Time of Flight Diffraction (TOFD) is a reliable nondestructive ultrasonic testing (UT) method used to determine flaws in welds. TOFD is used to find the location of a reflector with an ultrasonic pulse. It is used for welded structures such as pressure vessels and structural steel. TOFD’s main principle is to emit sound waves into a component and to measure the time from them to return. The difference of TOFD from other UT methods is that, rather than measuring only for the high amplitude sound waves that reflects off of the back of the component, it instead measures the response time of low amplitude waves that are diffracted by the tips of cracks. So; TOFD uses a pair of ultrasonic transducers, one as a transmitter and the other as a receiver. The low frequency waves propagate at an angle and only diffract back to the receiver if they hit a defect. If this happens, the time it takes for both waves to make it to the receiver can be used to create a complete image of the weld and identify the size and location of the damage. TOFD is one of the fastest methods of nondestructive testing because, unlike other types of UT methods, generally only one scan is required to find any defect information within the weld. It can locate and measure the size of many different types of defects with incredible precision. As a result; it can be said that having a high degree of repeatability, any flaws can be tracked over time.
Anahtar Kelimeler: Time of Flight Diffraction (TOFD), ultrasonic testing, non-destrcutive method, welding flaws
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