Identification of the Weakest Metallurgical Zone on Fracture Behavior of an Undermatched Welded Joint

Abstract

In the particular case of welded structures, the tearing resistance is strongly dependent on the mismatch of welded joint. In this context, the fracture behavior of an undermatched electron beam (EB) welded joint on thick plate of aluminum alloy 6061-T6 used for structural components of experimental nuclear reactors was investigated through experimental and numerical approaches. The local constitutive behavior of the various zones of the welded joint is characterized by means of a new measurement prototype and the corresponding Hollomon parameters are determined. Toughness tests are then carried out on Compact Tension specimens for different configurations of initial crack. The transferability of the identified fracture toughness at initiation of each metallurgical zone is studied through J1c tests on Single Edge Notched Tension specimens. For a reliable interpretation of toughness tests, Finite Element analysis is performed to account for the multimaterial effect not considered in a standard analysis. From these experimental and numerical results, a contrast in tensile and fracture behavior is highlighted which makes difficult the identification of the weakest metallurgical zone of the welded joint on fracture behavior.