Microstructure and chemical characterization of Linear Friction Welded aerospace materials with focus on dissimilar joints

This study is focused on a through characterization of the microstructure and chemical composition of dissimilar linear friction welded joints. First, Ti-6Al-2Sn-4Cr-2Mo (Ti6242) and Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti17) joints are described to identify the mechanisms behind the successful cohesion of the material surfaces. It was found that continuous dynamic recrystallization and cohesion took place through grain-boundary migration in a shared single phase beta-domain obtained through high temperature and high strain conditions. Then, the possibility of assembling Ti6242 and Inconel 718 is examined. Chemical results combined with microstructure and crystal orientation analyses showed that the intermixing zone formed between the materials was particularly heterogeneous, with the development of an intermediate bimodal microstructure, mainly composed of Ti-beta phase and Ti2Ni intermetallic phase.