The Laser Additive Manufacturing Technology Of Aluminum Alloy With Melting Wire

The laser additive manufacturing technology of aluminum alloy with melting wire using the laser beam as the heat source,and using 4043 aluminum alloy wire as additive manufacturing material,can rapidly and directly manufacture workpiece with complex structure and good mechanical properties,greatly improve the utilization rate of materials and shorten the production cycle.The subject based on robot laser additive manufacturing technology of aluminum alloy,taking aluminum alloy depositional unit and multilayer deposit as the research object,to research the influence of additive manufacturing process parameters on forming size and mechanical properties,and the microstructure of multilayer deposit was analyzed.Firstly,the research of the forming rule of depositional unit was carried out,to study the effects of different process parameters on the forming process of depositional unit.Within 0?20 mm,the increase of the defocusing amount can effectively reduce the splash;laser power,laser scanning speed and wire feeding speed need to be matched;the distance of the laser and wire determines whether the depositional unit forming is continuous,and the depositing unit was well formed in the range of 1 to 2 mm;when the shielding gas flow within the scope of 15?20 L/min,the protection effect is best.Secondly,multilayer deposit additive manufacturing process test was carried out.The influence of laser scanning speed,laser power,wire feeding speed,wire feeding mode and waiting time between layers on the forming lines and uniformity of multilayer deposit were discussed.The slower the laser scanning speed,the higher the deposition of the material,resulting in the insufficient spread of the molten pool.The increase in laser power will result in extra heat input applied to molten pool,and the increase in fluidity of the molten pool increases the deposition width.The effect of wire feeding speed on the size of the deposition is larger,as the feed speed increases,the increase of depositional metal will increase the inhomogeneity of the deposition.Then the effect of process parameters on the mechanical properties of multilayer deposit was studied and the microstructure was analyzed.The top layer of the multilayer deposit is equiaxed grain,and the metallographic structure in the middle and bottom regions is the columnar crystals along the temperature gradient.The bottom hardness value of the multilayer deposit is higher,and the grain size varies in different regions in the deposition layer.The fracture morphology of tensile specimen is mainly a large number of equiaxial dimples,which is typical ductile fracture.