Investigation of 3D anisotropic electrical conductivity in TIG welded 5A06 Al alloy using eddy currents

Electrical conductivity undergoes changes in the weld zones of the material. In this study, its anisotropic components along longitudinal, transverse and through-thickness directions have been investigated nondestructively using circular eddy current probe with Hall Effect sensor. The electromagnetic forward model has been solved with material resistivity input profiles corresponding to tensile and compressive residual stresses in a typical welded joint. For reconstruction of 3D anisotropic electrical conductivity, constrained linear least square optimization has been used. Compared with measurements based on calibration with homogeneous specimen or calculated assuming isotropic material properties in forward model, the results indicate that change in conductivity is significantly larger. A quantitative comparison is made between results based on isotropic and anisotropic material models. The conductivity mapping is required for residual stress measurement in components and structures.