Patent ID: 9181598
Filing Date: 2015-11-10
Classification: B21B,B32B,C21D,C22C,C23C,Y10T

Abstract:
1. An alloyed hot-dip galvanized steel sheet, which is a steel sheet comprising, in mass %, C: from 0.10 to 0.4%, Si: from 0.01 to 0.5%, Mn: from 1.0 to 3.0%, O: 0.006% or less, P: 0.04% or less, S: 0.01% or less, Al: from 0.1 to 3.0%, and N: 0.01% or less, with the balance being Fe and unavoidable impurities, wherein the structure of the steel sheet further comprises, in terms of volume fraction, 40% or more of the total content of bainite and martensite, from 8 to 60% of retained austenite, and less than 40% of ferrite, with the balance being an unavoidable structure, and alloying hot-dip galvanization is applied to the steel sheet surface; the alloyed hot-dip galvanized layer contains a Γ1 layer; a total thickness of the thickness Tγ1 of the Γ1 layer and the thickness Tγ of a Γ layer in the alloyed hot-dip galvanized layer is 2 μm or less and the ratio (Tγ1/Tγ) of thickness between a Γ1 phase and a Γ phase is 1 or less; the alloyed hot-dip galvanized layer contains a ζ layer and a δ layer; and the ratio {(Tζ+Tδ)/(Tγ1+Tγ)} of the total thickness of thickness Tζ of the ζ layer and thickness Tδ of the δ layer in the alloyed hot-dip galvanized layer to the total thickness of the Γ1 layer and the Γ layer is from 1.5 to 90.