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Improving Weld Quality by Arc-Excited Ultrasonic Treatment ZHANG Chunlei,, WU Minsheng, DU Jinglei Abstract Ultrasonic treatment of the solidifying metal is a promising method for improving the quality of fusion welding. A method to combine the ultrasonic waves to the welding process using arc-excited ultrasonic emission, called arc-ultrasonic, was high frequency modulation of the arc-plasma. The effects of arc-ultrasonic on the weld including the fusion zone, the partially melted zone and the heat-affected zone are described. The arc-ultrasonic energy changes the weld microstructure. In the fusion zone, the primary dendrite arm spacing decreases significantly and more acicular ferrite appears. In the partially melted zone, a large amount of fine grains appear. In the heat-affected zone, the width of the tempered zone increases with increasing modulation frequency and the microstructure is refined. The results show that arc-ultrasonic is a new and effective way for improving weld quality. Keywords arc-ultrasonic; fine grain; fusion zone; partially melted zone; heat-affected zone

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