| 摘要 |
The present invention suppresses not only a deterioration in the load bearing performance of a structural member in a motor vehicle body having a quenched portion with a tensile strength of 1470 MPa or more, but also a deterioration in impact absorption performance accompanying HAZ softening due to welding. Provided is a joining structure (10) for a member in a motor vehicle body, said joining structure (10) being formed by welding, at an overlapping portion: a steel first member (11) that has a closed hollow cross section without an outward-facing flange and is provided, in the length direction, with a quenched portion having a tensile strength of 1470 MPa or more, a base material portion having a tensile strength of less than 700 MPa, and a transition portion (17) between the quenched portion (16) and the base material portion (18); and a steel second member (12) that is overlapped with the first member (11). Therein, the overlapping portion spans from the quenched portion (16) of the first member (11) to the base material portion (18) via the transition portion (17), and there is a welded portion (13), formed by welding, in the transition portion (17) or base material portion (18) of the first member (11). |
