Effect of Forced Air Cooling on the Microstructures, Tensile Strength, and Hardness Distribution of Dissimilar Friction Stir Welded AA5A06-AA6061 Joints

Abstract

Friction stir welding (FSW) is a promising welding method for welding dissimilar materials without using welding flux. In the present work, 5A06-H112 and 6061-T651 aluminium alloys were successfully welded by friction stir welding with forced air cooling (FAC) and natural cooling (NC). Nanoindentation tests and microstructure characterisations revealed that forced air cooling, which can accelerate the cooling process and suppress the coarsening of grains and the dissolution of precipitate phases, contributes to strengthening and narrowing the weakest area of the joint. The tensile strength of joints with FAC were commonly improved by 10% compared to those with NC. Scanning electron microscopy (SEM) images of the fracture surface elucidated that FSW with FAC tended to increase the number and reduce the size of the dimples. These results demonstrated the advantages of FSW with FAC in welding heat-sensitive materials and provide fresh insight into welding industries.

Development of High-Fidelity Imaging Procedures to Establish the Local Material Behavior in Friction Stir Welded Stainless Steel Joints

“…This same finding has been confirmed elsewhere [24,25]. In addition to that, the cross-sectional micrograph of the weld nugget ( Figure 5c) displays the classical 'onion rings' [26][27][28] associated with the thermoplastic metal flow induced by the tool action during the FSW process. These elliptical onion rings are the compilation of multiple vortex layers, and the size of these layers are usually related to the tool geometry as well as FSW process parameters [28].…”

Welding Deformation Analysis, Using an Inherent Strain Method for Friction Stir Welded Electric Vehicle Aluminum Battery Housing, Considering Productivity

“…The welding deformation is small and the dimensional precision is high because there is little thermal effect on the base metal. In addition, it is easier to bond dissimilar materials, and the mechanical strength of the weld is 90% of the base metal, which is higher than the 80% of conventional TIG welding [5][6][7][8]. Stationary Developed by TWI (The Welding Institute) in 1991, FSW is a solid-state joining process which does not apply greater heat than the melting point to the base metal.…”

“…Sci. 2019, 9, 3848 3 of 15 In addition, it is easier to bond dissimilar materials, and the mechanical strength of the weld is 90% of the base metal, which is higher than the 80% of conventional TIG welding [5][6][7][8]. Stationary shoulder friction stir welding technology can improve the weld surface quality and minimize the reduction of cross-section [9].…”

High-Speed Deformation of Pinless FSWed Thin Sheets in AA6082 Alloy

“…Furthermore, Casalino et al investigated the mechanical properties and formability of FSWed joints in AA5754-H114 after cold rolling performed in order to remove the forging effect, due to the vertical force applied by the tool, in order to ensure a constant thickness of the welded blank [16]. Peng et al studied the microstructures, tensile properties, hardness distribution, and fracture features of dissimilar FSWed joints in AA5A06 and AA6061 under different process conditions [17]. Moreover, the fatigue behavior was investigated, as shown by Cisko et al on FSWed AA2099 alloy [18].…”