A laser-EMAT system for ultrasonic weld inspection

Non-destructive testing of welded metal components is an area where signifi cant cost savings can be made if preparation costs can be minimised. The la rgest cost associated with preparation is grinding off the weld cap in orde r to facilitate the detection of defects that may be present just under the cap. In addition, there are also potential savings to be made if the actua l testing time can be reduced or if the tests can be performed at elevated temperatures beyond which conventional contacting ultrasonic techniques can be practically used. This paper describes a non-contacting NDT method usin g a pulsed laser and an electromagnetic acoustic transducer (EMAT) which ha s the potential to interrogate the entire cross-section of a weld. (C) 1999 Elsevier Science B.V. All rights reserved.