Effect of surface roughness on ultrasonic echo amplitude in aluminium-copper alloy castings

In the present investigation, the influence of test surface roughness on ultrasonic back-wall echo (BWE) amplitude in Al-4.5% Cu alloy cast specimens has been studied. The results indicate that as the value of surface roughness of the specimen increases, the value of the relative BWE amplitude at a given probe frequency decreases. However, under the present set of experimental conditions, the decrease in BWE amplitude with the increase in surface roughness of the test specimen is found to be appreciable at 10 MHz probe frequency.