Technology Research Of Rotary Friction Brazing

At present the usual methods for the connection of the shaft and ring workpieceare adhesive, key coupling, interference connection, overall brazing, ect. But eachmethod has its limitations, so it is necessary to adopt a new method to join them. Inthis paper, by using self-made device based on brazing and friction welding theory,rotary friction brazing method is proposed firstly to brazing the shaft and ringworkpiece with the green and energy-efficient friction heat as a heat source. The effectof process parameters on the surface temperature and joint properties is studied, andthe result is compared with the traditional furnace brazing.The results show that rotating friction brazing can achieve the connection ofshaft and ring workpiece. When the rotating speed is1180r/min, radial pressure is1220N, the keeping pressure during the welding process is1220N, the welding gap is0.12mm, appearance of weld is good, temperature distribution of joint is uniform, theaverage shear strength of the joints is28.81MPa, which is reaching96﹪of the shearstrength of furnace brazing joint(30.33MPa).Through microstructure observing the rotating friction brazing joint and thefurnace brazing joint, the results show that the microstructure at the center of brazingzone consist of Sn solution and Pb based solid solution, as well as some coarseparticles with Sn and Pb composition, the number of coarse particle in the furnacebrazing joint is less, and the particle distribution is not uniform, but the number ofcoarse particle in the rotating friction braze joint is quantity, particle distribution isuniform, which is beneficial to improve the properties of welding joint. Both sides ofthe interface line are straight in furnace brazed joints, while the shape of interface lineis different on both sides of the rotating friction brazed joints, interface line on theside of shaft type workpiece is wavy, and interface line on the side of circular typeworkpiece is straight.SEM observation of rotary friction braze joint fracture surface shows that whenthe mechanical properties of the joint are high, there are some dimples in the fracture,the fracture site appears in the center of brazing metal. When the mechanicalproperties of the joint are poor, there are some smooth plane fracture zones in thefracture, the fracture morphology shows lamellar dissection, the fracture mode is brittle fracture, and the fracture site is in the interfacial region close to the base metal.