HOT DIP GALVANIZED STEEL SHEET OR HOT DIP GALVANNEALED STEEL SHEET HAVING TENSILE STRENGTH OF 1,180 MPa OR HIGHER AND EXCELLENT IN BALANCE OF STRENGTH-BENDABILITY

Japanese Patent JP2014237887

A

PROBLEM TO BE SOLVED: To provide a hot dip galvanized steel sheet having a tensile strength of 1,180 MPa or higher, and also, excellent in a balance of strength-bendability that bendability in a bending test by a V block method (critical bend radius/sheet thickness: R/t) satisfies 1.5 or lower.SOLUTION: Provided is a hot dip galvanizd steel sheet or a hot dip galvannealed steel sheet satisfying a prescribed chemical composition, and in which, in the surface layer part of the steel sheet of 5 μm or higher from the boundary between a plating layer and the steel sheet to a depth direction of the mother ground, Zn of 0.2 mass% or higher is solid-soluted, further, the Vickers hardness of the surface layer part of the steel sheet at 15 μm to a depth direction of the mother ground from the boundary between the plating layer and the steel sheet is 80% or lower of the central part of the mother ground, and also, the structure other than martensite and bainite of he steel sheet is 5% or lower by area ratio.

SHIBATA KOSUKE
MURAKAMI TOSHIO
KAJIWARA KATSURA
IKEDA MUNEAKI
NAKAYA MICHIHARU

JP2014043020A

December 18, 2014

March 05, 2014

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KOBE STEEL LTD

C22C38/00; C21D9/46; C22C38/04; C22C38/58

JP2010116593A	2010-05-27
JP2011225975A	2011-11-10
JP2008156734A	2008-07-10
JP2003268518A	2003-09-25
JP2009179852A	2009-08-13

WO2013047820A1

2013-04-04

Yoshimichi Takenaka
Seiji Kameoka
Hironori Takenaka
Toru Sakatani

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