Numerical simulation of welding performance for the micro welding of thin A3003 A1 sheet by Nd:YAG laser(I) (The effect of laser beam mode)

Abstract

In welding of thin A3003 A1 sheet by Nd:YAG laser beam, the laser beam mode is critical one among various welding parameters for welding process. In order to evaluate the effect of beam mode during laser welding process and to predict the welding performance by numerical simulation, a three-dimensional FDM is presented for heating with different laser pulse shape and related welding parameters.The simulation result shows that welding depth and instability were greatly affected by the change of beam mode in same welding parameters. As the beam mode approaches to a single mode structure, the welding depth and instability are increased. Meanwhile it approaches to a multi-mode structure, conduction welding pattern is obtained and the welding stability is increased. But if the pulse peak power is large enough for keyhole formation, a weld pool is suddenly overheated and evaporation is caused. Such behaviors would induce welding defects such as porosities and irregular surface roughness. Numerical simulation method can be used to predict the welding behavior of thin A1 alloy by Nd:YAG laser beam. By selection of proper laser beam mode and welding parameters, it is possible to prevent welding defects.In welding of thin A3003 A1 sheet by Nd:YAG laser beam, the laser beam mode is critical one among various welding parameters for welding process. In order to evaluate the effect of beam mode during laser welding process and to predict the welding performance by numerical simulation, a three-dimensional FDM is presented for heating with different laser pulse shape and related welding parameters.The simulation result shows that welding depth and instability were greatly affected by the change of beam mode in same welding parameters. As the beam mode approaches to a single mode structure, the welding depth and instability are increased. Meanwhile it approaches to a multi-mode structure, conduction welding pattern is obtained and the welding stability is increased. But if the pulse peak power is large enough for keyhole formation, a weld pool is suddenly overheated and evaporation is caused. Such behaviors would induce welding defects such as porosities and irregular surface roughness. Numerical simulation me...