Test of Focusing on Phased Array Ultrasonic Without Using Wedge

ASTM E2491—2008 provides the standard guide for evaluating performance characteristics of phased array ultrasonic testing instruments and systems. In this paper，we use the phased array technology to measure the beam focusing capability of phased array ultrasonic in direct contact condition according with ASTM E2491—2008, so that we can identify the causes and effects of the focusing capability in the factors such as the number of elements and the focal depth. In the test, the block designed in ASTM E2491—2008 was used, the elements used were 8,16 and 32,and the focal depths used were 10, 30, 50, 100, 150 and 200 mm, respectively. Through the test, we could find the focusing phenomenon clearly in the near field and we could not find this phenomenon outside the near field. When the elements used in the test increased, the focusing ability of the PAUT system increased as well. In the near field, when the focal depth increased, the focal spot size increased too, as well.