| 摘要 |
PROBLEM TO BE SOLVED: To provide a strength member for an automobile being light in weight, having excellent shaft collapse performance and high bending strength performance, and capable of preventing the occurrence of a crack even when using a high strength steel plate. SOLUTION: This long strength member 1 for the automobile is constituted such that it has cutout parts 3 at four corners of a basic rectangular cross section 2 and a cross-shaped closed cross section on the whole, a plate thickness of the cutout part 3 is thicker than a plate thickness of parts other than the cutout part, namely, a side wall 4 and a top wall 5 by 5 to 30%, and a hardness of the cutout part 3 is larger than a hardness of parts other than the cutout part, namely, the side wall 4 and the top wall 5 by 5% or more. Furthermore, the strength member 1 is formed by drawing or hydroforming. |
