Dissimilar Al-Cu joints are desirable due to the combination of the good electrical and thermal properties of copper with the economic advantages of aluminium. However, different chemical, mechanical and thermal properties turn dissimilar welding into a challenge with traditional fusion welding techniques. Friction stir welding appears to be a good alternative to welding dissimilar materials. Most of the works in Al-Cu FSW have been performed with Al on top. This work investigates the influence of heat input on the shear strength of aluminium-copper lap joints produced by FSW with a copper over aluminium lap configuration. Welds produced with the ω/ν rate of 200 rev.mm -1 or 500 rev.mm -1 resulted in the melting of the base materials and material leaking. Joints with shear tensile strength varying from 76 to 85% of the original resistance of AA6060 T5 were produced when the ω/ν rate was varied from 80 to 110 rev.mm -1 . The fracture was governed by tension overload on the aluminium sheet, resulting in little influence of welding defects, such as tunnelling, on the joint strength.
The study of machining nickel-based superalloys has assisted in developing new techniques associated with cutting processes and tools. Hastelloy Ò X offers ideal properties for engine manufacturing in the aerospace and aeronautical applications that require high surface qualities. Thus, this work investigates the effects of three input parameters (cutting speed, depth of cut, and lubricooling conditions) at three levels on the average roughness values in the finish turning using a PVD-coated carbide tool. The 0.1 mm/rev feed rate was kept fixed, and the parameters were combined, randomized, and optimized by the Box-Behnken Design of Experiment. The statistical results showed that the most significant input parameters were cutting speed and depth of cut and their respective interactions. Furthermore, the cutting conditions with lower cutting speed and depth of cut above 1.5x tool nose radius generated high roughness values due to chatter vibration. After optimization, the best average roughness value obtained was below 0.8 mm, with a 400% increase in the material removal rate.
Friction stir welding (FSW) is a solid state welding process that has been studied for dissimilar welding applications, especially aluminum and copper. However, the quality of dissimilar Al/Cu FSW joints is often impaired due to the formation of intermetallic compounds (IMCs), which affect both mechanical and electrical properties. This paper investigates the feasibility of FSW in producing dissimilar Al/Cu lap joints were copper is positioned over aluminum. In order to access the influence of rotational speed over the resulting joint, four different rotational speeds were tested for the same welding speed. The produced joints were then evaluated in terms of weld appearance, defects and the electrical resistance of the welded joints. Visual and ultrasound inspection indicated no discontinuity in any of the produced samples. Electrical resistance results indicate no influence of rotational speed. Moreover, electrical resistance of the Al/Cu FSW lap joints were smaller than the average between the electrical resistances of single metal joints welded with the tested materials in similar conditions. The experiments indicate that is possible to produce sound Al/Cu lap welds for the parameter window used, including the positioning of copper over aluminum, that is discouraged by literature. The small values of electrical resistance indicate no deleterious effect of IMCs over this characteristic.
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