Skeleton Member

Abstract: This skeleton member is formed by hot-stamping a steel sheet. The skeleton member is so formed as to have a closed cross-sectional part in which a cross-section perpendicular to the longitudinal direction of the member is closed. The closed cross-sectional part comprises: at least two flat portions each having a curvature radius greater than the maximum outside dimension of said cross-section; and a recessed bead portion formed between the two flat portions. The recessed bead portion has a pair of walls which have a curvature radius of at least 50 mm and which protrude from the respective opposing ends of the two flat portions toward the inside of the closed cross-sectional part by way of a pair of inflected parts that are inflected toward the interior of the closed cross-section. In each of the walls, the central part in the thickness direction has a Vickers hardness of at least 520 Hv. The width of each of the walls is 0.5-2.5 times the effective width We. A standard deviation ratio, which is determined by dividing the standard deviation of hardness frequency distribution at a surface part of the walls by the standard deviation of hardness frequency distribution at the central part in the thickness direction of the walls, is smaller than 1.0.

Patent Information

Applicants

Inventors

Specification

Documents

Application Documents