Numerical Simulation Of Temperature And Stress Field Of Double Laser Welding With Filler Wire

The laser welding process of aluminum alloy exist a lot of problems ,that is poor stability,serious pores sand large welding deformation , these problems limiting their application. Therefore, currently applications of laser welding technology of aluminum alloys focused on the dual-beam laser welding with filler wire. Although the dual -beam laser welding of aluminum may reduce or resolve poor stability of laser welding process,large welding deformation and other serious problems. However, the acquirement of temperature distribution, residual stress distribution and deformation of laser welding process for aluminum alloy by the experiment is not merely difficult, but is blind. Therefore, the text adopt the FEM to simulate the temperature field and stress-strain field of dual-beam laser welding with filler wire of the butt and the T-joint of aluminum to provide theoretical guidance for the experiment.By analyzing the physical characteristics of laser welding, determine the heat source model of the double-beam laser welding with filler wire, adopt the life and death element method to simulate the deposition process, taking physical properties of materials with variation of temperature, convection and radiation heat transfer and latent heat into the account. Based on the finite element software Marc, written Fortran subroutine to implement mobile heat load, by comparing and calculating the fusion line and the actual of butt joints and temperature cycling curves verify the accuracy of the model. On the basis of comparative analysis the welding temperature field distribution and weld cross-section of different arrangement of beams and energy, optimizing the technology and a reasonable way of heat load: when two beams cross into the 45 ? angle, the energy ratio is 2 : 1 ,the weld width of upper surface is smaller, but the dorsal melting width is greater .Based on the analysis of aluminum alloy double-beam laser welding temperature field establish the mathematical model of stress and strain fields of dual-beam laser welding of aluminum. The residual stress of double-beam laser welding of butt joint show that the distribution area of residual stress of parallel arrangement is larger than the region of 45°arrangement and the peak (157MPa) is less than the peak (176MPa) of 45°arrangement, after welding the butt joints occur a certain amount of angular distortion. The angular distortion of butt arrangement after welding is more.Analysis the strategies ,that is how to control the penetration of the flange and web of double-beam welded T-joint, the analysis think the angle should be 40°-50°, the offset distance at the flange should be 0-0.3mm, while the distance at the webs should be 0-0.2mm. the stress and strain field of T-joint are analyzed, results show that: T-joint welding residual stresses are mainly distributed in the vicinity of the fillet weld, and the maximum residual stress at the web reached 249MPa, after welding there are certain angle deformation and bending. At the flange edge the largest Y displacement reached 0.13mm.