Forming Mechanism And Experimental Research On Laser Powder Filling Welding Of Aluminum Alloy

Aluminum alloy has the advantages of low density,high specific strength,good machinability,etc.,and is widely used in marine ships,aerospace,civil automobiles and other industrial fields.At present,laser welding is mainly used in the industrial connection technology.There are many problems in laser welding of aluminum alloy,such as splash,porosity and collapse,among which the collapse problem is an important factor that affects the weld performance and will limit the wide application of aluminum alloy.It is a scientific problem that needs to be solved urgently in laser welding of aluminum alloy at present.Therefore,the experimental research on laser powder filling welding of 6061-T6 aluminum alloy with 1mm thickness is carried out,which is expected to solve the problem of collapse in the process of laser welding of aluminum alloy and improve the mechanical properties of the weld.The research is mainly carried out from the following aspects.Firstly,a single factor experimental study was carried out to analyze the influence law of laser power,welding speed,powder feeding amount and shielding gas flow rate on the weld formation.Then,the influence degree of each process parameter on the ratio of upper weld width to lower weld width,surface excess height and back bulge was analyzed by orthogonal test,and a set of suitable welding process parameters were determined for the subsequent research.Secondly,according to the selected welding process parameters,a comparative test with and without powder is carried out,and the feasibility of powder filling process is determined by observing the fullness degree of powder filling welding seam.Then,the microstructure of different areas of the weld was observed by metallography.The melting effect of filler powder was analyzed by scanning Al,Mg and Si elements near the fusion line of the weld with or without powder by SEM.With the help of microhardness test and tensile test,the influence of powder filling welding on the mechanical properties of the weld was obtained,and the fracture morphology was analyzed.Finally,the heat transfer model of laser welding of aluminum alloy is established to simulate and study the temperature field.Comparing the simulation results with the test results,it is verified that the simulation is accurate and reliable.The distribution characteristics of welding temperature field are analyzed.The thermal cycle curves of different positions in the cross-section of the weld were studied to obtain the temperature gradient and grain growth rate,so that the metallographic structure of different areas was deduced,which provided theoretical support for the analysis of the weld structure and morphology.