Development of ultrasonic inspection techniques using a matrix array transducer for acoustical anisotropic media

We have been developing ultrasonic testing techniques for acoustical anisotropic media. In this study, we have applied the phased array method using a matrix array transducer to directionally-solidified austenitic steels, i.e. homogeneous anisotropic media, as a first step. Behavior of ultrasonic wave propagation in anisotropic media was analyzed by means of point-source modeling and ray tracing. Insonification angle was optimized in consideration of beam divergence effect based on results of the point source modelling; delay laws and image distortion were calculated by propagation time of group velocity vectors using the ray tracing. We confirmed improvement of sizing accuracy by experiments for artificial notched in directionally-solidified austenitic steels. (author)