RELATION BETWEEN ULTRASONIC BACKSCATTERING AND MICROSTRUCTURE FOR POLYCRYSTALLINE MATERIALS

Within the framework of the maintenance of its nuclear power stations, EDF uses ultrasonic inspections to make sure of the lack of defects. But in some cases, the structure of polycrystalline materials can produce the scattering of the ultrasonic wave which results in an important attenuation of the signal and the appearance of structural noise. Industrial inspections on various components demonstrated the importance of these physical phenomena which can lead to decrease the performances of the ultrasonic inspections. In a first approach, the polycrystalline material studied is the Inconel 600@ alloy, which has an isotropic and homogeneous microstructure. Some mock‐ups with different grain sizes, were experimentally characterized to measure the ultrasonic attenuation and the structural noise. The measurements show the influence of the mean grain size on the values of attenuation and noise. At last, a 2D finite element modeling at a microstructural scale using ATHENA software, gives first coherent results.