Modelling tools for ultrasonic inspection of bimetallic welds

Audrey Gardahaut , Karim Jezzine , Didier Cassereau

Modelling tools for the ultrasonic inspection of bimetallic welds, which link ferritic and stainless steel parts, are presented. Those structures are difficult to control as anisotropy, heterogeneity and grain orientation distribution can impede the detection of defects. Dynamic ray tracing is an efficient method to simulate the ultrasonic propagation in welds. The weld can be described as a set of several anisotropic homogeneous domains with a given crystallographic orientation. In this case, the rays travel in straight lines inside each homogeneous domain. Nevertheless, if the domains are small compared to the wavelength and exhibit strong variations in grain orientation, a chaotic behaviour of rays may be observed, leading to inaccurate results. To overcome this problem, a smooth description of the grain orientation has to be used. To achieve such a description, the grain orientations are computed on a grid thanks to image processing techniques performed on a macrography of the weld. In this paper, we first present the image processing techniques that have been implemented. Then, we expose our first modelling results using dynamic ray tracing on a smooth description of the grain orientation and compare it to results obtained using a set of homogeneous domains to describe the weld and experimental results.

Mots clés: Dynamic Ray Tracing Method; Bimettallic Welds; Anisotropic and Heterogeneous Media; Simulation

Domaines: Acoustique [physics.class-ph]

Audrey Gardahaut, Karim Jezzine, Didier Cassereau. Modelling tools for ultrasonic inspection of bimetallic welds. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811043⟩