Research on Flexible Phased Array Technique for Testing the Inserted Fillet Welds

It is difficult to guarantee the welding quality of inserted fillet welds because of its special geometry and complicated stress condition. For the low detection efficiency of the conventional ultrasonic testing method, the false detection and the missed detection of the flaws occur frequently. For the above reasons, a new testing method is presented in this paper which based on the common structure characteristics of inserted fillet welds. The key point of this new method is to put the flexible phased array on the internal surface of the tube during the detection. The beam focusing model of flexible phased array is theoretically analyzed. The simulation on the acoustic field and defect response with CIVA software are completed to determine the phased array parameters, including array elements, array element size, deflection angle, ultrasonic frequency and so on. Then, a special ultrasonic detection system is designed and fabricated for testing the inserted fillet welds. In addition, the specimen of the inserted fillet welds with artificial flaws is manufactured and experiment research is carried out. Finally, the quality detection of actual product is successfully implemented. The results indicate that this technique can effectively detect the typical flaws such as crack, slag, porosity, etc.