Numerical modelling of shielding gas flow and heat transfer in laser welding process

Paper in proceeding, 2012

In the present study a three-dimensional model has been developed to study shielding gas in a laser welding process using computational fluid dynamics. Laser heating of titanium alloy Ti6Al4V was done by imposing a volumetric laser heat source. The model was implemented in the open source software OpenFOAM and applied to the investigation of the shielding gas behaviour over the base metal. Three different cases regarding the outlet shape of the shielding pipe were studied. In some laser welding processes a shielding plate is used to help protecting the welded area. The plate injects the additional shielding gas screen during the welding process. This plate is also considered in the modelling as the fourth case. The influence of the shape of the pipe outlet is discussed.The simulation results confirmed that the shielding plate can protect the welded area by covering the welding path with shielding gas. However, the simulation showed that the shielding gas leaving the plate flows towards the keyhole. It can thus bring some fumes over the keyhole which is not desired since it can make it difficult to track the welding with optical method.