Zn-ni electroplated steel sheet having excellent corrosion resistance and formability and manufacturing method therefor

Abstract

Provided is a Zn—Ni electroplated steel sheet having excellent corrosion resistance and formability and a manufacturing method therefor. The steel sheet includes: abase steel sheet; and a Zn—Ni plated layer formed on the base steel sheet, wherein a Ni alloying degree within the Zn—Ni plated layer is 7.5-14%, and the Ni amount is 40-50 atom % in a region within 1 pm toward the Zn—Ni plated layer from an interface of the base steel sheet and the Zn—Ni plated layer. Provided is a Zn—Ni electroplated steel sheet, which has superior corrosion resistance and formability despite having a relatively low nickel alloying degree, has excellent price competitiveness compared with that of a conventional Zn—Ni plated steel sheet and two-layer plated steel sheet, and can ensure high productivity.

1 . A Zn—Ni electroplated steel sheet having excellent corrosion resistance and workability, the Zn—Ni electroplated steel sheet comprising:
 a base steel sheet; and 
 a Zn—Ni plated layer formed on the base steel sheet, 
 wherein a Ni alloying degree in the Zn—Ni plated layer is 7.5 to 14%, and 
 a content of Ni is 40 to 50 atom % in a region within 1 pm from a boundary of the base steel sheet and the Zn—Ni plated layer toward the Zn—Ni plated layer. 
 
     
     
         2 . The electroplated steel sheet of  claim 1 , wherein a coating weight of the Zn—Ni plated layer, formed on one surface of the base steel sheet, is 20 to 50g/m 2 , and
 a coating weight of the Zn—Ni plated layer, formed on the other surface of the base steel sheet, is 0.25 to 0.8 times that of the coating weight of the Zn—Ni plated layer formed on one surface of the base steel sheet. 
 
     
     
         3 . A method of manufacturing a Zn—Ni electroplated steel sheet having excellent corrosion resistance and workability, the method comprising:
 preparing a base steel sheet; and 
 dipping the base steel sheet in a sulfuric acid bath, having a pH of 1 to 5, including a zinc sulfate heptaheptahydrate and a zinc sulfate heptahydrate, to form a Zn—Ni plated layer on the base steel sheet, 
 wherein a content of the zinc sulfate heptaheptahydrate is 45 to 93 g/L, and 
 a ratio of the zinc sulfate heptahydrate and the zinc sulfate heptaheptahydrate is 0.4 to 1.4. 
 
     
     
         4 . The method of  claim 3 , wherein in the forming the Zn—Ni plated layer,
 a coating weight of the Zn—Ni plated layer, coated on one surface of the base steel sheet, is 20 to 50g/m 2 , and 
 a coating weight of the Zn—Ni plated layer, coated on the other surface of the base steel sheet, is 0.25 to 0.8 times that of the coating weight of the Zn—Ni plated layer coated on one surface of the base steel sheet. 
 
     
     
         5 . The method of  claim 3 , after the forming of the plated layer, further comprising:
 heating the steel sheet to 190 to 260° C. on the basis of a peak metal temperature (PMT).   
     
     
         6 . The method of  claim 5 , wherein the heating is performed using induction hardening or hot-air hardening.