Study On Friction Stir Welding With High Rotational Speed Technology For 6082-T6 Aluminum Alloy And Simulation Of Temperature Field

High rotational speed friction stir welding is a new FSW technology,which has shown good performance in the welding of materials with a thickness of less than 1mm,especially aluminum and magnesium alloys.In this paper,1 mm thick 6082-T6 aluminum alloy as the research object,according to the welding characteristics of high speed friction stir welding,small needle with big shoulder as a design principle of various kinds of stir head for high speed friction stir welding process to explore,research the different mixing head and process parameters for the influence of the weld and the joint mechanical properties,select forming good mixing head and mechanical properties of the optimal welding parameters,the performance of corrosion on the connector and the relationship between the different heat treatment methods,using the combination of thermocouple and infrared temperature measurement way of measuring the welding heat i Wordn the process of change,Combined with the simulation results of ABAQUS,the temperature distribution law in the friction stir welding process was explored and the accuracy of the model was verified.It is found that the combination of shaft shoulder and agitating needle of different forms has great influence on the final welding effect,and the combination of concave shaft shoulder and agitating needle of round table can obtain better welding effect and economy.The shape and size of the mixing head and the welding parameters have great influence on the surface forming and mechanical properties of the joint.Among them,too large shoulder size will not only cause flaps and other welding defects,but also significantly reduce the tensile strength of the joint.When the welding speed is fixed,the strength increases first and then decreases when the rotation speed is increased.However,when the welding speed is fixed,there is no obvious regular change between the joint strength and the welding speed.The microhardness on the cross section of the welded joint generally presents a "W" pattern distribution.The hardness of the base material area is the highest,followed by the welding core area.The hardness of the heat engine affected area and the heat affected area is the lowest,among which the hardness of the forward side and the backward side is slightly higher.Different heat treatment has obvious influence on the corrosion resistance of the joint.In the intergranular corrosion test,the T4 heat-treated joints had the best performance,while the natural aging treatment joints had the worst intergranular corrosion resistance.In the same joint,the microstructure of the weld center showed the best intergranular corrosion resistance and the base metal area the worst,indicating that friction stir welding can improve the corrosion resistance of the metal.In the electrochemical corrosion test,the T6 heat-treated joints showed the best corrosion resistance while T4 heat-treated joints showed the fastest corrosion speed.There was no obvious relationship between the corrosion rate and corrosion resistance.The temperature variation trend of each point in the welding process is basically the same,and they all experienced the same thermal cycling process.The welding temperature is inversely proportional to the rotation speed.The highest temperature in the welding process occurs in the weld center.The temperature on the forward side is slightly higher than that on the backward side,and the temperature on the shaft shoulder is higher than that on other parts of the shaft shoulder.The temperature variation obtained from the simulation test is basically the same as that obtained from the actual temperature measurement test.