Method for Warm Forming of Super High Tensile Strength Steel Sheet

Abstract

Disclosed herein is a method for warm forming of a super high tensile strength steel sheet. The method may improve productivity and simultaneously maintain accurate strength by securing thermal structure stability and dimensional stability during heating and forming the super high tensile strength steel sheet. According to an exemplary embodiment of the present invention, the method for warm forming of a super high tensile strength steel sheet includes: heating a steel sheet having a single-phase structure at Al transformation temperature or less; pressing, in a mold, the heated steel sheet to be formed in a predetermined shape; and extracting and cooling the pressed steel sheet.

What is claimed is: 
     
         1 . A method for warm forming of a super high tensile strength steel sheet, comprising:
 heating a steel sheet having a single-phase structure at A 1  transformation temperature or less;   pressing, in a mold, the heated steel sheet to be formed in a predetermined shape; and   extracting and cooling the pressed steel sheet.   
     
     
         2 . The method of  claim 1 , wherein the steel sheet has a single-phase martensite structure or a single-phase ferrite structure. 
     
     
         3 . The method of  claim 2 , wherein the steel sheet having the single-phase ferrite structure has improved strength by precipitation hardening. 
     
     
         4 . The method of  claim 1 , wherein a temperature of the mold used in the pressing is controlled by heat transferred from the heated steel sheet without additional heating and cooling. 
     
     
         5 . A super high tensile strength steel sheet manufactured by a method of  claim 1 . 
     
     
         6 . A vehicle part comprising a super high tensile strength steel sheet of  claim 5 .