INSMO special report: Production of artificial defects and their applicability to qualification of ultrasonic inspection

The qualification of non-destructive test systems shall demonstrate in a realistic and reliable way the performance of different parts of the application. An inspection trial known as "practical test", where the component and accessibility as well as the defects resemble those of the real inspection situation, can be used as a very effective and concrete evidence of the capability of the system. Therefore the qualification activity but also the development of NDT applications require nowadays very often production of test samples and also manufacturing of different defects or defect simulations in them. Ultrasonic testing is usually used to detect different types of cracks. Real cracks are difficult to produce in a controlled way and therefore artificial defects with simple geometry are often used as reflectors to simulate the defects in the component. The ultrasonic response of the reflectors should be similar to real defects as much as possible. In practice the simulation is not always ideal and thus the imperfection and limitations should be known. The work described in this paper covers searching and testing of suitable defect and reflector manufacturing techniques for qualification sample production and examining their suitability and applicability in different situations.