| 摘要 |
<p>Provided is a car-body reinforcing member such as a side member or pillar, which has a bending portion to be two-or three-dimensionally bent and which has a super-high tensile strength higher than 1,100 MPa. The car-body reinforcing member is constituted of a cylinder including a bending portion to be two-or three-dimensionally bent, a cutting-or boring-scheduled portion, and a welding-scheduled portion, and having a closed section with no outward flange. The cylinder is composed of a super-high strength heat-treated portion heat-treated to a tensile strength higher than 1,100 MPa, a high strength heat-treated portion forming the remainder of the super-high strength heat-treated portion and heat-treated to have a tensile strength of 600 MPa to 1,100 MPa, and/or a low strength heat-treated portion heat-treated to have a tensile strength lower than 600 MPa or the aforementioned cutting-or boring-scheduled portion and welding-scheduled portion.</p> |
