Investigation of Total Welding Residual Stress by Using Ultrasonic Wave Velocity Variations

Objective of this study is prediction of residual stress in three pass welded stainless steel plates. In this approach residual stress through the thickness of the material is measured. Two 316L stainless steel plates are manufactured as the same samples. Three weld passes are applied to one of these samples. Other is zero stress state reference sample. According to the principle that Ultrasonic wave speed is constant for a material these waves are used to detect variations in the crystal structure of materials. The source of welding residual stress is welding heat. The relation between thermal stress and ultrasonic wave velocity variations are investigated. By using this relation and ultrasonic wave velocity changes between two samples, residual stress distribution throughout the welded sample is determined. 2D residual stress distribution data brought information that residual stress through the thickness of the material is high around weld beam. When compared to the previous studies on residual stress measurement, the residual stress through the thickness of the material is measured except surface residual stress. In addition, this study provides a practical approach for residual stress measurement.