Hot-stamped steel includes: a steel base metal including a tempered portion having hardness corresponding to 85% or less of the highest quenching hardness defined as a Vickers hardness at a depth position spaced away from a surface layer by ? times a sheet thickness in a case of performing water quenching after heating at a temperature equal to or higher than an A.sub.c3 point and retention for 30 minutes; and a Zn coating layer formed on the tempered portion of the base metal. The Zn coating layer includes a solid-solution layer including a solid-solution phase containing Fe and Zn that is solid-soluted in Fe, and a lamella layer including solid-solution phase and a capital gamma phase. In the Zn coating layer, an area ratio of the lamella layer is 30 to 100% and an area ratio of the solid-solution layer is 0 to 70%.

A method is disclosed for pressure forming a metal preform including shock annealing of the preform and subsequently preheating the preform prior to pressure forming. Shock annealing may be carried out as differential shock annealing in which different regions of the preform are annealed to different degrees. Preheating may be carried out by differentially preheating, optionally shock preheating, different regions of the preform for preheating at least those regions of the preform which will be subject to elevated expansion during pressure forming. Shock annealing by induction heating can lower energy consumption, reduce processing times and allow for larger expansion of the preform.

A hollow stabilizer (1) according to the invention is formed in a hollow shape and includes a bent portion (1c1, 1c2, m1-m5). With a thickness of an inner side of the bent portion (1c1, 1c2, m1-m5) being larger than a thickness of an outer side of the bent portion (1c1, 1c2, m1-m5), a hardness of the outer side of the bent portion (1c1, 1c2, m1-m5) is higher than a hardness of the inner side of the bent portion (1c1, 1c2, m1-m5) through quenching by cooling down after heating by electrical heating.

A method is disclosed for pressure forming a metal preform including shock annealing of the preform and subsequently preheating the preform prior to pressure forming. Shock annealing may be carried out as differential shock annealing in which different regions of the preform are annealed to different degrees. Preheating may be carried out by differentially preheating, optionally shock preheating, different regions of the preform for preheating at least those regions of the preform which will be subject to elevated expansion during pressure forming. Shock annealing by induction heating can lower energy consumption, reduce processing times and allow for larger expansion of the preform.

On at least one surface of a base metal plate (1) of an - transforming Fe or Fe alloy, a metal layer (2) containing ferrite former is formed. Next, the base metal plate (1) and the metal layer (2) are heated to an A3 point of the Fe or the Fe alloy, whereby the ferrite former are diffused into the base metal plate (1) to form an alloy region (1b) in a ferrite phase in which an accumulation degree of {200} planes is 25% or more and an accumulation degree of {222} planes is 40% or less. Next, the base metal plate (1) is heated to a temperature higher than the A3 point of the Fe or the Fe alloy, whereby the accumulation degree of the {200} planes is increased and the accumulation degree of the {222} planes is decreased while the alloy region (11b) is maintained in the ferrite phase.

A heating method, a heating apparatus, and a method of manufacturing a press-molded article using the heating method are provided. A pair of electrodes is arranged on a workpiece along a first direction. Each electrode has a length extending across a first heating area of a workpiece in the first direction. At least one of the electrodes is moved in the first heating area and along a second direction intersecting the first direction at a constant speed while applying electric current between the pair of electrodes to heat the first heating area by direct resistance heating. The electric current applied between the pair of electrodes is adjusted such that a heating temperature is adjusted for each segment into which the first heating area is divided so as to be side by side in the second direction.

The present invention relates to an apparatus and a method for processing a surface. The apparatus comprising a platform arranged to support a structure having an inner surface; at least one ball disposed adjacent to the inner surface; and a reflecting member having at least one reflecting surface; wherein the at least one ball is adapted to vibrate by a vibrating means and to collide with the inner surface and the reflecting surface thereby creating an impact to the inner surface.

Hot-stamped steel includes: a base metal that is steel including a tempered portion having hardness corresponding to 85% or less of the highest quenching hardness, the highest quenching hardness being defined as a Vickers hardness at a depth position spaced away from a surface layer by times a sheet thickness in a case of performing water quenching after heating at a temperature equal to or higher than an A.sub.c3 point and retention for 30 minutes; and a Zn coating layer that is formed on the tempered portion of the base metal. The Zn coating layer includes a solid-solution layer including a solid-solution phase that contains Fe and Zn that is solid-soluted in Fe, and a lamella layer that includes the solid-solution phase and a capital gamma phase. In the Zn coating layer, an area ratio of the lamella layer is 30 to 100% and an area ratio of the solid-solution layer is 0 to 70%.

A method for heat treatment of an object of sheet metal, includes the step of heating at least one selected portion of the object using an energy beam. The beam is projected onto a surface of the object so as to produce a primary spot on the object, the beam being repetitively scanned in two dimensions in accordance with a scanning pattern so as to establish an effective spot on the object, the effective spot having a two-dimensional energy distribution. The effective spot is displaced in relation to the surface of the object to progressively heat the at least one selected portion of the object. The scanning pattern includes interconnected curved segments.

A hollow stabilizer (1) according to the invention is formed in a hollow shape and includes a bent portion (1c1, 1c2, m1-m5). With a thickness of an inner side of the bent portion (1c1, 1c2, m1-m5) being larger than a thickness of an outer side of the bent portion (1c1, 1c2, m1-m5), a hardness of the outer side of the bent portion (1c1, 1c2, m1-m5) is higher than a hardness of the inner side of the bent portion (1c1, 1c2, m1-m5) through quenching by cooling down after heating by electrical heating.