Measurement of residual stress in the inner wall of steel pipe by ultrasonic

In this paper, we proposed a new method to measure the residual stress of the inner wall of steel pipe based on acoustoelasticity theory, and established a measurement system. In the system, two probes were used, one is a transmitter and the other one is a receiver. Critically refracted longitudinal wave was emitted in the surface and subsurface of the inner wall of the pipe. Carrying with the probes, a crawling device moves along the pipe bus directions was utilized. The system could then measure the distribution of residual stress in the inner wall of steel pipe along the generatrix direction. The feasibility of measuring the longitudinal residual stress in the inner wall of steel pipe with this system had been proved.