Quantitative estimation to circular holes in steel for non-destructive testing using ultrasonic phased array

This paper studied how to quantify circular hole in steel with ultrasonic phased array technology. Ultrasonic pulses emitted from array elements will be reflected by defects, cracks or something else. The echo signals will carry the information of the reflector. When the reflector is a circular hole, two echoes will be received. From the two echoes we may obtain the size of the circular hole. We used the difference of the two signals' sound path to estimate the size of a series of circular holes with different diameters in steel. The experimental results for circular holes in steel showed that the size of these holes could be obtained with an error within 0.1mm by this quantitative method. The minimum hole with diameter 0.5mm in the sample could also be quantitatively estimated. Finite element method was used to simulate the ultrasonic pulses propagation in order to quantify defects better. The results of the simulation agreed well with the experiments, which was very valuable for further study in quantifying defects using ultrasonic phased array.