Abstract
Friction Surfacing is a process employed to deposit metallic coatings, whereby similar and dissimilar material combinations can be realized. The process can be applied as a local repair technology or the coating material can locally modify the surfaces. One advantage of this process is that the coatings are deposited in solid state without reaching the melting range of materials, thereby avoiding dilution with the substrate. The involved severe plastic deformation under high temperatures alters the microstructure of the coating material, leaving it fully dynamically recrystallized.
The current work focuses on deposition of Ti-6Al-4V coatings. For this material the process parameter rotational speed plays a significant role in the material’s response during processing. Two different regimes with a threshold at 2000 min-1 exist, upon which the flow behaviour of Ti-6Al-4V significantly differs, affecting amongst others the coating dimensions. Microstructural analysis reveals that the material is deformed in high temperature β phase, and the high cooling rates (46.4 Ks-1) lead to martensitic transformation. The β grain size differs in the low and high rotational speed regime. This study shows that metallurgical processes play an important role in Friction Surfacing, since they influence all relevant process characteristics, including microstructure, material efficiency and process forces.
