Effect of oxygen content in local shielding atmosphere on cladding quality of Ti6Al4V during annular laser metal deposition

In annular laser metal deposition (ALMD), Ti6Al4V alloy is sensitive to oxygen. this research, a coaxial double-layer shielding gas nozzle was used provide local inert atmosphere. The influence of the oxygen concentration in shield on cladding quality evaluated regarding appearance, chemical composition, microhardness, microstructure, and phase constituent. results show that surface discoloration layer related contamination level. When level atmosphere below about 1000 ppm, shiny silver clad can be achieved, nitrogen deposited material those allowable for ASTM Grade 5. addition, as decreases, microhardness samples decreases gradually, microstructural characteristics experience change from blocky plate α′ martensite within coarse prior β-grain boundary acicular fine boundary.