Numerical Simulation Investigation On Residual Stress Ang Deformation Of 2219 Aluminum Alloy TIG Welding Joints

For the manufacturing of rocket fuel storage tank,aluminum alloy is uesd as a common material due to its high specific strength and low weight,but it has large welding residual stress and deformation,and it has high hot cracking sensitivity,the problem has been the focus of welding researchers.During the control methods of aluminium alloy welding reidual stress and dieformation,preheating is a procedure that can be adopted,however,there are few studies concentrated on the mechanism of preheating on welding stress and deformation.In this paper,the numerical simulation method was adopted,and the dynamic evolution process of welding stress,deformation and the distribution of welding residual stress and deformation under different welding conditions were studied.The mechanism of preheating on welding residual stress and deformation were analyzed and summarized to optimize the welding process and enrich the theory of controlling welding stress and deformation.The MSC.Marc finite element analysis software was used to simulate the welding process of 2219 aluminium alloy.The welding temperature field,stress field,deformation process and the final distribution of welding residual stress and plate buckling deformation of 2219 aluminum alloy sheet under conventional TIG welding conditions(room temperature)were studied and analyzed by numerical method,and the finite model was validated by experiments.On this basis,the numerical simulation of welding process at different preheating temperatures(100,200 and 300 ℃)was carried out according to the mode of equal temperature peak value(adjusting the welding powers at different preheating temperatures to keep the peak temperature consistent).By comparation,it is found that the temperature gradient between the weld and its surrounding material decreases,the welding process stress decreases and the welding residual stress decreases under preheating condition,which also has a positive effect on the welding deformation control of the aluminum alloy sheet.When the preheating temperature is 200 ℃ and the welding power is 1200 W,the residual stress elimination rate is 18%,and the deformation elimination rate is 93%.In order to further optimize the welding parameters,the welding power was set as 1200 W,and the numerical simulation of welding process at different preheating temperatures(150,100 and 50 ℃)was carried out based on the low temperature peak method(keeping the same welding power and changing the preheating temperature).By analysis and comparison,it is found that there is no obvious effect on welding residual stress at different preheating temperatures,but the warpage deformation increases gradually with the decrease of preheating temperature,which is consistent with the results of welding experiments.Ultimately,the minimum welding residual stress and deformation joints is obtained under the preheating process at 200 ℃.