DOI: 10.14489/td.2015.12.pp.076-079

Stepanova L.N., Lebedev E.Y., Kabanov S.I., Ramazanov I.S., Kireenko V.V., Moiseev A.A., Vonsovskii A.V., Kanifadin K.V.
MULTIPLE-PASS WELDING DEFECTS MONITORING TECHNOLOGY BY ACOUSTIC EMISSION METHOD
(pp. 76-79)

Abstract. The development of the technology of non-destructive testing (NDT) of multi-pass welding defects is connected with new promising methods of developing and implementation of joint welds real-time quality estimation. It is necessary for zero defect number requirements of welds fitting to develop defects location technology that can be used synchronously with multi-pass welding process. Such a task can be solved by application of acoustic emission (AE) method that is capable to keep track of weld defects generation by means of registering acoustic signals which are radiated during phase transformations in metals. In practice, a weld has usually a form of a complex closed curve that makes registered AE signals more difficult to locate. Furthermore, it is necessary to estimate detected defects danger rate to reject defective weld in time. Critically dangerous defects are to be detected during formation or the work content of their correction is increasing sufficiently. That is why the problem of increasing of the AE method noise immunity for detection of welding defects during formation is important and robust estimation method of located signals sources parameters is demanded. The article deals with the defects detecting method for multi-pass welding process of closed circular with use of the digital system for acoustic emission diagnostic STsAD-16.10. Automatically controllable “floating” threshold of selection provides reliable filtering of noise and stable AE signals registration process. Welding defects are detected by AE signals cumulative amplitude of distribution calculated by their location. Two-lag method of auto definition of signals arrival time to piezo-antenna sensors allowed to increase location precision of detected AE sources. Welding defects has been simulated for method availability check by violating the welding process and foreign inclusions as titanium wire and slag pieces embedding to the weld. Polar coordinates defects location facilitated AE data comparison with confirmatory NDT methods results. Ultrasonic and X-ray nondestructive testing methods has been used. NDT methods results comparison indicated considering method sufficient reliability and efficiency for multi-pass welding quality in real-time monitoring.

Keywords: multiple-pass welding, defect, fault injection, location, acoustic emission.

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