Structural Member, Vehicle-Body Structure and Bumper Reinforcement

A structural member includes a closed-cross-section structure having a hat member and a closing plate , and a reinforcing member (supplementary strengthening member (“SSM”)) . The hat member includes two side walls and , each of which includes a high-strength portion A, A with a yield strength not lower than 500 MPa and low-strength portions B, B with a yield strength of 60 to 85% of the yield strength of the high-strength portion. As determined along the direction of extension of the ridges of the hat member, both ends of the reinforcing member overlap the high-strength portions A and B of the side walls and . Adjacent to at least one of both ends of the reinforcing member , the border between the high-strength portions A and A and the low-strength portions B and B is positioned in a region starting at a position 1/3, and ending at a position 3/2, of the height H of the side wall distant from that end of the reinforcing member as determined along the direction of extension of the ridges away from the reinforcing member