Steel sheet for hot stamping and hot-stamped member
A steel sheet for hot stamping that further improves productivity of a hot-stamped member, has excellent appearance and has excellent spot weldability, and a hot-stamped member. The steel sheet for hot stamping includes, on the whole of at least one surface of the steel sheet, a surface-treated film whose emissivity at a wavelength of 8.0 μm at 25° C. is 60% or more, in which the surface-treated film contains carbon black, and one or more of oxides selected from a Zr oxide, a Zn oxide, and a Ti oxide, in which the carbon black and the oxides exist while being dispersed over the entire surface-treated film, the surface-treated film has a silica content of 0 to 0.3 g/m 2 , and when an adhesion amount of the carbon black and an adhesion amount of the oxides are set to X CB (g/m 2 ) and X Oxide (g/m 2 ), respectively, an equation (1) is satisfied.
1 . A steel sheet for hot stamping comprising, on the whole of at least one surface of the steel sheet,
a surface-treated film whose emissivity at a wavelength of 8.0 μm at 25° C. is 60% or more, wherein:
the surface-treated film contains carbon black, and one or more of a Zr oxide, a Zn oxide, and a Ti oxide, in which the carbon black and the oxides exist while being dispersed over the entire surface-treated film;
the surface-treated film has a silica content of 0 to 0.3 g/m 2 ;
when an adhesion amount of the carbon black and an adhesion amount of the oxides are set to X CB (g/m 2 ) and X Oxide (g/m 2 ), respectively, an equation (1) below is satisfied,
118.9≤24280/{6700/(100+76× X CB )+18000/(130+65× X Oxide )}≤332.0 Equation (1), and
on one side or both sides of the steel sheet for hot stamping, a metal-plated layer is provided between a base material of the steel sheet and the surface-treated film,
wherein the metal-plated layer is aluminum plating, or Al—Si plating.
2 . The steel sheet for hot stamping according to claim 1 , wherein
the surface-treated film contains the carbon black of 5.0 to 40.0 vol %, and contains the oxides of 1.0 to 30.0 vol %.
3 . The steel sheet for hot stamping according to claim 1 , wherein
a ratio X Oxide /X CB between the adhesion amount X CB (g/m 2 ) of the carbon black and the adhesion amount X Oxide (g/m 2 ) of the oxides is 0.20 or more and 200.00 or less.
4 . The steel sheet for hot stamping according to claim 1 , wherein
the adhesion amount X CB of the carbon black is 0.030 g/m 2 or more, and the adhesion amount X Oxide of the oxides is 0.030 g/m 2 or more.
5 . The steel sheet for hot stamping according to claim 1 , wherein
an emissivity of the surface-treated film at a wavelength of 8.0 μm at 700° C. is 60% or more.
6 . A hot-stamped member, comprising the steel sheet according to claim 1 and having
the surface-treated film on the whole of at least one surface of the steel sheet, wherein:
the surface-treated film contains one or more of the Zr oxide, the Zn oxide, and the Ti oxide, in which the adhesion amount X Oxide of the oxides is 0.030 g/m 2 or more; and
the surface-treated film has the silica content of 0 to 0.3 g/m 2 .