Distortion Validation of Laser Beam Welded SS316LN Steel Plates

A finite element modelling starts with the heat equation, heat flux input and thermal modelling and the material definition. In this study a laser welding model with heat transfer is defined and analyzed for a 3mm thick SS316LN material, the temperature dependent thermal and structural properties are taken for analysis. The laser has not formed the keyhole, yet lateral conduction forms the weld bead will progress and convection and radiation from the top surface. Modelling of these thermal inputs with symmetric BC's of heat at the fusion zone centre was used in modelling ANSYS solid70 element to obtain the Thermal temperature distribution. Sequentially, this thermal load is given as input to the solid45 to obtain the structural distortion. An orthogonal Array of 9 experiments with three levels of Laser Power, Weld speed and Shield gas flow rate were conducted and analyzed. The optimum levels obtained were 2750Watts, 2500 mm/min and 10LPM. The shield gas flow rate was related to the convective heat transfer coefficient, h in the model. Experimental validation of distortion by experiments had within 8% agreement.