Improvement weldability of dissimilar joints (Ti6Al4V/Al6013) for aerospace industry by Laser beam welding

Abstract

The discovery of new metal alloys and the technological advancement in welding processes are key resources for the aerospace industry to obtain cost reduction and better reliability. Thus, welded joints of dissimilar materials such as aluminum and titanium alloys has been explored due to its combined low density and high mechanical performance. Otherwise, welding of dissimilar metals may present deleterious factors to the welded joint as the formation of intermetallic and/or brittle second phase and residual stress. This project investigates the weldability of dissimilar welded joint (Al6013/Ti-6Al-4V) by Laser beam welding. The approach will be done in terms of mechanical properties and microstructural characterization. For this purpose, optimal laser offset from the joint line and the related heat input has been found. It was observed that offset controls the amount of the intermetallic compound layer in the fusion zone. Large pores were observed on the Al side of the weld metal when the offset is zero. The microstructure on the aluminum side consisted of \(\alpha\)-Al grains and the dispersed precipitates. Heat input and offset also influenced in the volumetric fraction of the precipitates. Martensite \({{\alpha }}^{{\prime }}\) and secondary acicular \({\alpha }\) phase was found in the titanium side. Furthermore, intermetallic compound of TiAl base phase such as TiAl, Ti3Al4, and Ti2Al3 was formed. Tensile strength of welded joint was 60% of the Al alloy. In addition, for the same offset and higher heat input, there was an increase in the hardness of the interface.