摘要
A normal ultrasonic transducer of 5 MHz is modified using different delay lines and wedges design （made from Perspex）. Such modification is for ameliorate the capability of the transducer to detect sub-surface flaws. Some prepared Aluminum pieces were subjected to different crosshead speed （200 and 350 ram/rain）. The ultrasonic pulse echo method was used at room temperature. The measurements have been done before and after each tensile stress. Flaws were found at different distances from the specimen＇s surface. Results showed that such delay lines and wedges were suitable to detect sub-surface flaws that were initiated under the effect of stress. In addition, a crosshead speed increment caused more sub-surface flaws formation.
