Hot stamped body

Abstract

Provided is a hot stamped body having a predetermined chemical composition and a microstructure comprising, by area ratio, at least one of martensite, bainite, and tempered martensite: 90% or more in total, wherein a standard deviation in grain size distribution of former austenite grains is 5.0 μm or less, and a total amount of segregation of at least one of Mo, W, Ta, Re, Os, Ir, and Tc at the former austenite grain boundaries is 0.10 atm % or more.

1 . A hot stamped body having a chemical composition comprising, by mass %,
 C: 0.40 to 0.70%,   Si: 0.010 to 3.00%,   Mn: 0.50 to 3.00%,   P: 0.100% or less,   S: 0.0100% or less,   N: 0.0200% or less,   O: 0.0200% or less,   Al: 0.0010 to 0.500%,   Nb: 0.0010 to 0.100%,   Ti: 0.010 to 0.200%,   Cr: 0.010 to 1.00%,   Mo: 0.0010 to 1.000%,   B: 0.0005 to 0.0200%,   Co: 0 to 4.00%,   Ni: 0 to 3.00%,   Cu: 0 to 3.00%,   V: 0 to 3.00%,   Ca: 0 to 1.000%,   Mg: 0 to 1.000%,   REM: 0 to 1.000%,   Sb: 0 to 1.00%,   Sn: 0 to 1.00%,   Zr: 0 to 1.00%,   As: 0 to 0.100%,   at least one of W, Ta, Re, Os, Ir, and Tc: 0 to 1.00% in total, and   balance: Fe and impurities, and   a microstructure comprising, by area ratio, at least one of martensite, bainite, and tempered martensite: 90% or more in total, wherein   a standard deviation in grain size distribution of former austenite grains is 5.0 μm or less, and   a total amount of segregation of at least one of Mo, W, Ta, Re, Os, Ir, and Tc at former austenite grain boundaries is 0.10 atm % or more.   
     
     
         2 . The hot stamped body according to  claim 1 , wherein the amount of segregation of Mo at the former austenite grain boundaries is 0.10 atm % or more. 
     
     
         3 . The hot stamped body according to  claim 1 , wherein the total amount of segregation is 0.15 atm % or more. 
     
     
         4 . The hot stamped body according to  claim 2 , wherein the total amount of segregation is 0.15 atm % or more.