ABSTRACT This paper deals with the influence of the water contact on wet underwater welding. An example of a rectangular plate with a bead on plate weld is presented. The welding residual stresses are calculated using the finite element method. The results of the" wet underwater welding process are compared to those of the dry welding process. The instationary temperature field and the welding residual stresses are mainly influenced through the water contact. The results show the importance of welding residual stresses in the defect assessment of wet underwater welded structures. The maximum tensile residual stress of the wet weld is about 20 % higher than that of the dry weld in the vicinity of the weld seam.
INTRODUCTION The high flexibility and the low costs of wet underwater welding are important advantages compared with dry underwater welding. But the use of wet underwater welding techniques is restricted by the quality of welds. The heat transfer to water mainly affects the welding residual stresses and the microstructure of wet welds. The influence of the water contact on the welding residual stresses of underwater welds is investigated in this paper. The heat transfer from a heated body to a surrounding fluid is, of a rather complex nature due to phase change of fluid. Therefore, no closed form solution of the heat transfer in case of wet underwater welding has been found until today. But the influence of the water on the temperature distribution is of a special interest. The temperature gradient in time and space is important for the material properties in the heat affected zone and for the welding residual stresses. An example of a bead on plate weld with the Plasma-MIG welding technique (Draugelates et al.,1992; Draugelates et al., 1993) is investigated. The results are calculated for a dry welding process and for a wet (dry spot) underwater welding process.