Generation of Guided Waves Using Magnetostrictive Nanostructured Sensing Elements for Pipe Inspection

The investigation addresses the generation of guided wave in an aluminium pipe using rapidly quenched magnetostrictive ribbons prepared by melt spinning technique. The experimentation involved development of a sensing device which has the capability of excitation of guided waves as well as sensing the back-wall signals using the magnetostrictive sensor elements. The device comprised of a transmitting coil ‘TC’, a receiving coil ‘RC’ and a biasing coil ‘BC’ placed between TC and RC. The sensor materials used in the study were rapidly solidified nanostructured ribbons of Co36Fe36Si3Al1B20Nb4, Fe78Si8B14, Fe80Si8B12 and Fe40Ni40B20 alloys. The effect of as-spun and annealed ribbons on the sensor output signal was studied. The Fe80Si8B12 ribbons showed highest back-wall signal after annealing at 400oC for 15 minutes.