Steel sheet for warm press forming, warm-pressed member, and manufacturing methods thereof

Abstract

Provided is a warm-pressed member comprising, by weight %, C: 0.01% to 0.5%, Si: 3.0% or less (excluding 0%), Mn: 3% to 15%, P: 0.0001% to 0.1%, S: 0.0001% to 0.03%, Al: 3.0% or less (excluding 0%), N: 0.03% or less (excluding 0%), and the balance of Fe and inevitable impurities. After a warm press forming process and a cooling process, the warm-pressed member has a microstructure comprising: 5 volume % to 50 volume % of retained austenite; and at least one of ferrite, martensite, tempered martensite, and bainite as a remainder.

1 . A warm-pressed member comprising, by weight %, C: 0.01% to 0.5%, Si: 3.0% or less (excluding 0%), Mn: 3% to 15%, P: 0.0001% to 0.1%, S: 0.0001% to 0.03%, Al: 3.0% or less (excluding 0%), N: 0.03% or less (excluding 0%), and the balance of Fe and inevitable impurities,
 wherein after a warm press forming process and a cooling process, the warm-pressed member has a microstructure comprising: 5 volume % to 50 volume % of retained austenite; and at least one of ferrite, martensite, tempered martensite, and bainite as a remainder.   
     
     
         2 . The warm-pressed member of  claim 1 , wherein the warm-pressed member has a tensile strength of 1000 MPa or greater and an elongation of 10% or greater. 
     
     
         3 . The warm-pressed member of  claim 1 , further comprising 0.001% to 0.4% of at least one selected from the group consisting of Ti, Nb, Zr, and V. 
     
     
         4 . The warm-pressed member of  claim 1 , further comprising 0.005% to 2.0% of at least one of Cu and Ni. 
     
     
         5 . The warm-pressed member of  claim 1 , further comprising 0.0001% to 1.0% of at least one of Sb and Sn. 
     
     
         6 . The warm-pressed member of  claim 1 , further comprising 0.0001% to 0.01% of B.