Method of manufacturing a quenched member and quenched member

1. A quenched member comprising:

a steel sheet formed into a rectangular cross section having one-surface at which first and second terminal edges of the steel sheet are adjacent to and face each other at a same side of the rectangular cross-section of the quenched member, the one-surface comprising a first undulating portion in the first terminal edge in a direction along which the terminal edges extend,

wherein the first undulating portion includes curved portions that are curved in a sheet thickness direction of the steel sheet; and

an intersecting-portion at which the first undulating portion in the first terminal edge and the second terminal edge cross each other as viewed perpendicular to a plane that is parallel to the first and second terminal edges, which face each other.

2. The quenched member according to claim 1 , wherein of the second terminal edge includes a second undulating portion, the second undulating portion includes curved portions that are curved in the sheet-thickness direction of the steel sheet, and the first undulating portion and the second undulating portion cross each other in the intersecting-portion as viewed perpendicular to a plane that is parallel to the first and second terminal edges, which face each other.

3. The quenched member according to claim 2 , wherein the curved portions are curved toward an inner side of the rectangular cross-section.

4. The quenched member according to claim 2 , wherein the curved portions of each of the first undulating portion and the second undulating portion are located in different positions from each other in the direction along which the terminal edges extend.

5. The quenched member according to claim 1 ,

wherein the quenched member is curved in a curving direction, and

wherein a ratio of a height of the quenched member in the curving direction, to the sheet-thickness of the steel sheet in a lateral cross-section, is 40 or less.

6. The quenched member according to claim 1 , wherein the sheet thickness of the steel sheet is 2.3 millimeters or less.

7. The quenched member according to claim 1 , wherein an angle formed between an opposing-surface that faces the one-surface, and a side-surface that links the opposing-surface and the one-surface, is from 80 degrees to 100 degrees.

8. A method of manufacturing the quenched member according to claim 1 , the method comprising:

heating a pressed intermediate article to an Ac3 transformation point of the steel sheet or higher, the intermediate article having been processed so as to have the rectangular cross-section and so as to include a terminal portion at which the two terminal edges of the steel sheet are aligned with each other at the same side of the rectangular cross-section;

quenching the heated intermediate article inside a die; and

further comprising pressing the steel sheet into the intermediate article.

9. The method of manufacturing the quenched member according to claim 8 , wherein quenching the intermediate article includes subjecting the intermediate article to hot bending such that the one-surface, which includes the terminal portion, curves toward an outer side of the one-surface along which the terminal portion extends.

10. The method of manufacturing the quenched member according to claim 8 , wherein the terminal edges of the steel sheet contact each other.

11. The method of manufacturing the quenched member according to claim 8 , wherein a ratio of a height of the quenched member in a curving direction, to a sheet-thickness of the steel sheet in a lateral cross-section, is 40 or less.

12. The method of manufacturing the quenched member according to claim 8 , wherein a sheet-thickness of the steel sheet is 2.3 millimeters or less.