| 5083 aluminum alloy is a kind of high-Mg rust-proof aluminum alloy with high specific strength,high fatigue strength,good corrosion resistance and good welding performance,so it is widely used in the fields of industrial manufacturing and military equipment.The aluminum alloy products used in these fields are generally treated with anodic oxidation,and they also generally adopt laser welding for the connection of structures.Production practices suggest that direct welding on the anodic oxide film of aluminum alloy leads to poorer welding quality compared to the welding on anodic oxide film-removed aluminum alloy substrate.Therefore,in order to improve the welding quality of 5083 aluminum alloy,laser cleaning is adopted to effectively and environmentally remove the anodic oxide film.The combined effects of vaporization mechanism,laser shock wave and transient thermal shock peeling lead to the removal of anodic oxide film from the surface of 5083 aluminum alloy.In terms of laser cleaning effect,it is considered that the closer is the surface's oxygen content after cleaning to that of the substrate,the better the cleaning effect will be.Through laser cleaning parameter combinations,laser array cleaning is conducted on the 5?m-thick anodic oxide film on the surface of 5083 aluminum alloy,and an optimum combination of laser parameters is preliminarily identified for laser cleaning;single-factor experiments are designed,and it is concluded that the laser cleaning effect improves and then deteriorates with the increase in the laser power or with the increase in the pulse width.Further,the optimal combination of laser parameters for the laser cleaning of 5?m-thick anodic oxide film is determined and validated,namely,laser power(P)=42w,scanning velocity(V)=4725mm/s,frequency(f)= 250 KHZ,pulse width(T)=100ns.Next,based on the same laser welding parameters,the laser-cleaned 5083 aluminum alloy sheets and the 5083 aluminum alloy sheets without being laser cleaned are welded respectively via seamless self-fluxing welding method to explore the influence of laser cleaning of anodic oxide film on the welding quality of 5083 aluminum alloy laser welding.According to the results,the laser-cleaned 5083 aluminum alloy sheet's laser welding has smaller welding width and welding thickness compared to that of the 5083 aluminum alloy sheet without being laser cleaned.After the anodic oxide film is removed through laser cleaning,the porosity of welding seam can be significantly reduced;no matter whether the anodic oxide film is removed through laser cleaning or not,during the laser welding process,the hardness on the cross section of welding seam is distributed as follows: hardness of weld-metal zone < hardness of heat-affected zone < hardness of substrate zone.For the laser-cleaned 5083 aluminum alloy sheet,the hardness of weld-metal zone and heat-affected zones is higher than that of 5083 aluminum alloy sheet without being laser cleaned;the tensile strength of welded joints also improves by 57% after the anodic oxide film is removed by laser cleaning,compared with that of the uncleaned;ductile fracture occurs to the welded joints at the time of stretching due to micro-porous gathering no matter laser cleaning is implemented or not;?m-thick anodic oxide film will significantly reduce the welding quality of laser welding.To sum up,the process of removing 5?m-thick anodic oxide film from the surface of 5083 aluminum alloy by laser cleaning is studied,and the influence and action mechanism of laser cleaning of anodic oxide film on the welding quality of laser welding are explored;it is concluded that the removal of anodic oxide film by laser cleaning before laser welding will greatly improve the welding quality. |
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