Zinc-plated steel sheet for hot pressing having outstanding surface characteristics, hot-pressed moulded parts obtained using the same, and a production method for the same

摘要

Provided is a zinc-plated steel sheet for hot pressing having outstanding surface characteristics, comprising: a steel foundation plate comprising a metal surface diffusion layer of which the Gibbs free energy reduction per mole of oxygen during oxidation is less than that of Cr; an aluminum-rich layer containing at least 30 wt. % of aluminum formed on the surface diffusion layer, and a zinc plating layer formed on the aluminum-rich layer. In this way, a metal having a low affinity for oxygen is coated to an effective thickness prior to annealing and thus the creation of annealing oxides at the surface of the steel sheet is suppressed and a uniform zinc plating layer is formed, and alloying of the zinc plating layer is promoted during press-processing heat treatment. Cracking in the steel foundation plate during hot press molding is prevented.

主权项

1. A zinc-plated steel sheet for hot pressing having excellent surface characteristics comprising:
a base steel sheet including a metal surface diffusion layer, in which a reduced amount of Gibbs free energy for one mole of oxygen during an oxidation reaction is smaller than that of Cr (chromium), to a depth of about 1 μm from a surface; an Al (aluminum)-rich layer containing about 30 wt % or more of Al formed on the surface diffusion layer of the metal in which a reduced amount of Gibbs free energy for one mole of oxygen during an oxidation reaction is smaller than that of Cr; and a zinc plating layer formed on the Al-rich layer, wherein an annealing oxide having an average thickness of about 150 nm or less is non-uniformly distributed between the surface diffusion layer and the Al-rich layer, and a content of the metal, in which a reduced amount of Gibbs free energy for one mole of oxygen during an oxidation reaction is smaller than that of Cr, to a depth of about 1 μm from the surface of the base steel sheet is about 0.1 wt % or more.