The hot-rolled coated steel sheet comprising: in wt %, C: 0.05-0.14%, Si: 0.1-1.0%, Mn: 1.0-2.0%, P: 0.001-0.05%, S: 0.001-0.01%, AI: 0.01-0.1%, Cr: 0.005-1.0%, Ti: 0.005-0.13%, Nb: 0.005-0.03%, N: 0.001-0.01%, Fe residues, and other inevitable impurities; a mixed structure of ferrite and bainite as a main phase; and as a remaining structure, one or more selected from the group consisting of martensite, austenite, and phase martensite (MA), wherein a fraction of the ferrite and bainite is 95-99 area % and Equation 1 is satisfied. [Equation 1] FCO.sub.{110}<112>+FCO.sub.{112}<111>≥10 where, FCO.sub.{110}<112> and FCO.sub.{112}<111>, each representing an area fraction occupied by a structure having ac crystal orientation of {110}<112> and {112}<111>.

The present disclosure provides a hot-press formed part comprising a plated steel sheet and an aluminum alloy plated layer formed on the plated steel sheet, wherein the aluminum alloy plated layer comprises: an alloying layer (I) formed on the plated steel sheet and containing, by weight %, 5-30% of Al; an alloying layer (II) formed on the alloying layer (I) and containing, by weight %, 30 to 60% of Al; an alloying layer (III) formed on the alloying layer (II) and containing, by weight %, 20-50% of Al and 5-20% of Si; and an alloying layer (IV) formed continuously or discontinuously on at least a part of the surface of the alloying layer (III), and containing 30-60% of Al, wherein the rate of the alloying layer (III) exposed on the outermost surface of the aluminum alloy plated layer is 10% or more.

This manufacturing method of a hot press-formed article includes a heating step of heating an Al-plated steel sheet and a forming step of obtaining a hot press-formed article using a die after the heating step, the Al-plated steel sheet has a base steel sheet, an Al plating layer, and a coating layer, the coating layer is a metal layer containing at least one metal of Mg, Ca, V, Ti, and Zn, a metal oxide layer containing an oxide of one or more of Mg, Ca, V, Ti, and Zn, or a mixed layer including the metal layer and the metal oxide layer, the die has a hard layer on a surface, HV.sub.Die that is a surface hardness of the die at a position of the hard layer is HV1500 or more and HV3800 or less, and a temperature Tm of the Al-plated steel sheet at a start of forming and an average movement velocity V of the die in the forming step satisfy 800−(HV.sub.Die/40)≤Tm≤850−(V/4)−(HV.sub.Die/100).

A hardened part coated with a phosphatable coating is provided. The part is made by a method that includes providing a steel sheet pre-coated with a metallic coating including from 4.0 to 20.0% by weight of zinc, from 1.0 to 3.5% by weight of silicon, optionally from 1.0 to 4.0% by weight of magnesium, and optionally additional elements chosen from Pb, Ni, Zr, or Hf, the content by weight of each additional element being less than 0.3% by weight, the balance being aluminum and unavoidable impurities and residuals elements. The steel sheet is cut to obtain a blank, the blank is thermally treated at a temperature between 840 and 950° C. to obtain a fully austenitic microstructure in the steel, the blank is transferred into a press tool and hot-formed to obtain a part. The part is cooled to obtain a martensitic or martensitic-bainitic microstructure or made of at least 75% of equiaxed ferrite, from 5 to 20% of martensite and bainite in amount less than or equal to 10%.

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.

A hot-dip galvanized steel sheet wherein the hot-dip galvanized steel sheet comprises a base steel sheet and a hot-dip galvanized layer, a ferrite phase is, by volume fraction, 50% or less in a range of ⅛ thickness to ⅜ thickness centered at a position of ¼ thickness from the surface of the base steel sheet, a hard structure is 50% or more, wherein the hot-dip galvanized steel sheet has the hot-dip galvanized layer in which Fe is 5.0% or less and Al is 1.0% or less, and columnar grains formed of a ζ phase is 20% or more in an entire interface between the plated layer and the base steel sheet, on the surface of the base steel sheet in which a volume fraction of a residual austenite is 3% or less and a ratio of a volume fraction of the hard structure is 0.10 times or more to 0.90 times or less of that of the hard structure in the range of ⅛ thickness to ⅜ thickness in a range of 20 μm depth in a steel sheet direction originating an interface between the hot-dip galvanized layer and the base steel sheet, and wherein the hot-dip galvanized steel sheet has a refined layer at the side of the interface in the base steel sheet, and wherein an average thickness of the refined layer, an average grain size of ferrite in the refined layer and a maximum size of the oxide included in the refined layer are defined respectively.

