Hot press formed product having excellent corrosion resistance and method for preparing same

Abstract

Provided is a method for preparing a hot press formed product. The method includes: immersing base iron in a Zn—Al—Mg-based plating bath, and performing plating to obtain a Zn—Al—Mg-based plated steel material; heating the Zn—Al—Mg-based plated steel material to a heating temperature of 600-950° C. at a rate of 10° C./sec or more in a heating furnace; and forming the Zn—Al—Mg-based plated steel material which has reached the heating temperature with a mold simultaneously with quenching. A residence time is 120 seconds or less, the residence time representing a time during which the Zn—Al—Mg-based plated steel material which has reached the heating temperature resides in the heating furnace.

1 . A method for preparing a hot press formed product, comprising:
 immersing base iron in a Zn—Al—Mg-based plating bath, and performing plating to obtain a Zn—Al—Mg-based plated steel material;   heating the Zn—Al—Mg-based plated steel material to a heating temperature of 600-950° C. at a rate of 10° C./sec or more in a heating furnace; and   forming the Zn—Al—Mg-based plated steel material which has reached the heating temperature with a mold simultaneously with quenching,   wherein a residence time is 120 seconds or less, the residence time representing a time during which the Zn—Al—Mg-based plated steel material which has reached the heating temperature resides in the heating furnace.   
     
     
         2 . The method of  claim 1 , wherein the heating temperature is 800° C. or more and 950° C. or less, an average heating rate to the heating temperature is 20° C./sec or more, and the residence time is 60 seconds or less. 
     
     
         3 . The method of  claim 1 , wherein the heating is carried out by any one method of radiant heating, high-frequency induction heating and ohmic heating. 
     
     
         4 . The method of  claim 1 , wherein the heating is carried out under an inert gas atmosphere. 
     
     
         5 . The method of  claim 1 , wherein the content ratio of Al to Mg (Al/Mg) in the Zn—Al—Mg-based plating bath is 0.8 or more. 
     
     
         6 . The method of  claim 1 , wherein the base iron is a cold rolled steel plate, and the cold rolled steel plate has a surface roughness of 2.0 μm or less before plating. 
     
     
         7 . The method of  claim 1 , wherein the base iron contains: 0.15-0.35% by weight of C, 0.5% by weight or less (exclusive of 0%) of Si, 0.5-8.0% by weight of Mn, and 0.0020-0.0050% by weight of B, with a balance of Fe and unavoidable impurities. 
     
     
         8 . The method of  claim 7 , further comprising the following before obtaining the plated steel material:
 pre-plating one or more metals selected from the group consisting of Fe, Ni, Cu, Sn and Sb to an average thickness of 5-100 nm on a surface of the base iron; and   annealing the pre-plated base iron.   
     
     
         9 . The method of  claim 8 , wherein the annealing is carried out under 1-15% by volume of hydrogen gas and remaining nitrogen gas. 
     
     
         10 . The method of  claim 1 , wherein the Zn—Al—Mg based plating bath comprises 0.9-3.5% by weight of Mg, 1.0-15% by weight of Al, with a balance of Zn and other unavoidable impurities.