Ultrasonic testing of austenitic stainless steel welds is often difficult because the ultrasonic beam is subjected to many perturbations : deviation, partition, distortions and sometimes ghost echoes. These perturbations are due to the anisotropic and heterogeneous metallurgical structure of the welds. We are carrying out a research program in order to evaluate the influence of the main parameters of the structure on the perturbations of the beam. This program largely leans on modeling which can bring a theoretical justification for experimental results and allows to reduce the number of required tests. We present some modeling results obtained on various types of welds with two different computer codes : ULTSON, a 2D finite element code, and CHAMP-SONS, a 3D semi-analytical one. The modeling results are compared with experiments. CHARACTERIZATION OF AUSTENITIC WELDS FOR MODELING INPUT DATA Metallurgical Structure of an Austenitic Weld This study was performed on mockups representative of 316L industrial austenitic stainless steel welds. They were manufactured using a manual welding process with coated electrodes (weld thickness 40 mm). We developed a method of characterization of the metallurgical structure of austenitic welds, which would allow to understand the perturbations of the beam and would be compatible with the needs of modeling codes. We deliberately choose a description at a macroscopic scale in order to simplify the modeling process [ 11.

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