0.1-0.5% TiAl particles, with the remainder being iron (Fe) and inevitable impurities, at a finish-rolling temperature equal to or higher than an Ar3 point of the steel slab to obtain hot-rolled steel sheet; and coiling the hot-rolled steel sheet at a temperature between 300° C. and 700° C.

Assignees

• Hyundai Steel Co

Inventors

• Chung Jun Ho
• Kim Seong-Ju
• Shin Hyo Dong

Classifications

• C21D8/02

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

• C22C38/26

  with niobium or tantalum · CPC title

• C22C38/24

  with vanadium · CPC title

• C22C38/22

  with molybdenum or tungsten · CPC title

• C22C38/001

  containing N · CPC title