Analysis of ultrasonic C-scan image features and image processing for spot welding

A focused ultrasonic transducer is used for precise,step-by-step,surface ultrasonic scanning inspection of spot welds.Two methods for generating characteristic data matrices of ultrasonic echo signals of the spot welds are established.One is based on the ultrasonic echo amplitude and the other is based on frequency spectrum.Both methods generate scanning inspection data arrays and provide clear C-scan images.Based on C-scan noise reduction,the Krisch edge detection operator for edge detection-a gray window transform-reflects the shapes of the spot welds and allows quantitative determination of their size.The method based on the ultrasonic echo amplitude provides a greater quantitative detection accuracy.