Evaluation of welding residual stress in stainless steel pipes by using the LCR ultrasonic waves

Abstract

The ultrasonic residual stresses evaluation is based on the acoustoelastic effect that refers to the velocity change of the elastic waves when propagating in a stressed media. The experimental method using the longitudinal critically refracted (LCR) waves requires an acoustoelastic calibration and an accurate measurement of the time-of-flight on both stressed and unstressed media. This paper evaluates welding residual stresses in welded pipe-pipe joint of austenitic stainless steel. The residual stresses in inner and outer surface of pipes were evaluated by LCR ultrasonic waves by using 1 Mhz, 2 Mhz, 4 Mhz and 5 Mhz transducers. It has been shown that the difference in residual stresses between inner and outer surfaces of pipes and also between base metal and welded zone can be inspected by LCR waves.