| 摘要 |
Provided is a hot dip galvanized steel plate having a hot dip galvanized layer on the surface of a base material steel plate. The base material steel plate contains 0.1 to less than 0.40% C, 0.5 to 3.0% Si, 1.5 to 3.0% Mn by mass, the quantity of O is limited to 0.006% or less, quantity of P to 0.04% or less, quantity of S to 0.01% or less, quantity of Al to 2.0% or less and quantity of N to 0.01% or less by mass, with the remainder consisting of iron and unavoidable impurities. The microstructure of the base material steel plate contains 40% or more ferrite, 8 to less than 60% residual austenite, in volume fraction, with the remainder consisting of bainite or martensite. In a plate thickness range of 5/8 to 3/8 from the surface of the base material steel plate, the polar density of specific crystal orientation is within a predetermined range. The hot dip galvanized layer contains less than 7% by mass Fe with the remainder consisting of Zn, Al and unavoidable impurities. Thus, the high-strength hot dip galvanized steel plate of the invention has excellent moldability, weak material anisotropy and an ultimate tensile strength of 980 MPa or more. |
