Torsion beam axle having ring member friction-welded to trailing arm

The present invention relates to a torsion beam axle comprising a torsion beam whose both end parts have a circular cross section and a pair of trailing arms which are integrally coupled to the both end parts of the torsion beam, wherein the trailing arm is formed with a circular joining surface which has at least a predetermined width in a radial direction to correspond to the end part of the torsion beam, and the torsion beam axle further comprises a ring member having axially one end surface which is correspondingly contacted to the circular joining surface and coupled thereto by friction welding, and the other end surface which is correspondingly contacted to the end part of the torsion beam and welded thereto. Therefore, an enhanced coupling force between the trailing arm and the torsion beam which are of different materials therebetween can be maintained.