Research On FSW Process Of 2219 Aluminum Alloy Thick Plate Based On Temperature Field Analysis

2219 aluminum alloy has many advantages such as light weight,high specific strength,good corrosion resistance,good thermal conductivity.Its good weldability and material mechanical properties make it an ideal material for rocket fuel tank.Friction stir welding(FSW)is the preferred welding process for rocket fuel tank assembly due to small grain size,good bonding strength and tensile strength,and small residual stress of the welded joint.However,when the welding thickness of CZ-9 rocket fuel tank reaches 18 mm,the temperature difference between upper and lower parts of the weldment increase greatly,the welding strengthening phase is dissolved back,and the difference of microstructure and properties is great along the thickness direction,so it is difficult to guarantee the connection strength after welding.The welding temperature field is significantly affected by the welding process parameters and the structure parameters of the tool.At present,the temperature distribution law of FSW 2219 aluminum alloy thick plate is still in the exploratory stage,and the influence law of process parameters and structure parameters of the tool on the temperature field is still unknown,which has become the bottleneck restricting the temperature control in the welding process and needs to be further explored urgently.To explore the temperature distribution law of FSW 2219 aluminum alloy thick plate and realize the optimization of welding process parameters and structure parameters of the tool,this paper first considers the detail morphology of the tool and establishes a simulation model of FSW 18 mm thick 2219 aluminum alloy with single shoulder based on ABAQUS/CEL and explores the temperature field characteristics of the FSW process.The simulation model is verified by the temperature measurement experiment.The influence of welding process parameters such as rotational speed and welding speed on the peak temperature,minimum temperature and temperature difference of temperature field in the core area of weldment is investigated.The influence of the detailed topography features such as diameter of shaft shoulder,thread and taper angle,concave angle of shaft shoulder and tool taper angle on the welding temperature field is studied,and the optimal detailed topographical parameters of the tool are obtained.FSW experiment verified the excellent welding performance of the simulated optimized tool.A simulation model of FSW with double tool is established based on ABAQUS/CEL to explore the characteristics of the temperature field of the symmetric double side composite FSW.The influence of the tool shoulder diameter,welding speed,rotational speed and direction on welding temperature field is investigated.Taking the minimum temperature difference of the temperature field in the core area of weldment as the optimization goal,a better combination of welding process parameters and the tool structure size is obtained.Finally,the characteristics of the temperature field of the "Asymmetric" double tool FSW and the influence of the relative distance of the tools on the welding temperature field are explored.This study can provide basic guidance of simulation technology for the FSW temperature field research of 2219 aluminum alloy with large thickness,and provide reference for the selection of welding process parameters and mixing head structural parameters of both single shaft shoulder and double side composite FSW.It provides the research foundation for realizing high quality FSW of 2219 aluminum alloy thick plate.