Thermo-mechanical Analysis of the LaserWelding of Stainless Steel 304
Y. Javid and M. Ghoreishi
An uncoupled thermo-mechanical finite element (FE) model has been developed to simulate the laser beam welding (LBW) process of AISI 304 and calculate the transient temperature profile and residual stresses due to the laser welding process. At first, a non-linear three-dimensional (3-D) transient thermal model is developed, which calculates the temperature distribution in the local weld area and predicts the keyhole and weld bead size and shape. After thermal analysis, the FE method is verified through the experimental work. Subsequently, using the thermal history of the thermal analysis, a mechanical analysis of the LBW butt-joint is performed, from which the joint residual stresses are calculated. Then the predicted residual stresses are compared with those of the experimental works. The thermal load attributed to laser beam was implemented to the work-piece by using a developed subroutine. Due to the high temperature variations and the material phase changes occurring during the laser welding process, the thermal and mechanical material properties are introduced temperature dependent. All the major physical phenomena associated to the LBW process, such as heat radiation, thermal conduction and convection heat losses are taken into account in the developed thermal model. Finally a good accordance was found between simulated and experimental results, shows that the model is appropriate for the laser beam welding process simulation. Also the results show that the temperature profile and weld bead dimensions are strong function of the heat source and conductivity of material. It is also found that the laser power and welding speed have a significant effect on residual stresses.
Keywords: Laser beam welding (LBW), stainless steel, simulation, finite element (FE), keyhole, weld pool, residual stress.