Experimental, numerical, and analytical investigations on the charge weld evolution in extruded profiles

Charge welds are unavoidable product defects generated during the continuous extrusion of metallic materials that extend to a certain variable length and that are marked by lower mechanical properties than the base material. The portion of the profile containing the charge welds thus needs to be scrapped and an accurate prediction of this portion becomes mandatory, not only for the final user of the profile, in order to avoid in-service product failures, but also for extruders and die makers in order to increase the process efficiency. In the present work, four case studies carried out in the years by the authors on the prediction of the charge weld extension are reviewed and systematically compared in terms of experimental and numerical results. Data are furthermore compared with the predictions of analytical models reported in literature for the scrap length calculation and of an industrial empirical rule based on the extrusion ratio. Final aim of the work is to highlight potentials and limits of each predictive method and to assess their applicability in the everyday industrial practice.