Evaluation of residual stress states in welded parts - Using ultrasonic techniques

The acousto-elastic effect of ultrasonic waves enables the nondestructive evaluation of stress states in a surface layer up to about 10 mm thickness as well as in the bulk of components. Ultrasonic techniques have already been proved as on efficient nondestructive tool to evaluate stress states in screws, rails, plates, rolls, tubes and other components. In order to evaluate stress states in welded parts, the complex interaction of stress, texture and changes of the microstructure in and close to a weld seam has to be investigated in more detail. There are some theoretical and experimental investigations which show very encouraging results. But because of the complexity of different influences on the ultrasonic measuring quantities, it is felt that only the joint activities of different ultrasonic specialists will achieve a technique for a nondestructive evaluation of surface and bulk stresses in welded parts. (IZFP