| The 2219 aluminum alloy with high strength is a kind of ideal material widely used in aerospace fuel tank,which has excellent high and low temperature mechanical performance,weldability and comprehensive mechanical properties.With the continuous development of aerospace undertaking in our country,the requirement of the reliability of the quality of 2219 aluminum alloy is increasing.Therefore,in this paper,2219 aluminum alloy friction stir welding and tungsten argon arc welding’s residual stress of joint measurement and removal are studied.This paper proposes a new stress measurement method bas ing on X-ray diffraction-grazing incidence method.This method overcomes the traditional inaccurate problem which results from gradient of X-ray diffraction of 2θ-sin2ψ measuring method.This paper analyzes in detail the measuring principle and method,and the 2219-T6 aluminum alloy’s friction stir welding and tungsten argon arc welding surface and thickness direction’s distribution regularity of residual stress can be determined through the experiment condition.The results show that the plate surface and the thickness direction’s residual stress are measured accurately and reliably using the method of grazing incidence.Using the induction heating process remove the stress of board welding seam area for local heat treatment.Induction heating device is mainly composed of induction heating power supply,sensor and the circulating water cooling system.Induction heating device’s design should based on the actual workpiece material,size,and heat treatment process requirements to choose the work frequency of the power supply,heating power,coil and magnetic conductor,etc.At the same time,according to the heating area of the workpiece and the heating process requirement,the experiment should design reasonable structure of the workpiece positioning device and ensure the workpiece heated at reasonable position.Finally,according to the requirements of different heat treatment temperature,induction heating related parameters are measured.Experiments have measured the peak heating temperature of 190.1 ?C,140.5 ?C and 140.5 ?C,and the induction heating temperature-time curves at various points,accordingly got the plate moving rate which are 5.0 mm/s,8.3 mm/s and 14.3 mm/s.The joint mechanical properties,structure and the microscopic mechanism of stress removal of 2219 aluminum alloy friction stir welding and tungsten argon arc welding of induction heating process before and after are analyzed.Tungsten argon arc weld area organization is isometric dendrite,and θ(Al2Cu)phase distribute in the intergranular and uneven distribution between branches;friction stir welding is fine isometric organization.XRD and TEM observation show that two weld seam area are α(Al)substrate,and tungsten argon arc weld area’s precipitated phase network are formed at the grain boundary in the process of welding.The center of the friction stir welding joint weld obtain present granul ar precipitated phase.The experiment measured tensile strength is 445 MPa and elongation is about 13%,respectively.When the heat treatment temperature is 190 ?C,TIG welding tensile strength is about 60% of parent metal and stretching rate is about 4.15%;FSW weld’s tensile strength is about 74% of parent metal and elongation rate is about 5.5%.Due to the induction heating temperature below the recrystallization temperature and time is shorter,so the induction heating before and after process’ s joint mechanical properties change smaller.Microstructure observation find that θ phase grow up a little after heat treatment,at the same time accompanied by metastable phase θ’exhalation.The changing precipitation and dislocation of joint area have a direct influence on the stress relaxation. |
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