Hot-stamp formed body

Abstract

This hot-stamp formed body is a hot-stamp formed body comprising a steel sheet, in which the steel sheet has a predetermined chemical composition, an average B concentration in a region from a depth of 5.0 μm from a surface of the steel sheet to a depth of 25.0 μm from the surface is 0.700 times or less than a B concentration at a position of a depth of 100 μm from the surface, an average B concentration in a region from a depth of 0.5 μm from the surface to a depth of 4.0 μm from the surface is 1.600 times or more than the B concentration at the position of the depth of 100 μm from the surface, and an average O concentration in the region from the depth of 0.5 μm from the surface to the depth of 4.0 μm from the surface is more than 0.0150 mass %.

1 . A hot-stamp formed body comprising a steel sheet, an entirety or a part of the steel sheet comprising, as a chemical composition, by mass %:
 C: more than 0.32% and 0.70% or less;   Si: less than 2.00%;   Mn: 0.01% to 3.00%;   P: 0.200% or less;   S: 0.0200% or less;   sol. Al: 0.001% to 1.000%;   N: 0.0200% or less;   O: 0.0005% to 0.0200%;   B: 0.0005% to 0.0200%;   Cr: 0% to 2.00%;   Mo: 0% to 2.00%;   W: 0% to 2.00%;   Cu: 0% to 2.00%;   Ni: 0% to 2.00%;   Ti: 0% to 0.200%;   Nb: 0% to 0.200%;   V: 0% to 0.200%;   Zr: 0% to 0.200%;   Ca: 0% to 0.1000%;   Mg: 0% to 0.1000%;   REM: 0% to 0.1000%;   Sn: 0% to 0.200%;   As: 0% to 0.100%;   Bi: 0% to 0.0500%; and   a remainder comprising Fe and impurities,   wherein a tensile strength is 1900 MPa or more,   an average B concentration in a region from a depth of 5.0 μm from a surface of the steel sheet to a depth of 25.0 μm from the surface is 0.700 times or less than a B concentration at a position of a depth of 100 μm from the surface,   an average B concentration in a region from a depth of 0.5 μm from the surface to a depth of 4.0 μm from the surface is 1.600 times or more than the B concentration at the position of the depth of 100 μm from the surface, and   an average O concentration in the region from the depth of 0.5 μm from the surface to the depth of 4.0 μm from the surface is more than 0.0150 mass %.   
     
     
         2 . The hot-stamp formed body according to  claim 1  comprising, as the chemical composition, by mass %, one or more of:
 Cr: 0.01% to 2.00%; 
 Mo: 0.01% to 2.00%; 
 W: 0.01% to 2.00%; 
 Cu: 0.01% to 2.00%; 
 Ni: 0.01% to 2.00%; 
 Ti: 0.001% to 0.200%; 
 Nb: 0.001% to 0.200%; 
 V: 0.001% to 0.200%; 
 Zr: 0.001% to 0.200%; 
 Ca: 0.0001% to 0.1000%; 
 Mg: 0.0001% to 0.1000%; 
 REM: 0.0001% to 0.1000%; 
 Sn: 0.001% to 0.200%; 
 As: 0.001% to 0.100%; and 
 Bi: 0.001% to 0.0500%.