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Advances in Materials Science and Engineering
Volume 2013, Article ID 746187, 8 pages
http://dx.doi.org/10.1155/2013/746187
Research Article

Employing the Waves to Measure Longitudinal Residual Stresses in Different Depths of a Stainless Steel Welded Plate

1Department of Mechanical Engineering, Semnan Branch, Islamic Azad University, Semnan 35131-37111, Iran
2Faculty of Manufacturing Technologies, Technical University of Košice with a Seat in Prešov, Bayerova 1, 080 01 Prešov, Slovakia

Received 23 February 2013; Accepted 9 July 2013

Academic Editor: S. Miyazaki

Copyright © 2013 Yashar Javadi and Sergej Hloch. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ultrasonic stress measurement is based on the acoustoelasticity law which presents the relationship between the stress and acoustic wave velocity in engineering materials. The technique uses longitudinal critically refracted ( ) waves that travel parallel to the material surface. The wave is a bulk longitudinal wave that propagates within an effective depth underneath the surface while the penetration depth of a wave depends on its frequency. It is possible to measure the residual stress in different depths by employing different frequencies of the waves. This paper evaluates welding residual stresses in different depths of a plate made of austenitic stainless steel (304L). The penetration depths are accurately measured for the waves produced by 1 MHz, 2 MHz, 4 MHz, and 5 MHz transducers. Residual stresses through the thickness of the plate are then evaluated by employing four different series of transducers. It has been concluded that the method is nondestructive, easy and fast, portable, readily available, and low cost and bulk measuring technique which can be accurately employed in through-thickness stress measurement of austenitic stainless steels.