What is referred to when varying the position of the search unit in immersion testing?

The term that refers to varying the position of the search unit in immersion testing is angulation. Angulation involves changing the angle at which the ultrasonic waves are introduced into the material being tested. This technique is crucial in optimizing the detection of flaws by allowing the ultrasonic sound waves to interact with potential discontinuities at various angles. It helps in achieving better sound beam coverage and enhances the probability of flaw detection, especially when dealing with complex geometries or varying material thicknesses.

In immersion testing, where the transducer is submerged in a coupling medium (often water), adjusting the angle of the transducer can significantly impact the sensitivity and resolution of the inspection. By varying the angle, inspectors can effectively target specific areas of interest, making angulation a key aspect of the testing process.