High-strength galvanized steel sheet having excellent formability and crashworthiness

Patent metadata

Field	Value
Publication number	US-9290834-B2
Application number	US-201114349503-A
Country	US
Kind code	B2
Filing date	Oct 7, 2011
Priority date	Oct 7, 2011
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A galvanized steel sheet has a composition containing, by mass %, C: 0.05% or more and 0.5% or less, Si: 0.01% or more and 2.5% or less, Mn: 0.5% or more and 3.5% or less, P: 0.003% or more and 0.100% or less, S: 0.02% or less, Al: 0.010% or more and 0.5% or less, B: 0.0002% or more and 0.005% or less, Ti: 0.05% or less, a relationship of Ti>4N being satisfied, and the balance comprising Fe and inevitable impurities, and a microstructure containing 60% or more and 95% or less of tempered martensite in terms of area ratio and 5% or more and 20% or less of retained austenite in terms of area ratio.

First claim

The invention claimed is:

1. A high-strength galvanized steel sheet having excellent formability and crashworthiness, comprising a substrate and a galvanized layer provided on a surface of the substrate, wherein the substrate has a composition containing, by mass %,
C: 0.05% or more and 0.5% or less, Si: 0.01% or more and 2.5% or less, Mn: 0.5% or more and 3.5% or less, P: 0.003% or more and 0.100% or less, S: 0.02% or less, Al: 0.010% or more and 0.5% or less, B: 0.0002% or more and 0.005% or less, Ti: 0.05% or less, a relationship of Ti>4N being satisfied, and the balance comprising Fe and inevitable impurities, and a microstructure containing 60% or more and 95% or less of tempered martensite in terms of area ratio and 5% or more and 20% or less of retained austenite in terms of area ratio, the tempered martensite having an average grain diameter of 5 μM or less.

2. The high-strength galvanized steel sheet according to claim 1 , wherein the microstructure further contains between 0% and 10% of ferrite in terms of area ratio and/or between 0% and 10% of martensite in terms of area ratio.

3. The high-strength galvanized steel sheet according to claim 2 , wherein the composition further contains at least one selected from the group consisting of, by mass %, Cr: 0.005% or more and 2.00% or less, Mo: 0.005% or more and 2.00% or less, V: 0.005% or more and 2.00% or less, Ni: 0.005% or more and 2.00% or less, and Cu: 0.005% or more and 2.00% or less.

4. The high-strength galvanized steel sheet according to claim 2 , wherein the composition further contains, by mass %, Nb: 0.01% or more and 0.20% or less.

5. The high-strength galvanized steel sheet according to claim 2 , wherein the composition further contains, by mass %, at least one selected from the group consisting of Ca: 0.001% or more and 0.005% or less and REM: 0.001% or more and 0.005% or less.

6. The high-strength galvanized steel sheet according to claim 2 , wherein the galvanized layer is a galvannealed layer.

7. The high-strength galvanized steel sheet according to claim 1 , wherein the composition further contains at least one selected from the group consisting of, by mass %, Cr: 0.005% or more and 2.00% or less, Mo: 0.005% or more and 2.00% or less, V: 0.005% or more and 2.00% or less, Ni: 0.005% or more and 2.00% or less, and Cu: 0.005% or more and 2.00% or less.

8. The high-strength galvanized steel sheet according to claim 3 , wherein the composition further contains, by mass %, Nb: 0.01% or more and 0.20% or less.

9. The high-strength galvanized steel sheet according to claim 7 , wherein the composition further contains, by mass %, at least one selected from the group consisting of Ca: 0.001% or more and 0.005% or less and REM: 0.001% or more and 0.005% or less.

10. The high-strength galvanized steel sheet according to claim 7 , wherein the galvanized layer is a galvannealed layer.

11. The high-strength galvanized steel sheet according to claim 1 , wherein the composition further contains, by mass %, Nb: 0.01% or more and 0.20% or less.

12. The high-strength galvanized steel sheet according to claim 11 , wherein the composition further contains, by mass %, at least one selected from the group consisting of Ca: 0.001% or more and 0.005% or less and REM: 0.001% or more and 0.005% or less.

13. The high-strength galvanized steel sheet according to claim 11 , wherein the galvanized layer is a galvannealed layer.

14. The high-strength galvanized steel sheet according to claim 1 , wherein the composition further contains, by mass %, at least one selected from the group consisting of Ca: 0.001% or more and 0.005% or less and REM: 0.001% or more and 0.005% or less.

15. The high-strength galvanized steel sheet according to claim 14 , wherein the galvanized layer is a galvannealed layer.

16. The high-strength galvanized steel sheet according to claim 1 , wherein the galvanized layer is a galvannealed layer.

Assignees

• Hasegawa Hiroshi
• Nakagaito Tatsuya
• Kaneko Shinjiro
• Nagataki Yasunobu
• Suzuki Yoshitsugu
• Jfe Steel Corp

Inventors

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

Classifications

• C21D8/02

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

• Y10T428/12972

  Containing 0.01-1.7% carbon [i.e., steel] · CPC title

• C22C38/002

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

• C22C38/16

  containing copper · CPC title

• C22C38/12

  containing tungsten, tantalum, molybdenum, vanadium, or niobium · CPC title