Research On Ultrasonic Assisted Laser Welding Process Of 6061 Aluminum Alloy

With the increasing popularity of the concept of protecting the environment,"light weight" has gradually become a popular term.The laser welding technology of aluminum alloys has been widely used for this reason.However,due to the special physical and chemical characteristics of aluminum alloys,It often faces many problems during laser welding,such as pores,cracks,and joint softening.The problem of deformation when welding aluminum alloy thin plates is even more headache.These problems have always plagued many scholars.In order to solve the above problems,this paper applies ultrasonic technology to the laser welding process and builds an ultrasonic assisted laser welding test platform.At the same time,a 1mm thick 6061 aluminum alloy sheet is us ed as the research object to carry out the ultrasonic assisted laser welding test.(1)The characteristics of ultrasonic wave and its effect on liquid medium and the mechanism of ultrasonic wave in welding process are introduced.The application and research status of ultrasonic technology in the field of post-weld treatment to reduce deformation,metal solidification and welding are introduced.An ultrasonic assisted laser welding test platform was built.(2)Using the single factor test method,the infl uence of different ultrasonic power,laser power,welding speed,defocusing amount and shielding gas flow rate on the welding deformation of 1mm thick aluminum alloy sheet was studied.The results show that the increase of ultrasonic power and welding spee d will significantly reduce the deformation of the specimen;the increase of laser power will increase the deformation of the specimen;when the defocus is zero,the deformation of the specimen is the largest,positive and negative The amount of deformatio n when defocusing will decrease and the amount of deformation when negative defocusing is slightly smaller than that of positive defocusing;the increase of the flow of shielding gas slightly reduces the amount of deformation of the specimen.(3)Five factors and five levels of orthogonal tests were designed to explore the influence of the above five parameters on welding deformation.Through analysis of the test data,it was found that for the deflection deformation,the influence of various factors on the order from large to small is welding speed,laser power,ultrasonic power,shielding gas flow,and defocusing amount;and for angle deformation,the order is welding speed,laser power,ultrasonic power,defocusing amount,shielding gas flow rate.And the optimal process parameter combination that can obtain the minimum deformation is obtained.The flexural deformation of the corresponding specimen is0.42 mm,and the angular deformation is 0.26 mm.(4)A single factor test method was used to investigate the influence of ultrasonic power on the quality and microstructure of the weld formation.It was found that ultrasonic waves will cause the weld to collapse and the degree of collapse will increase with the increase of ultrasonic power;the increase of ultras onic power It can reduce the columnar crystals in the weld fusion zone and eventually be completely replaced by equiaxed crystals.At the same time,it can also refine the size of the equiaxed crystals in the central area of the weld;not only that,the in crease in ultrasonic power can also significantly improve the mechanics of the weld.