The present invention relates to a steel sheet for a hot press formed member having excellent coating adhesion, and a method for manufacturing the same. A steel sheet for hot press forming according to one aspect of the present invention is an aluminum alloy plated steel sheet, wherein an average Fe content in a plating layer may be 40 wt % or more, and a concentration gradient of a section having a Fe content of 45 wt % to 80 wt % in the plating layer may 7 wt %/μm or less of a concentration gradient at a section having an Fe content of 45% to 80% in the plating layer in a thickness direction from a surface of the plating layer according to a result of GDS analysis.

The present invention relates to a steel sheet for a hot press formed member having excellent coating adhesion, and a method for manufacturing the same. A steel sheet for hot press forming according to one aspect of the present invention is an aluminum alloy plated steel sheet, wherein an average Fe content in a plating layer may be 40 wt % or more, and a concentration gradient of a section having a Fe content of 45 wt % to 80 wt % in the plating layer may 7 wt %/μm or less of a concentration gradient at a section having an Fe content of 45% to 80% in the plating layer in a thickness direction from a surface of the plating layer according to a result of GDS analysis.

The present invention relates to a molten metal plated steel sheet manufacturing method for cooling a molten galvanized layer with high efficiency when manufacturing a molten galvanized steel sheet, and the purpose of the present invention is to provide a method for manufacturing a molten galvanized plating, wherein a molten galvanized steel sheet having an aesthetically pleasing surface without fitting defects, drop mark defects, and linear comb-pattern defects can be stably obtained by cooling a galvanized layer with high efficiency during a molten metal plated steel sheet manufacturing process. This method for manufacturing a molten galvanized steel sheet having excellent surface properties is characterized by comprising the steps in which a molten galvanized layer is formed on the surface of a steel sheet while the steel sheet passes through a galvanizing pot, the thickness of the galvanized layer formed on the surface of the steel sheet is adjusted while the steel sheet passes through a gas wiping device, the steel sheet that has had the thickness of the galvanized layer adjusted undergoes a primary cooling while passing through a bottom cooler, and the galvanized steel sheet that has undergone the primary cooling undergoes a secondary cooling while passing through a cooling chamber, wherein: the primary cooling is performed with cooling air blown from the bottom cooler until right before a galvanizing solution of the galvanized layer attached to the surface of the steel sheet becomes solidified, the amount of air blown being adjusted according to the temperature of the galvanized layer attached to the surface of the steel sheet; and the secondary cooling is performed with ionic air generated from an ionic air generator provided in the cooling chamber and a spray solution sprayed from a solution atomization part, the secondary cooling being performed from the start of the solidification of the galvanizing solution until the end of the solidification, and the cooling chamber cooling the galvanized steel sheet while moving up and down according to the temperature of the galvanized layer attached to the surface of the galvanized steel sheet.

The present invention relates to a molten metal plated steel sheet manufacturing method for cooling a molten galvanized layer with high efficiency when manufacturing a molten galvanized steel sheet, and the purpose of the present invention is to provide a method for manufacturing a molten galvanized plating, wherein a molten galvanized steel sheet having an aesthetically pleasing surface without fitting defects, drop mark defects, and linear comb-pattern defects can be stably obtained by cooling a galvanized layer with high efficiency during a molten metal plated steel sheet manufacturing process. This method for manufacturing a molten galvanized steel sheet having excellent surface properties is characterized by comprising the steps in which a molten galvanized layer is formed on the surface of a steel sheet while the steel sheet passes through a galvanizing pot, the thickness of the galvanized layer formed on the surface of the steel sheet is adjusted while the steel sheet passes through a gas wiping device, the steel sheet that has had the thickness of the galvanized layer adjusted undergoes a primary cooling while passing through a bottom cooler, and the galvanized steel sheet that has undergone the primary cooling undergoes a secondary cooling while passing through a cooling chamber, wherein: the primary cooling is performed with cooling air blown from the bottom cooler until right before a galvanizing solution of the galvanized layer attached to the surface of the steel sheet becomes solidified, the amount of air blown being adjusted according to the temperature of the galvanized layer attached to the surface of the steel sheet; and the secondary cooling is performed with ionic air generated from an ionic air generator provided in the cooling chamber and a spray solution sprayed from a solution atomization part, the secondary cooling being performed from the start of the solidification of the galvanizing solution until the end of the solidification, and the cooling chamber cooling the galvanized steel sheet while moving up and down according to the temperature of the galvanized layer attached to the surface of the galvanized steel sheet.