Ultrasonic evaluation of solid-state welds

Ultrasonic techniques for evaluating the quality of solid-state weld interfaces have been investigated over the past several years. Promising results have been obtained on a variety of solid-state welds by extracting features from the ultrasonic wave forms and applying pattern recognition algorithms to separate acceptable from unacceptable welds. The general conclusion is that the ultrasonic features most sensitive to interfacial bonding are those dependent on high frequencies. However, no single feature has been discovered that is adequate to yield separation of good vs. poor welds, since the microstructural response is also frequency dependent.