To provide a steel sheet for hot stamping suitable for manufacturing, through hot-stamping working, a component having portions with different strengths, and a hot-stamped member having portions with different strengths. A steel sheet for hot stamping according to the present invention includes, on a surface of the steel sheet: a site having a surface-treated film whose emissivity at a wavelength of 8.0 m at 25 C. is 60% or more; and a site at which the surface-treated film is not provided, in which the surface-treated film contains carbon black, and one or more of oxides selected from a group consisting 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.sup.2, and when an adhesion amount of the carbon black and an adhesion amount of the oxides are set to X.sub.CB (g/m.sup.2) and X.sub.Oxide (g/m.sup.2), respectively, an equation (1) below is satisfied.

The present invention relates to a self-collapsed protective coating composition and use thereof. In particular, the invention relates to a self-collapsed protective coating composition for hot stamping of steel material, which can protect the surface of steel material from oxide scale and provide ease for subsequent welding.

The present invention relates to a self-collapsed protective coating composition and use thereof. In particular, the invention relates to a self-collapsed protective coating composition for hot stamping of steel material, which can protect the surface of steel material from oxide scale and provide ease for subsequent welding.

A method of heat-treating for a metal molded article includes: a shape holding layer formation step of forming on a shape holding layer having a melting point higher than a solidus temperature Ts of a composition of the metal molded article on a surface of the metal molded article by treating the metal molded article; and a first heat-treatment step of performing a first heat treatment on the metal molded article at a first temperature T1, after forming the shape holding layer. When a reference temperature Ta is a temperature lower than the solidus temperature Ts by 100 C., and Tm is the melting point of the shape holding layer, the shape holding layer formation step and the first heat-treatment step are performed so as to satisfy an expression TaT1Tm.

A method of heat-treating for a metal molded article includes: a shape holding layer formation step of forming on a shape holding layer having a melting point higher than a solidus temperature Ts of a composition of the metal molded article on a surface of the metal molded article by treating the metal molded article; and a first heat-treatment step of performing a first heat treatment on the metal molded article at a first temperature T1, after forming the shape holding layer. When a reference temperature Ta is a temperature lower than the solidus temperature Ts by 100 C., and Tm is the melting point of the shape holding layer, the shape holding layer formation step and the first heat-treatment step are performed so as to satisfy an expression TaT1Tm.

This invention discloses a metal coating method whereby an abrasion resistant and wear resistant coating is first applied to the metal object, the coated metal object is then fused onto the metal object, followed by cooling in a press quench machine, and the resulting coated metal object is more abrasion resistant and wear resistant while retaining the metal object's original shape.

This invention discloses a metal coating method whereby an abrasion resistant and wear resistant coating is first applied to the metal object, the coated metal object is then fused onto the metal object, followed by cooling in a press quench machine, and the resulting coated metal object is more abrasion resistant and wear resistant while retaining the metal object's original shape.

A thermal treatment process of a ferrous alloy sheet is provided. The process includes the step of performing a thermal treatment on said sheet when running, by immersing it into at least one molten oxides bath. The molten oxides bath has a viscosity lower than 3.Math.10.sup.1 Pa.Math.s, the surface of the bath is in contact with a non-oxidizing atmosphere and the molten oxides are inert towards iron. The difference between the temperature of the ferrous alloy sheet at the entry of the bath and the temperature of the bath is between 25 C. and 900 C. The residues of oxides remaining on the surfaces of the ferrous alloy sheet at the exit of the bath are eliminated. A device for implementing this process is also provided.

To provide 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. A steel sheet for hot stamping according to the present invention 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 ?m 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 group consisting 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.sup.2, and when an adhesion amount of the carbon black and an adhesion amount of the oxides are set to X.sub.CB (g/m.sup.2) and X.sub.Oxide (g/m.sup.2), respectively, an equation (1) is satisfied.

A heating step, in which a stainless member is heated to a temperature within or above a heating phase-transformation temperature range (Ar) in which the stainless member is phase-transformed, is executed. A cooling step in which the stainless member heated in the heating step is cooled to a temperature below a cooling phase-transformation temperature range (Mr) in which the stainless member is phase-transformed, is executed. In the cooling step, cooling of the stainless member is suppressed in a control temperature range including the cooling phase-transformation temperature range (Mr).