Preliminary Investigation of the Microstructure and Mechanical Behaviour of 2024 Aluminium Alloy Friction Spot Welds

Abstract

Friction Spot Welding (FSpW) is a new solid-state joining process able to produce similar and dissimilar overlap connections in different classes of materials. Advantages of this new technique are: short production cycles, high performance joints, absence of filler materials and good surface finishing supported by material refilling in the spot area. Although few authors have addressed the microstructural and mechanical behavior of friction spot welds of Aluminum alloys, there is still a lack of a systematic evaluation on the process-properties relationship. In this work the AA2024-T3 alloy (rolled sheets) was selected for the welding procedure. Design of Experiment and Analyses of Variance techniques were employed to evaluate joint shear strength under static loading. Sound joints with elevated shear strength were achieved and the influence of the main process parameters on joint strength evaluated.

Soldagem por ponto no estado sólido de ligas leves

“…A Figura 9 apresenta as especificações mínimas de resistência para as tecnologias de união em questão. Os dados da curva do processo RSW referemse às ligas de Al cujos valores da tensão limite de resistência à tração são superiores a 386 MPa, que é o caso da liga 2024-T3, com um valor de aproximadamente 425 MPa [35]. Quanto à curva de rebitagem, os dados referem-se a rebites do tipo sólido do mesmo material.…”

“…Para efeito de comparação, a carga de cisalhamento da liga de Al 2024-T3 da Figura 8 equivale a aproximadamente 10,1 kN em chapas de 2 mm de espessura [35]. Considerando uma junta sobreposta obtida por RSW em chapas de mesma dimensão, a resistência ao cisalhamento estabelecida é de 5 kN.…”

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.…”

“…This joining process does not increase the weight of the structure because no additional fastener or rivet is used. Compared to conventional fusion welding processes, refill FSSW consumes less energy and produces joints with a good surface finish [4,5]. Some published works [5][6][7][8][9][10][11][12][13][14][15] have reported that refill FSSW has been successfully used to weld relatively thin materials, up to 2-mm-thick, in similar and dissimilar joint combinations with good mechanical properties.…”

“…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.…”