Full Thermal-Mechanical Coupled Numerical Simulation And Experimental Study Of 6061 Aluminum Alloy In Friction Stir Welding

Friction Stir Welding(FSW)is an environmentally friendly welding technology that requires no shielding gas during the welding process,is inexpensive and has a good welding shape.The temperature field during the welding process will affect the structure and stress-strain distribution of the welded joint,which will affect the quality of the welded joint.However,friction stir welding is a complex process with multiple physical fields coupled.Conventional experimental temperature measurement methods require a lot of manpower and material resources,and it is difficult to fully understand the temperature field during welding.In order to understand the temperature field distribution during friction stir welding,this paper uses a combination of finite element simulation and experimental verification to study the temperature field of 6061-T6 aluminum alloy during welding.The temperature changes of each temperature measurement point of welding samples under different working conditions were recorded in real time,and the influence of welding parameters on temperature changes and the influence of temperature on stress distribution were analyzed.By analyzing the physical process of friction stir welding,the welding process was simulated with ANSYS finite element software,and the temperature field and stress field during the welding process were analyzed.The research contents and results are as follows:(1)The welding process under different welding parameters is simulated.The results show that: under different welding parameters,the temperature field distribution area changes uniformly,and the high temperature area is elliptical,moving in the welding direction with welding progress;the higher the speed,The slower the welding speed,the higher the peak temperature,the larger the high temperature range.(2)Under the welding parameters of 400?1200rpm,100mm/min,the welding stress increases with the increase of the rotation speed,the peak value of stress appears on both sides of the shoulder,the distribution is asymmetric,and the stress is high at high temperature.The partial stress range of the plate in the z-axis direction is-100MPa?60MPa.The longitudinal stress in the area near the center line of the weld is tensile stress,which is gradually converted into compressive stress toward the edge of the base material.(3)As welding proceeds,the strain distribution gradually assumes the shape of a saddle surface.The lower plate of the shoulder is depressed downward,and the plate at the edge of the shoulder protrudes upward.(4)Microscopic observation and electrochemical testing of the welded joints: under the combined action of heat and stirring,the weld nugget area forms fine equiaxed crystals with the best corrosion resistance;the heat-affected zone is not fully stirred and the grains Bending deformation occurs;grains appear coarsened in the heat affected zone under the influence of heat.(5)The temperature measurement experiment results show that: the higher the speed,the slower the welding speed,the closer to the center of the weld,and the farther away from the welding start point,the higher the peak temperature;the temperature change curves of the forward and backward sides basically coincide,only at the peak The temperature is slightly different.The simulation results agree well with the experimental results.