The Study On Laser Welding Technique Of Pure Aluminum

In recent years, due to the rapid development of laser technology, laser weldingtechnology is also more and more widely used. Compared with the conventional weldingmethod, laser welding has the advantages of small heat input, focused power, big weldingdepth, narrow welding joint, small heat affected area, noncontact welding. Therefore, laserwelding can be competent for some traditional methods which material is not easy to weld.Because aluminum is a metal which hardness is especially low, it is easy to heatconduction and keep labile form, and chemical properties is lively, it usually form a verythin oxide film on the surface, Make welding aluminum difficult. It often occur thephenomenon such as expansion deformation on welding joint when we use sometraditional methods to weld (such as TIG welding). While using laser welding, thesedefects will be greatly reduced. This experiment is to study laser welding process of1mmand2mm pure aluminum plate, its mark is1050A.This paper adopts three kinds laser model for welding experiment of aluminum plate.It is respectively: Single-mode fiber laser welding, Multimode200μm fiber laser weldingand Multimode400μm fiber laser welding. First, in the surface of aluminum plate forwelding process optimization, mainly change the parameters such as laser power, weldingspeed and defocusing amount to find out the influencing factors of each weldingappearance. Through comparison and analysis, we can find out the better processparameters. Within the scope of the better process parameters are for laser tailor-weldedaluminum contrast test and find out the optimal process parameters. We will research themicrostructure and mechanical property on the welding joint by metallographic microscopeand hardness tester, to analyze the causes of welding joint porosity, and through theexperiment to find the solution.Through comparison and analysis, for laser welding of aluminum, the faster weldingspeed, the lower porosity, the effect of welding is the most ideal, when laser power is3000W, welding speed is7m/min, defocusing is0. From fusion line to weld center area, it is mainly in growth with columnar crystal structure, in the center of weld area, it is mainlyin growth with isometric crystal structure. From parent metal to heat affected area, and thento weld center, the hardness gradually reduce, softening phenomenon in weld joint willappear.