For nondestructive evaluation (NDE) of defects in rods a new technique is presented using ultrasonic C-Scan system. Improved image processing and analysis method in C-scan allow more information to be extracted for characterization of defects. Mechanical arrangement has been made which allows scanning of rod along the circumference as well as along the axis. The arrangement can be attached to any existing C-scan system.

A number of aluminum and steel rods in diameters ranging from 10 mm to 50 mm and about 300 mm in length have been used. Defects of varying dimensions and shape such as notches, holes, cut were produced in the rods. Experiments were performed using 5 MHZ and 20 MHZ broad band transducers excited by short duration negative spike. Transducer and test rod were fully immersed in water as in immersion testing.

Longitudinal waves are transmitted into the curved surface of rod in pulse echo mode to get the C-scan image. Scanned image is analyzed to evaluate the defects. Actual and observed defects size are compared. Factors effecting the test accuracy and deciding the minimum diameter of rods that could be tested using the present technique are discussed. The method has been found to be superior than the helical scanning method from defect characterisation point of view.