Some studies on weld bead geometries for laser spot welding process using finite element analysis

Nd:YAG laser beam welding is a high power density welding process which has the capability to focus the beam to a very small spot diameter of about 0.4 mm. It has favorable characteristics namely, low heat input, narrow heat affected zone and lower distortions, as compared to conventional welding processes. In this study, finite element method (FEM) is applied for predicting the weld bead geometry i.e. bead length (BL), bead width (BW) and depth of penetration (DP) in laser spot welding of AISI 304 stainless steel sheet of thickness 2.5 mm. The input parameters of laser spot welding such as beam power, incident angle of the beam and beam exposure time are varied for conducting experimental trials and numerical simulations. Temperature-dependent thermal properties of AISI 304 stainless steel, the effect of latent heat of fusion, and the convective and radiative aspects of boundary conditions are considered while developing the finite element model. The heat input to the developed model is assumed to be a three-dimensional conical Gaussian heat source. Finite-element simulations of laser spot welding were carried out by using Ansys Parametric Design Language (APDL) available in finite-element code, ANSYS. The results of the numerical analysis provide the shape of the weld beads for different ranges of laser input parameters that are subsequently compared with the results obtained through experimentation and it is found that they are in good agreement.