HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET AND MANUFACTURING METHOD THEREFOR

Title:

HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET AND MANUFACTURING METHOD THEREFOR

Document Type and Number:

WIPO Patent Application WO/2010/087529

Kind Code:

A1

Abstract:

Provided are a high-strength hot-dip galvanized steel sheet that requires no addition of large amounts of Mo, Cr or other expensive elements or any special CGL heat history, and has low YP, high BH, excellent aging resistance and excellent corrosion resistance, and a manufacturing method therefor. The steel includes, by mass%, C: more than 0.015% and less than 0.100%, Si: 0.3% or less, Mn: less than 1.90%, P: 0.15‑0.05%, S: 0.03% or less, sol. Al: 0.01‑0.5%, N: 0.005% or less, Cr: less than 0.30%, B: 0.0003‑0.005%, and Ti: less than 0.014%, where 2.2 ≦ [Mneq] ≦ 3.1 and 0.42 ≦ 8[%P] + 150B* ≦ 0.73 are satisfied. The steel structure has ferrite and a second phase. The surface area ratio of the second phase is 3-15%, the ratio of martensite and residual γ surface area ratio to the second phase surface area ratio is more than 70%, and the ratio of the surface area ratio present at the grain boundary triple points, of the second phase surface area ratio, is 50% or more.

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Inventors:

ONO YOSHIHIKO (JP)
TAKAHASHI KENJI (JP)
OKUDA KANEHARU (JP)
TAIRA SHOICHIRO (JP)

Application Number:

PCT/JP2010/051737

Publication Date:

August 05, 2010

Filing Date:

February 02, 2010

Export Citation:

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Assignee:

JFE STEEL CORP (JP)
ONO YOSHIHIKO (JP)
TAKAHASHI KENJI (JP)
OKUDA KANEHARU (JP)
TAIRA SHOICHIRO (JP)

International Classes:

C22C38/00; C21D9/46; C22C38/38; C22C38/60; C23C2/06; C23C2/28

Domestic Patent References:

WO2009008551A1

2009-01-15

Foreign References:

JP2001207237A	2001-07-31
JPH10330903A	1998-12-15
JPS6240405A	1987-02-21
JP2005008904A	2005-01-13
JP2005029867A	2005-02-03
JP2008019502A	2008-01-31
JP2007211338A	2007-08-23
JP2006233294A	2006-09-07

Other References: