Characterization of austenitic stainless steel welds for ultrasonic NDT

Electricite de France has started a study in collaboration with the Metallurgical and Materials Physics Study Group (GEMPPM) of INSA-Lyon, to evaluate the effect of metallurgical structures of austenitic stainless steel welds on wave propagation for application to ultrasonic nondestructive testing. Experimentally, the anisotropic and heterogeneous characteristics of austenitic welds together with a coarse-grained structure (elongated and oriented grains) lead to the following phenomena: scattering, attenuation, skewing, splitting, and divergence of the ultrasonic beam. To study and predict these phenomena, simulation studies are most helpful. The theory of wave propagation into anisotropic and homogeneous media already allows the prediction of beam skewing and divergence effects. When considering the more complicated case of heterogeneous anisotropic structures, simulation studies require realistic descriptions of the various kind of weld structures which can be encountered. The present paper discusses th...