Numerical Analysis Of Temperature Field And Residual Stress Of Axial Vibration Composite Rotating Friction Stir Welding

Axial vibration composite rotary friction stir welding is developed in the traditional friction stir welding technology,by directly in the mixing head to add axial high-frequency vibration,the use of vibration to provide high-frequency small displacement and rotary motion of the composite butt welding And the addition of vibration changes the size and distribution of the heat source in the traditional welding process.At the same time,vibration as an energy into the weld,the weld area to improve the mobility of materials,refinement of the grain,can effectively improve the quality of the weld joints.In this paper,7075 aluminum alloy plate as the research object,according to the actual welding process and heat transfer characteristics,through the establishment of mathematical models.The effect of vibration on the welding temperature field,the deformation of the welding plate and the residual stress field after welding was analyzed.The influence of vibration on the welding process was studied by ANS YS finite element software.The welding parameters,the vibration parameters and the structure parameters of the stirrer are analyzed to influence the welding temperature field and residual stress field.It was found that the steady state temperature was maintained at about 498 °C during the welding process and the highest temperature was at the center of the mixing pin.After welding to room temperature after the deformation of the welding plate deformation in longitudinal and transverse direction of the main deformation of the maximum position in the weld center position,the maximum deformation of about 0.374mm.The residual stress of the welded plate is mainly longitudinal residual stress,the transverse and normal residual stress is close to 0 Mpa,and the longitudinal residual stress is 170 Mpa,which is symmetrical distribution in the vertical weld direction.After the vibration is added,the steady-state welding temperature is effectively increased by about 80 ?.To achieve the same steady-state welding temperature,adding vibration after welding forging force than the traditional friction stir welding 19%smaller.Vibration welding on the deformation of the welding plate is small,compared to the traditional friction welding vibration to change the size of the residual stress and distribution.The welding peak temperature in the steady state is different,and the temperature affects the size and distribution of the residual stress.The higher the temperature,the more uniform the stress distribution,the residual stress has a critical range,in this range the higher the temperature the lower the residual stress,the higher the critical temperature range,the greater the residual stress.The research of this subject has important guiding significance for perfecting the basic theory of axial vibration compound rotary friction welding and determining the reasonable process parameter of the new welding technology.