Microstructure and mechanical properties of pure titanium models fabricated by selective laser melting

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.