High-strength galvanized steel sheet having excellent formability and crashworthiness and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-2017130293-A1
Application number	US-201715405819-A
Country	US
Kind code	A1
Filing date	Jan 13, 2017
Priority date	Apr 16, 2010
Publication date	May 11, 2017
Grant date	—

Abstract

A galvanized steel sheet has formability and crashworthiness, consists of 0.03% to 0.13% C, 1.0% to 2.0% Si, 2.4% to 3.5% Mn, 0.001% to 0.05% P, 0.0001% to 0.01% S, 0.001% to 0.1% Al, 0.0005% to 0.01% N, and 0.0003% to 0.01% B on a mass basis; and optionally contains at least one selected from the following A-C: A: at least one selected from the group consisting of 0.0005% to 0.1% Ti and 0.0005% to 0.05% Nb on a mass basis; B: at least one selected from the group consisting of 0.01% to 1.0% Mo, 0.01% to 2.0% Ni, and 0.01% to 2.0% Cu on a mass basis; and C: 0.001% to 0.005% Ca on a mass basis; the remainder being Fe and unavoidable impurities, and a microstructure containing a tempered martensitic phase and a bainitic phase such that the sum of an area fraction of the tempered martensitic phase and an area fraction of the bainitic phase is 30% or more, the area fraction of the tempered martensitic phase is 30% or more in the absence of the bainitic phase, wherein a distance of closest approach of the tempered martensitic phase is 10 μm or less and contents of C, Mn, and B satisfy (1):
(% Mn)+1000×(% B)≧35×(% C)  ( 1 ).

First claim

What is claimed is:

1 . A galvanized steel sheet having formability and crashworthiness, consisting of 0.03% to 0.13% C, 1.0% to 2.0% Si, 2.4% to 3.5% Mn, 0.001% to 0.05% P, 0.0001% to 0.01% S, 0.001% to 0.1% Al, 0.0005% to 0.01% N, and 0.0003% to 0.01% B on a mass basis; and optionally containing at least one selected from the following A-C:
A: at least one selected from the group consisting of 0.0005% to 0.1% Ti and 0.0005% to 0.05% Nb on a mass basis; B: at least one selected from the group consisting of 0.01% to 1.0% Mo, 0.01% to 2.0% Ni, and 0.01% to 2.0% Cu on a mass basis; and C: 0.001% to 0.005% Ca on a mass basis; the remainder being Fe and unavoidable impurities, and a microstructure containing a tempered martensitic phase and a bainitic phase such that the sum of an area fraction of the tempered martensitic phase and an area fraction of the bainitic phase is 30% or more, the area fraction of the tempered martensitic phase is 30% or more in the absence of the bainitic phase, wherein a distance of closest approach of the tempered martensitic phase is 10 μm or less and contents of C, Mn, and B satisfy (1):
(% Mn)+1000×(% B)≧35×(% C)  (1).

2 . The galvanized steel sheet according to claim 1 , wherein average grain diameter of the tempered martensitic phase is 2.0 μm or more.

3 . The galvanized steel sheet according to claim 1 , wherein the galvanized steel sheet is a galvannealed steel sheet.

4 . The galvanized steel sheet according to claim 2 , wherein the galvanized steel sheet is a galvannealed steel sheet.

5 . The galvanized steel sheet according to claim 1 , wherein the galvanized steel sheet has a TS of 980 MPa or more.

6 . The galvanized steel sheet according to claim 1 , wherein the galvanized steel sheet satisfies
TS×El≧ 18,000 MPa·%.

7 . The galvanized steel sheet according to claim 1 , wherein the galvanized steel sheet has a λ of 40% or more.

Assignees

• Jfe Steel Corp

Inventors

• Kaneko Shinjiro
• Nakagaito Tatsuya
• Hasegawa Hiroshi
• Nagataki Yasunobu

Classifications

• C22C38/16

  containing copper · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C23C2/40

  Plates; Strips · CPC title

• C21D9/46 Primary

  for sheet metals · CPC title

• C22C38/02

  containing silicon · CPC title