Numerical simulation and experimental study of hybrid laser-electric arc welding between dissimilar Mg alloys

This work aims to establish a suitable numerical simulation model for hybrid laser-electric arc heat source welding of dissimilar Mg alloys between AZ31 and AZ80. Based on the energy conservation law and Fourier’s law of heat conduction, the differential equations of the three-dimensional temperature field for nonlinear transient heat conduction are built. According to the analysis of nonlinear transient heat transfer, the equations representing initial conditions and boundary conditions are obtained. The “double ellipsoidal heat source + 3D Gaussian heat source”combination was chosen to construct the laser-electric arc hybrid heat source. The weld bead morphologies and the distribution of temperature, stress, displacement and plastic strains are numerically simulated. The actual welding experiments were performed by a hybrid laser-electric arc welding machine. The interaction mechanism between laser and electric arc in the hybrid welding of Mg alloys is discussed in detail. The hybrid heat source can promote the absorption of laser energy and electric arc in the molten pool, resulting in more uniform energy distribution in the molten pool and the corresponding improvement of welding parameters. This work can provide theoretical guidance and data supports for the optimization of the hybrid laser-electric arc welding processes for Mg alloys.

激光脉冲对碳电极活化的研究

用１．０６μｍ波长的激光脉冲对玻璃碳电极、碳纤维电极进行了照射处理，处理后的碳电极表面活性有很大改善，Ｆｅ３＋／２＋、抗坏血酸的电极反应速率显著提高。初步认为，这种结果是在瞬间强激光的作用下，清除了表面惰性层，改变了表面微结构，暴露出更多的活性质点所致。