Study On The Relationship Between Process Parameters And Mechanical Properties Of Friction Stir Welding Of 1060 Aluminum Plate

Friction stir welding has been widely used in industrial production.Exploring the relationship between welding variables and realizing efficient and simple calculation from process parameters to mechanical properties can provide theoretical basis for the application of friction stir welding.In this paper,the friction stir welding experiment of3 mm thick rolled 1060 aluminum plate was carried out.The relationship among the process parameters,temperature,joint microstructure and joint mechanical properties was researched.when the welding running,the temperature was collected by thermocouples at different positions,and a moving heat source finite element heat transfer model was established to analyze the temperature.The microstructure and macroscopic morphology of the Weld cross section were observed by microscope.The mechanical properties of the joint were researched by tensile test,microhardness test and fracture scanning analysis.Specific research results are as follows:The temperature of the joint increases at first and decreases after reaching the top value.The maximum temperature went smaller in the direction away from the weld,and the more far away from the weld,the smaller the temperature gradient.the top surface temperature of the workpiece is the highest and goes down downward in the thickness direction.The welding temperature is related to the welding parameters.The welding temperature goes higher with the increasing of the rotating speed and lower with the welding speed.Under different welding parameters,the average value of the peak temperature on both has a linear relationship with the maximum temperature of the weld,and the logarithm of each of them have a linear relationship with the logarithm of the ratio of the square of the rotating speed to the welding speed.The welding defects are mainly affected by the welding temperature,and there are holes or tunnels in the samples with the temperature below 267.9?.There is no flash on the surface of the sample at higher welding temperature.The length to width ratio of grain from the base metal of rolled 1060 aluminum plate is larger than that of other materials,and has higher dislocation strengthening.The grain size in the HAZ is larger than that in the basement material,and its shape does not change.The width of the TMAZ on the advance side is smaller than that on the retire side and is more obvious.The grain size of nugget is smaller in the bottom than in the middle than in the top.The average grain size in the weld nugget is related to the temperature,and the logarithm of Zenner-Hollomon parameters of nugget are linear with the logarithm of the average grain diameter in the nugget.The max tensile strength of 142.6MPa which is 85% of the basement metal got from850 rpm and 200mm/min.While the minimum tensile strength in 950 rpm and 100mm/min is 126.5 MPa,which is 75% of the basement material.The tensile strength does not show an obvious stable trend with respect to welding parameters.The yield strength of the joint is related to the grain size of the nugget The hardness distribution looks like a W,and the lowest average hardness value of the thickness direction came from the edge of tool pin,and the nugget is softer than the base metal.The broken location appeared at nugget near the edge of tool pin.The upper and lower edges of the tensile fracture are mixed fractures with more brittle fractures,while most of the other areas show the appearance of ductile fracture.The verified yield strength is within 6% of the predicted value.