Bumper Beam

A bumper beam includes a closing plate and a hat member . The hat member includes a top plate , two flanges , and two walls . The hat member includes a high-strength portion H and low-strength portions L. The high-strength portion H includes a longitudinally middle portion of each of the two walls and extends a length of at least 250 mm. The high-strength portion H has a tensile strength not lower than 1.5 GPa. The low-strength portions L are located outward of the high-strength portion and extends a length not smaller than the height of the walls. The low-strength portions have a tensile strength lower than the tensile strength of the longitudinally middle portion of the two walls.