An investigation on friction spot welding of AA2198‐T8 thin sheets

Abstract

The feasibility of joining 1.6‐mm‐thick sheets of AA2198‐T8 by the novel friction spot welding technology and the resulting microstructural features on the welds cross sections were assessed, with further evaluation of the process parameters on the weld performance. Besides the intrinsic discontinuity related to the interface between the sheets, the hook feature was found to be inherent to the welding process, and its morphology was determinant to the weld performance and fracture mode. A beneficial response on the shear strength was achieved with the minimization of the hook feature because of the absence of a potential site for crack nucleation, although the generation of other defects, depending on the combination of parameters, could erase this benefit. Through statistical analysis, the most influent parameters on the weld performance were plunge depth and welding time. In the present study, regardless of the weld discontinuities, the optimum shear strength revealed a satisfactory performance in mechanical terms for aerospace applications.

Refill friction stir spot welding of AlSi10Mg alloy produced by laser powder bed fusion to wrought AA7075-T6 alloy

“…Cao et al [14] stated that lower hook height leads to higher ULSF values. Moreover, lower RS (1000-1100 rpm) usually leads to better lap shear strength in highstrength aluminium alloys, as less extensive material plasticisation and mixing take place, leading to lower hook height [15][16][17]. This corresponds with the ULSF results for this work's medium and high…”

Tool wear mechanisms and effects on refill friction stir spot welding of AA2198-T8 sheets

“…10(b) (r ¼ À0.51) indicates a moderate negative correlation between h and LSS. This inverse relationship was also found by Cao et al [25] in AA6061 and Barros et al [26] for AA2198 welds. In both cases, the reduction of LSS values along the hook height is explained as a result of the reduction of sheet effective thickness to resist the applied load.…”

Effect of stirring time on the mechanical behavior of friction stir spot weld of Al 6061-T6 lap-shear configuration

“…The crack initiation and propagation is found to have been occurred by the hook. 1,29–31 The hook in the 4 s of stirring case is shown in Figure 6. The hook is inclined upward to the top sheet, which can influence the static and fatigue strength significantly.…”