Processing and banding in AA2524 and AA2024 friction stir welding

Abstract

An attempt has been made to clarify the relationship between the periodicity of process parameters and that of the micro-/mesostructural banding in friction stir welding (FSW). The oscillation of FSW parameters was measured and analysed during baseline experiments without welding and during a series of FSW of AA2524 and AA2024 aluminium alloys; the banded structures in all the welds were also characterised. It is found that independent of the tool runout, there are well defined periodic variations in the process forces, the translational resistance force F x ) and Z axis force F z of the welding tool in all joints. The measured band spacing is closely correlated with the oscillation period of process forces F x and F z , exerted on and by the welding tool. The direct and consistent relationship observed between periodicity in variation of F x and F z and the metallurgical structure, e.g. grain size, particle distribution, band width and microhardness, indicate that the formation of banded structures in FSW joints is related to the periodic variation of welding parameters.

Effects of Rotation Speed and Forward Speed on Stir Zone Formation During Friction Stir Processing of Al-7Si-0.3Mg Alloy

“…The trends of M decreasing as ω increases and increasing slightly as v increases observed in these figures are in general agreement with those recently established in literature [8,[13][14][15]. The present data in Figure 7b shows clearly that E s ( ω , v) is almost not affected by ω values, meaning…”

“…Many researchers have observed the change in flow volumes as FS parameters are altered [5][6][7][8][9][10][11][12], although no precise quantification on flow volumes or study on how the individual and combined flow volumes are affected by v and ω have been conducted. On the thermal side, torque (M), power (P=M ω ) and specific energy (E s =M ω /v) are measurable quantities that are often related to temperature and heat input [8,[13][14][15]. How these variables relate to flow volumes has not yet been established, despite some suggestions made [8].…”

“…On the thermal side, torque (M), power (P=M ω ) and specific energy (E s =M ω /v) are measurable quantities that are often related to temperature and heat input [8,[13][14][15]. How these variables relate to flow volumes has not yet been established, despite some suggestions made [8]. From the consideration that FSP is used for microstructure modification and refinement, FSP parameters relating to the individual and combined volumes forming the processed zone is vitally important to be understood.…”

Material Flow and the Shear Layer in the Upper Weld Zone during Friction Stir Welding of Aluminium Alloys

“…Hence, sticking condition was not established in the present experimental conditions. This is in a disagreement to the suggested sticking condition prevailing during FSW [16]. 4 …”

Process forces during friction stir channeling in an aluminum alloy

“…Long and Reynolds (2006) studied the effects of material properties and process parameters on traverse forces and weld defect formation (via material flow patterns) using fluid dynamics simulation. Yan et al (2007) studied the relationship between the periodicity of process parameters and that of the micro-and meso-structural banding in FSW. The oscillation of FSW parameters during baseline experiments without welding and during a series of FSW of AA2524 and AA2024 aluminum alloys were measured and analyzed for the banded structures in all the welds.…”