A common phenomenon in the dissimilar joints is the presence of brittle compounds in the joining interface region. The brittle phases can decrease by introduction of interlayers in the joining interface, such as silicon, that inhibits the formation of Al3Ti and AlTi3 phases in joining process between titanium and aluminium alloys. In the present work, the joining of titanium and aluminium alloys have been carried out using a Yb:fiber laser, considering the prior silicon film deposited on titanium alloy interface by DC magnetron sputtering. Butt joint conditions were maintained constant: laser average power, process speed and beam positioning along the interface joining toward aluminium alloy (1200 W, 3.0 m/min and 0.3 mm, respectively). Metallographic analyses were carried out on the cross-section joint by optical and electronic microscopies. When the melted aluminium alloy wet the solid-state titanium alloy, a more restrict compound layer was formed in the joining interface. EDS line scanning in the joining interface showed a reduction of compound layer thickness, considering the silicon as interlayer, reaching the mean value of 3 µm, i.e., up to five times thinner if compared to joining without silicon during the process.

Três processos de união de perfis de alumínio concorrem para a manufatura de painéis estruturais (união entre revestimento e reforçadores) aeronáuticos: rebitagem, Friction Stir Welding (FSW) e soldagem a laser (Laser Beam Welding - LBW). Esses processos têm vantagens e desvantagens particulares, as quais foram analisadas no presente estudo focando, especificamente, nas propriedades de tração do conjunto unido. Dois ensaios mecânicos foram considerados, T-pull test e Hoop test. No que tange ao ensaio T-pull, as amostras soldadas por LBW apresentam maior capacidade de suportar cargas. Isso se deve à melhor distribuição de cargas, quando a solicitação mecânica se faz pelo reforçador. No caso do ensaio Hoop, onde a solicitação mecânica se dá exclusivamente no revestimento, os resultados obtidos por FSW são notadamente superiores aos obtidos pelos demais processos, em termos de tensão máxima, tensão de escoamento e de alongamento máximo. Conclui-se que tanto o LBW quanto o FSW são métodos de soldagem com possibilidade de substituir a rebitagem comumente aplicada nas aeronaves comerciais.

Three welding processes for aluminum parts have been considered for the aircraft fabrication: riveting, friction stir welding (FSW) and laser beam welding (LBW). These processes have advantages and threats, which were analyzed in the present work focusing on T-pull and Hoop tensile properties. Concerning T-pull tests, LBW coupons presented higher ability to withstand the applied loads. This was due to the better distribution of loads when the strain is done to the stringer direction. In the case of the Hoop tests, which stress only the skin, the results obtained after FSW were notably higher in terms of ultimate tensile stress, yield stress and maximum strain. It was concluded that both LBW and FSW could replace riveting usually applied for commercial aircraft manufacturing.

Interest in laser beam welding for aerospace applications is continuously growing, mainly for aluminum alloys. The joints quality is usually assessed by non-destructive inspection (NDI). In this work, bead on plate laser welds on 1.6 mm thick AA6013 alloy sheets, using a 2 kW Yb-fiber laser were obtained and inspected by pulse/echo ultrasonic phased-array technique. Good and poor quality welds were inspected in order to verify the limits of inspection, comparing also to X-ray radiography and metallographic inspections. The results showed that ultrasonic phased array technique was able to identify the presence of grouped porosity, through the attenuation of the amplitude of the echo signal. This attenuation is attributed to the scattering of the waves caused by micro pores, with individual size below the resolution limit of the equipment, but when grouped, can cause a perceptive effect on the reflection spectra.