Performance Analysis And Forming Mechanism Research Of Friction Stir Joining Zone Of H62 Brass Sheet

H62 brass often needs to be welded（or connected）in the process of use.Traditional fusion welding often has defects such as blowholes,shrinkage cavities and microcracks in its welding zone,so its welding zone performance is poor,which affects the practical engineering application.Friction Stir Joining（FSJ）is a green,energy-saving and efficient new solid-state bonding technology.It can avoid the above defects and improve the performance of the bonding zone when joining H62 brass.In this paper,the friction stir joining of 2 mm thick H62 brass is carried out,and the temperature field during the welding process is simulated and analyzed,and the flash forming and the flow law of plasticized metal during the welding process are studied.At the same time,the mechanical properties,wear resistance and corrosion resistance of the connection zone are also analyzed.The details are as follows:（1）In this paper,the integral screw-free stirring pin stirring tool with shoulder diameters of 6 mm,8 mm and 10 mm are used respectively,and the well-formed friction-stir connection zone is obtained by friction-stir connection of 2 mm thick H62 brass in a larger process interval with the rotating speed of the stirring tool of 6000～10000 rpm,the advancing speed of the stirring tool of 400～600 mm/min and the spindle inclination angle of 5;（2）The metallographic structure of the joint zone is analyzed,and the grain refinement is obvious,and a large number of equiaxed grains appear in the center of the joint zone,and the edge of the joint zone changes significantly with the change of process parameters.When the diameter of the shoulder of the mixing tool is 6 mm,the connection area is roughly symmetrical;When the diameter of the shoulder of the mixing tool is 10 mm,the range of the forward side of the connection area is larger than that of the backward side;（3）By analyzing the microhardness and tensile properties under various process parameters,it is concluded that the tensile strength of the joint area is the highest when the shoulder diameter of the mixing tool is8 mm,the rotating speed of the mixing tool is 8000 rpm and the advancing speed of the mixing tool is 600 mm/min,and the tensile strength of the joint area reaches 95%of the base material when the shoulder diameter of the mixing tool is 10 mm;The highest microhardness is located in the center of the joint zone,and the other areas are the heat engine affected zone,the base material and the heat affected zone from high to low.The highest microhardness is145.36HV_0.2,which is 117.3%of the base material.（4）Through the analysis of wear resistance and corrosion resistance under various process parameters,it is concluded that the friction coefficient is the smallest and lower than the base material when the shoulder diameter of the stirring tool is 8 mm,the rotating speed is 8000rpm,and the advancing speed is 400 mm/min.The wear mechanism is analyzed by SEM of the worn sample surface,and the friction stir joint sample is adhesive wear.When the shoulder diameter of the mixing tool is 10 mm,the rotation speed is 6000 rpm,and the forward speed is 500mm/min,the corrosion resistance is the best and better than that of the base material,and the corrosion form of the friction stir joint sample is dezincification corrosion.（5）By simulating the temperature field in the process of friction stir connection,it is concluded that the central temperature of the connection area increases with the increase of the diameter of the shoulder of the mixing tool,and the central temperature of the connection area is higher at the beginning of the connection than at the end of the connection;Combined with the simulation of temperature field,the surface macro-morphology,microstructure morphology,flash forming and defect forming of the joint area,the flow law of plasticized metal in the process of friction stir welding of H62 brass sheet was obtained.