Z. Gao, J. Huang, Y. Wu, Shanghai Jiaotong University, Shanghai, China
Rivet joint technology has now been applied in the automotive industry and aerospace for many years. Laser welding has developed to an advanced level of maturity. Laser spot welding taking place rivet joint have some potential advantages include time saving, reduction cost, material usage and weight and so on. Commercially available LY12 aluminum alloy is selected as the workpiece which typical used in aircraft structures, rivetes, hardware, truck wheels, screw machine products and other miscellaneous structural applications, 2mm and 1.2mm two kind of different thickness materials are welded by special pulse controlled laser spot lap joint welding. The energy, time of pulse, that is on-time and defocus are varied in order to obtain a good weld profile, decrease porosity and cracking. The causes of porosity and cracking in the weld and HAZ are described. Macrograph and microstructure of weld are analyzed at different welding process parameters by optical microscopy and SEM, and inclusions and precipitates among the weld are observed by SEM with an EDAX analysis. Meanwhile mechanical properties such as, hardness test and shear strength are tested. Furthermore, shear strength of rivet joint and laser spot welding are compared.
Summary: 1. From this research, summarize the relationship between laser pulse energy, time and defocus with weld depth, width and porosity.
2. Phase, inclusions and precipitate identify by SEM after laser spot welding finish.
3. Hardness and shear strength are test,shear strength test result confirm the advantage of laser spot welding than rivet joint.
