Weld geometry and tensile strength in laser welded thin sheet metals

Weld geometries and their effects on the ultimate tensile strength (UTS) of welded specimens were studied experimentally for type 316 stainless steel sheets. Bead on plate welding with 0.1 and 0.2 mm thick workpieces and lap welding with 0.1 mm thick workpieces were carried out. The results showed that the strength of lap welds is influenced by the weld geometry to a large extent. A three-dimensional quasi-steady state heat conduction model was developed to understand the heat flow mechanism during laser welding of sheet metals of finite thickness. The temperature distribution and weld geometry were calculated using the mathematical model and the theoretical results were found to compare well with experimental data. More energy is used to produce melt pools in thinner workpieces than in thicker ones. The model can be used to select suitable process parameters to achieve a predetermined UTS by controlling the weld geometry.