Ultrasonic sizing of embedded vertical cracks in ferritic steel welds

Experimental Investigations to Evaluate the Validity and Performance of NDT Procedures for In-Service Inspections

“…The specimens containing the embedded vertical cracks were examined using two ultrasonic techniques based on transit time: flaw tip echo method and mode conversion method. Excellent agreement between the estimated crack height and the actual crack height was obtained with an accuracy of ±1 mm [8].…”

“…When an ultrasonic beam of a certain angle meets a defect, an echo is obtained from that defect edge. The height of the defect is geometrically determined by using the refraction angle of the probe and the distance traveled by the beam from the position assigned to the maximum echo value until the end of the defect [8].…”

Quantitative Ultrasonic Evaluation of Surface-Breaking Crack Height Based on Neural Network

“…According to the principle of Huygens, when the reflection plane at the end of crack is vertical to the incident beam, the intensity of reflected wave will be enhanced, while the diffracted wave will be weakened even vanished. Hence, tip echo waves are usually taken into consideration [2]. In the current work, the surface-breaking crack is supposed to initiate at the bottom surface, here, h is the vertical height of the crack, w 1 , w 2 is the beam path of the upper and the end tip of the crack, respectively, β is the refraction angle, T the height of specimen.…”

“…A great deal of failures for welding structure and in-service component are caused by the extension of internal and surface-breaking cracks [1,2], in order to prevent components from causing unexpected catastrophe, detection and evaluation of surface-breaking cracks are thus of great importance for industrial assessment. Various nondestructive techniques employing ultrasonic, eddy current, X-ray diffraction and magnetic powder have been broadly implemented in real engineering fields [3].…”

“…Frequently-used ultrasonic techniques for evaluation of cracks heights include tip echo method on basis of bulk shear and longitudinal waves [4], surface Rayleigh waves approach [5], back-scattering resonance [6] and mode conversion method [2,7], in which, tip echo method with shear wave is in general use. It is obvious that the accuracy of previous studies is largely determined by human operator with particular training and experiences.…”