Investigation of Clamping Effect on the Welding Sub-surface Residual Stress and Deformation by Using the Ultrasonic Stress Measurement and Finite Element Method

In this study, sub-surface residual stress and deformations, produced by the welding process, are investigated by using ultrasonic stress measurement method and finite element (FE) simulation. The FE analysis is employed to evaluate the residual stresses and deformations caused by the tungsten inert gas welding of 304L stainless steel plates. Residual stresses obtained from the FE analysis are then used to validate results of the ultrasonic stress measurement method, which is fulfilled by employing longitudinal critically refracted (LCR)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$L_{CR})$$\end{document} waves. By using four different frequencies of ultrasonic probes, the sub-surface residual stress fields are mapped in four different depths of the examined material. Two different plates are welded with and without the use of clamp to investigate the clamping effect on the residual stress and deformation. By employing the through-thickness measurement of residual stresses, the clamping effect on the sub-surface distribution of the residual stresses is also studied. As a result, the LCR\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$L_{CR}$$\end{document} ultrasonic method is accurate enough to distinguish the surface and sub-surface residual stresses in the clamped and non-clamped welding plate. Consequently, the longitudinal residual stresses have been increased by using the clamp during the welding of stainless steel plates. However, using the clamp significantly influences the amount and distribution of longitudinal residual stress in the base metal. Regarding the welding deformation results, it has been concluded that employing the clamp considerably decreases the deformations of the stainless steel plates.