Rafael Humberto Mota de Siqueira

Comparing mechanical behaviour of aluminium welds produced by laser beam welding (LBW), friction stir welding (FSW), and riveting for aeronautical structures

Abstract Three welding processes for aluminium parts have been considered for aircraft fabrication: riveting, friction stir welding (FSW) and laser beam welding (LBW). These processes have advantages and threats, which were analysed 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 in 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.

ESTUDO DA FORMAÇÃO DE TRINCAS A QUENTE EM LIGAS DE ALUMÍNIO DE ALTA RESISTÊNCIA SOLDADAS POR LASER DE Yb:FIBRA

Resumo O objetivo da presente contribuição é discutir o aparecimento das trincas a quente em três ligas de alumínio, AA2024, AA6063 e AA6013, soldadas a laser. Para tanto um laser do tipo Yb:fibra foi usado em condições de aportes térmicos diferentes. Os resultados indicam uma tendência ao trincamento em várias condições experimentais. No entanto, para os parâmetros de processo utilizados e para as ligas estudadas, observa-se que quando a liga possui entre 0,6% e 1% de silício a sensibilidade ao trincamento diminui. Palavras-chave: Alumínio de Alta Resistência; Soldagem a Laser; Trincamento a Quente; Laser

High Cycle Fatigue Behavior and Microstructural Characterization of 6013-T4 Aluminum Alloy Laser Welded Joints

Laser beam welding (LBW) may be used in the place of the traditional riveting process for the welding of the stringers to the skin in aircrafts. This work intends to investigate the mechanical behavior of laser welded aluminum AA6013, subjected to post-welding heating treatments (PWHT). A fiber laser with an average power of 1.5 kW was used to weld two 1.6mm thick sheets in T-joint configuration. After welding, the samples were separated in three groups: the first just welded, the second subjected to a PWHT during 4 hours at 190°C and the third during 2 hours at 205°C. Hoop tensile tests showed that the thermal treatment at 190 oC for four hours increased the tensile strength in 76 MPa, but the strain had decreased 4%; the thermal treatment at 205 oC for two hours increased maximum strength in 65MPa, with a decrease in strain of 5%. In T-pull tensile tests, the tensile properties of as-welded and PWHT samples remained the same. Standard S-N curve showed that the welding reduce the number of cycles to failure for the tested stairs. PWHT did not affect fatigue properties.