Microstructural Evolution in Joints of Ti-6Al-4V Alloy by Friction Stir Spot Welding

Abstract

Friction stir spot welding (FSSW) is a process of recent development and interest, mainly in titanium alloys, since there are previous studies of aluminum alloys, magnesium, steel and polymers. Titanium alloys have a wide range of applications in the aeronautical industry, mainly in the components of commercial aircrafts as landing gear. Therefore, this work was focused on the Ti-6Al-4V alloy, this type of alloy has alpha (α) and beta (β) phases, giving a better balance between its mechanical properties as hardness and tensile strength. The FSSW process was performed using a high speed machining center, with a rotational speed of 500 RPM, plunge speed of 2 mm/s and 3 sec in dwell time, in sheets with a thickness of 1.5 mm and overlap length of 20 mm. The results showed the effect of process variables during FSSW process on microstructure of Ti-6Al-4V alloy caused by the thermal effect and plastic deformation of the welding process, obtaining an appropriate combination of parameters and binding flawless.

Key-words
Titanium alloy Ti-6Al-4V; Microstructural analysis; Friction Stir Spot Welding (FSSW); Aeronautical alloy; Thermo-mechanically affected zone