Influência do defeito tipo cunha no comportamento mecânico de juntas de liga de alumínio 2198 soldadas por fricção por ponto (FSpW)
Fecha
2015-02-01Autor
Barros, Pablo Aronne Funchal de
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One of the main considerations in selecting materials to manufacture
aircraft structures is related to weight saving [1]. In this context, the promising
aluminum-lithium alloys have been receiving special attention in aerospace
applications due to its attractive combination of low density, high specific
strength and corrosion resistance [2-5]. Due to difficulties joining these alloys by
conventional welding processes associated to their high thermal conductivity
and low melting temperature, solid-state joining technologies emerge as great
possibilities to simultaneously solve problems of solidification defects and
increasing weight. The feasibility of Friction Spot Welding (FSpW) in joining
sheets of lightweight material (e.g. aluminum alloys) places this technology as a
potential replacement to the spot-like joint processes, as resistance spot
welding (RSW) and laser spot welding (LSW), for application in automotive and
aerospace industries [6-8]. In this work, the influence of hook defect on the lap
shear strength (LSS) of AA2198-T8 friction spot welds was studied. The effects
of process parameters was evaluated in terms of LSS and related to the
microstructural configurations. The values of hook length measurements and
the LSS were used as response in optimization process developed using the
statistical tool of DoE technique with Taguchi Method. Finally it was possible to
compare the hook behavior with lap shear strength results. The higher influence
on the weld performance was exerted by plunge depth whereas rotational
speed was found to be a less significant parameter. Through the minimization of
the hook defect, a beneficial response on the weld performance was observed,
which was associated to the absence of a potential site for crack nucleation. In
spite of inherent discontinuities, promising results were found for aluminum
joints for aerospace applications.