TOFD technique
Representative Ultrasonic Testing of Welds
Conventional method is the ultrasonic contact pulse reflection technique using shear wave angle probe. However, if flaw is planar-shaped, for example, crack and lack of fusion, and the angle between propagation direction of ultrasonic waves and planar-shaped flaw is nearly horizontal, energy of reflected waves from the flaw is weak. As a result, it is difficult to detect the flaw.
TOFD technique is known as a highly accurate method for measuring the length and height of flaw. Because TOFD technique employs diffraction waves generated from tips of the flaw instead of reflected waves, so the gradient of flaw has little influence on the measured results.
