Ultrasonic Characterization of Residual Stress and Flaws in Cast Steel Railroad Wheels

Two ongoing safety problems in cast steel railroad wheels are the buildup of residual stress in the rim and the growth of cracks in the tread. Electromagnetic-acoustic transducer (EMAT) technology shows promise for the nondestructive evaluation of both. The acoustoelastic effect generates a small but measurable acoustic birefringence in the presence of stress fields, while Rayleigh waves are sensitive to surface disruptions from flaws. Experimental investigations of both problems indicate that these noncontact inspection methods lend themselves to automated use in a railyard.