Metallurgy and mechanical performance of AZ31 magnesium alloy friction spot welds

Texture Development and Material Flow Behavior During Refill Friction Stir Spot Welding of AlMgSc

“…Since its invention, refill FSSW has been used for joining similar metals or materials [6][7][8][9][10] as well as joining dissimilar materials. [11][12][13][14] HZG proved that refill FSSW creates joints with superior mechanical properties to similar processes.…”

Process optimization and microstructure analysis in refill friction stir spot welding of 3-mm-thick Al-Mg-Si aluminum alloy

“…The SZ is characterized by fine grain structure due to dynamic recrystallization [4,9,16,21]. This region underwent severe plastic deformation due to the sleeve and pin movement and was exposed to high temperature, as illustrated in Figure 6c.…”

“…Refill FSSW uses a non-consumable tool consisting of a stationary clamping ring, rotating pin and sleeve [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The sleeve-plunge process variant is presented in Figure 1.…”

“…The hook is defined as a partially bonded region and is a transition from the unbonded interface separating the overlapped plates to the fully metallurgically bonded region. During loading, the hook acts as stress concentrator and provides a potential path for crack initiation and propagation [16]. The formation of the hook is induced by tool movement during plunging/retracting and is associated with the welding parameters [7].…”

“…An increase in the weld strength is initially observed as the welded area becomes larger. However, the hook has a greater influence at greater size, which then overrides the benefits of having a large welded area [16]. However, the formation of the joint microstructure, which also affects the weld strength, is governed by welding parameters and has not been fully understood yet.…”