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Evaluation of residual stress states in welded plates using ultrasonic techniques

: Chu, S.-L.; Peukert, H.; Schneider, E.

Macherauch, E.; Hauk, V.:
Residual stresses in science and technology. Vol.1
Oberursel, 1987
Aufsatz in Buch
Fraunhofer IZFP ()
elastic constant of higher order; microstructure; residual stress state; texture; ultrasonic technique; welded plate

For the advanced safety design of technical components, the signs and the magnitudes of both, the operating and residual stress states have to be known. The knowledge of the stress state is particular important for areas with defects. In welded parts various defects like cracks, porosity, slag inclusions are oftenly found in regions near the weld seam where also high residual stresses exist. Residual stress states in and close to a weld seam are rather complex as a consequence of a variety of influencing parameters of the material, of the geometry and of the welding process. These parameters change the stress states caused by shrinkage, quenching and phase transformation processes. Although the different sources of residual stresses as well as the various influencing factors are known, it is still difficult to predict the welding stresses. Nondestructive techniques are needed in order to prove the predictions, to evaluate the stress states; or summarizing, in order to assure the qualit y of welded structures. Complementary to the destructive and x-ray techniques, ultrasonic techniques permit to evaluate not only surface stress states but also stresses in the bulk of components. Ultrasonic techniques need only short measuring times and are easy to apply, without the preassumption of specially treated surfaces. Ultrasonic techniques to evaluate (residual) stress states are applied since at least a decade. (IZFP)