Bumper beam

A bumper beam comprising:

• a closing plate;
• and
• a hat member curved along a longitudinal direction to protrude in a direction of the closing plate,
• wherein the hat member includes:
• a top plate;
• two first ridges each positioned on a respective one of both ends of the top plate;
• two flanges joined to the closing plate;
• two second ridges each positioned at an inner end of a respective one of the flanges;
• and
• two walls each positioned between a respective one of the first ridges and a respective one of the second ridges,
• wherein the hat member includes:
• a high-strength portion including a longitudinally middle portion of each of the two walls,
• the high-strength portion extending a length of at least 250 mm and having a tensile strength not lower than 1.5 GPa;
• and
• a low-strength portion provided in the hat member curved along the longitudinal direction to protrude in the direction of the closing plate,
• the low-strength portion located outward of the high-strength portion in the longitudinal direction,
• the low-strength portion extending a length not smaller than a height of the walls as determined along the longitudinal direction,
• the low-strength portion extending from one of the two second ridges through the two walls and the top plate to the other one of the two second ridges, and
• the low-strength portion having a tensile strength lower than a tensile strength of the longitudinally middle portions of the two walls.