Ultrasonic wave simulation using numerical model based on grain structure in dissimilar metal welding and its experimental validation

The ultrasonic testing (UT) for a dissimilar metal welding part is difficult due to the acoustic anisotropy and local heterogeneity. The ultrasonic wave in the weld is skewed along crystallographic directions and scattered by metal grain boundaries. Here we propose a UT simulation tool to predict wave propagation in the weld. The tool is based on the explicit finite element method (FEM) and an image-based modeling. The image-based FEM uses the voxel element of adequate size to model the shape of metal grains. Crystallographic information obtained by pictures of the EBSP, photos after chemical etching, among other are fed into the image-based FEM directly, and then the wave propagation in the weld are calculated. The accuracy of the image-based FEM simulation is validated with visualizations of wave propagation by a laser vibrometric measurement. Here an austenitic stainless steel specimen whose crystallographic direction is in one direction is used for the validation. (author)