INFLUÊNCIA DO MATERIAL DO BACKING NO FLUXO DE CALOR E NA FORMAÇÃO DE ZONAS DEFORMADAS PELO PROCESSO FSW EM LIGAS DE ALUMÍNIO
FRICTION STIR WELGING OF ALUMINIUM ALLOYS
Rosales, Marcio José C.; Alcântara, Nelson Guedes de; Santos, Jorge Fernandez dos
http://dx.doi.org/10.4322/tmm.00503008
Tecnol. Metal. Mater., vol.5, n3, p.167-172, 2009
Resumo
O desenvolvimento de novos materiais estruturais – especialmente ligas leves e aços de elevada resistência mecânica – vem sendo amplamente impulsionado pelas indústrias automotiva e aeroespacial. Embora sua aplicação seja muitas vezes limitada em função da dificuldade de unirem-se tais materiais, Friction Stir Welding (FSW) é um processo de soldagem no estado sólido que proporciona ótimo desempenho. Para o melhor controle do processo, este estudo analisa as condições térmicas (geração e fluxo de calor) e de deformação plástica das ligas do sistema Al-Mg-Si e Al-Cu-Mg, por meio do uso de três diferentes materiais que compõem o backing bar (cobre, aço e cerâmico). Além de influenciar a transferência de calor e impedir a perda de material na junta, o backing contribui para alterações microestruturais e a consolidação do material na raiz da solda. O presente trabalho visa relacionar a influência do backing na formação de zonas deformadas pelo processo FSW, a fim de compreender a transferência de calor em relação às variáveis do processo. A extração e o fluxo de calor variam em função da condutividade do backing e da resistência à deformação plástica dos materiais.
Palavras-chave
Friction stir welding, Backing bar, Ligas de alumínio, Transferência de calor
Abstract
Although new structural and advanced materials are being considered for use in the automotive and aircraft industries, especially lightweight alloys as well as advanced high strength steels, the successful introduction of such materials depends on the availability of proven joining technologies that can provide for high quality and performance joints. Solid-state joining techniques such as Friction Stir Welding (FSW) are a natural choice since welds are produced at low temperatures thus the low heat input provides for limited distortion; and microstructural as well as mechanical degradation. Great effort is currently being made in the joining of Al-Cu-Mg and lately in the Al-Mg-Si alloys because of their high strength, improved formability and application in airframe structures. The backing bar plays an important role in heat transfer from the join or stir zone, which in turn must influence weld microstructure as well as consolidation of material in the root of the join. This study has been undertaken to investigate issues concerning heat generation, heat transfer and plastic deformation within the stir zone of friction stir welded aircraft aluminium alloys.
Keywords
Friction stir welding, Backing bar, Aluminum alloys, Heat transfer
References
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3 ULYSSE, P. Three-dimensional modelling of the friction stir-welding process. International Journal of Machine Tools & Manufacture, v. 42, n. 14, p. 1549-57, Sept. 2004.
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7 Vilaça, P.; Quintino, L.; Santos, J.F.; Zettler, R.; Sheikhi, S. Quality assessment of friction stir welding joints via an analytical thermal model. Materials Science and Engineering A, v. 445-6, p. 501-8, Febr. 2007.
2 Zettler, R.; Lomolino, S.; Santos, J.F.; Donath, T.; Beckmann, F.; Lippman, T.; Lohwasser, D. A study on material flow in FSW of AA 2024-T351 and AA 6056-T4 alloys. In: INTERNATIONAL FSW SYMPOSIUM, 5., 2004, Metz, França. [S.n.t.]. p. 1-13.
3 ULYSSE, P. Three-dimensional modelling of the friction stir-welding process. International Journal of Machine Tools & Manufacture, v. 42, n. 14, p. 1549-57, Sept. 2004.
4 Russell, M. J.; Schercliff, H.R. Analytical modelling of microstructure development in friction stir welding. In: INTERNATIONAL FSW SYMPOSIUM, 1. 1999, Thousand Oaks. [S.l.: s.ed.], 2001. p. 1-11.
5 Colegrove, P. 3 Dimensional flow and thermal modelling of the friction stir welding process. In: INTERNATIONAL FSW SYMPOSIUM, 2., 2000, Stockholm, Suécia. [S.n.t.]. p.1-11.
6 Lienert, T.J.; Stellwag, W.L.; Lehman, L.R. Heat inputs, peak temperatures and process efficiencies for FSW. In: INTERNATIONAL FSW SYMPOSIUM, 4., 2003, Utah. [S.n.t.]. p.1-10.
7 Vilaça, P.; Quintino, L.; Santos, J.F.; Zettler, R.; Sheikhi, S. Quality assessment of friction stir welding joints via an analytical thermal model. Materials Science and Engineering A, v. 445-6, p. 501-8, Febr. 2007.
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