Joining structure

1. A joining structure comprising:

a first metal sheet; and

a pair of second metal sheets,

wherein each of the pair of second metal sheets is overlapped on the first metal sheet in a state where an end surface of one of the second metal sheets and an end surface of the other second metal sheet face each other,

wherein the end surfaces that face each other are integrally joined to the first metal sheet by means of a single mass of melted metal, and

wherein the pair of second metal sheets is a pair of inward flanges provided in a material-axis-direction end part of a metal-formed sheet having a constant quadrangular sectional shape in the material axis direction.

2. The joining structure according to claim 1 ,

wherein the pair of second metal sheets is present on the same plane.

3. The joining structure according to claim 1 ,

wherein a distance between the end surfaces that face each other is equal to or more than 0 mm and less than 1 mm.

4. The joining structure according to claim 1 ,

wherein the following Conditional Expression (a) is satisfied when a sheet thickness of the pair of second metal sheets is defined as t (mm) and the distance between the end surfaces that face each other is defined as G (mm),

0 mm 2 ≤G×t< 1 mm 2   (a).

5. The joining structure according to claim 1 ,

wherein the distance between the end surfaces that face each other is less than 40% of the sheet thickness of the second metal sheets.

6. The joining structure according to claim 1 ,

wherein an extension length of the end surfaces that face each other is equal to or more than 3 mm and less than 50 mm.

7. The joining structure according to claim 1 ,

wherein the metal-formed sheet is a side sill of an automobile vehicle body, and the first metal sheet is a portion of a lower A pillar of the automobile vehicle body.