| Friction stir welding in the field of aluminum alloy to connect a wide range of applications in the field of aerospace, marine and rail vehicles have been large-scale use of friction stir welding technology. Conventional friction stir welding weld heat input gradient, resulting in weld joint tensile morphology the mixed-type fracture; the weld back of incomplete penetration, root defects and small kiss then; ring welding due to the geometry of the weldment, makes it difficult to provide a rigid support, restricted the friction stir welding in rocket tank large cylindrical pieces of circular welded. The bobbin tool was stirred for friction welding technique appears to improve the conventional friction stir welding technique to provide a new solution for the welding of the aluminum alloy plate.The friction stir welding process temperature field is an important factor to affect the mechanical properties and microstructure of welded joints, distribution and evolution is an important basis for analysis of the welding process, have a major impact on the flow of the weld metal, welding stress and deformation analysis. In this paper, the large general-purpose commercial finite element analysis software ANSYS Workbench13.0to establish a numerical model of the aluminum alloy sheet, continuity equation, momentum equation and energy conservation equation to form a non-linear control equation describes the bobbin tool friction stir welding the temperature field distribution. The simulation results show that:the shaft shoulder is the main source of heat input, accounting for more than80%of the heat input; dumbbell was asymmetric distribution of the temperature field of the weld cross-section, unlike the conventional welded conical distribution; welding highest temperature in the vertical shaft shoulder481℃and442℃, respectively, a difference of39℃. Analysis to determine the temperature field simulation of welding parameters range is:the welding speed80-160mm/min, and speed1000-2000r/min.Designed on the basis of the numerical simulation the bobbin tool friction stir welding head, docking tailor-welded single block size to450mm×150mm×3mm of6061-T4aluminum alloy plate and weld microstructure and mechanical properties of analyzed. From the welding the results, different combinations of process parameters on weld a very clear distinction, appearance can be obtained when the welding speed of120mm/min speed of1500r/min, good shape, no obvious defects inside the welding deformation small weld. Welded joints without going through any post-weld heat treatment, the average tensile strength reached150.79MPa, the the rear average elongation rate of17.67%,84.31%and104%of the base material is superior to conventional friction stir. Metallographic test weld S line, found through many trials contrast, S line friction stir welding process of aluminum oxide with the the agitation mixing head into the weld. The tensile mechanical properties after welding tests showed that the S line is the weak binding of the weld, tensile fracture basic S line along the weld. |
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