Effect of heat treatments on microstructure/small-scale properties of additive manufactured Ti-6Al-4V

In the present study, the effect of various heat treatments on the microstructure and micromechanical properties of a Ti-6Al-4V alloy processed by a laser powder bed fusion (L-PBF) technique is investigated. Heat treatment cycles employed in this study include solutionizing at 950 °C (for 1 h) followed by three different cooling rates (water quenching, air cooling, and furnace cooling) as well as solutionizing followed by water quenching and artificial aging. To assess the small-scale properties, a nanoindentation testing technique is employed. Microstructural quantitative analyses (i.e., optical microscopy and scanning electron microscopy) were performed extensively on the as-fabricated and heat-treated samples. Artificially aged specimens showed the highest microhardness of all the heat-treated samples, followed by air-cooled and furnace-cooled samples.