Study On The Laser Brazing Process Of 6061-T6 Aluminum Sheet With Filler Wire

Aluminum alloy has a lot of advantages such as light weight,high strength,good formability,corrosion resistance and other,has been more and more widely used in the field of aerospace,electronics industry and automobile manufacturing.The assembly of the car body for the accuracy of the plate is very demanding,there is large thermal deformation exists in the traditional fusion welding,serious restrictions on the aluminum alloy sheet in the automotive body application.And laser brazing with a small deformation,good weld appearance and other characteristics,which provides a new technical means for the connection of thin aluminum alloy.This article for the car white body commonly used lap joint form,the influence of process parameters on the forming and joint performance of brazing seam of aluminum alloy was studied.And the process range of good brazing forming can be realized.It has certain guiding significance for the promotion and application of thin aluminum alloy in automobile white body.In this paper,the effects of laser operating position,brazing speed,wire feed speed,laser power and defocus amount on the forming of aluminum alloy laser brazing are studied.And the common forming defects in the brazing process are summarized and analyzed.The results show that: A good position of the laser is a prerequisite for obtaining a good brazing seam,and the matching between the welding parameters is a key factor.The ratio of wire feed speed to brazing speed(K value)is between 1.8 and 2.1,The ratio of laser power to brazing speed(line energy E value)is between 130 and 160 J/ mm,can obtain a good brazing seam.On the basis of the study of brazing seam forming,the microstructures of the joints were observed by an optical microscope and a scanning electron microscope,the brazing interface were further analyzed by EDS.The results show that: The brazing seam and the lower plate have a distinct interface for a typical brazed connection,SEM found that the interface is a white bright band interface layer,and with the increase of heat input,the interface layer thickness increases;By EDS phase analysis,it can be found that the interfacial diffusion occurs at the interface.The quality of aluminum alloy laser brazed joint under different laser power was evaluated by the tensile strength,microhardness and corrosion resistance of the joint.The results show that: The increase in laser power contributes to the improvement of the tensile strength of the joint in the case of avoiding excessive melting of the base metal,The heat affected zone(HAZ)of the joint has softened,and the joint softening area increases with the increase of laser power,overaged brings serious strengthening phase particles grow is the main reason for the occurrence of HAZ softening;The corrosion resistance of the joint decreases with increasing laser power,the excessive melting of the base material and the large grain size caused by the higher power are the main reasons for the decrease of the corrosion resistance of the joint.