Measurement of residual stresses in materials and welded elements using ultrasonic method

The application of an ultrasonic non-destructive method for residual stress (RS) measurements has shown that, in many cases, this technique is very efficient and allows measuring the RS both in laboratory conditions and in real structures in field for a wide range of materials. Using this technique, one can measure the RS at the same points many times, studying for instance, the changes of RS under the action of service loading or effectiveness of stress-relieving techniques. The ultrasonic computerized complex (UCC) for non-destructive measurement of residual and applied stresses that was developed recently includes a measurement unit with transducers and basic supporting software. The developed system allows measuring the RS either averaged through thickness or in surface or subsurface layers and displaying the results in a form of a continuous curve on the screen of the instrument. The present version of UCC allows measuring the averaged through thickness biaxial RS in plates 2 - 150 mm thick and surface/subsurface RS at the predetermined depth. The results of ultrasonic RS measurement in large scale welded specimens and structures are also discussed in this paper.