Mechanism Research On Controlof TC4 Sheet Buckling Deformation With Impactingand Rotating Extrusion Method During Welding

Thin-walled titanium alloy welding structures have been widely used in the aviation, aerospace and chemical industry due to the advantages such as light weight, high strength and coefficient of load. However, large residual stress and wave-like deformation are produced in the weldment after welding. Therefore, the residual stress and deformation of TC4 sheet sizing 200mm×100mm×1mm are studied in this paper.Firstly, the condition of the plate instability is studied, from which the critical buckling stress is obtained. Secondly, experimental studies on control TC4 plate buckling deformation with impacting rotation and compression method during welding are carried out. Finally, the mechanism of impacting rotation and compression is analysised.Thermal buckling finite element model is set up based on Abaqus software, then the critical buckling stress of thin plate is calculated, which is smaller than the one calculated with direct pressure. During the simulation of conventional TIG welding of TC4 plate, the magnitude of deflection is 14.35mm, while the average deflection is 14mm in practice.The optimal process parameters of impacting rotation and compression method during welding are established in experiments, that is, the voltage of electric impulse hammer is taken as 180V, the location of impacting rotation and compression is 75mm at the rear of welding pool. The magnitude of deflection is reduced to about 2mm while 5mm after welding. By tensile, metallographic, fracture and residual stress test, the properties of the joint with the impacting rotation and compression method during welding are not reduced, while the residual stress, lower than 25MPa, is greatly reduced. Sometimes, the residual stress even change to compressive stress in the center of weldThe force generated by impacting rotation and compression method couples with the heat stress, which makes the plastic deformation in the weld is more easier. At the same time, the yield strength decreases with the temperature and the impacting zone is in high temperature, which both control the residual stress and buckling deformation of TC4 with interaction of these two factors. The optimal temperature range established by the finite element method is 600-700℃,which is in the unloading zone. Because of the small temperature difference, the residual stress produced in the unloading elastic recovery zone is small. The simulation results present in this paper are verified to be in good agreement with the experiment values.