铝合金激光+GMAW复合热源焊熔池形态的分析
毕业论文关键词：铝合金；激光焊；GMAW；复合焊；热源模型；熔池形态
Abstract Aluminum alloy has the features, including low density, high strength, large thermal conductivity, corrosion resistant capability is strong, Thus the welding of aluminum alloy structure is widely used in industrial products. As a new type of welding process, Laser+GMAW welding composite heat source combines laser welding and the double advantage of GMAW welding, and overcomes the disadvantages of both, and produces the additional energy synergy effect, and is with implementation of aluminum alloy the great potential of high quality, high efficiency welding. But the laser+GMAW composite brazing a single heat source, and there is a lot of process parameters which is difficult to optimize, and those hinder the process of popularization and application. Comprehensive consideration of aluminum alloy composite thermal physical properties and welding process characteristics, based on FLUENT software, laser+GMAW is established, the highly effective aluminum alloy composite three-dimensional transient heat weld pool fluid flow numerical model. The model considers the arc heat input and laser heat input and the coupling effect between and among thermal enthalpy drop; Double ellipsoid heat source model is used to describe electric arc heat input; Using the conical heat source model to describe thermal input; Will drop as a transitional process from the molten pool of a particular area of liquid metal flows into the molten pool temperature process; According to the role of vapor reaction determine the pore morphology. With the model of aluminum alloy under different process parameters with the laser+GMAW composite welding heat source of thermal field and flow field numerical simulation, and compared with the experimental results, the size of the welding so that the model is verified and optimized. The results showed that: when the laser power is 3000W, the small size of molten pool, the shallow hole depth; holes front wall metal has always been to melt the bottom flow of the molten pool near the back wall of metal flow is relatively complex; when the laser power is 5000W, molten pool holes in repeated hole instability process and closed. small hole at the bottom of the front wall of metal flow and then at the back flow of molten pool, or along the thick wall upward mobility; after hole wall metal flow is associated with small hole depth and dynamic behavior.
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