Research On The Laser Welding Between Different Metal Material

As a new type of welding method, laser welding have many advantages than traditional welding method in a high energy density, low heat input, narrow heat affected zone, high-aspect ratio, and so on. With the advent of kW continuous CO2 laser, kilowatt-Nd:YAG laser, laser welding technology has been widely used in aerospace, shipbuilding, automobile manufacturing, plastics processing and other fields.In this paper, laser optimal parameter selection methods of laser welding is studied, and the theory of laser deep penetration welding, heat conduct welding is introduced. Based on the heat transfer theory in heating materials by laser, calculating formulae and selecting methods of laser's power density, pulse shape, pulse width, and defocus amount and focal length of focusing lens have been derived. Also, Laser spot welding technology is introduced and welding process of various forms materials is analyzed.According to calculating formulae and selecting methods of laser's power density, pulse shape, pulse width, and defocus amount and focal length of focusing lens, the dissimilar metals, Copper-Aluminum board, welding experiment is finished by using laser spot welding technology. And the samples are tested in anti-tensile, temperature changes and high temperature resistant.The conclusion of analysis of test results: According to this theory ,the sample at 100℃, tensile strength properties and temperature changes properties are good; at 200℃, temperature changes properties is good; between 200℃-400℃, temperature changes properties is general; at 500℃, the sample itself is shedding in its own gravity and uniform heating after high temperature treatment. Though the trial achieves some success, the material is too hard to be bended near the welding spot and there are still joint cracks at some spots, which need to be improved in the future.These theories and experimental analysis provide a basis for the laser welding machine's design, manufacture, apply.