Quality prediction of longitudinal seam welds in aluminium profile extrusion based on simulation

The paper presents the analysis of different quality criteria of longitudinal seam welds that appear in aluminium profiles during extrusion using porthole dies. The physical background and limitations of the most widely used criteria are discussed. A new improved dimensionless welding quality criterion that takes into account the unbalances of metal flow is proposed by the authors. It is based on analysis of simulation results obtained by QForm Extrusion FEM software and experiments. The authors also introduced a comparative classification of longitudinal seam welds based on the practical application of profiles. It allows the user to characterise the quality of a seam weld depending on its specific application and make a decision regarding its suitability for certain technical requirements. The proposed criterion has been approved by industrial experiments for different types of profiles. Particularly its numerical critical value has been found for AA 6082 alloy. The quantitative correspondence between welding types and values of developed criterion is also defined.