Identification of the Gradient of Mechanical Properties in Electron Beam Welded Joints of Thick Al6061-T6 Plate

In this paper, the mechanical behavior of the different metallurgical zones of the Electron Beam welded joint of thick Aluminum alloy 6061-T6 plates was identified by means of a single tensile test on round specimen oriented transversely to the fusion line. Commonly, the analysis of tensile tests allows a global characterization of the weld joint behavior. However, in this work, specific post processing of results was developed in order to determine in addition to standard findings, the local behavior on each position of the weld joint. The identified behavior laws are then simplified using the Hollomon analytical model. Hence, an evolution of the Hollomon parameters (n, K) along the weld joint is proposed. To validate the experimental methodology and the analytical approach, the experimental tensile test on crossed tensile specimen was numerically modeled. Experimental results and numerical simulations were in a good agreement which denotes of the reliability of the identified gradient model. In a second step, for more accurate characterization of the electron beam welded joint, an optimized geometry of tensile specimen was numerically dimensioned and tested. From these analyses, a relatively large heat affected zone with significant gradients of mechanical properties was highlighted. The fusion zone was qualified as the softest metallurgical zone but with a high strain hardening effect in contrary with the heat affected zone where the fracture occurs.