Study On FSLW Process Of 6061-T6 Aluminum Alloy

6061-T6 aluminum alloy has been widely used in aerospace,rail transit,shipbuilding and other fields due to its advantages of high specific strength,good toughness and low density.Traditional processing methods such as melting casting are commonly used for aluminum alloy,which have long development time,great flexibility and wide adaptability.Although conventional melting casting has certain advantages,it also has certain shortcomings.Especially for aluminum alloys,there are many procedures for liquid metal forming,which is difficult to accurately control,which makes the quality of castings not stable enough,the forming structure is loose,and the grains are coarse.Defects such as shrinkage cavity,shrinkage porosity and pores are easy to occur inside,resulting in lower mechanical properties.The emergence of friction stir lap welding technology as a solid-phase processing technology provides new ideas for aluminum alloy processing and manufacturing.In this paper,a 2mm thickness of 6061-T6 aluminum alloy was used as raw material and five layers of friction stir lap welding were carried out through certain processing parameters to obtain a well-formed plate with five layers.And carry out the following research:(1)The processes of linear FSLW and loopback FSLW were studied respectively.Through the test and optimization of the spindle speed,feed speed and the initial pressure value of the spindle three technological parameters,to get the appropriate processing parameters,and the fixture to optimize,to get good processing forming.Finally,the forming results of the two machining tracks are compared and the best machining track is selected.(2)The best solid solution aging process parameters were optimized by different solid solution aging treatments for the laminated plates with a fixed processing parameter,and the tensile strength and elongation of the tensile samples were taken as the optimal criteria.The optimal aging process parameters were solution treatment at 550℃ for 1h and aging treatment at 210℃ for 2h.(3)The macroscopic morphology and microstructure of the laminated linear and loopback sections were observed to study the internal material flow characteristics and the change of the microscopic grain.The results show that the original grains are recrystallized dynamically and the closer they are to the bottom plate,the better the bonding effect is.(4)The tensile properties of welded plates with different parameters were tested.The tensile strength,elongation and fracture morphology were combined to analyze the variation of the tensile properties with the processing parameters.The horizontal and vertical microhardness tests were carried out on the hardness samples under each welding parameter,and the variation of the microhardness with the processing parameters was analyzed in combination with the microstructure characteristics.(5)The electrochemical corrosion test,salt spray corrosion test and friction and wear test were carried out respectively for the FSLW plates under different processing parameters.By observing the macroscopic and microscopic morphologies of the samples under various parameters,and combining with the quality changes of the samples before and after the test,the corrosion resistance and wear resistance of the FSLW plates were studied and analyzed.Figure[35]table[9]reference[62]...