A METHOD FOR DETECTION OF DEFECTS DURING WELDING BY ULTRASONIC TESTING

摘要

The invention relates to a method of on-line detection and control of defects forming in an object during a welding operation, comprising the steps of providing an ultrasonic testing system having multiple transducers (6,7,8),the transducers (6,7,8) being movable in correspondence with the movement of a welding torch; transmitting a first ultrasonic sound wave (4) via a first transducer (6) directed to an unwelded area (9) of the object; transmitting a second ultrasonic sound wave (4) via a second transducer (7) directed to a molten pool (10); transmitting a third ultrasonic sound wave (4) via a third transducer (8) to a just-solidified part (11) of the weld; capturing the sound waves reflected from the three different areas (9,10,11) in the respective transducers (6,7,8) from which the ultrasound waves (4) were initially transmitted, the reflected signals representing the defects or discontinuities prevailing or developing in the corresponding areas (9,10,11); characterized by comprising converting the captured sound signals into electric signals and displaying the electric signals in respective display devices (13,14,15), the display devices (13,14,15) each having echo indicators (12,16,17); comparing the electric signals with the echo indicators (12,16,17) in the display devices (13,14,15) to determine the magnitude of defects or discontinuities; and adjusting the welding parameters corresponding to the detected defects to avoid formation of further defects, wherein a positional value (W2) of the echo-indicator (17) at the display device (15) if greater than that (WI) of the echo-indicator (12) at the display device (13), the resultant weld is considered to be defect-free.