High Frequency, Angle Beam EMATs for Weld Inspection

Accompanying the requirements for higher quality welds in structural parts, there is a growing demand for more rapid and automatic methods for their nondestructive inspection. Conventional X-ray methods are inherently slow and are difficult to automate. Furthermore, they often present a safety hazard that adds mass and bureaucracy to the application of the method. Ultrasonics, on the other hand, can be very rapid, is easily made automatic, and does not present any safety problems. Its main drawbacks are the requirement for a carefully aligned transducer, a plumbing system to supply liquid couplant, and an educated operator to maintain the alignment and coupling throughout the scan of the weld line. Since electromagnetic acoustic transducers (EMATs)1 eliminate the need for a couplant fluid, they would appear to offer a major improvement for weld inspection technology.