Iron-aluminum-based plated steel sheet for hot press forming, having excellent hydrogen delayed fracture properties and spot welding properties, and manufacturing method therefor

Abstract

The present invention provides an iron-aluminum-based plated steel sheet, and a manufacturing method therefor, the iron-aluminum-based plated steel sheet comprising a base steel sheet and a plated layer formed on the surface of the base steel sheet, wherein the alloy plated layer comprises: a diffusion layer comprising an Fe—Al-based intermetallic compound having a cubic structure; and an alloyed layer formed on the diffusion layer and composed of an alloy phase differing from that of the cubic structure, the thickness of the diffusion layer is 3-20 μm, and the thickness of the diffusion layer is greater than 50% of the total thickness of the plated layer.

1 . A method of manufacturing an iron-aluminum-based plated steel sheet for hot press forming, the method comprising:
 preparing a base steel sheet;   obtaining an aluminum plated steel sheet through dipping the base steel sheet in an aluminum plating bath including, by wt %, 0.0001% to 7% of silicon (Si), 1.1% to 15% of magnesium (Mg), a balance of aluminum (Al), and other inevitable impurities to plate the base steel sheet with a coating amount of 10 to 40 g/m 2  per side; and   obtaining an iron-aluminum-based plated steel sheet through online alloying of performing a heat treatment by maintaining the aluminum plated steel sheet for 1 to 20 seconds within a heating temperature range of 670° C. to 900° C. after the plating.   
     
     
         2 . The method of  claim 1 , further comprising spraying aluminum powder particles onto a surface of the aluminum plated steel sheet, after obtaining the aluminum plated steel sheet. 
     
     
         3 . The method of  claim 2 , wherein an average particle diameter of the aluminum powder particles is 5 μm to 40 μm. 
     
     
         4 . The method of  claim 1 , wherein the base steel sheet includes, by wt %, 0.04% to 0.5% of carbon (C), 0.01% to 2% of silicon (Si), 0.01% to 10% of manganese (Mn), 0.001% to 1.0% of aluminum (Al), 0.05% or less of phosphorus (P), 0.02% or less of sulfur (S), 0.02% or less of nitrogen (N), a balance of iron (Fe), and other inevitable impurities. 
     
     
         5 . The method of  claim 4 , wherein the base steel sheet further includes, by wt %, one or more of 0.01% to 4.0% of the sum of one or more selected from the group consisting of chromium (Cr), molybdenum (Mo), and tungsten (W), 0.001% to 0.4% of the sum of one or more selected from the group consisting of titanium (Ti), niobium (Nb), zirconium (Zr), and vanadium (V), 0.005% to 2.0% of copper (Cu)+nickel (Ni), 0.001% to 1.0% of antimony (Sb)+tin (Sn), and 0.0001% to 0.01% of boron (B).