Abstract: Ultrasonic inspection on the welded seam of austenitic stainless steels is a difficult and hot issue since the typical anisotropic behaviors will appear in this kind of welded joint. The propagation behaviors of ultrasonic beam in the tubing weldment with austenitic buttering are investigated with the help of multi-Gaussian beam models. The anisotropic coefficients used in the multi-Gaussian beam model are discussed and provided. The beam propagations in Lucite wedges, buttering layers and base steels are simulated, and the beam steering and focusing influences due to both of the curved surface and the anisotropic behavior are analyzed in detail. Furthermore, an ultrasonic measurement model for the tubing weldment with austenitic buttering is developed by combining the multi-Gaussian beam model and a scattering model with the separation variable method. This model can be used to predict the testing signals from the side-drilled holes below the anisotropic buttering layer. Also the accuracy of the provided model is verified by the comparisons of the model predictions with the experimental results, and the signal amplitude and phase of the both are in good agreement.

Key words: Austenitic stainless steel, Buttering weldment, Multi-Gaussian beam model, Ultrasonic measurement model