EFFECT OF HEAT TREATMENT ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES AND CORROSION BEHAVIOR OF Ti-6Al-4V VIA DIRECT METAL LASER SINTERING

In this paper, the results of an experimental investigation of the effect of three types of post heat treatments: 1) solution treatment and aging, 2) stress relieving and 3) annealing on the corrosion behavior of Ti-6Al-4V fabricated via direct metal laser sintering (DMLS) are presented. The microstructure and phase evolution as affected by heat treatment temperature were examined through scanning electron microscopy and X-ray diffraction. The Vickers microhardness as affected by various heat treatments are compared. The corrosion behavior of the specimens were measured electrochemically in simulated body fluid at 37^oC. It was found out that non-equilibrium α’ phase with small amount of β nuclei was formed in the as-fabricated sample. Heat treatments allow the formation of β phase and the agglomeration of β precipitates to occur at elevated temperature. Improvement in the corrosion resistance was observed in the solution treated and aged samples, 650^oC stress relieved and annealed samples.