Prediction of Position and Extent of Charge Welds in Hollow Profile Extrusion

In billet-to-billet direct aluminum extrusion, the high hydrostatic pressure field produces joining of the two consequent billets; however, the mechanical properties of the transition zone are lower, thus requiring the scrapping of the charge-welded segment. The localization of the segment to be discarded is a complex matter. This work aims to investigate the interaction between the different welding phenomena inside an industrial multi-profile die, in order to determine the exact position and the minimal profile length to be discarded. Experimental investigations were performed on an industrial extrusion of four hollow profiles in EN AW-6060 alloy through a multi-hole die. Location and dimension of the charge weld was retrieved and compared with finite element (FE) simulations of the process, thus evaluating the possibility of using the code as a reliable tool for the localization and determination of the scrap, particularly if new die design strategies must also be evaluated in terms of reduction of the zone extension.