Automobile member

1. An automobile member which is long in one direction and of which a cross section perpendicular to a longitudinal direction is a hollow cross section, the automobile member comprising:

a hat-shaped first member that has a first flange, a second flange, a first wall portion erected from the first flange, a second wall portion erected from the second flange, and a web connecting the first wall portion and the second wall portion to each other;

a second member that is spot-joined to the first flange and the second flange;

a first joining plate that is joined to an inner wall surface of the first wall portion and an inner wall surface of the second member; and

a second joining plate that is joined to an inner wall surface of the second wall portion and an inner wall surface of the second member;

wherein the first flange and the second member are joined to each other via a plurality of first melted and solidified portions formed along the longitudinal direction,

wherein the first joining plate and the inner wall surface of the first wall portion are joined to each other via a second melted and solidified portion,

wherein the first joining plate and the inner wall surface of the second member are joined to each other via a third melted and solidified portion, and

wherein at least a part of the second melted and solidified portion and at least a part of the third melted and solidified portion are positioned in a region between two first melted and solidified portions adjacent to each other in the longitudinal direction.

2. The automobile member according to claim 1 ,

wherein the second melted and solidified portion and the third melted and solidified portion are formed in a spot shape.

3. The automobile member according to claim 2 ,

wherein in the longitudinal direction, a position of the second melted and solidified portion and a position of the third melted and solidified portion are the same as each other.

4. The automobile member according to claim 3 ,

wherein when the shortest distance between two first melted and solidified portions adjacent to each other in the longitudinal direction is Lf1, the second melted and solidified portion and the third melted and solidified portion are disposed in a region between a position separated from a middle point between the two first melted and solidified portions adjacent to each other to one side in the longitudinal direction by 0.8×Lf1/2and a position separated from the middle point to the other side in the longitudinal direction by 0.8×Lf1/2.

5. The automobile member according to claim 1 ,

wherein the second melted and solidified portion and the third melted and solidified portion are formed in a bead shape.

6. The automobile member according to claim 1 ,

wherein the second flange and the second member are joined to each other via a plurality of fourth melted and solidified portions formed along the longitudinal direction,

wherein the second joining plate and the inner wall surface of the second wall portion are joined to each other via a fifth melted and solidified portion,

wherein the second joining plate and the inner wall surface of the second member are joined to each other via a sixth melted and solidified portion, and

wherein at least a part of the fifth melted and solidified portion and at least a part of the sixth melted and solidified portion are positioned in a region between two fourth melted and solidified portions adjacent to each other in the longitudinal direction.

7. The automobile member according to claim 6 ,

wherein in the longitudinal direction, a position of the fifth melted and solidified portion and a position of the sixth melted and solidified portion are the same as each other.

8. The automobile member according to claim 7 ,

wherein when the shortest distance between two fourth melted and solidified portions adjacent to each other in the longitudinal direction is Lf2, the fifth melted and solidified portion and the sixth melted and solidified portion are disposed in a region between a position separated from a middle point between the two fourth melted and solidified portions adjacent to each other to one side in the longitudinal direction by 0.8×Lf2/2 and a position separated from the middle point to the other side in the longitudinal direction by 0.8×Lf2/2.

9. The automobile member according to claim 6 ,

wherein the fifth melted and solidified portion and the sixth melted and solidified portion are formed in a bead shape.

10. The automobile member according to claim 1 ,

wherein the second member is a hat-shaped member having a first flange, a second flange, a first wall portion erected from the first flange, a second wall portion erected from the second flange, and a web connecting the first wall portion and the second wall portion to each other,

wherein the first flange of the first member and the first flange of the second member are spot-joined to each other, and the second flange of the first member and the second flange of the second member are spot-joined to each other,

wherein a width WL (mm) of the first wall portion of the first member and a width WS (mm) of the first wall portion of the second member satisfy the following Expression (1),

wherein the first joining plate is joined to the first wall portion of the first member and the first wall portion of the second member, and

wherein the second joining plate is joined to the second wall portion of the first member and the second wall portion of the second member,

0< WS/WL< 0.8   Expression (1).

11. The automobile member according to claim 1 ,

wherein the second member is a rectangular flat sheet extending in the longitudinal direction and is divided into a first flange joint portion, a second flange joint portion, and a central joint portion between the first flange joint portion and the second flange joint portion along a width direction of the second member,

wherein the first flange joint portion of the second member and the first flange of the first member are spot-joined to each other, and the second flange joint portion of the second member and the second flange of the first member are spot-joined to each other,

wherein the first joining plate is a sheet material having an L-shaped cross section and is joined to the first wall portion of the first member and the central joint portion of the second member, and

wherein the second joining plate is a sheet material having an L-shaped cross section and is joined to the second wall portion of the first member and the central joint portion of the second member.

12. The automobile member according to claim 1 ,

wherein the first joining plate and the second joining plate extend from one end portion toward the other end portion of the automobile member in the longitudinal direction over a length ranging from 100 mm to 600 mm.