Effect of Welding Residual Stress for Ultrasonic Testing Echo of Fillet Weld

After theoretical analysis of the abnormal echo in ultrasonic testing of fillet weld, and practical confirmation, verified that welding residual stress influenced the transmission characteristic of ultrasonic waves in steel, thus the cause of the abnormal echo was correctly judged and the testing result was exactly evaluated. It was point out several problems shall be serious and be studied intensively.