Plated steel sheet for hot press forming having excellent impact resistance, hot press formed part, and manufacturing methods thereof

Abstract

The present invention relates to a plated steel sheet for hot press forming, a hot press formed part, and manufacturing methods thereof and, more specifically, a plated steel sheet for hot press forming having excellent impact resistance, a hot press formed part, and manufacturing methods thereof.

1 - 25 . (canceled) 
     
     
         26 . A part comprising: a base steel comprising, by wt %, 0.06 to 0.5% of carbon (C) and 0.01 to 0.1% of antimony (Sb); and a plating layer formed on a surface of the base steel,
 wherein the base steel comprises an antimony (Sb)-enriched layer therein, and   when contents of elements are analyzed in a thickness direction of the base steel using a glow discharge spectrometer, a content of carbon (C) at a depth at which a content of antimony (Sb) in the antimony (Sb)-enriched layer exhibits a maximum value (Sb max ) is 80% or less of a nominal carbon content (C 0 ) of the base steel.   
     
     
         27 . The part of  claim 26 , wherein in the part, the content of carbon (C) at the depth at which the content of antimony (Sb) shows the maximum value (Sb max ) is 15 to 80% of the nominal carbon content (C 0 ) of the base steel. 
     
     
         28 . The part of  claim 26 , wherein the part has an R value defined in the following Relational Expression 1 of 1.5 or more, and
 a B value defined in the following Relational Expression 2 of 0.01 or more:   
       
         
           
             
               
                 
                   
                     R 
                     = 
                     
                       
                         s 
                         ⁢ 
                         
                           b 
                           max 
                         
                       
                       
                         s 
                         ⁢ 
                         
                           b 
                           
                             c 
                             ⁢ 
                             o 
                             ⁢ 
                             a 
                             ⁢ 
                             t 
                           
                         
                       
                     
                   
                 
                 
                   
                     [ 
                     
                       Relational 
                       ⁢ 
                           
                       Expression 
                       ⁢ 
                           
                       1 
                     
                     ] 
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     B 
                     = 
                     
                       
                         
                           ( 
                           
                             
                               s 
                               ⁢ 
                               
                                 b 
                                 max 
                               
                             
                             - 
                             
                               s 
                               ⁢ 
                               
                                 b 
                                 coat 
                               
                             
                           
                           ) 
                         
                         2 
                       
                       × 
                       Δ 
                       ⁢ 
                       t 
                     
                   
                 
                 
                   
                     [ 
                     
                       Relational 
                       ⁢ 
                           
                       Expression 
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                       2 
                     
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         wherein Sb max  represents a maximum value of the content of Sb in the Sb-enriched layer, Sb coat  represents an average Sb content in the plating layer, and units thereof are wt %, and Δt represents a straight distance between an interface where the plating layer and the base steel are in contact with each other and a point at which Sb max  is measured, and a unit thereof is μm. 
       
     
     
         29 . The part of  claim 26 , wherein a softening rate (β) in a region from an interface between the base steel and the plating layer to a depth of 45 to 100 μm in the thickness direction is 2 to 7%. 
     
     
         30 . The part of  claim 26 , wherein a region from an interface between the base steel and the plating layer to a depth of 50 μm in the thickness direction has a microstructure comprising less than 5 area % of ferrite. 
     
     
         31 . The part of  claim 26 , wherein a region from an interface between the base steel and the plating layer to a depth of 50 μm in the thickness direction has a microstructure comprising martensite as a main phase, less than 5 area % of ferrite, and a balance of upper and lower bainite. 
     
     
         32 . The part of  claim 26 , wherein the base steel comprises 0.06 to 0.5% of carbon (C), 0.01 to 0.1% of antimony (Sb), 0.001 to 2% of silicon (Si), 0.1 to 4% of manganese (Mn), 1% or less of molybdenum (Mo), 0.05% or less of phosphorus (P), 0.02% or less of sulfur(S), 0.001 to 1% of aluminum (Al), 1% or less of chromium (Cr), 0.02% or less of nitrogen (N), 0.1% or less of titanium (Ti), 0.01% or less of boron (B), and a balance of iron (Fe) and impurities. 
     
     
         33 . The part of  claim 26 , wherein the plating layer is formed of aluminum or an aluminum alloy. 
     
     
         34 . The part of  claim 26 , wherein the part has a product of a tensile strength and a bending angle of 80,000 MPa·° or more. 
     
     
         35 . The part of  claim 26 , wherein the amount of diffusible hydrogen in the part is 0.2 ppm or less. 
     
     
         36 . A manufacturing method of a part, comprising:
 manufacturing a blank using the plated steel sheets;   heating the blank to a temperature range of Ac 3  to 975° C. and maintaining the blank for 10 to 1,000 seconds; and   forming and cooling the heated blank,   wherein the manufacturing method of a plated steel sheet, comprising:   preparing a cold-rolled steel sheet comprising, by wt %, 0.06 to 0.5% of carbon (C) and 0.01 to 0.1% of antimony (Sb);   annealing the cold-rolled steel sheet in a temperature range of Ac 1  to Ac 3 ; and   plating the annealed cold-rolled steel sheet,   wherein during the annealing, a product of an annealing time and an absolute humidity is 10,000 to 80,000 s·g/m 3 , and   during the annealing, based on a surface temperature of the steel sheet, an average temperature increase rate from room temperature to 500° C. is 2.7 to 10.0° C./s, an average temperature increase rate in a section of 500 to 700° C. is 0.5 to 2.5° C./s, and an average temperature increase rate from 700° C. to an annealing temperature is 0.01 to 0.4° C./s.   
     
     
         37 . The manufacturing method of  claim 36 , wherein during the cooling, the cooling is performed at a cooling rate of 20° C./s or more.