No abstract

This work deals with the characterization of ductile damage in Aluminum 6061-T6 alloy. In this paper we discuss the stress triaxiality effect on the initiation and the evolution of damage through a sequence of tensile tests conducted on round specimens with different rate of trixialities and tearing tests on precracked Compact Tension specimens. Scattering of ductility and toughness values was highlighted between the three characteristic directions studied in this topic. Based on the experimental results, numerical simulation has been performed in order to analyze and predict ductile fracture initiation of this aluminum alloy by simulating void growth according to the Rice-Tracey micromechanical model. The numerical simulation was conducted in two steps: first the critical void growth ratio (R / R0)c was evaluated for tensile cylindrical specimens with different degrees of triaxiality and then used to analyze crack growth initiation on Compact Tension specimen. Due to the Al-6061-T6 highly sensitivity to triaxiality, a necessary adaptation of the Rice-Tracey model’s coefficient was made.

No abstract

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.