Microcrack-reduced, hot press-formed article, and method for manufacturing same

Abstract

Provided are a hot press-formed article and a method for manufacturing the same. The article is manufactured by hot press forming a galvanized steel sheet comprising a base steel plate and a zinc-based coat layer formed on a surface of the base steel plate, wherein the zinc-based coat layer contains at least one element selected from the group consisting of Sb, Sn, and Bi in a total amount of 0.05% to 2.0% by weight, and a balanced amount of Zn and inevitable impurities, at least 70% by weight of the at least one element selected from the group consisting of Sb, Sn, Bi being concentrated in a region 3 μm or less distant from the surface of an alloyed zinc-based coat layer, formed by alloying the zinc-based coat layer, of the hot press-formed article.

1 . A hot press-formed article manufactured by hot press forming a galvanized steel sheet including a base steel sheet and a zinc-based plated layer formed on a surface of the base steel sheet,
 wherein the zinc-based plated layer includes at least one element selected from the group consisting of Sb, Sn, and Bi in a total amount of 0.05 to 2.0 wt %, a balance of Zn, and inevitable impurities, and   at least 70 wt % of the at least one element selected from the group consisting of Sb, Sn, Bi is concentrated in a region 3 μm or less away from a surface of an alloyed zinc-based plated layer, formed by alloying the zinc-based plated layer, of the hot press-formed article.   
     
     
         2 . The hot press-formed article of  claim 1 , wherein the zinc-based plated layer includes at least one element selected from the group consisting of Sb, Sn, and Bi in a total amount of 0.3 to 1.5 wt %. 
     
     
         3 . The hot press-formed article of  claim 1 , wherein the zinc-based plated layer further includes 0.1 to 5.0 wt % of Al and 0.1 to 5.0 wt % of Mg. 
     
     
         4 . The hot press-formed article of  claim 1 , wherein a degree of alloying of Fe of the alloyed zinc-based plated layer is 30 to 85%. 
     
     
         5 . A method for manufacturing a hot press-formed article, the method comprising:
 preparing a zinc-based plated steel sheet;   primarily heating the zinc-based plated steel sheet to a temperature of 640 to 680° C. at a rate of 3.5 to 4.2° C./sec;   secondarily heating the primarily-heated zinc-based plated steel sheet to a temperature of 900 to 930° C. at a rate of 1.1 to 1.6° C./sec;   maintaining the secondarily-heated zinc-based plated steel sheet at a constant temperature for 1 to 5 minutes; and   molding the zinc-based plated steel sheet maintained at the constant temperature with a die and simultaneously quenching the steel sheet,   wherein the zinc-based plated steel sheet includes a base steel sheet and a zinc-based plated layer formed on a surface of the base steel sheet and including at least one element selected from the group consisting of Sb, Sn, and Bi in a total amount of 0.05 to 2.0 wt %.   
     
     
         6 . The method of  claim 5 , wherein the zinc-based plated layer includes at least one element selected from the group consisting of Sb, Sn, and Bi in a total amount of 0.3 to 1.5 wt %. 
     
     
         7 . The method of  claim 5 , wherein the zinc-based plated layer further includes 0.1 to 5.0 wt % of Al and 0.1 to 5.0 wt % of Mg.