| Titanium alloy and aluminum alloy as the important lightweight materials in the aerospace,Marine engineering,petrochemical and other fields is widely used,titanium aluminum composite material is a combination of excellent characteristics of two kinds of material,not only than strength,high stiffness,and facilitating the overall structured,greatly reduces the manufacturing,assembly,operation and maintenance costs,become the hotspot in research of high-tech.As a solid state welding technology,friction stir welding can realize the welding of metal base dissimilar alloy,maintain the metallurgical properties of the base alloy and effectively control the interweld compound.Based on titanium/aluminum composite welding lap process as the research object,using the friction stir welding of titanium/aluminum lap welding process and performance research,through overlapping test,performance test and microscopic characterization methods,analysis of the mechanical properties of welded joint and tissue morphology,explore the forming mechanism of the lap joint and fracture mechanism,the results of the study on titanium/aluminum dissimilar alloy friction stir welded lap joints quality has the important practical application value.First single channel of friction stir welding welding technology is studied,through the experimental study on the mixing head down quantity were 0.1 mm and 0.2 mm and0.3 mm macro morphology and mechanical properties of welded joint,determine the 0.2mm for the best,on the basis of further study on the mixing head rotation speed(600 r/min and 900 r/min,1200 r/min and 1500 r/min),welding speed(60 mm/min,100 mm/min,140mm/min,180 mm/min)on the quality of the weld,The optimized welding process was obtained.The microstructure of the interface and HOOK was studied by SEM,EDS and XRD experiments.The forming mechanism of the lap interface of the joint was explored,and the intermetallic compounds during lap welding were characterized.Secondly,the mechanical properties of the friction stir welded single weld joint were tested,and the microhardness of aluminum side,titanium side,interface and Hook of the welded joint under different processes were studied,and the influence rule of welding parameters on the microhardness was obtained.The influence of welding parameters on the fracture load of the joint was obtained by tensile shear test and fracture analysis of the joint under different processes,and the fracture mechanism of the single-channel lap joint was obtained.Finally in conventional single channel friction stir welding and friction stir welding is studied on the basis of multi-channel welding technology,respectively to weld spacing is 3mm,6 mm,9 mm and 12 mm welding experiment was carried out,under different welding parameters is studied in multi-channel welding head of macro morphology,microstructure,mechanical properties and discern the microhardness of the welding on the joint of multichannel,breaking load,the influence law of interfacial morphology,explores the forming mechanism and fracture mechanism of the welding joint of multichannel. |
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