Non-Destructive Evaluation Of Spot-Weld Quality

This chapter discusses non-destructive evaluation of spot welds, with emphasis on ultrasonic inspection of resistance spot welds in mild steel. Detection of stick welds and of small nuggets surrounded by a zinc corona are the principal challenges faced by resistance spot-weld inspection. The post-process single-element ultrasonic method is the most common inspection technique currently employed in manufacturing environments. Recent interest has centered on imaging techniques, which offer spatially resolved information and increased sensitivity, and on in-process inspection, which allows examination of the events that occur during the course of the welding process. These techniques are described and their strengths and weaknesses are discussed.