A study of laser welding modes with varying beam energy levels

The energy of a laser beam is generally calculated based on the laser power and its processing speed. In this work, the laser welding modes such as conduction, conduction-penetration, and keyhole welding of thickness 1.6, 2, and 2.5 mm AISI304 stainless steel sheets, respectively, are studied at different beam energy levels. A series of bead-on-plate trials are conducted using a 500W continuous wave Nd:YAG laser source to study the beam-material interaction and the influence of laser power and welding speed on the formation of weld pool. In addition to the experimental study, a three-dimensional finite-element model is developed to analyse the transient heat flow and to predict the formation of the weld pool. The correlation among the parameters including laser power, welding speed, beam incident angle, and the characteristic geometry of weld pool are established. Temperature-dependent thermal properties of AISI304 stainless steel, the effect of latent heat of fusion, and the convective and radiative aspects of boundary conditions are considered in the model. The heat input to the developed model is assumed to be a three-dimensional conical Gaussian heat source. Finite-element simulations are carried out by using finite-element code, SYSWELD, and FORTRAN subroutines available within the code are used to obtain the numerical results. The result of the numerical analysis provides the shape of the molten pool with different beam energy levels, which is then compared with the results obtained through experimentation. It is observed that the results obtained from finite-element simulation and the experimental trials are in good agreement.