Models made of pure titanium by selective laser melting microstructure and mechanical characteristics

Abstract

Three-dimensional titanium models are created using the selective laser melting technique 
and a neodymium-doped yttrium aluminum garnet (Nd:YAG) pulsed laser, and then their pore structure, 
hardness, and mechanical characteristics are studied. Pore structure is shown to be sensitive to peak 
power, scan speed, and hatching pitch in both optical and scanning electron micrographs. Compared to 
wrought material (125-160 HV), the Vickers hardness of laser-formed specimens is roughly 240 HV 
(0.2 kgf). X-ray photoelectron spectroscopy (XPS) depth profiling reveals oxygen pick-up during laser 
shaping of the titanium prototype in an argon-filled, closed chamber. Titanium models were produced by 
varying the hatching pitch and laser power, and their fatigue strength was evaluated. Reduced hatching pitch 
or hot isostatic pressing (HIP) may increase the fatigue strength of the as-formed models. After HIP, 
the fatigue strength of the specimens is on par with that of the wrought material.