Evaluation of Ultrasonic Method Capability in Measurement of Longitudinal Welding Residual Stress through Thickness

One of the abilities of Ultrasonic method which has been less investigated, in comparison with other residual stress measurement methods, is the residual stress measurement capability in specimen depths. this capability is due to ultrasonic waves penetration in different depths of specimen, according to their transmittance frequency. In this research, the capability of Ultrasonic method in measurement of longitudinal welding residual stress in specimen depth has been studied. For this goal, four series of Ultrasonic sensors, including 1, 2, 4 and 5 MHz were used in order to reach four depths of pieces of aluminum alloy series 5000 joined by TIG welding. Welding residual stresses were simulated in Abaqus software. Then, simulation model was validated by comparing with the results of X-ray diffraction experimental method. The validated FEM model with x-ray diffraction method was used for validation of residual stress obtained from Ultrasonic method in four depths. Finally, good agreement was observed. Ultrasonic method could measure longitudinal residual stresses with the maximum error of 12% of yield stress of aluminum plate. The accuracy of this method in measurement of the maximum longitudinal residual stress was greater than 92%.