Characterization of seam weld quality in AA6082 extruded profiles

The performance of the extruded profile in subsequent manufacturing processes such as bending or forming is limited by the strength of the weakest weld. In literature, owing to the great variety of extruded profile shapes, different techniques for testing welds have been proposed: tensile tests, bending tests or wedge insertion among the others. In this paper the production of an I shape extruded profile, suitable for mechanical testing, has been described and analyzed. This profile was produced both with and without material welding, by the use of a bridge before the flat die, thus reproducing the typical welding condition of a hollow profile extrusion. Different preheating temperatures of the billet, production rates and welding chamber heights were used and their influence on the weld quality was analyzed. The welded profiles were characterized by means of both tensile tests (strength, elongation and fracture strain) and crack propagation tests, in order to understand the relationships between process parameters, die design and weld properties. The results were compared with unwelded profiles. Metallographic analyses were also performed in order to explain fracture mechanisms.