Hot-dip zn-alloy-plated steel sheet

Abstract

This hot-dip Zn-alloy-plated steel sheet comprises: a steel sheet; a hot-dip Zn-alloy-plated layer arranged on a surface of the steel sheet; and a complex oxide coating film arranged on a surface of the hot-dip Zn-alloy-plated layer. The complex oxide coating film includes vanadium and a constituent component of the hot-dip Zn-alloy-plated layer, and the entire surface of the coating film satisfies the following formula (1): S[Hydroxide]/(S[Hydroxide]+S[Oxide])×100≦40. In formula (1): S[Oxide] is the area exhibited by a peak having a center at approximately 1022 eV ascribable to a Zn oxide in an intensity profile in XPS analysis of the surface of the complex oxide coating film; and S[Hydroxide] is the area exhibited by a peak having a center at approximately 1023 eV ascribable to a Zn hydroxide in an intensity profile in XPS analysis of the surface of the complex oxide coating film.

1 . A hot-dip Zn alloy-plated steel sheet comprising:
 a steel sheet;   a hot-dip Zn alloy plating layer disposed on a surface of the steel sheet; and   a composite oxide film disposed on a surface of the hot-dip Zn alloy plating layer;   wherein the composite oxide film comprises constituent components of the hot-dip Zn alloy plating layer and vanadium, and the composite oxide film satisfies, at a whole of a surface of the composite oxide film, following Equation 1:   
       
         
           
             
               
                 
                   
                     
                       
                         
                           S 
                            
                           
                             [ 
                             Hydroxide 
                             ] 
                           
                         
                         
                           
                             S 
                              
                             
                               [ 
                               Hydroxide 
                               ] 
                             
                           
                           + 
                           
                             S 
                              
                             
                               [ 
                               Oxide 
                               ] 
                             
                           
                         
                       
                       × 
                       100 
                     
                     ≤ 
                     40 
                   
                 
                 
                   
                     ( 
                     
                       Equation 
                        
                       
                           
                       
                        
                       1 
                     
                     ) 
                   
                 
               
             
           
         
         S[Oxide] is a peak area derived from Zn oxide and centered at approximately 1022 eV in an intensity profile of the XPS analysis of the surface of the composite oxide film; and S[Hydroxide] is a peak area derived from Zn hydroxide and centered at approximately 1023 eV in the intensity profile of the XPS analysis of the surface of the composite oxide film. 
       
     
     
         2 . The hot-dip Zn alloy-plated steel sheet according to  claim 1 , wherein:
 the hot-dip Zn alloy plating layer comprises 1.0 to 22.0% by mass of Al, 0.1 to 10.0% by mass of Mg, and the balance of the hot-dip Zn alloy plating layer being Zn and unavoidable impurities.   
     
     
         3 . The hot-dip Zn alloy-plated steel sheet according to  claim 2 , wherein:
 the hot-dip Zn alloy plating layer further comprises at least one selected from the group consisting of 0.001 to 2.0% by mass of Si, 0.001 to 0.1% by mass of Ti, and 0.001 to 0.045% by mass of B.   
     
     
         4 . The hot-dip Zn alloy-plated steel sheet according to  claim 1 , wherein an adhering amount of the vanadium contained in the composite oxide film is in the range of 0.01 to 10.0 mg/m 2 . 
     
     
         5 . The hot-dip Zn alloy-plated steel sheet according to  claim 2 , wherein an adhering amount of the vanadium contained in the composite oxide film is in the range of 0.01 to 10.0 mg/m 2 . 
     
     
         6 . The hot-dip Zn alloy-plated steel sheet according to  claim 3 , wherein an adhering amount of the vanadium contained in the composite oxide film is in the range of 0.01 to 10.0 mg/m 2 .