Surface breaking crack characterization with TFM

Frédéric Reverdy

Senior Application and Products Engineer

A while back I had a post about surface breaking crack characterization using TFM on calibrated notches (read here). This post showed that it is possible to accurately size cracks located on the OD surface. We are now looking at a real crack inside a fillet weld with the probe positioned on the same side as the defect, the probe moves along the crack. We can see, in the left image, the position of the TFM zone at the surface of the component. The TFM image shows the crack initiated at the top surface and propagating down. We get top and bottom diffraction as well as intermediary echoes coming from the facets of the crack. It is possible to measure the height of the crack. The right image represents the Sideview. It shows the maximum along each line of the TFM image along the displacement, this way we are sure to capture the deepest diffraction echo. We can follow the evolution of the crack in the perpendicular direction. We can see that the crack gets smaller on each side of the image. This method can complementary to dye penetrant, magnetoscopy or Eddy currents to size defects after they have been found.

#Gekko #TFM #M2M #SurfaceCrack