It is used for the permanent fixation of two or more pieces.

Rivet is a semi-permanent metal mechanical fastener, formed by a cylindrical body and a head, made of steel, aluminum, copper or brass.
The rivets rigidly attach parts or plates, mainly in metal structures.

Steel rivets with round head, with standard diameters of 10 to 36 mm (d) and standard lengths of 10 to 150 mm (L) are used in metal structures.