| Laser spot welding will take the place of the traditional joining methods such as resistance welding and rivet connection for its high precision and high efficiency. Welding of aluminum is widely used in aviation manufacture.However, laser spot welding of aluminum has some problems, such as instability, porosity, crack, crater, and low tensile strength. In this paper, such as formation mechanics of various defects was studied and the methods such as pulse shaping and dual beam laser spot welding were used to resolve these problems.The experimental results indicate that, the main reason of process instability is the high reflection of aluminum, and the cascade ionizing of shielding gas when high laser power was used. The main defects of laser spot welding of aluminum are crater, hot crack and porosity which created by oxide film and keyhole instability,. The voids at fusion zone and surface crater have greatly effect on weld strength. The quality of weld was improved by using appropriate parameters and backing shielding gas.Furthermore various pulse shapes were used to improve the quality of welding. The result shows that enhance spike pulse shape can be helpful for the high reflection of aluminum. The porosity and crack can be decreased by cool-down pulse shape. Surface crater and void which created by oxide film can be reduced by ramp-up pulse shape. The porosity, crack and crater can be reduced by the saw-like pulse shape which combines the effect of cool-down and ramp-up pulse shape.At last, dual beam laser spot welding of aluminum was investigated. Using different processing parameter was studied. Compared to single beam laser spot welding, keyhole diameter can be increased by dual beam spot welding and the molten pool is stable. The porosity will be controlled. And the diameters of fusion zone become larger, so the strength of the weld joint will be enhanced. The weld joint of dual beam spot welding is better, which has fewer gas holes and the strength can increase above 40%.
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