Effect of Laser Sintering Parameters on the Microstructure, Mechanical Properties and Corrosion Behavior of Titanium Grade 5 Alloy

Abstract Direct Metal Laser Sintered (DMLSed) titanium grade 5 alloy (Ti-6Al-4V alloy) is one of the widely used 3D Printed alloy in structural aerospace components. In the present work, the effect of laser sintering on the microstructure and the mechanical and corrosion behavior of DMLSed Ti-6Al-4V alloy has been studied. The samples were printed by varying the laser power and scan speed over a wide range, one parameter at a time. The fabricated Ti-6Al-4V alloy predominantly showed the martensitic structure, which governs the overall performance of the printed alloy. The mechanism of martensitic laths formation in the microstructures is presented to understand their evolution and effect on the mechanical behavior. As a result, the tensile strength and hardness of the fabricated Ti-6Al-4V alloy increased by nearly 33 and 5%, respectively, when the laser power was increased from 150 to 300 W at a fixed scan speed of 1250 mm/s. An 8% increase in tensile strength and 1-2% increase in hardness was observed when the scan speed was increased from 500 to 1250 mm/s, at a fixed laser power of 150 W. The corrosion resistance of fabricated Ti-6Al-4V alloy improved with an increase in laser power but deteriorated with an increase in scan speed. This study led to new insights into the microstructural evolution of direct laser-sintered Ti-6Al-4V alloy, which is likely to assist in producing superior quality DMLS parts.